/*
 * Copyright (C) 2005 Junio C Hamano
 */
#include "cache.h"
#include "config.h"
#include "tempfile.h"
#include "quote.h"
#include "diff.h"
#include "diffcore.h"
#include "delta.h"
#include "xdiff-interface.h"
#include "color.h"
#include "attr.h"
#include "run-command.h"
#include "utf8.h"
#include "object-store.h"
#include "userdiff.h"
#include "submodule-config.h"
#include "submodule.h"
#include "hashmap.h"
#include "ll-merge.h"
#include "string-list.h"
#include "argv-array.h"
#include "graph.h"
#include "packfile.h"
#include "help.h"

#ifdef NO_FAST_WORKING_DIRECTORY
#define FAST_WORKING_DIRECTORY 0
#else
#define FAST_WORKING_DIRECTORY 1
#endif

static int diff_detect_rename_default;
static int diff_indent_heuristic = 1;
static int diff_rename_limit_default = 400;
static int diff_suppress_blank_empty;
static int diff_use_color_default = -1;
static int diff_color_moved_default;
static int diff_color_moved_ws_default;
static int diff_context_default = 3;
static int diff_interhunk_context_default;
static const char *diff_word_regex_cfg;
static const char *external_diff_cmd_cfg;
static const char *diff_order_file_cfg;
int diff_auto_refresh_index = 1;
static int diff_mnemonic_prefix;
static int diff_no_prefix;
static int diff_stat_graph_width;
static int diff_dirstat_permille_default = 30;
static struct diff_options default_diff_options;
static long diff_algorithm;
static unsigned ws_error_highlight_default = WSEH_NEW;

static char diff_colors[][COLOR_MAXLEN] = {
	GIT_COLOR_RESET,
	GIT_COLOR_NORMAL,	/* CONTEXT */
	GIT_COLOR_BOLD,		/* METAINFO */
	GIT_COLOR_CYAN,		/* FRAGINFO */
	GIT_COLOR_RED,		/* OLD */
	GIT_COLOR_GREEN,	/* NEW */
	GIT_COLOR_YELLOW,	/* COMMIT */
	GIT_COLOR_BG_RED,	/* WHITESPACE */
	GIT_COLOR_NORMAL,	/* FUNCINFO */
	GIT_COLOR_BOLD_MAGENTA,	/* OLD_MOVED */
	GIT_COLOR_BOLD_BLUE,	/* OLD_MOVED ALTERNATIVE */
	GIT_COLOR_FAINT,	/* OLD_MOVED_DIM */
	GIT_COLOR_FAINT_ITALIC,	/* OLD_MOVED_ALTERNATIVE_DIM */
	GIT_COLOR_BOLD_CYAN,	/* NEW_MOVED */
	GIT_COLOR_BOLD_YELLOW,	/* NEW_MOVED ALTERNATIVE */
	GIT_COLOR_FAINT,	/* NEW_MOVED_DIM */
	GIT_COLOR_FAINT_ITALIC,	/* NEW_MOVED_ALTERNATIVE_DIM */
	GIT_COLOR_FAINT,	/* CONTEXT_DIM */
	GIT_COLOR_FAINT_RED,	/* OLD_DIM */
	GIT_COLOR_FAINT_GREEN,	/* NEW_DIM */
	GIT_COLOR_BOLD,		/* CONTEXT_BOLD */
	GIT_COLOR_BOLD_RED,	/* OLD_BOLD */
	GIT_COLOR_BOLD_GREEN,	/* NEW_BOLD */
};

static const char *color_diff_slots[] = {
	[DIFF_CONTEXT]		      = "context",
	[DIFF_METAINFO]		      = "meta",
	[DIFF_FRAGINFO]		      = "frag",
	[DIFF_FILE_OLD]		      = "old",
	[DIFF_FILE_NEW]		      = "new",
	[DIFF_COMMIT]		      = "commit",
	[DIFF_WHITESPACE]	      = "whitespace",
	[DIFF_FUNCINFO]		      = "func",
	[DIFF_FILE_OLD_MOVED]	      = "oldMoved",
	[DIFF_FILE_OLD_MOVED_ALT]     = "oldMovedAlternative",
	[DIFF_FILE_OLD_MOVED_DIM]     = "oldMovedDimmed",
	[DIFF_FILE_OLD_MOVED_ALT_DIM] = "oldMovedAlternativeDimmed",
	[DIFF_FILE_NEW_MOVED]	      = "newMoved",
	[DIFF_FILE_NEW_MOVED_ALT]     = "newMovedAlternative",
	[DIFF_FILE_NEW_MOVED_DIM]     = "newMovedDimmed",
	[DIFF_FILE_NEW_MOVED_ALT_DIM] = "newMovedAlternativeDimmed",
	[DIFF_CONTEXT_DIM]	      = "contextDimmed",
	[DIFF_FILE_OLD_DIM]	      = "oldDimmed",
	[DIFF_FILE_NEW_DIM]	      = "newDimmed",
	[DIFF_CONTEXT_BOLD]	      = "contextBold",
	[DIFF_FILE_OLD_BOLD]	      = "oldBold",
	[DIFF_FILE_NEW_BOLD]	      = "newBold",
};

static NORETURN void die_want_option(const char *option_name)
{
	die(_("option '%s' requires a value"), option_name);
}

define_list_config_array_extra(color_diff_slots, {"plain"});

static int parse_diff_color_slot(const char *var)
{
	if (!strcasecmp(var, "plain"))
		return DIFF_CONTEXT;
	return LOOKUP_CONFIG(color_diff_slots, var);
}

static int parse_dirstat_params(struct diff_options *options, const char *params_string,
				struct strbuf *errmsg)
{
	char *params_copy = xstrdup(params_string);
	struct string_list params = STRING_LIST_INIT_NODUP;
	int ret = 0;
	int i;

	if (*params_copy)
		string_list_split_in_place(&params, params_copy, ',', -1);
	for (i = 0; i < params.nr; i++) {
		const char *p = params.items[i].string;
		if (!strcmp(p, "changes")) {
			options->flags.dirstat_by_line = 0;
			options->flags.dirstat_by_file = 0;
		} else if (!strcmp(p, "lines")) {
			options->flags.dirstat_by_line = 1;
			options->flags.dirstat_by_file = 0;
		} else if (!strcmp(p, "files")) {
			options->flags.dirstat_by_line = 0;
			options->flags.dirstat_by_file = 1;
		} else if (!strcmp(p, "noncumulative")) {
			options->flags.dirstat_cumulative = 0;
		} else if (!strcmp(p, "cumulative")) {
			options->flags.dirstat_cumulative = 1;
		} else if (isdigit(*p)) {
			char *end;
			int permille = strtoul(p, &end, 10) * 10;
			if (*end == '.' && isdigit(*++end)) {
				/* only use first digit */
				permille += *end - '0';
				/* .. and ignore any further digits */
				while (isdigit(*++end))
					; /* nothing */
			}
			if (!*end)
				options->dirstat_permille = permille;
			else {
				strbuf_addf(errmsg, _("  Failed to parse dirstat cut-off percentage '%s'\n"),
					    p);
				ret++;
			}
		} else {
			strbuf_addf(errmsg, _("  Unknown dirstat parameter '%s'\n"), p);
			ret++;
		}

	}
	string_list_clear(&params, 0);
	free(params_copy);
	return ret;
}

static int parse_submodule_params(struct diff_options *options, const char *value)
{
	if (!strcmp(value, "log"))
		options->submodule_format = DIFF_SUBMODULE_LOG;
	else if (!strcmp(value, "short"))
		options->submodule_format = DIFF_SUBMODULE_SHORT;
	else if (!strcmp(value, "diff"))
		options->submodule_format = DIFF_SUBMODULE_INLINE_DIFF;
	else
		return -1;
	return 0;
}

int git_config_rename(const char *var, const char *value)
{
	if (!value)
		return DIFF_DETECT_RENAME;
	if (!strcasecmp(value, "copies") || !strcasecmp(value, "copy"))
		return  DIFF_DETECT_COPY;
	return git_config_bool(var,value) ? DIFF_DETECT_RENAME : 0;
}

long parse_algorithm_value(const char *value)
{
	if (!value)
		return -1;
	else if (!strcasecmp(value, "myers") || !strcasecmp(value, "default"))
		return 0;
	else if (!strcasecmp(value, "minimal"))
		return XDF_NEED_MINIMAL;
	else if (!strcasecmp(value, "patience"))
		return XDF_PATIENCE_DIFF;
	else if (!strcasecmp(value, "histogram"))
		return XDF_HISTOGRAM_DIFF;
	return -1;
}

static int parse_one_token(const char **arg, const char *token)
{
	const char *rest;
	if (skip_prefix(*arg, token, &rest) && (!*rest || *rest == ',')) {
		*arg = rest;
		return 1;
	}
	return 0;
}

static int parse_ws_error_highlight(const char *arg)
{
	const char *orig_arg = arg;
	unsigned val = 0;

	while (*arg) {
		if (parse_one_token(&arg, "none"))
			val = 0;
		else if (parse_one_token(&arg, "default"))
			val = WSEH_NEW;
		else if (parse_one_token(&arg, "all"))
			val = WSEH_NEW | WSEH_OLD | WSEH_CONTEXT;
		else if (parse_one_token(&arg, "new"))
			val |= WSEH_NEW;
		else if (parse_one_token(&arg, "old"))
			val |= WSEH_OLD;
		else if (parse_one_token(&arg, "context"))
			val |= WSEH_CONTEXT;
		else {
			return -1 - (int)(arg - orig_arg);
		}
		if (*arg)
			arg++;
	}
	return val;
}

/*
 * These are to give UI layer defaults.
 * The core-level commands such as git-diff-files should
 * never be affected by the setting of diff.renames
 * the user happens to have in the configuration file.
 */
void init_diff_ui_defaults(void)
{
	diff_detect_rename_default = DIFF_DETECT_RENAME;
}

int git_diff_heuristic_config(const char *var, const char *value, void *cb)
{
	if (!strcmp(var, "diff.indentheuristic"))
		diff_indent_heuristic = git_config_bool(var, value);
	return 0;
}

static int parse_color_moved(const char *arg)
{
	switch (git_parse_maybe_bool(arg)) {
	case 0:
		return COLOR_MOVED_NO;
	case 1:
		return COLOR_MOVED_DEFAULT;
	default:
		break;
	}

	if (!strcmp(arg, "no"))
		return COLOR_MOVED_NO;
	else if (!strcmp(arg, "plain"))
		return COLOR_MOVED_PLAIN;
	else if (!strcmp(arg, "blocks"))
		return COLOR_MOVED_BLOCKS;
	else if (!strcmp(arg, "zebra"))
		return COLOR_MOVED_ZEBRA;
	else if (!strcmp(arg, "default"))
		return COLOR_MOVED_DEFAULT;
	else if (!strcmp(arg, "dimmed-zebra"))
		return COLOR_MOVED_ZEBRA_DIM;
	else if (!strcmp(arg, "dimmed_zebra"))
		return COLOR_MOVED_ZEBRA_DIM;
	else
		return error(_("color moved setting must be one of 'no', 'default', 'blocks', 'zebra', 'dimmed-zebra', 'plain'"));
}

static int parse_color_moved_ws(const char *arg)
{
	int ret = 0;
	struct string_list l = STRING_LIST_INIT_DUP;
	struct string_list_item *i;

	string_list_split(&l, arg, ',', -1);

	for_each_string_list_item(i, &l) {
		struct strbuf sb = STRBUF_INIT;
		strbuf_addstr(&sb, i->string);
		strbuf_trim(&sb);

		if (!strcmp(sb.buf, "ignore-space-change"))
			ret |= XDF_IGNORE_WHITESPACE_CHANGE;
		else if (!strcmp(sb.buf, "ignore-space-at-eol"))
			ret |= XDF_IGNORE_WHITESPACE_AT_EOL;
		else if (!strcmp(sb.buf, "ignore-all-space"))
			ret |= XDF_IGNORE_WHITESPACE;
		else if (!strcmp(sb.buf, "allow-indentation-change"))
			ret |= COLOR_MOVED_WS_ALLOW_INDENTATION_CHANGE;
		else
			error(_("ignoring unknown color-moved-ws mode '%s'"), sb.buf);

		strbuf_release(&sb);
	}

	if ((ret & COLOR_MOVED_WS_ALLOW_INDENTATION_CHANGE) &&
	    (ret & XDF_WHITESPACE_FLAGS))
		die(_("color-moved-ws: allow-indentation-change cannot be combined with other white space modes"));

	string_list_clear(&l, 0);

	return ret;
}

int git_diff_ui_config(const char *var, const char *value, void *cb)
{
	if (!strcmp(var, "diff.color") || !strcmp(var, "color.diff")) {
		diff_use_color_default = git_config_colorbool(var, value);
		return 0;
	}
	if (!strcmp(var, "diff.colormoved")) {
		int cm = parse_color_moved(value);
		if (cm < 0)
			return -1;
		diff_color_moved_default = cm;
		return 0;
	}
	if (!strcmp(var, "diff.colormovedws")) {
		int cm = parse_color_moved_ws(value);
		if (cm < 0)
			return -1;
		diff_color_moved_ws_default = cm;
		return 0;
	}
	if (!strcmp(var, "diff.context")) {
		diff_context_default = git_config_int(var, value);
		if (diff_context_default < 0)
			return -1;
		return 0;
	}
	if (!strcmp(var, "diff.interhunkcontext")) {
		diff_interhunk_context_default = git_config_int(var, value);
		if (diff_interhunk_context_default < 0)
			return -1;
		return 0;
	}
	if (!strcmp(var, "diff.renames")) {
		diff_detect_rename_default = git_config_rename(var, value);
		return 0;
	}
	if (!strcmp(var, "diff.autorefreshindex")) {
		diff_auto_refresh_index = git_config_bool(var, value);
		return 0;
	}
	if (!strcmp(var, "diff.mnemonicprefix")) {
		diff_mnemonic_prefix = git_config_bool(var, value);
		return 0;
	}
	if (!strcmp(var, "diff.noprefix")) {
		diff_no_prefix = git_config_bool(var, value);
		return 0;
	}
	if (!strcmp(var, "diff.statgraphwidth")) {
		diff_stat_graph_width = git_config_int(var, value);
		return 0;
	}
	if (!strcmp(var, "diff.external"))
		return git_config_string(&external_diff_cmd_cfg, var, value);
	if (!strcmp(var, "diff.wordregex"))
		return git_config_string(&diff_word_regex_cfg, var, value);
	if (!strcmp(var, "diff.orderfile"))
		return git_config_pathname(&diff_order_file_cfg, var, value);

	if (!strcmp(var, "diff.ignoresubmodules"))
		handle_ignore_submodules_arg(&default_diff_options, value);

	if (!strcmp(var, "diff.submodule")) {
		if (parse_submodule_params(&default_diff_options, value))
			warning(_("Unknown value for 'diff.submodule' config variable: '%s'"),
				value);
		return 0;
	}

	if (!strcmp(var, "diff.algorithm")) {
		diff_algorithm = parse_algorithm_value(value);
		if (diff_algorithm < 0)
			return -1;
		return 0;
	}

	if (!strcmp(var, "diff.wserrorhighlight")) {
		int val = parse_ws_error_highlight(value);
		if (val < 0)
			return -1;
		ws_error_highlight_default = val;
		return 0;
	}

	if (git_color_config(var, value, cb) < 0)
		return -1;

	return git_diff_basic_config(var, value, cb);
}

int git_diff_basic_config(const char *var, const char *value, void *cb)
{
	const char *name;

	if (!strcmp(var, "diff.renamelimit")) {
		diff_rename_limit_default = git_config_int(var, value);
		return 0;
	}

	if (userdiff_config(var, value) < 0)
		return -1;

	if (skip_prefix(var, "diff.color.", &name) ||
	    skip_prefix(var, "color.diff.", &name)) {
		int slot = parse_diff_color_slot(name);
		if (slot < 0)
			return 0;
		if (!value)
			return config_error_nonbool(var);
		return color_parse(value, diff_colors[slot]);
	}

	/* like GNU diff's --suppress-blank-empty option  */
	if (!strcmp(var, "diff.suppressblankempty") ||
			/* for backwards compatibility */
			!strcmp(var, "diff.suppress-blank-empty")) {
		diff_suppress_blank_empty = git_config_bool(var, value);
		return 0;
	}

	if (!strcmp(var, "diff.dirstat")) {
		struct strbuf errmsg = STRBUF_INIT;
		default_diff_options.dirstat_permille = diff_dirstat_permille_default;
		if (parse_dirstat_params(&default_diff_options, value, &errmsg))
			warning(_("Found errors in 'diff.dirstat' config variable:\n%s"),
				errmsg.buf);
		strbuf_release(&errmsg);
		diff_dirstat_permille_default = default_diff_options.dirstat_permille;
		return 0;
	}

	if (git_diff_heuristic_config(var, value, cb) < 0)
		return -1;

	return git_default_config(var, value, cb);
}

static char *quote_two(const char *one, const char *two)
{
	int need_one = quote_c_style(one, NULL, NULL, 1);
	int need_two = quote_c_style(two, NULL, NULL, 1);
	struct strbuf res = STRBUF_INIT;

	if (need_one + need_two) {
		strbuf_addch(&res, '"');
		quote_c_style(one, &res, NULL, 1);
		quote_c_style(two, &res, NULL, 1);
		strbuf_addch(&res, '"');
	} else {
		strbuf_addstr(&res, one);
		strbuf_addstr(&res, two);
	}
	return strbuf_detach(&res, NULL);
}

static const char *external_diff(void)
{
	static const char *external_diff_cmd = NULL;
	static int done_preparing = 0;

	if (done_preparing)
		return external_diff_cmd;
	external_diff_cmd = getenv("GIT_EXTERNAL_DIFF");
	if (!external_diff_cmd)
		external_diff_cmd = external_diff_cmd_cfg;
	done_preparing = 1;
	return external_diff_cmd;
}

/*
 * Keep track of files used for diffing. Sometimes such an entry
 * refers to a temporary file, sometimes to an existing file, and
 * sometimes to "/dev/null".
 */
static struct diff_tempfile {
	/*
	 * filename external diff should read from, or NULL if this
	 * entry is currently not in use:
	 */
	const char *name;

	char hex[GIT_MAX_HEXSZ + 1];
	char mode[10];

	/*
	 * If this diff_tempfile instance refers to a temporary file,
	 * this tempfile object is used to manage its lifetime.
	 */
	struct tempfile *tempfile;
} diff_temp[2];

struct emit_callback {
	int color_diff;
	unsigned ws_rule;
	int blank_at_eof_in_preimage;
	int blank_at_eof_in_postimage;
	int lno_in_preimage;
	int lno_in_postimage;
	const char **label_path;
	struct diff_words_data *diff_words;
	struct diff_options *opt;
	struct strbuf *header;
};

static int count_lines(const char *data, int size)
{
	int count, ch, completely_empty = 1, nl_just_seen = 0;
	count = 0;
	while (0 < size--) {
		ch = *data++;
		if (ch == '\n') {
			count++;
			nl_just_seen = 1;
			completely_empty = 0;
		}
		else {
			nl_just_seen = 0;
			completely_empty = 0;
		}
	}
	if (completely_empty)
		return 0;
	if (!nl_just_seen)
		count++; /* no trailing newline */
	return count;
}

static int fill_mmfile(struct repository *r, mmfile_t *mf,
		       struct diff_filespec *one)
{
	if (!DIFF_FILE_VALID(one)) {
		mf->ptr = (char *)""; /* does not matter */
		mf->size = 0;
		return 0;
	}
	else if (diff_populate_filespec(r, one, 0))
		return -1;

	mf->ptr = one->data;
	mf->size = one->size;
	return 0;
}

/* like fill_mmfile, but only for size, so we can avoid retrieving blob */
static unsigned long diff_filespec_size(struct repository *r,
					struct diff_filespec *one)
{
	if (!DIFF_FILE_VALID(one))
		return 0;
	diff_populate_filespec(r, one, CHECK_SIZE_ONLY);
	return one->size;
}

static int count_trailing_blank(mmfile_t *mf, unsigned ws_rule)
{
	char *ptr = mf->ptr;
	long size = mf->size;
	int cnt = 0;

	if (!size)
		return cnt;
	ptr += size - 1; /* pointing at the very end */
	if (*ptr != '\n')
		; /* incomplete line */
	else
		ptr--; /* skip the last LF */
	while (mf->ptr < ptr) {
		char *prev_eol;
		for (prev_eol = ptr; mf->ptr <= prev_eol; prev_eol--)
			if (*prev_eol == '\n')
				break;
		if (!ws_blank_line(prev_eol + 1, ptr - prev_eol, ws_rule))
			break;
		cnt++;
		ptr = prev_eol - 1;
	}
	return cnt;
}

static void check_blank_at_eof(mmfile_t *mf1, mmfile_t *mf2,
			       struct emit_callback *ecbdata)
{
	int l1, l2, at;
	unsigned ws_rule = ecbdata->ws_rule;
	l1 = count_trailing_blank(mf1, ws_rule);
	l2 = count_trailing_blank(mf2, ws_rule);
	if (l2 <= l1) {
		ecbdata->blank_at_eof_in_preimage = 0;
		ecbdata->blank_at_eof_in_postimage = 0;
		return;
	}
	at = count_lines(mf1->ptr, mf1->size);
	ecbdata->blank_at_eof_in_preimage = (at - l1) + 1;

	at = count_lines(mf2->ptr, mf2->size);
	ecbdata->blank_at_eof_in_postimage = (at - l2) + 1;
}

static void emit_line_0(struct diff_options *o,
			const char *set_sign, const char *set, unsigned reverse, const char *reset,
			int first, const char *line, int len)
{
	int has_trailing_newline, has_trailing_carriage_return;
	int needs_reset = 0; /* at the end of the line */
	FILE *file = o->file;

	fputs(diff_line_prefix(o), file);

	has_trailing_newline = (len > 0 && line[len-1] == '\n');
	if (has_trailing_newline)
		len--;

	has_trailing_carriage_return = (len > 0 && line[len-1] == '\r');
	if (has_trailing_carriage_return)
		len--;

	if (!len && !first)
		goto end_of_line;

	if (reverse && want_color(o->use_color)) {
		fputs(GIT_COLOR_REVERSE, file);
		needs_reset = 1;
	}

	if (set_sign) {
		fputs(set_sign, file);
		needs_reset = 1;
	}

	if (first)
		fputc(first, file);

	if (!len)
		goto end_of_line;

	if (set) {
		if (set_sign && set != set_sign)
			fputs(reset, file);
		fputs(set, file);
		needs_reset = 1;
	}
	fwrite(line, len, 1, file);
	needs_reset = 1; /* 'line' may contain color codes. */

end_of_line:
	if (needs_reset)
		fputs(reset, file);
	if (has_trailing_carriage_return)
		fputc('\r', file);
	if (has_trailing_newline)
		fputc('\n', file);
}

static void emit_line(struct diff_options *o, const char *set, const char *reset,
		      const char *line, int len)
{
	emit_line_0(o, set, NULL, 0, reset, 0, line, len);
}

enum diff_symbol {
	DIFF_SYMBOL_BINARY_DIFF_HEADER,
	DIFF_SYMBOL_BINARY_DIFF_HEADER_DELTA,
	DIFF_SYMBOL_BINARY_DIFF_HEADER_LITERAL,
	DIFF_SYMBOL_BINARY_DIFF_BODY,
	DIFF_SYMBOL_BINARY_DIFF_FOOTER,
	DIFF_SYMBOL_STATS_SUMMARY_NO_FILES,
	DIFF_SYMBOL_STATS_SUMMARY_ABBREV,
	DIFF_SYMBOL_STATS_SUMMARY_INSERTS_DELETES,
	DIFF_SYMBOL_STATS_LINE,
	DIFF_SYMBOL_WORD_DIFF,
	DIFF_SYMBOL_STAT_SEP,
	DIFF_SYMBOL_SUMMARY,
	DIFF_SYMBOL_SUBMODULE_ADD,
	DIFF_SYMBOL_SUBMODULE_DEL,
	DIFF_SYMBOL_SUBMODULE_UNTRACKED,
	DIFF_SYMBOL_SUBMODULE_MODIFIED,
	DIFF_SYMBOL_SUBMODULE_HEADER,
	DIFF_SYMBOL_SUBMODULE_ERROR,
	DIFF_SYMBOL_SUBMODULE_PIPETHROUGH,
	DIFF_SYMBOL_REWRITE_DIFF,
	DIFF_SYMBOL_BINARY_FILES,
	DIFF_SYMBOL_HEADER,
	DIFF_SYMBOL_FILEPAIR_PLUS,
	DIFF_SYMBOL_FILEPAIR_MINUS,
	DIFF_SYMBOL_WORDS_PORCELAIN,
	DIFF_SYMBOL_WORDS,
	DIFF_SYMBOL_CONTEXT,
	DIFF_SYMBOL_CONTEXT_INCOMPLETE,
	DIFF_SYMBOL_PLUS,
	DIFF_SYMBOL_MINUS,
	DIFF_SYMBOL_NO_LF_EOF,
	DIFF_SYMBOL_CONTEXT_FRAGINFO,
	DIFF_SYMBOL_CONTEXT_MARKER,
	DIFF_SYMBOL_SEPARATOR
};
/*
 * Flags for content lines:
 * 0..12 are whitespace rules
 * 13-15 are WSEH_NEW | WSEH_OLD | WSEH_CONTEXT
 * 16 is marking if the line is blank at EOF
 */
#define DIFF_SYMBOL_CONTENT_BLANK_LINE_EOF	(1<<16)
#define DIFF_SYMBOL_MOVED_LINE			(1<<17)
#define DIFF_SYMBOL_MOVED_LINE_ALT		(1<<18)
#define DIFF_SYMBOL_MOVED_LINE_UNINTERESTING	(1<<19)
#define DIFF_SYMBOL_CONTENT_WS_MASK (WSEH_NEW | WSEH_OLD | WSEH_CONTEXT | WS_RULE_MASK)

/*
 * This struct is used when we need to buffer the output of the diff output.
 *
 * NEEDSWORK: Instead of storing a copy of the line, add an offset pointer
 * into the pre/post image file. This pointer could be a union with the
 * line pointer. By storing an offset into the file instead of the literal line,
 * we can decrease the memory footprint for the buffered output. At first we
 * may want to only have indirection for the content lines, but we could also
 * enhance the state for emitting prefabricated lines, e.g. the similarity
 * score line or hunk/file headers would only need to store a number or path
 * and then the output can be constructed later on depending on state.
 */
struct emitted_diff_symbol {
	const char *line;
	int len;
	int flags;
	enum diff_symbol s;
};
#define EMITTED_DIFF_SYMBOL_INIT {NULL}

struct emitted_diff_symbols {
	struct emitted_diff_symbol *buf;
	int nr, alloc;
};
#define EMITTED_DIFF_SYMBOLS_INIT {NULL, 0, 0}

static void append_emitted_diff_symbol(struct diff_options *o,
				       struct emitted_diff_symbol *e)
{
	struct emitted_diff_symbol *f;

	ALLOC_GROW(o->emitted_symbols->buf,
		   o->emitted_symbols->nr + 1,
		   o->emitted_symbols->alloc);
	f = &o->emitted_symbols->buf[o->emitted_symbols->nr++];

	memcpy(f, e, sizeof(struct emitted_diff_symbol));
	f->line = e->line ? xmemdupz(e->line, e->len) : NULL;
}

struct moved_entry {
	struct hashmap_entry ent;
	const struct emitted_diff_symbol *es;
	struct moved_entry *next_line;
};

/**
 * The struct ws_delta holds white space differences between moved lines, i.e.
 * between '+' and '-' lines that have been detected to be a move.
 * The string contains the difference in leading white spaces, before the
 * rest of the line is compared using the white space config for move
 * coloring. The current_longer indicates if the first string in the
 * comparision is longer than the second.
 */
struct ws_delta {
	char *string;
	unsigned int current_longer : 1;
};
#define WS_DELTA_INIT { NULL, 0 }

struct moved_block {
	struct moved_entry *match;
	struct ws_delta wsd;
};

static void moved_block_clear(struct moved_block *b)
{
	FREE_AND_NULL(b->wsd.string);
	b->match = NULL;
}

static int compute_ws_delta(const struct emitted_diff_symbol *a,
			     const struct emitted_diff_symbol *b,
			     struct ws_delta *out)
{
	const struct emitted_diff_symbol *longer =  a->len > b->len ? a : b;
	const struct emitted_diff_symbol *shorter = a->len > b->len ? b : a;
	int d = longer->len - shorter->len;

	if (strncmp(longer->line + d, shorter->line, shorter->len))
		return 0;

	out->string = xmemdupz(longer->line, d);
	out->current_longer = (a == longer);

	return 1;
}

static int cmp_in_block_with_wsd(const struct diff_options *o,
				 const struct moved_entry *cur,
				 const struct moved_entry *match,
				 struct moved_block *pmb,
				 int n)
{
	struct emitted_diff_symbol *l = &o->emitted_symbols->buf[n];
	int al = cur->es->len, cl = l->len;
	const char *a = cur->es->line,
		   *b = match->es->line,
		   *c = l->line;

	int wslen;

	/*
	 * We need to check if 'cur' is equal to 'match'.
	 * As those are from the same (+/-) side, we do not need to adjust for
	 * indent changes. However these were found using fuzzy matching
	 * so we do have to check if they are equal.
	 */
	if (strcmp(a, b))
		return 1;

	if (!pmb->wsd.string)
		/*
		 * The white space delta is not active? This can happen
		 * when we exit early in this function.
		 */
		return 1;

	/*
	 * The indent changes of the block are known and stored in
	 * pmb->wsd; however we need to check if the indent changes of the
	 * current line are still the same as before.
	 *
	 * To do so we need to compare 'l' to 'cur', adjusting the
	 * one of them for the white spaces, depending which was longer.
	 */

	wslen = strlen(pmb->wsd.string);
	if (pmb->wsd.current_longer) {
		c += wslen;
		cl -= wslen;
	} else {
		a += wslen;
		al -= wslen;
	}

	if (al != cl || memcmp(a, c, al))
		return 1;

	return 0;
}

static int moved_entry_cmp(const void *hashmap_cmp_fn_data,
			   const void *entry,
			   const void *entry_or_key,
			   const void *keydata)
{
	const struct diff_options *diffopt = hashmap_cmp_fn_data;
	const struct moved_entry *a = entry;
	const struct moved_entry *b = entry_or_key;
	unsigned flags = diffopt->color_moved_ws_handling
			 & XDF_WHITESPACE_FLAGS;

	if (diffopt->color_moved_ws_handling &
	    COLOR_MOVED_WS_ALLOW_INDENTATION_CHANGE)
		/*
		 * As there is not specific white space config given,
		 * we'd need to check for a new block, so ignore all
		 * white space. The setup of the white space
		 * configuration for the next block is done else where
		 */
		flags |= XDF_IGNORE_WHITESPACE;

	return !xdiff_compare_lines(a->es->line, a->es->len,
				    b->es->line, b->es->len,
				    flags);
}

static struct moved_entry *prepare_entry(struct diff_options *o,
					 int line_no)
{
	struct moved_entry *ret = xmalloc(sizeof(*ret));
	struct emitted_diff_symbol *l = &o->emitted_symbols->buf[line_no];
	unsigned flags = o->color_moved_ws_handling & XDF_WHITESPACE_FLAGS;

	ret->ent.hash = xdiff_hash_string(l->line, l->len, flags);
	ret->es = l;
	ret->next_line = NULL;

	return ret;
}

static void add_lines_to_move_detection(struct diff_options *o,
					struct hashmap *add_lines,
					struct hashmap *del_lines)
{
	struct moved_entry *prev_line = NULL;

	int n;
	for (n = 0; n < o->emitted_symbols->nr; n++) {
		struct hashmap *hm;
		struct moved_entry *key;

		switch (o->emitted_symbols->buf[n].s) {
		case DIFF_SYMBOL_PLUS:
			hm = add_lines;
			break;
		case DIFF_SYMBOL_MINUS:
			hm = del_lines;
			break;
		default:
			prev_line = NULL;
			continue;
		}

		key = prepare_entry(o, n);
		if (prev_line && prev_line->es->s == o->emitted_symbols->buf[n].s)
			prev_line->next_line = key;

		hashmap_add(hm, key);
		prev_line = key;
	}
}

static void pmb_advance_or_null(struct diff_options *o,
				struct moved_entry *match,
				struct hashmap *hm,
				struct moved_block *pmb,
				int pmb_nr)
{
	int i;
	for (i = 0; i < pmb_nr; i++) {
		struct moved_entry *prev = pmb[i].match;
		struct moved_entry *cur = (prev && prev->next_line) ?
				prev->next_line : NULL;
		if (cur && !hm->cmpfn(o, cur, match, NULL)) {
			pmb[i].match = cur;
		} else {
			pmb[i].match = NULL;
		}
	}
}

static void pmb_advance_or_null_multi_match(struct diff_options *o,
					    struct moved_entry *match,
					    struct hashmap *hm,
					    struct moved_block *pmb,
					    int pmb_nr, int n)
{
	int i;
	char *got_match = xcalloc(1, pmb_nr);

	for (; match; match = hashmap_get_next(hm, match)) {
		for (i = 0; i < pmb_nr; i++) {
			struct moved_entry *prev = pmb[i].match;
			struct moved_entry *cur = (prev && prev->next_line) ?
					prev->next_line : NULL;
			if (!cur)
				continue;
			if (!cmp_in_block_with_wsd(o, cur, match, &pmb[i], n))
				got_match[i] |= 1;
		}
	}

	for (i = 0; i < pmb_nr; i++) {
		if (got_match[i]) {
			/* Advance to the next line */
			pmb[i].match = pmb[i].match->next_line;
		} else {
			moved_block_clear(&pmb[i]);
		}
	}

	free(got_match);
}

static int shrink_potential_moved_blocks(struct moved_block *pmb,
					 int pmb_nr)
{
	int lp, rp;

	/* Shrink the set of potential block to the remaining running */
	for (lp = 0, rp = pmb_nr - 1; lp <= rp;) {
		while (lp < pmb_nr && pmb[lp].match)
			lp++;
		/* lp points at the first NULL now */

		while (rp > -1 && !pmb[rp].match)
			rp--;
		/* rp points at the last non-NULL */

		if (lp < pmb_nr && rp > -1 && lp < rp) {
			pmb[lp] = pmb[rp];
			pmb[rp].match = NULL;
			pmb[rp].wsd.string = NULL;
			rp--;
			lp++;
		}
	}

	/* Remember the number of running sets */
	return rp + 1;
}

/*
 * If o->color_moved is COLOR_MOVED_PLAIN, this function does nothing.
 *
 * Otherwise, if the last block has fewer alphanumeric characters than
 * COLOR_MOVED_MIN_ALNUM_COUNT, unset DIFF_SYMBOL_MOVED_LINE on all lines in
 * that block.
 *
 * The last block consists of the (n - block_length)'th line up to but not
 * including the nth line.
 *
 * NEEDSWORK: This uses the same heuristic as blame_entry_score() in blame.c.
 * Think of a way to unify them.
 */
static void adjust_last_block(struct diff_options *o, int n, int block_length)
{
	int i, alnum_count = 0;
	if (o->color_moved == COLOR_MOVED_PLAIN)
		return;
	for (i = 1; i < block_length + 1; i++) {
		const char *c = o->emitted_symbols->buf[n - i].line;
		for (; *c; c++) {
			if (!isalnum(*c))
				continue;
			alnum_count++;
			if (alnum_count >= COLOR_MOVED_MIN_ALNUM_COUNT)
				return;
		}
	}
	for (i = 1; i < block_length + 1; i++)
		o->emitted_symbols->buf[n - i].flags &= ~DIFF_SYMBOL_MOVED_LINE;
}

/* Find blocks of moved code, delegate actual coloring decision to helper */
static void mark_color_as_moved(struct diff_options *o,
				struct hashmap *add_lines,
				struct hashmap *del_lines)
{
	struct moved_block *pmb = NULL; /* potentially moved blocks */
	int pmb_nr = 0, pmb_alloc = 0;
	int n, flipped_block = 1, block_length = 0;


	for (n = 0; n < o->emitted_symbols->nr; n++) {
		struct hashmap *hm = NULL;
		struct moved_entry *key;
		struct moved_entry *match = NULL;
		struct emitted_diff_symbol *l = &o->emitted_symbols->buf[n];

		switch (l->s) {
		case DIFF_SYMBOL_PLUS:
			hm = del_lines;
			key = prepare_entry(o, n);
			match = hashmap_get(hm, key, NULL);
			free(key);
			break;
		case DIFF_SYMBOL_MINUS:
			hm = add_lines;
			key = prepare_entry(o, n);
			match = hashmap_get(hm, key, NULL);
			free(key);
			break;
		default:
			flipped_block = 1;
		}

		if (!match) {
			int i;

			adjust_last_block(o, n, block_length);
			for(i = 0; i < pmb_nr; i++)
				moved_block_clear(&pmb[i]);
			pmb_nr = 0;
			block_length = 0;
			continue;
		}

		l->flags |= DIFF_SYMBOL_MOVED_LINE;

		if (o->color_moved == COLOR_MOVED_PLAIN)
			continue;

		if (o->color_moved_ws_handling &
		    COLOR_MOVED_WS_ALLOW_INDENTATION_CHANGE)
			pmb_advance_or_null_multi_match(o, match, hm, pmb, pmb_nr, n);
		else
			pmb_advance_or_null(o, match, hm, pmb, pmb_nr);

		pmb_nr = shrink_potential_moved_blocks(pmb, pmb_nr);

		if (pmb_nr == 0) {
			/*
			 * The current line is the start of a new block.
			 * Setup the set of potential blocks.
			 */
			for (; match; match = hashmap_get_next(hm, match)) {
				ALLOC_GROW(pmb, pmb_nr + 1, pmb_alloc);
				if (o->color_moved_ws_handling &
				    COLOR_MOVED_WS_ALLOW_INDENTATION_CHANGE) {
					if (compute_ws_delta(l, match->es,
							     &pmb[pmb_nr].wsd))
						pmb[pmb_nr++].match = match;
				} else {
					pmb[pmb_nr].wsd.string = NULL;
					pmb[pmb_nr++].match = match;
				}
			}

			flipped_block = (flipped_block + 1) % 2;

			adjust_last_block(o, n, block_length);
			block_length = 0;
		}

		block_length++;

		if (flipped_block && o->color_moved != COLOR_MOVED_BLOCKS)
			l->flags |= DIFF_SYMBOL_MOVED_LINE_ALT;
	}
	adjust_last_block(o, n, block_length);

	for(n = 0; n < pmb_nr; n++)
		moved_block_clear(&pmb[n]);
	free(pmb);
}

#define DIFF_SYMBOL_MOVED_LINE_ZEBRA_MASK \
  (DIFF_SYMBOL_MOVED_LINE | DIFF_SYMBOL_MOVED_LINE_ALT)
static void dim_moved_lines(struct diff_options *o)
{
	int n;
	for (n = 0; n < o->emitted_symbols->nr; n++) {
		struct emitted_diff_symbol *prev = (n != 0) ?
				&o->emitted_symbols->buf[n - 1] : NULL;
		struct emitted_diff_symbol *l = &o->emitted_symbols->buf[n];
		struct emitted_diff_symbol *next =
				(n < o->emitted_symbols->nr - 1) ?
				&o->emitted_symbols->buf[n + 1] : NULL;

		/* Not a plus or minus line? */
		if (l->s != DIFF_SYMBOL_PLUS && l->s != DIFF_SYMBOL_MINUS)
			continue;

		/* Not a moved line? */
		if (!(l->flags & DIFF_SYMBOL_MOVED_LINE))
			continue;

		/*
		 * If prev or next are not a plus or minus line,
		 * pretend they don't exist
		 */
		if (prev && prev->s != DIFF_SYMBOL_PLUS &&
			    prev->s != DIFF_SYMBOL_MINUS)
			prev = NULL;
		if (next && next->s != DIFF_SYMBOL_PLUS &&
			    next->s != DIFF_SYMBOL_MINUS)
			next = NULL;

		/* Inside a block? */
		if ((prev &&
		    (prev->flags & DIFF_SYMBOL_MOVED_LINE_ZEBRA_MASK) ==
		    (l->flags & DIFF_SYMBOL_MOVED_LINE_ZEBRA_MASK)) &&
		    (next &&
		    (next->flags & DIFF_SYMBOL_MOVED_LINE_ZEBRA_MASK) ==
		    (l->flags & DIFF_SYMBOL_MOVED_LINE_ZEBRA_MASK))) {
			l->flags |= DIFF_SYMBOL_MOVED_LINE_UNINTERESTING;
			continue;
		}

		/* Check if we are at an interesting bound: */
		if (prev && (prev->flags & DIFF_SYMBOL_MOVED_LINE) &&
		    (prev->flags & DIFF_SYMBOL_MOVED_LINE_ALT) !=
		       (l->flags & DIFF_SYMBOL_MOVED_LINE_ALT))
			continue;
		if (next && (next->flags & DIFF_SYMBOL_MOVED_LINE) &&
		    (next->flags & DIFF_SYMBOL_MOVED_LINE_ALT) !=
		       (l->flags & DIFF_SYMBOL_MOVED_LINE_ALT))
			continue;

		/*
		 * The boundary to prev and next are not interesting,
		 * so this line is not interesting as a whole
		 */
		l->flags |= DIFF_SYMBOL_MOVED_LINE_UNINTERESTING;
	}
}

static void emit_line_ws_markup(struct diff_options *o,
				const char *set_sign, const char *set,
				const char *reset,
				int sign_index, const char *line, int len,
				unsigned ws_rule, int blank_at_eof)
{
	const char *ws = NULL;
	int sign = o->output_indicators[sign_index];

	if (o->ws_error_highlight & ws_rule) {
		ws = diff_get_color_opt(o, DIFF_WHITESPACE);
		if (!*ws)
			ws = NULL;
	}

	if (!ws && !set_sign)
		emit_line_0(o, set, NULL, 0, reset, sign, line, len);
	else if (!ws) {
		emit_line_0(o, set_sign, set, !!set_sign, reset, sign, line, len);
	} else if (blank_at_eof)
		/* Blank line at EOF - paint '+' as well */
		emit_line_0(o, ws, NULL, 0, reset, sign, line, len);
	else {
		/* Emit just the prefix, then the rest. */
		emit_line_0(o, set_sign ? set_sign : set, NULL, !!set_sign, reset,
			    sign, "", 0);
		ws_check_emit(line, len, ws_rule,
			      o->file, set, reset, ws);
	}
}

static void emit_diff_symbol_from_struct(struct diff_options *o,
					 struct emitted_diff_symbol *eds)
{
	static const char *nneof = " No newline at end of file\n";
	const char *context, *reset, *set, *set_sign, *meta, *fraginfo;
	struct strbuf sb = STRBUF_INIT;

	enum diff_symbol s = eds->s;
	const char *line = eds->line;
	int len = eds->len;
	unsigned flags = eds->flags;

	switch (s) {
	case DIFF_SYMBOL_NO_LF_EOF:
		context = diff_get_color_opt(o, DIFF_CONTEXT);
		reset = diff_get_color_opt(o, DIFF_RESET);
		putc('\n', o->file);
		emit_line_0(o, context, NULL, 0, reset, '\\',
			    nneof, strlen(nneof));
		break;
	case DIFF_SYMBOL_SUBMODULE_HEADER:
	case DIFF_SYMBOL_SUBMODULE_ERROR:
	case DIFF_SYMBOL_SUBMODULE_PIPETHROUGH:
	case DIFF_SYMBOL_STATS_SUMMARY_INSERTS_DELETES:
	case DIFF_SYMBOL_SUMMARY:
	case DIFF_SYMBOL_STATS_LINE:
	case DIFF_SYMBOL_BINARY_DIFF_BODY:
	case DIFF_SYMBOL_CONTEXT_FRAGINFO:
		emit_line(o, "", "", line, len);
		break;
	case DIFF_SYMBOL_CONTEXT_INCOMPLETE:
	case DIFF_SYMBOL_CONTEXT_MARKER:
		context = diff_get_color_opt(o, DIFF_CONTEXT);
		reset = diff_get_color_opt(o, DIFF_RESET);
		emit_line(o, context, reset, line, len);
		break;
	case DIFF_SYMBOL_SEPARATOR:
		fprintf(o->file, "%s%c",
			diff_line_prefix(o),
			o->line_termination);
		break;
	case DIFF_SYMBOL_CONTEXT:
		set = diff_get_color_opt(o, DIFF_CONTEXT);
		reset = diff_get_color_opt(o, DIFF_RESET);
		set_sign = NULL;
		if (o->flags.dual_color_diffed_diffs) {
			char c = !len ? 0 : line[0];

			if (c == '+')
				set = diff_get_color_opt(o, DIFF_FILE_NEW);
			else if (c == '@')
				set = diff_get_color_opt(o, DIFF_FRAGINFO);
			else if (c == '-')
				set = diff_get_color_opt(o, DIFF_FILE_OLD);
		}
		emit_line_ws_markup(o, set_sign, set, reset,
				    OUTPUT_INDICATOR_CONTEXT, line, len,
				    flags & (DIFF_SYMBOL_CONTENT_WS_MASK), 0);
		break;
	case DIFF_SYMBOL_PLUS:
		switch (flags & (DIFF_SYMBOL_MOVED_LINE |
				 DIFF_SYMBOL_MOVED_LINE_ALT |
				 DIFF_SYMBOL_MOVED_LINE_UNINTERESTING)) {
		case DIFF_SYMBOL_MOVED_LINE |
		     DIFF_SYMBOL_MOVED_LINE_ALT |
		     DIFF_SYMBOL_MOVED_LINE_UNINTERESTING:
			set = diff_get_color_opt(o, DIFF_FILE_NEW_MOVED_ALT_DIM);
			break;
		case DIFF_SYMBOL_MOVED_LINE |
		     DIFF_SYMBOL_MOVED_LINE_ALT:
			set = diff_get_color_opt(o, DIFF_FILE_NEW_MOVED_ALT);
			break;
		case DIFF_SYMBOL_MOVED_LINE |
		     DIFF_SYMBOL_MOVED_LINE_UNINTERESTING:
			set = diff_get_color_opt(o, DIFF_FILE_NEW_MOVED_DIM);
			break;
		case DIFF_SYMBOL_MOVED_LINE:
			set = diff_get_color_opt(o, DIFF_FILE_NEW_MOVED);
			break;
		default:
			set = diff_get_color_opt(o, DIFF_FILE_NEW);
		}
		reset = diff_get_color_opt(o, DIFF_RESET);
		if (!o->flags.dual_color_diffed_diffs)
			set_sign = NULL;
		else {
			char c = !len ? 0 : line[0];

			set_sign = set;
			if (c == '-')
				set = diff_get_color_opt(o, DIFF_FILE_OLD_BOLD);
			else if (c == '@')
				set = diff_get_color_opt(o, DIFF_FRAGINFO);
			else if (c == '+')
				set = diff_get_color_opt(o, DIFF_FILE_NEW_BOLD);
			else
				set = diff_get_color_opt(o, DIFF_CONTEXT_BOLD);
			flags &= ~DIFF_SYMBOL_CONTENT_WS_MASK;
		}
		emit_line_ws_markup(o, set_sign, set, reset,
				    OUTPUT_INDICATOR_NEW, line, len,
				    flags & DIFF_SYMBOL_CONTENT_WS_MASK,
				    flags & DIFF_SYMBOL_CONTENT_BLANK_LINE_EOF);
		break;
	case DIFF_SYMBOL_MINUS:
		switch (flags & (DIFF_SYMBOL_MOVED_LINE |
				 DIFF_SYMBOL_MOVED_LINE_ALT |
				 DIFF_SYMBOL_MOVED_LINE_UNINTERESTING)) {
		case DIFF_SYMBOL_MOVED_LINE |
		     DIFF_SYMBOL_MOVED_LINE_ALT |
		     DIFF_SYMBOL_MOVED_LINE_UNINTERESTING:
			set = diff_get_color_opt(o, DIFF_FILE_OLD_MOVED_ALT_DIM);
			break;
		case DIFF_SYMBOL_MOVED_LINE |
		     DIFF_SYMBOL_MOVED_LINE_ALT:
			set = diff_get_color_opt(o, DIFF_FILE_OLD_MOVED_ALT);
			break;
		case DIFF_SYMBOL_MOVED_LINE |
		     DIFF_SYMBOL_MOVED_LINE_UNINTERESTING:
			set = diff_get_color_opt(o, DIFF_FILE_OLD_MOVED_DIM);
			break;
		case DIFF_SYMBOL_MOVED_LINE:
			set = diff_get_color_opt(o, DIFF_FILE_OLD_MOVED);
			break;
		default:
			set = diff_get_color_opt(o, DIFF_FILE_OLD);
		}
		reset = diff_get_color_opt(o, DIFF_RESET);
		if (!o->flags.dual_color_diffed_diffs)
			set_sign = NULL;
		else {
			char c = !len ? 0 : line[0];

			set_sign = set;
			if (c == '+')
				set = diff_get_color_opt(o, DIFF_FILE_NEW_DIM);
			else if (c == '@')
				set = diff_get_color_opt(o, DIFF_FRAGINFO);
			else if (c == '-')
				set = diff_get_color_opt(o, DIFF_FILE_OLD_DIM);
			else
				set = diff_get_color_opt(o, DIFF_CONTEXT_DIM);
		}
		emit_line_ws_markup(o, set_sign, set, reset,
				    OUTPUT_INDICATOR_OLD, line, len,
				    flags & DIFF_SYMBOL_CONTENT_WS_MASK, 0);
		break;
	case DIFF_SYMBOL_WORDS_PORCELAIN:
		context = diff_get_color_opt(o, DIFF_CONTEXT);
		reset = diff_get_color_opt(o, DIFF_RESET);
		emit_line(o, context, reset, line, len);
		fputs("~\n", o->file);
		break;
	case DIFF_SYMBOL_WORDS:
		context = diff_get_color_opt(o, DIFF_CONTEXT);
		reset = diff_get_color_opt(o, DIFF_RESET);
		/*
		 * Skip the prefix character, if any.  With
		 * diff_suppress_blank_empty, there may be
		 * none.
		 */
		if (line[0] != '\n') {
			line++;
			len--;
		}
		emit_line(o, context, reset, line, len);
		break;
	case DIFF_SYMBOL_FILEPAIR_PLUS:
		meta = diff_get_color_opt(o, DIFF_METAINFO);
		reset = diff_get_color_opt(o, DIFF_RESET);
		fprintf(o->file, "%s%s+++ %s%s%s\n", diff_line_prefix(o), meta,
			line, reset,
			strchr(line, ' ') ? "\t" : "");
		break;
	case DIFF_SYMBOL_FILEPAIR_MINUS:
		meta = diff_get_color_opt(o, DIFF_METAINFO);
		reset = diff_get_color_opt(o, DIFF_RESET);
		fprintf(o->file, "%s%s--- %s%s%s\n", diff_line_prefix(o), meta,
			line, reset,
			strchr(line, ' ') ? "\t" : "");
		break;
	case DIFF_SYMBOL_BINARY_FILES:
	case DIFF_SYMBOL_HEADER:
		fprintf(o->file, "%s", line);
		break;
	case DIFF_SYMBOL_BINARY_DIFF_HEADER:
		fprintf(o->file, "%sGIT binary patch\n", diff_line_prefix(o));
		break;
	case DIFF_SYMBOL_BINARY_DIFF_HEADER_DELTA:
		fprintf(o->file, "%sdelta %s\n", diff_line_prefix(o), line);
		break;
	case DIFF_SYMBOL_BINARY_DIFF_HEADER_LITERAL:
		fprintf(o->file, "%sliteral %s\n", diff_line_prefix(o), line);
		break;
	case DIFF_SYMBOL_BINARY_DIFF_FOOTER:
		fputs(diff_line_prefix(o), o->file);
		fputc('\n', o->file);
		break;
	case DIFF_SYMBOL_REWRITE_DIFF:
		fraginfo = diff_get_color(o->use_color, DIFF_FRAGINFO);
		reset = diff_get_color_opt(o, DIFF_RESET);
		emit_line(o, fraginfo, reset, line, len);
		break;
	case DIFF_SYMBOL_SUBMODULE_ADD:
		set = diff_get_color_opt(o, DIFF_FILE_NEW);
		reset = diff_get_color_opt(o, DIFF_RESET);
		emit_line(o, set, reset, line, len);
		break;
	case DIFF_SYMBOL_SUBMODULE_DEL:
		set = diff_get_color_opt(o, DIFF_FILE_OLD);
		reset = diff_get_color_opt(o, DIFF_RESET);
		emit_line(o, set, reset, line, len);
		break;
	case DIFF_SYMBOL_SUBMODULE_UNTRACKED:
		fprintf(o->file, "%sSubmodule %s contains untracked content\n",
			diff_line_prefix(o), line);
		break;
	case DIFF_SYMBOL_SUBMODULE_MODIFIED:
		fprintf(o->file, "%sSubmodule %s contains modified content\n",
			diff_line_prefix(o), line);
		break;
	case DIFF_SYMBOL_STATS_SUMMARY_NO_FILES:
		emit_line(o, "", "", " 0 files changed\n",
			  strlen(" 0 files changed\n"));
		break;
	case DIFF_SYMBOL_STATS_SUMMARY_ABBREV:
		emit_line(o, "", "", " ...\n", strlen(" ...\n"));
		break;
	case DIFF_SYMBOL_WORD_DIFF:
		fprintf(o->file, "%.*s", len, line);
		break;
	case DIFF_SYMBOL_STAT_SEP:
		fputs(o->stat_sep, o->file);
		break;
	default:
		BUG("unknown diff symbol");
	}
	strbuf_release(&sb);
}

static void emit_diff_symbol(struct diff_options *o, enum diff_symbol s,
			     const char *line, int len, unsigned flags)
{
	struct emitted_diff_symbol e = {line, len, flags, s};

	if (o->emitted_symbols)
		append_emitted_diff_symbol(o, &e);
	else
		emit_diff_symbol_from_struct(o, &e);
}

void diff_emit_submodule_del(struct diff_options *o, const char *line)
{
	emit_diff_symbol(o, DIFF_SYMBOL_SUBMODULE_DEL, line, strlen(line), 0);
}

void diff_emit_submodule_add(struct diff_options *o, const char *line)
{
	emit_diff_symbol(o, DIFF_SYMBOL_SUBMODULE_ADD, line, strlen(line), 0);
}

void diff_emit_submodule_untracked(struct diff_options *o, const char *path)
{
	emit_diff_symbol(o, DIFF_SYMBOL_SUBMODULE_UNTRACKED,
			 path, strlen(path), 0);
}

void diff_emit_submodule_modified(struct diff_options *o, const char *path)
{
	emit_diff_symbol(o, DIFF_SYMBOL_SUBMODULE_MODIFIED,
			 path, strlen(path), 0);
}

void diff_emit_submodule_header(struct diff_options *o, const char *header)
{
	emit_diff_symbol(o, DIFF_SYMBOL_SUBMODULE_HEADER,
			 header, strlen(header), 0);
}

void diff_emit_submodule_error(struct diff_options *o, const char *err)
{
	emit_diff_symbol(o, DIFF_SYMBOL_SUBMODULE_ERROR, err, strlen(err), 0);
}

void diff_emit_submodule_pipethrough(struct diff_options *o,
				     const char *line, int len)
{
	emit_diff_symbol(o, DIFF_SYMBOL_SUBMODULE_PIPETHROUGH, line, len, 0);
}

static int new_blank_line_at_eof(struct emit_callback *ecbdata, const char *line, int len)
{
	if (!((ecbdata->ws_rule & WS_BLANK_AT_EOF) &&
	      ecbdata->blank_at_eof_in_preimage &&
	      ecbdata->blank_at_eof_in_postimage &&
	      ecbdata->blank_at_eof_in_preimage <= ecbdata->lno_in_preimage &&
	      ecbdata->blank_at_eof_in_postimage <= ecbdata->lno_in_postimage))
		return 0;
	return ws_blank_line(line, len, ecbdata->ws_rule);
}

static void emit_add_line(const char *reset,
			  struct emit_callback *ecbdata,
			  const char *line, int len)
{
	unsigned flags = WSEH_NEW | ecbdata->ws_rule;
	if (new_blank_line_at_eof(ecbdata, line, len))
		flags |= DIFF_SYMBOL_CONTENT_BLANK_LINE_EOF;

	emit_diff_symbol(ecbdata->opt, DIFF_SYMBOL_PLUS, line, len, flags);
}

static void emit_del_line(const char *reset,
			  struct emit_callback *ecbdata,
			  const char *line, int len)
{
	unsigned flags = WSEH_OLD | ecbdata->ws_rule;
	emit_diff_symbol(ecbdata->opt, DIFF_SYMBOL_MINUS, line, len, flags);
}

static void emit_context_line(const char *reset,
			      struct emit_callback *ecbdata,
			      const char *line, int len)
{
	unsigned flags = WSEH_CONTEXT | ecbdata->ws_rule;
	emit_diff_symbol(ecbdata->opt, DIFF_SYMBOL_CONTEXT, line, len, flags);
}

static void emit_hunk_header(struct emit_callback *ecbdata,
			     const char *line, int len)
{
	const char *context = diff_get_color(ecbdata->color_diff, DIFF_CONTEXT);
	const char *frag = diff_get_color(ecbdata->color_diff, DIFF_FRAGINFO);
	const char *func = diff_get_color(ecbdata->color_diff, DIFF_FUNCINFO);
	const char *reset = diff_get_color(ecbdata->color_diff, DIFF_RESET);
	const char *reverse = ecbdata->color_diff ? GIT_COLOR_REVERSE : "";
	static const char atat[2] = { '@', '@' };
	const char *cp, *ep;
	struct strbuf msgbuf = STRBUF_INIT;
	int org_len = len;
	int i = 1;

	/*
	 * As a hunk header must begin with "@@ -<old>, +<new> @@",
	 * it always is at least 10 bytes long.
	 */
	if (len < 10 ||
	    memcmp(line, atat, 2) ||
	    !(ep = memmem(line + 2, len - 2, atat, 2))) {
		emit_diff_symbol(ecbdata->opt,
				 DIFF_SYMBOL_CONTEXT_MARKER, line, len, 0);
		return;
	}
	ep += 2; /* skip over @@ */

	/* The hunk header in fraginfo color */
	if (ecbdata->opt->flags.dual_color_diffed_diffs)
		strbuf_addstr(&msgbuf, reverse);
	strbuf_addstr(&msgbuf, frag);
	strbuf_add(&msgbuf, line, ep - line);
	strbuf_addstr(&msgbuf, reset);

	/*
	 * trailing "\r\n"
	 */
	for ( ; i < 3; i++)
		if (line[len - i] == '\r' || line[len - i] == '\n')
			len--;

	/* blank before the func header */
	for (cp = ep; ep - line < len; ep++)
		if (*ep != ' ' && *ep != '\t')
			break;
	if (ep != cp) {
		strbuf_addstr(&msgbuf, context);
		strbuf_add(&msgbuf, cp, ep - cp);
		strbuf_addstr(&msgbuf, reset);
	}

	if (ep < line + len) {
		strbuf_addstr(&msgbuf, func);
		strbuf_add(&msgbuf, ep, line + len - ep);
		strbuf_addstr(&msgbuf, reset);
	}

	strbuf_add(&msgbuf, line + len, org_len - len);
	strbuf_complete_line(&msgbuf);
	emit_diff_symbol(ecbdata->opt,
			 DIFF_SYMBOL_CONTEXT_FRAGINFO, msgbuf.buf, msgbuf.len, 0);
	strbuf_release(&msgbuf);
}

static struct diff_tempfile *claim_diff_tempfile(void) {
	int i;
	for (i = 0; i < ARRAY_SIZE(diff_temp); i++)
		if (!diff_temp[i].name)
			return diff_temp + i;
	BUG("diff is failing to clean up its tempfiles");
}

static void remove_tempfile(void)
{
	int i;
	for (i = 0; i < ARRAY_SIZE(diff_temp); i++) {
		if (is_tempfile_active(diff_temp[i].tempfile))
			delete_tempfile(&diff_temp[i].tempfile);
		diff_temp[i].name = NULL;
	}
}

static void add_line_count(struct strbuf *out, int count)
{
	switch (count) {
	case 0:
		strbuf_addstr(out, "0,0");
		break;
	case 1:
		strbuf_addstr(out, "1");
		break;
	default:
		strbuf_addf(out, "1,%d", count);
		break;
	}
}

static void emit_rewrite_lines(struct emit_callback *ecb,
			       int prefix, const char *data, int size)
{
	const char *endp = NULL;
	const char *reset = diff_get_color(ecb->color_diff, DIFF_RESET);

	while (0 < size) {
		int len;

		endp = memchr(data, '\n', size);
		len = endp ? (endp - data + 1) : size;
		if (prefix != '+') {
			ecb->lno_in_preimage++;
			emit_del_line(reset, ecb, data, len);
		} else {
			ecb->lno_in_postimage++;
			emit_add_line(reset, ecb, data, len);
		}
		size -= len;
		data += len;
	}
	if (!endp)
		emit_diff_symbol(ecb->opt, DIFF_SYMBOL_NO_LF_EOF, NULL, 0, 0);
}

static void emit_rewrite_diff(const char *name_a,
			      const char *name_b,
			      struct diff_filespec *one,
			      struct diff_filespec *two,
			      struct userdiff_driver *textconv_one,
			      struct userdiff_driver *textconv_two,
			      struct diff_options *o)
{
	int lc_a, lc_b;
	static struct strbuf a_name = STRBUF_INIT, b_name = STRBUF_INIT;
	const char *a_prefix, *b_prefix;
	char *data_one, *data_two;
	size_t size_one, size_two;
	struct emit_callback ecbdata;
	struct strbuf out = STRBUF_INIT;

	if (diff_mnemonic_prefix && o->flags.reverse_diff) {
		a_prefix = o->b_prefix;
		b_prefix = o->a_prefix;
	} else {
		a_prefix = o->a_prefix;
		b_prefix = o->b_prefix;
	}

	name_a += (*name_a == '/');
	name_b += (*name_b == '/');

	strbuf_reset(&a_name);
	strbuf_reset(&b_name);
	quote_two_c_style(&a_name, a_prefix, name_a, 0);
	quote_two_c_style(&b_name, b_prefix, name_b, 0);

	size_one = fill_textconv(o->repo, textconv_one, one, &data_one);
	size_two = fill_textconv(o->repo, textconv_two, two, &data_two);

	memset(&ecbdata, 0, sizeof(ecbdata));
	ecbdata.color_diff = want_color(o->use_color);
	ecbdata.ws_rule = whitespace_rule(o->repo->index, name_b);
	ecbdata.opt = o;
	if (ecbdata.ws_rule & WS_BLANK_AT_EOF) {
		mmfile_t mf1, mf2;
		mf1.ptr = (char *)data_one;
		mf2.ptr = (char *)data_two;
		mf1.size = size_one;
		mf2.size = size_two;
		check_blank_at_eof(&mf1, &mf2, &ecbdata);
	}
	ecbdata.lno_in_preimage = 1;
	ecbdata.lno_in_postimage = 1;

	lc_a = count_lines(data_one, size_one);
	lc_b = count_lines(data_two, size_two);

	emit_diff_symbol(o, DIFF_SYMBOL_FILEPAIR_MINUS,
			 a_name.buf, a_name.len, 0);
	emit_diff_symbol(o, DIFF_SYMBOL_FILEPAIR_PLUS,
			 b_name.buf, b_name.len, 0);

	strbuf_addstr(&out, "@@ -");
	if (!o->irreversible_delete)
		add_line_count(&out, lc_a);
	else
		strbuf_addstr(&out, "?,?");
	strbuf_addstr(&out, " +");
	add_line_count(&out, lc_b);
	strbuf_addstr(&out, " @@\n");
	emit_diff_symbol(o, DIFF_SYMBOL_REWRITE_DIFF, out.buf, out.len, 0);
	strbuf_release(&out);

	if (lc_a && !o->irreversible_delete)
		emit_rewrite_lines(&ecbdata, '-', data_one, size_one);
	if (lc_b)
		emit_rewrite_lines(&ecbdata, '+', data_two, size_two);
	if (textconv_one)
		free((char *)data_one);
	if (textconv_two)
		free((char *)data_two);
}

struct diff_words_buffer {
	mmfile_t text;
	unsigned long alloc;
	struct diff_words_orig {
		const char *begin, *end;
	} *orig;
	int orig_nr, orig_alloc;
};

static void diff_words_append(char *line, unsigned long len,
		struct diff_words_buffer *buffer)
{
	ALLOC_GROW(buffer->text.ptr, buffer->text.size + len, buffer->alloc);
	line++;
	len--;
	memcpy(buffer->text.ptr + buffer->text.size, line, len);
	buffer->text.size += len;
	buffer->text.ptr[buffer->text.size] = '\0';
}

struct diff_words_style_elem {
	const char *prefix;
	const char *suffix;
	const char *color; /* NULL; filled in by the setup code if
			    * color is enabled */
};

struct diff_words_style {
	enum diff_words_type type;
	struct diff_words_style_elem new_word, old_word, ctx;
	const char *newline;
};

static struct diff_words_style diff_words_styles[] = {
	{ DIFF_WORDS_PORCELAIN, {"+", "\n"}, {"-", "\n"}, {" ", "\n"}, "~\n" },
	{ DIFF_WORDS_PLAIN, {"{+", "+}"}, {"[-", "-]"}, {"", ""}, "\n" },
	{ DIFF_WORDS_COLOR, {"", ""}, {"", ""}, {"", ""}, "\n" }
};

struct diff_words_data {
	struct diff_words_buffer minus, plus;
	const char *current_plus;
	int last_minus;
	struct diff_options *opt;
	regex_t *word_regex;
	enum diff_words_type type;
	struct diff_words_style *style;
};

static int fn_out_diff_words_write_helper(struct diff_options *o,
					  struct diff_words_style_elem *st_el,
					  const char *newline,
					  size_t count, const char *buf)
{
	int print = 0;
	struct strbuf sb = STRBUF_INIT;

	while (count) {
		char *p = memchr(buf, '\n', count);
		if (print)
			strbuf_addstr(&sb, diff_line_prefix(o));

		if (p != buf) {
			const char *reset = st_el->color && *st_el->color ?
					    GIT_COLOR_RESET : NULL;
			if (st_el->color && *st_el->color)
				strbuf_addstr(&sb, st_el->color);
			strbuf_addstr(&sb, st_el->prefix);
			strbuf_add(&sb, buf, p ? p - buf : count);
			strbuf_addstr(&sb, st_el->suffix);
			if (reset)
				strbuf_addstr(&sb, reset);
		}
		if (!p)
			goto out;

		strbuf_addstr(&sb, newline);
		count -= p + 1 - buf;
		buf = p + 1;
		print = 1;
		if (count) {
			emit_diff_symbol(o, DIFF_SYMBOL_WORD_DIFF,
					 sb.buf, sb.len, 0);
			strbuf_reset(&sb);
		}
	}

out:
	if (sb.len)
		emit_diff_symbol(o, DIFF_SYMBOL_WORD_DIFF,
				 sb.buf, sb.len, 0);
	strbuf_release(&sb);
	return 0;
}

/*
 * '--color-words' algorithm can be described as:
 *
 *   1. collect the minus/plus lines of a diff hunk, divided into
 *      minus-lines and plus-lines;
 *
 *   2. break both minus-lines and plus-lines into words and
 *      place them into two mmfile_t with one word for each line;
 *
 *   3. use xdiff to run diff on the two mmfile_t to get the words level diff;
 *
 * And for the common parts of the both file, we output the plus side text.
 * diff_words->current_plus is used to trace the current position of the plus file
 * which printed. diff_words->last_minus is used to trace the last minus word
 * printed.
 *
 * For '--graph' to work with '--color-words', we need to output the graph prefix
 * on each line of color words output. Generally, there are two conditions on
 * which we should output the prefix.
 *
 *   1. diff_words->last_minus == 0 &&
 *      diff_words->current_plus == diff_words->plus.text.ptr
 *
 *      that is: the plus text must start as a new line, and if there is no minus
 *      word printed, a graph prefix must be printed.
 *
 *   2. diff_words->current_plus > diff_words->plus.text.ptr &&
 *      *(diff_words->current_plus - 1) == '\n'
 *
 *      that is: a graph prefix must be printed following a '\n'
 */
static int color_words_output_graph_prefix(struct diff_words_data *diff_words)
{
	if ((diff_words->last_minus == 0 &&
		diff_words->current_plus == diff_words->plus.text.ptr) ||
		(diff_words->current_plus > diff_words->plus.text.ptr &&
		*(diff_words->current_plus - 1) == '\n')) {
		return 1;
	} else {
		return 0;
	}
}

static void fn_out_diff_words_aux(void *priv, char *line, unsigned long len)
{
	struct diff_words_data *diff_words = priv;
	struct diff_words_style *style = diff_words->style;
	int minus_first, minus_len, plus_first, plus_len;
	const char *minus_begin, *minus_end, *plus_begin, *plus_end;
	struct diff_options *opt = diff_words->opt;
	const char *line_prefix;

	if (line[0] != '@' || parse_hunk_header(line, len,
			&minus_first, &minus_len, &plus_first, &plus_len))
		return;

	assert(opt);
	line_prefix = diff_line_prefix(opt);

	/* POSIX requires that first be decremented by one if len == 0... */
	if (minus_len) {
		minus_begin = diff_words->minus.orig[minus_first].begin;
		minus_end =
			diff_words->minus.orig[minus_first + minus_len - 1].end;
	} else
		minus_begin = minus_end =
			diff_words->minus.orig[minus_first].end;

	if (plus_len) {
		plus_begin = diff_words->plus.orig[plus_first].begin;
		plus_end = diff_words->plus.orig[plus_first + plus_len - 1].end;
	} else
		plus_begin = plus_end = diff_words->plus.orig[plus_first].end;

	if (color_words_output_graph_prefix(diff_words)) {
		fputs(line_prefix, diff_words->opt->file);
	}
	if (diff_words->current_plus != plus_begin) {
		fn_out_diff_words_write_helper(diff_words->opt,
				&style->ctx, style->newline,
				plus_begin - diff_words->current_plus,
				diff_words->current_plus);
	}
	if (minus_begin != minus_end) {
		fn_out_diff_words_write_helper(diff_words->opt,
				&style->old_word, style->newline,
				minus_end - minus_begin, minus_begin);
	}
	if (plus_begin != plus_end) {
		fn_out_diff_words_write_helper(diff_words->opt,
				&style->new_word, style->newline,
				plus_end - plus_begin, plus_begin);
	}

	diff_words->current_plus = plus_end;
	diff_words->last_minus = minus_first;
}

/* This function starts looking at *begin, and returns 0 iff a word was found. */
static int find_word_boundaries(mmfile_t *buffer, regex_t *word_regex,
		int *begin, int *end)
{
	if (word_regex && *begin < buffer->size) {
		regmatch_t match[1];
		if (!regexec_buf(word_regex, buffer->ptr + *begin,
				 buffer->size - *begin, 1, match, 0)) {
			char *p = memchr(buffer->ptr + *begin + match[0].rm_so,
					'\n', match[0].rm_eo - match[0].rm_so);
			*end = p ? p - buffer->ptr : match[0].rm_eo + *begin;
			*begin += match[0].rm_so;
			return *begin >= *end;
		}
		return -1;
	}

	/* find the next word */
	while (*begin < buffer->size && isspace(buffer->ptr[*begin]))
		(*begin)++;
	if (*begin >= buffer->size)
		return -1;

	/* find the end of the word */
	*end = *begin + 1;
	while (*end < buffer->size && !isspace(buffer->ptr[*end]))
		(*end)++;

	return 0;
}

/*
 * This function splits the words in buffer->text, stores the list with
 * newline separator into out, and saves the offsets of the original words
 * in buffer->orig.
 */
static void diff_words_fill(struct diff_words_buffer *buffer, mmfile_t *out,
		regex_t *word_regex)
{
	int i, j;
	long alloc = 0;

	out->size = 0;
	out->ptr = NULL;

	/* fake an empty "0th" word */
	ALLOC_GROW(buffer->orig, 1, buffer->orig_alloc);
	buffer->orig[0].begin = buffer->orig[0].end = buffer->text.ptr;
	buffer->orig_nr = 1;

	for (i = 0; i < buffer->text.size; i++) {
		if (find_word_boundaries(&buffer->text, word_regex, &i, &j))
			return;

		/* store original boundaries */
		ALLOC_GROW(buffer->orig, buffer->orig_nr + 1,
				buffer->orig_alloc);
		buffer->orig[buffer->orig_nr].begin = buffer->text.ptr + i;
		buffer->orig[buffer->orig_nr].end = buffer->text.ptr + j;
		buffer->orig_nr++;

		/* store one word */
		ALLOC_GROW(out->ptr, out->size + j - i + 1, alloc);
		memcpy(out->ptr + out->size, buffer->text.ptr + i, j - i);
		out->ptr[out->size + j - i] = '\n';
		out->size += j - i + 1;

		i = j - 1;
	}
}

/* this executes the word diff on the accumulated buffers */
static void diff_words_show(struct diff_words_data *diff_words)
{
	xpparam_t xpp;
	xdemitconf_t xecfg;
	mmfile_t minus, plus;
	struct diff_words_style *style = diff_words->style;

	struct diff_options *opt = diff_words->opt;
	const char *line_prefix;

	assert(opt);
	line_prefix = diff_line_prefix(opt);

	/* special case: only removal */
	if (!diff_words->plus.text.size) {
		emit_diff_symbol(diff_words->opt, DIFF_SYMBOL_WORD_DIFF,
				 line_prefix, strlen(line_prefix), 0);
		fn_out_diff_words_write_helper(diff_words->opt,
			&style->old_word, style->newline,
			diff_words->minus.text.size,
			diff_words->minus.text.ptr);
		diff_words->minus.text.size = 0;
		return;
	}

	diff_words->current_plus = diff_words->plus.text.ptr;
	diff_words->last_minus = 0;

	memset(&xpp, 0, sizeof(xpp));
	memset(&xecfg, 0, sizeof(xecfg));
	diff_words_fill(&diff_words->minus, &minus, diff_words->word_regex);
	diff_words_fill(&diff_words->plus, &plus, diff_words->word_regex);
	xpp.flags = 0;
	/* as only the hunk header will be parsed, we need a 0-context */
	xecfg.ctxlen = 0;
	if (xdi_diff_outf(&minus, &plus, fn_out_diff_words_aux, diff_words,
			  &xpp, &xecfg))
		die("unable to generate word diff");
	free(minus.ptr);
	free(plus.ptr);
	if (diff_words->current_plus != diff_words->plus.text.ptr +
			diff_words->plus.text.size) {
		if (color_words_output_graph_prefix(diff_words))
			emit_diff_symbol(diff_words->opt, DIFF_SYMBOL_WORD_DIFF,
					 line_prefix, strlen(line_prefix), 0);
		fn_out_diff_words_write_helper(diff_words->opt,
			&style->ctx, style->newline,
			diff_words->plus.text.ptr + diff_words->plus.text.size
			- diff_words->current_plus, diff_words->current_plus);
	}
	diff_words->minus.text.size = diff_words->plus.text.size = 0;
}

/* In "color-words" mode, show word-diff of words accumulated in the buffer */
static void diff_words_flush(struct emit_callback *ecbdata)
{
	struct diff_options *wo = ecbdata->diff_words->opt;

	if (ecbdata->diff_words->minus.text.size ||
	    ecbdata->diff_words->plus.text.size)
		diff_words_show(ecbdata->diff_words);

	if (wo->emitted_symbols) {
		struct diff_options *o = ecbdata->opt;
		struct emitted_diff_symbols *wol = wo->emitted_symbols;
		int i;

		/*
		 * NEEDSWORK:
		 * Instead of appending each, concat all words to a line?
		 */
		for (i = 0; i < wol->nr; i++)
			append_emitted_diff_symbol(o, &wol->buf[i]);

		for (i = 0; i < wol->nr; i++)
			free((void *)wol->buf[i].line);

		wol->nr = 0;
	}
}

static void diff_filespec_load_driver(struct diff_filespec *one,
				      struct index_state *istate)
{
	/* Use already-loaded driver */
	if (one->driver)
		return;

	if (S_ISREG(one->mode))
		one->driver = userdiff_find_by_path(istate, one->path);

	/* Fallback to default settings */
	if (!one->driver)
		one->driver = userdiff_find_by_name("default");
}

static const char *userdiff_word_regex(struct diff_filespec *one,
				       struct index_state *istate)
{
	diff_filespec_load_driver(one, istate);
	return one->driver->word_regex;
}

static void init_diff_words_data(struct emit_callback *ecbdata,
				 struct diff_options *orig_opts,
				 struct diff_filespec *one,
				 struct diff_filespec *two)
{
	int i;
	struct diff_options *o = xmalloc(sizeof(struct diff_options));
	memcpy(o, orig_opts, sizeof(struct diff_options));

	ecbdata->diff_words =
		xcalloc(1, sizeof(struct diff_words_data));
	ecbdata->diff_words->type = o->word_diff;
	ecbdata->diff_words->opt = o;

	if (orig_opts->emitted_symbols)
		o->emitted_symbols =
			xcalloc(1, sizeof(struct emitted_diff_symbols));

	if (!o->word_regex)
		o->word_regex = userdiff_word_regex(one, o->repo->index);
	if (!o->word_regex)
		o->word_regex = userdiff_word_regex(two, o->repo->index);
	if (!o->word_regex)
		o->word_regex = diff_word_regex_cfg;
	if (o->word_regex) {
		ecbdata->diff_words->word_regex = (regex_t *)
			xmalloc(sizeof(regex_t));
		if (regcomp(ecbdata->diff_words->word_regex,
			    o->word_regex,
			    REG_EXTENDED | REG_NEWLINE))
			die("invalid regular expression: %s",
			    o->word_regex);
	}
	for (i = 0; i < ARRAY_SIZE(diff_words_styles); i++) {
		if (o->word_diff == diff_words_styles[i].type) {
			ecbdata->diff_words->style =
				&diff_words_styles[i];
			break;
		}
	}
	if (want_color(o->use_color)) {
		struct diff_words_style *st = ecbdata->diff_words->style;
		st->old_word.color = diff_get_color_opt(o, DIFF_FILE_OLD);
		st->new_word.color = diff_get_color_opt(o, DIFF_FILE_NEW);
		st->ctx.color = diff_get_color_opt(o, DIFF_CONTEXT);
	}
}

static void free_diff_words_data(struct emit_callback *ecbdata)
{
	if (ecbdata->diff_words) {
		diff_words_flush(ecbdata);
		free (ecbdata->diff_words->opt->emitted_symbols);
		free (ecbdata->diff_words->opt);
		free (ecbdata->diff_words->minus.text.ptr);
		free (ecbdata->diff_words->minus.orig);
		free (ecbdata->diff_words->plus.text.ptr);
		free (ecbdata->diff_words->plus.orig);
		if (ecbdata->diff_words->word_regex) {
			regfree(ecbdata->diff_words->word_regex);
			free(ecbdata->diff_words->word_regex);
		}
		FREE_AND_NULL(ecbdata->diff_words);
	}
}

const char *diff_get_color(int diff_use_color, enum color_diff ix)
{
	if (want_color(diff_use_color))
		return diff_colors[ix];
	return "";
}

const char *diff_line_prefix(struct diff_options *opt)
{
	struct strbuf *msgbuf;
	if (!opt->output_prefix)
		return "";

	msgbuf = opt->output_prefix(opt, opt->output_prefix_data);
	return msgbuf->buf;
}

static unsigned long sane_truncate_line(struct emit_callback *ecb, char *line, unsigned long len)
{
	const char *cp;
	unsigned long allot;
	size_t l = len;

	cp = line;
	allot = l;
	while (0 < l) {
		(void) utf8_width(&cp, &l);
		if (!cp)
			break; /* truncated in the middle? */
	}
	return allot - l;
}

static void find_lno(const char *line, struct emit_callback *ecbdata)
{
	const char *p;
	ecbdata->lno_in_preimage = 0;
	ecbdata->lno_in_postimage = 0;
	p = strchr(line, '-');
	if (!p)
		return; /* cannot happen */
	ecbdata->lno_in_preimage = strtol(p + 1, NULL, 10);
	p = strchr(p, '+');
	if (!p)
		return; /* cannot happen */
	ecbdata->lno_in_postimage = strtol(p + 1, NULL, 10);
}

static void fn_out_consume(void *priv, char *line, unsigned long len)
{
	struct emit_callback *ecbdata = priv;
	const char *reset = diff_get_color(ecbdata->color_diff, DIFF_RESET);
	struct diff_options *o = ecbdata->opt;

	o->found_changes = 1;

	if (ecbdata->header) {
		emit_diff_symbol(o, DIFF_SYMBOL_HEADER,
				 ecbdata->header->buf, ecbdata->header->len, 0);
		strbuf_reset(ecbdata->header);
		ecbdata->header = NULL;
	}

	if (ecbdata->label_path[0]) {
		emit_diff_symbol(o, DIFF_SYMBOL_FILEPAIR_MINUS,
				 ecbdata->label_path[0],
				 strlen(ecbdata->label_path[0]), 0);
		emit_diff_symbol(o, DIFF_SYMBOL_FILEPAIR_PLUS,
				 ecbdata->label_path[1],
				 strlen(ecbdata->label_path[1]), 0);
		ecbdata->label_path[0] = ecbdata->label_path[1] = NULL;
	}

	if (diff_suppress_blank_empty
	    && len == 2 && line[0] == ' ' && line[1] == '\n') {
		line[0] = '\n';
		len = 1;
	}

	if (line[0] == '@') {
		if (ecbdata->diff_words)
			diff_words_flush(ecbdata);
		len = sane_truncate_line(ecbdata, line, len);
		find_lno(line, ecbdata);
		emit_hunk_header(ecbdata, line, len);
		return;
	}

	if (ecbdata->diff_words) {
		enum diff_symbol s =
			ecbdata->diff_words->type == DIFF_WORDS_PORCELAIN ?
			DIFF_SYMBOL_WORDS_PORCELAIN : DIFF_SYMBOL_WORDS;
		if (line[0] == '-') {
			diff_words_append(line, len,
					  &ecbdata->diff_words->minus);
			return;
		} else if (line[0] == '+') {
			diff_words_append(line, len,
					  &ecbdata->diff_words->plus);
			return;
		} else if (starts_with(line, "\\ ")) {
			/*
			 * Eat the "no newline at eof" marker as if we
			 * saw a "+" or "-" line with nothing on it,
			 * and return without diff_words_flush() to
			 * defer processing. If this is the end of
			 * preimage, more "+" lines may come after it.
			 */
			return;
		}
		diff_words_flush(ecbdata);
		emit_diff_symbol(o, s, line, len, 0);
		return;
	}

	switch (line[0]) {
	case '+':
		ecbdata->lno_in_postimage++;
		emit_add_line(reset, ecbdata, line + 1, len - 1);
		break;
	case '-':
		ecbdata->lno_in_preimage++;
		emit_del_line(reset, ecbdata, line + 1, len - 1);
		break;
	case ' ':
		ecbdata->lno_in_postimage++;
		ecbdata->lno_in_preimage++;
		emit_context_line(reset, ecbdata, line + 1, len - 1);
		break;
	default:
		/* incomplete line at the end */
		ecbdata->lno_in_preimage++;
		emit_diff_symbol(o, DIFF_SYMBOL_CONTEXT_INCOMPLETE,
				 line, len, 0);
		break;
	}
}

static void pprint_rename(struct strbuf *name, const char *a, const char *b)
{
	const ch