Merge branch 'sb/blame-color'

"git blame" learns to unhighlight uninteresting metadata from the
originating commit on lines that are the same as the previous one,
and also paint lines in different colors depending on the age of
the commit.

* sb/blame-color:
  builtin/blame: add new coloring scheme config
  builtin/blame: highlight recently changed lines
  builtin/blame: dim uninteresting metadata lines

3 files changed, 200 insertions, 4 deletions

diff --git a/Documentation/config.txt b/Documentation/config.txt
index 460c14f047..7d8383433c 100644
--- a/Documentation/config.txt
+++ b/Documentation/config.txt
@@ -1251,6 +1251,33 @@ color.status.<slot>::
 	status short-format), or
 	`unmerged` (files which have unmerged changes).
 
+color.blame.repeatedLines::
+	Use the customized color for the part of git-blame output that
+	is repeated meta information per line (such as commit id,
+	author name, date and timezone). Defaults to cyan.
+
+color.blame.highlightRecent::
+	This can be used to color the metadata of a blame line depending
+	on age of the line.
++
+This setting should be set to a comma-separated list of color and date settings,
+starting and ending with a color, the dates should be set from oldest to newest.
+The metadata will be colored given the colors if the the line was introduced
+before the given timestamp, overwriting older timestamped colors.
++
+Instead of an absolute timestamp relative timestamps work as well, e.g.
+2.weeks.ago is valid to address anything older than 2 weeks.
++
+It defaults to 'blue,12 month ago,white,1 month ago,red', which colors
+everything older than one year blue, recent changes between one month and
+one year old are kept white, and lines introduced within the last month are
+colored red.
+
+blame.coloring::
+	This determines the coloring scheme to be applied to blame
+	output. It can be 'repeatedLines', 'highlightRecent',
+	or 'none' which is the default.
+
 color.transport::
 	A boolean to enable/disable color when pushes are rejected. May be
 	set to `always`, `false` (or `never`) or `auto` (or `true`), in which
diff --git a/builtin/blame.c b/builtin/blame.c
index bfdf7cc132..4202584f97 100644
--- a/builtin/blame.c
+++ b/builtin/blame.c
@@ -7,6 +7,7 @@
 
 #include "cache.h"
 #include "config.h"
+#include "color.h"
 #include "builtin.h"
 #include "commit.h"
 #include "diff.h"
@@ -23,6 +24,7 @@
 #include "dir.h"
 #include "progress.h"
 #include "blame.h"
+#include "string-list.h"
 
 static char blame_usage[] = N_("git blame [<options>] [<rev-opts>] [<rev>] [--] <file>");
 
@@ -46,6 +48,8 @@ static int xdl_opts;
 static int abbrev = -1;
 static int no_whole_file_rename;
 static int show_progress;
+static char repeated_meta_color[COLOR_MAXLEN];
+static int coloring_mode;
 
 static struct date_mode blame_date_mode = { DATE_ISO8601 };
 static size_t blame_date_width;
@@ -316,10 +320,12 @@ static const char *format_time(timestamp_t time, const char *tz_str,
 #define OUTPUT_PORCELAIN	010
 #define OUTPUT_SHOW_NAME	020
 #define OUTPUT_SHOW_NUMBER	040
-#define OUTPUT_SHOW_SCORE      0100
-#define OUTPUT_NO_AUTHOR       0200
+#define OUTPUT_SHOW_SCORE	0100
+#define OUTPUT_NO_AUTHOR	0200
 #define OUTPUT_SHOW_EMAIL	0400
-#define OUTPUT_LINE_PORCELAIN 01000
+#define OUTPUT_LINE_PORCELAIN	01000
+#define OUTPUT_COLOR_LINE	02000
+#define OUTPUT_SHOW_AGE_WITH_COLOR	04000
 
 static void emit_porcelain_details(struct blame_origin *suspect, int repeat)
 {
@@ -367,6 +373,63 @@ static void emit_porcelain(struct blame_scoreboard *sb, struct blame_entry *ent,
 		putchar('\n');
 }
 
+static struct color_field {
+	timestamp_t hop;
+	char col[COLOR_MAXLEN];
+} *colorfield;
+static int colorfield_nr, colorfield_alloc;
+
+static void parse_color_fields(const char *s)
+{
+	struct string_list l = STRING_LIST_INIT_DUP;
+	struct string_list_item *item;
+	enum { EXPECT_DATE, EXPECT_COLOR } next = EXPECT_COLOR;
+
+	colorfield_nr = 0;
+
+	/* Ideally this would be stripped and split at the same time? */
+	string_list_split(&l, s, ',', -1);
+	ALLOC_GROW(colorfield, colorfield_nr + 1, colorfield_alloc);
+
+	for_each_string_list_item(item, &l) {
+		switch (next) {
+		case EXPECT_DATE:
+			colorfield[colorfield_nr].hop = approxidate(item->string);
+			next = EXPECT_COLOR;
+			colorfield_nr++;
+			ALLOC_GROW(colorfield, colorfield_nr + 1, colorfield_alloc);
+			break;
+		case EXPECT_COLOR:
+			if (color_parse(item->string, colorfield[colorfield_nr].col))
+				die(_("expecting a color: %s"), item->string);
+			next = EXPECT_DATE;
+			break;
+		}
+	}
+
+	if (next == EXPECT_COLOR)
+		die (_("must end with a color"));
+
+	colorfield[colorfield_nr].hop = TIME_MAX;
+}
+
+static void setup_default_color_by_age(void)
+{
+	parse_color_fields("blue,12 month ago,white,1 month ago,red");
+}
+
+static void determine_line_heat(struct blame_entry *ent, const char **dest_color)
+{
+	int i = 0;
+	struct commit_info ci;
+	get_commit_info(ent->suspect->commit, &ci, 1);
+
+	while (i < colorfield_nr && ci.author_time > colorfield[i].hop)
+		i++;
+
+	*dest_color = colorfield[i].col;
+}
+
 static void emit_other(struct blame_scoreboard *sb, struct blame_entry *ent, int opt)
 {
 	int cnt;
@@ -375,15 +438,35 @@ static void emit_other(struct blame_scoreboard *sb, struct blame_entry *ent, int
 	struct commit_info ci;
 	char hex[GIT_MAX_HEXSZ + 1];
 	int show_raw_time = !!(opt & OUTPUT_RAW_TIMESTAMP);
+	const char *default_color = NULL, *color = NULL, *reset = NULL;
 
 	get_commit_info(suspect->commit, &ci, 1);
 	oid_to_hex_r(hex, &suspect->commit->object.oid);
 
 	cp = blame_nth_line(sb, ent->lno);
+
+	if (opt & OUTPUT_SHOW_AGE_WITH_COLOR) {
+		determine_line_heat(ent, &default_color);
+		color = default_color;
+		reset = GIT_COLOR_RESET;
+	}
+
 	for (cnt = 0; cnt < ent->num_lines; cnt++) {
 		char ch;
 		int length = (opt & OUTPUT_LONG_OBJECT_NAME) ? GIT_SHA1_HEXSZ : abbrev;
 
+		if (opt & OUTPUT_COLOR_LINE) {
+			if (cnt > 0) {
+				color = repeated_meta_color;
+				reset = GIT_COLOR_RESET;
+			} else  {
+				color = default_color ? default_color : NULL;
+				reset = default_color ? GIT_COLOR_RESET : NULL;
+			}
+		}
+		if (color)
+			fputs(color, stdout);
+
 		if (suspect->commit->object.flags & UNINTERESTING) {
 			if (blank_boundary)
 				memset(hex, ' ', length);
@@ -433,6 +516,8 @@ static void emit_other(struct blame_scoreboard *sb, struct blame_entry *ent, int
 			printf(" %*d) ",
 			       max_digits, ent->lno + 1 + cnt);
 		}
+		if (reset)
+			fputs(reset, stdout);
 		do {
 			ch = *cp++;
 			putchar(ch);
@@ -607,6 +692,30 @@ static int git_blame_config(const char *var, const char *value, void *cb)
 		parse_date_format(value, &blame_date_mode);
 		return 0;
 	}
+	if (!strcmp(var, "color.blame.repeatedlines")) {
+		if (color_parse_mem(value, strlen(value), repeated_meta_color))
+			warning(_("invalid color '%s' in color.blame.repeatedLines"),
+				value);
+		return 0;
+	}
+	if (!strcmp(var, "color.blame.highlightrecent")) {
+		parse_color_fields(value);
+		return 0;
+	}
+
+	if (!strcmp(var, "blame.coloring")) {
+		if (!strcmp(value, "repeatedLines")) {
+			coloring_mode |= OUTPUT_COLOR_LINE;
+		} else if (!strcmp(value, "highlightRecent")) {
+			coloring_mode |= OUTPUT_SHOW_AGE_WITH_COLOR;
+		} else if (!strcmp(value, "none")) {
+			coloring_mode &= ~(OUTPUT_COLOR_LINE |
+					    OUTPUT_SHOW_AGE_WITH_COLOR);
+		} else {
+			warning(_("invalid value for blame.coloring"));
+			return 0;
+		}
+	}
 
 	if (git_diff_heuristic_config(var, value, cb) < 0)
 		return -1;
@@ -690,6 +799,8 @@ int cmd_blame(int argc, const char **argv, const char *prefix)
 		OPT_BIT('s', NULL, &output_option, N_("Suppress author name and timestamp (Default: off)"), OUTPUT_NO_AUTHOR),
 		OPT_BIT('e', "show-email", &output_option, N_("Show author email instead of name (Default: off)"), OUTPUT_SHOW_EMAIL),
 		OPT_BIT('w', NULL, &xdl_opts, N_("Ignore whitespace differences"), XDF_IGNORE_WHITESPACE),
+		OPT_BIT(0, "color-lines", &output_option, N_("color redundant metadata from previous line differently"), OUTPUT_COLOR_LINE),
+		OPT_BIT(0, "color-by-age", &output_option, N_("color lines by age"), OUTPUT_SHOW_AGE_WITH_COLOR),
 
 		/*
 		 * The following two options are parsed by parse_revision_opt()
@@ -714,6 +825,7 @@ int cmd_blame(int argc, const char **argv, const char *prefix)
 	unsigned int range_i;
 	long anchor;
 
+	setup_default_color_by_age();
 	git_config(git_blame_config, &output_option);
 	init_revisions(&revs, NULL);
 	revs.date_mode = blame_date_mode;
@@ -949,8 +1061,17 @@ parse_done:
 
 	blame_coalesce(&sb);
 
-	if (!(output_option & OUTPUT_PORCELAIN))
+	if (!(output_option & (OUTPUT_COLOR_LINE | OUTPUT_SHOW_AGE_WITH_COLOR)))
+		output_option |= coloring_mode;
+
+	if (!(output_option & OUTPUT_PORCELAIN)) {
 		find_alignment(&sb, &output_option);
+		if (!*repeated_meta_color &&
+		    (output_option & OUTPUT_COLOR_LINE))
+			strcpy(repeated_meta_color, GIT_COLOR_CYAN);
+	}
+	if (output_option & OUTPUT_ANNOTATE_COMPAT)
+		output_option &= ~(OUTPUT_COLOR_LINE | OUTPUT_SHOW_AGE_WITH_COLOR);
 
 	output(&sb, output_option);
 	free((void *)sb.final_buf);
diff --git a/t/t8012-blame-colors.sh b/t/t8012-blame-colors.sh
new file mode 100755
index 0000000000..ed38f74de9
--- /dev/null
+++ b/t/t8012-blame-colors.sh
@@ -0,0 +1,48 @@
+#!/bin/sh
+
+test_description='colored git blame'
+. ./test-lib.sh
+
+PROG='git blame -c'
+. "$TEST_DIRECTORY"/annotate-tests.sh
+
+test_expect_success 'colored blame colors contiguous lines' '
+	git -c color.blame.repeatedLines=yellow blame --color-lines --abbrev=12 hello.c >actual.raw &&
+	git -c color.blame.repeatedLines=yellow -c blame.coloring=repeatedLines blame --abbrev=12 hello.c >actual.raw.2 &&
+	test_cmp actual.raw actual.raw.2 &&
+	test_decode_color <actual.raw >actual &&
+	grep "<YELLOW>" <actual >darkened &&
+	grep "(F" darkened > F.expect &&
+	grep "(H" darkened > H.expect &&
+	test_line_count = 2 F.expect &&
+	test_line_count = 3 H.expect
+'
+
+test_expect_success 'color by age consistently colors old code' '
+	git blame --color-by-age hello.c >actual.raw &&
+	git -c blame.coloring=highlightRecent blame hello.c >actual.raw.2 &&
+	test_cmp actual.raw actual.raw.2 &&
+	test_decode_color <actual.raw >actual &&
+	grep "<BLUE>" <actual >colored &&
+	test_line_count = 10 colored
+'
+
+test_expect_success 'blame color by age: new code is different' '
+	cat >>hello.c <<-EOF &&
+		void qfunc();
+	EOF
+	git add hello.c &&
+	GIT_AUTHOR_DATE="" git commit -m "new commit" &&
+
+	git -c color.blame.highlightRecent="yellow,1 month ago, cyan" blame --color-by-age hello.c >actual.raw &&
+	test_decode_color <actual.raw >actual &&
+
+	grep "<YELLOW>" <actual >colored &&
+	test_line_count = 10 colored &&
+
+	grep "<CYAN>" <actual >colored &&
+	test_line_count = 1 colored &&
+	grep qfunc colored
+'
+
+test_done