1 files changed, 423 insertions, 0 deletions
diff --git a/internal/text/goldmark_custom_renderer.go b/internal/text/goldmark_custom_renderer.go
new file mode 100644
index 000000000..438692577
--- /dev/null
+++ b/internal/text/goldmark_custom_renderer.go
@@ -0,0 +1,423 @@
+// GoToSocial
+// Copyright (C) GoToSocial Authors admin@gotosocial.org
+// SPDX-License-Identifier: AGPL-3.0-or-later
+//
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Affero General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU Affero General Public License for more details.
+//
+// You should have received a copy of the GNU Affero General Public License
+// along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+package text
+
+import (
+	"context"
+	"errors"
+	"strings"
+
+	"github.com/superseriousbusiness/gotosocial/internal/db"
+	"github.com/superseriousbusiness/gotosocial/internal/gtscontext"
+	"github.com/superseriousbusiness/gotosocial/internal/gtserror"
+	"github.com/superseriousbusiness/gotosocial/internal/gtsmodel"
+	"github.com/superseriousbusiness/gotosocial/internal/id"
+	"github.com/superseriousbusiness/gotosocial/internal/log"
+	"github.com/superseriousbusiness/gotosocial/internal/uris"
+	"github.com/yuin/goldmark"
+	"github.com/yuin/goldmark/ast"
+	"github.com/yuin/goldmark/parser"
+	"github.com/yuin/goldmark/renderer"
+	mdutil "github.com/yuin/goldmark/util"
+)
+
+// customRenderer fulfils the following goldmark interfaces:
+//
+//   - renderer.NodeRenderer
+//   - goldmark.Extender.
+//
+// It is used as a goldmark extension by FromMarkdown and
+// (variants of) FromPlain.
+//
+// The custom renderer extracts and re-renders mentions, hashtags,
+// and emojis that are encountered during parsing, writing out valid
+// HTML representations of these elements.
+//
+// The customRenderer has the following side effects:
+//
+//   - May use its db connection to retrieve existing and/or
+//     store new mentions, hashtags, and emojis.
+//   - May update its *FormatResult to append discovered
+//     mentions, hashtags, and emojis to it.
+type customRenderer struct {
+	ctx          context.Context
+	db           db.DB
+	parseMention gtsmodel.ParseMentionFunc
+	accountID    string
+	statusID     string
+	emojiOnly    bool
+	result       *FormatResult
+}
+
+func (cr *customRenderer) RegisterFuncs(reg renderer.NodeRendererFuncRegisterer) {
+	reg.Register(kindMention, cr.renderMention)
+	reg.Register(kindHashtag, cr.renderHashtag)
+	reg.Register(kindEmoji, cr.renderEmoji)
+}
+
+func (cr *customRenderer) Extend(markdown goldmark.Markdown) {
+	// 1000 is set as the lowest
+	// priority, but it's arbitrary.
+	const prio = 1000
+
+	if cr.emojiOnly {
+		// Parse + render only emojis.
+		markdown.Parser().AddOptions(
+			parser.WithInlineParsers(
+				mdutil.Prioritized(new(emojiParser), prio),
+			),
+		)
+	} else {
+		// Parse + render emojis, mentions, hashtags.
+		markdown.Parser().AddOptions(parser.WithInlineParsers(
+			mdutil.Prioritized(new(emojiParser), prio),
+			mdutil.Prioritized(new(mentionParser), prio),
+			mdutil.Prioritized(new(hashtagParser), prio),
+		))
+	}
+
+	// Add this custom renderer.
+	markdown.Renderer().AddOptions(
+		renderer.WithNodeRenderers(
+			mdutil.Prioritized(cr, prio),
+		),
+	)
+}
+
+/*
+	MENTION RENDERING STUFF
+*/
+
+// renderMention takes a mention
+// ast.Node and renders it as HTML.
+func (cr *customRenderer) renderMention(
+	w mdutil.BufWriter,
+	source []byte,
+	node ast.Node,
+	entering bool,
+) (ast.WalkStatus, error) {
+	if !entering {
+		return ast.WalkSkipChildren, nil
+	}
+
+	// This function is registered
+	// only for kindMention, and
+	// should not be called for
+	// any other node type.
+	n, ok := node.(*mention)
+	if !ok {
+		log.Panic(cr.ctx, "type assertion failed")
+	}
+
+	// Get raw mention string eg., '@someone@domain.org'.
+	text := string(n.Segment.Value(source))
+
+	// Handle mention and get text to render.
+	text = cr.handleMention(text)
+
+	// Write returned text into HTML.
+	if _, err := w.WriteString(text); err != nil {
+		// We don't have much recourse if this fails.
+		log.Errorf(cr.ctx, "error writing HTML: %s", err)
+	}
+
+	return ast.WalkSkipChildren, nil
+}
+
+// handleMention takes a string in the form '@username@domain.com'
+// or '@localusername', and does the following:
+//
+//   - Parse the mention string into a *gtsmodel.Mention.
+//   - Insert mention into database if necessary.
+//   - Add mention to cr.results.Mentions slice.
+//   - Return mention rendered as nice HTML.
+//
+// If the mention is invalid or cannot be created,
+// the unaltered input text will be returned instead.
+func (cr *customRenderer) handleMention(text string) string {
+	mention, err := cr.parseMention(cr.ctx, text, cr.accountID, cr.statusID)
+	if err != nil {
+		log.Errorf(cr.ctx, "error parsing mention %s from status: %s", text, err)
+		return text
+	}
+
+	if cr.statusID != "" {
+		if err := cr.db.PutMention(cr.ctx, mention); err != nil {
+			log.Errorf(cr.ctx, "error putting mention in db: %s", err)
+			return text
+		}
+	}
+
+	// Append mention to result if not done already.
+	//
+	// This prevents multiple occurences of mention
+	// in the same status generating multiple
+	// entries for the same mention in result.
+	func() {
+		for _, m := range cr.result.Mentions {
+			if mention.TargetAccountID == m.TargetAccountID {
+				// Already appended.
+				return
+			}
+		}
+
+		// Not appended yet.
+		cr.result.Mentions = append(cr.result.Mentions, mention)
+	}()
+
+	if mention.TargetAccount == nil {
+		// Fetch mention target account if not yet populated.
+		mention.TargetAccount, err = cr.db.GetAccountByID(
+			gtscontext.SetBarebones(cr.ctx),
+			mention.TargetAccountID,
+		)
+		if err != nil {
+			log.Errorf(cr.ctx, "error populating mention target account: %v", err)
+			return text
+		}
+	}
+
+	// Replace the mention with the formatted mention content,
+	// eg. `@someone@domain.org` becomes:
+	// `<span class="h-card"><a href="https://domain.org/@someone" class="u-url mention">@<span>someone</span></a></span>`
+	var b strings.Builder
+	b.WriteString(`<span class="h-card"><a href="`)
+	b.WriteString(mention.TargetAccount.URL)
+	b.WriteString(`" class="u-url mention">@<span>`)
+	b.WriteString(mention.TargetAccount.Username)
+	b.WriteString(`</span></a></span>`)
+	return b.String()
+}
+
+/*
+	HASHTAG RENDERING STUFF
+*/
+
+// renderHashtag takes a hashtag
+// ast.Node and renders it as HTML.
+func (cr *customRenderer) renderHashtag(
+	w mdutil.BufWriter,
+	source []byte,
+	node ast.Node,
+	entering bool,
+) (ast.WalkStatus, error) {
+	if !entering {
+		return ast.WalkSkipChildren, nil
+	}
+
+	// This function is registered
+	// only for kindHashtag, and
+	// should not be called for
+	// any other node type.
+	n, ok := node.(*hashtag)
+	if !ok {
+		log.Panic(cr.ctx, "type assertion failed")
+	}
+
+	// Get raw hashtag string eg., '#SomeHashtag'.
+	text := string(n.Segment.Value(source))
+
+	// Handle hashtag and get text to render.
+	text = cr.handleHashtag(text)
+
+	// Write returned text into HTML.
+	if _, err := w.WriteString(text); err != nil {
+		// We don't have much recourse if this fails.
+		log.Errorf(cr.ctx, "error writing HTML: %s", err)
+	}
+
+	return ast.WalkSkipChildren, nil
+}
+
+// handleHashtag takes a string in the form '#SomeHashtag',
+// and does the following:
+//
+//   - Normalize + validate the hashtag.
+//   - Get or create hashtag in the db.
+//   - Add hashtag to cr.results.Tags slice.
+//   - Return hashtag rendered as nice HTML.
+//
+// If the hashtag is invalid or cannot be retrieved,
+// the unaltered input text will be returned instead.
+func (cr *customRenderer) handleHashtag(text string) string {
+	normalized, ok := NormalizeHashtag(text)
+	if !ok {
+		// Not a valid hashtag.
+		return text
+	}
+
+	getOrCreateHashtag := func(name string) (*gtsmodel.Tag, error) {
+		var (
+			tag *gtsmodel.Tag
+			err error
+		)
+
+		// Check if we have a tag with this name already.
+		tag, err = cr.db.GetTagByName(cr.ctx, name)
+		if err != nil && !errors.Is(err, db.ErrNoEntries) {
+			return nil, gtserror.Newf("db error getting tag %s: %w", name, err)
+		}
+
+		if tag != nil {
+			// We had it!
+			return tag, nil
+		}
+
+		// We didn't have a tag with
+		// this name, create one.
+		tag = &gtsmodel.Tag{
+			ID:   id.NewULID(),
+			Name: name,
+		}
+
+		if err = cr.db.PutTag(cr.ctx, tag); err != nil {
+			return nil, gtserror.Newf("db error putting new tag %s: %w", name, err)
+		}
+
+		return tag, nil
+	}
+
+	tag, err := getOrCreateHashtag(normalized)
+	if err != nil {
+		log.Errorf(cr.ctx, "error generating hashtags from status: %s", err)
+		return text
+	}
+
+	// Append tag to result if not done already.
+	//
+	// This prevents multiple uses of a tag in
+	// the same status generating multiple
+	// entries for the same tag in result.
+	func() {
+		for _, t := range cr.result.Tags {
+			if tag.ID == t.ID {
+				// Already appended.
+				return
+			}
+		}
+
+		// Not appended yet.
+		cr.result.Tags = append(cr.result.Tags, tag)
+	}()
+
+	// Replace tag with the formatted tag content, eg. `#SomeHashtag` becomes:
+	// `<a href="https://example.org/tags/somehashtag" class="mention hashtag" rel="tag">#<span>SomeHashtag</span></a>`
+	var b strings.Builder
+	b.WriteString(`<a href="`)
+	b.WriteString(uris.GenerateURIForTag(normalized))
+	b.WriteString(`" class="mention hashtag" rel="tag">#<span>`)
+	b.WriteString(normalized)
+	b.WriteString(`</span></a>`)
+
+	return b.String()
+}
+
+/*
+	EMOJI RENDERING STUFF
+*/
+
+// renderEmoji doesn't actually turn an emoji
+// ast.Node into HTML, but instead only adds it to
+// the custom renderer results for later processing.
+func (cr *customRenderer) renderEmoji(
+	w mdutil.BufWriter,
+	source []byte,
+	node ast.Node,
+	entering bool,
+) (ast.WalkStatus, error) {
+	if !entering {
+		return ast.WalkSkipChildren, nil
+	}
+
+	// This function is registered
+	// only for kindEmoji, and
+	// should not be called for
+	// any other node type.
+	n, ok := node.(*emoji)
+	if !ok {
+		log.Panic(cr.ctx, "type assertion failed")
+	}
+
+	// Get raw emoji string eg., ':boobs:'.
+	text := string(n.Segment.Value(source))
+
+	// Handle emoji and get text to render.
+	text = cr.handleEmoji(text)
+
+	// Write returned text into HTML.
+	if _, err := w.WriteString(text); err != nil {
+		// We don't have much recourse if this fails.
+		log.Errorf(cr.ctx, "error writing HTML: %s", err)
+	}
+
+	return ast.WalkSkipChildren, nil
+}
+
+// handleEmoji takes a string in the form ':some_emoji:',
+// and does the following:
+//
+//   - Try to get emoji from the db.
+//   - Add emoji to cr.results.Emojis slice if found and useable.
+//
+// This function will always return the unaltered input
+// text, since emojification is handled elsewhere.
+func (cr *customRenderer) handleEmoji(text string) string {
+	// Check if text points to a valid
+	// local emoji by using its shortcode.
+	//
+	// The shortcode is the text
+	// between enclosing ':' chars.
+	shortcode := strings.Trim(text, ":")
+
+	// Try to fetch emoji as a locally stored emoji.
+	emoji, err := cr.db.GetEmojiByShortcodeDomain(cr.ctx, shortcode, "")
+	if err != nil && !errors.Is(err, db.ErrNoEntries) {
+		log.Errorf(nil, "db error getting local emoji with shortcode %s: %s", shortcode, err)
+	}
+
+	if emoji == nil {
+		// No emoji found for this
+		// shortcode, oh well!
+		return text
+	}
+
+	if *emoji.Disabled || !*emoji.VisibleInPicker {
+		// Emoji was found but not useable.
+		return text
+	}
+
+	// Emoji was found and useable.
+	// Append to result if not done already.
+	//
+	// This prevents multiple uses of an emoji
+	// in the same status generating multiple
+	// entries for the same emoji in result.
+	func() {
+		for _, e := range cr.result.Emojis {
+			if emoji.Shortcode == e.Shortcode {
+				// Already appended.
+				return
+			}
+		}
+
+		// Not appended yet.
+		cr.result.Emojis = append(cr.result.Emojis, emoji)
+	}()
+
+	return text
+}