Make references to Git commits clickable

Automatically detect Git commit identifiers, shorten them, and make them
link to the cgit interface.

Implements FS#43290.
Signed-off-by: Lukas Fleischer <lfleischer@archlinux.org>

aurweb/scripts/rendercomment.py

 #!/usr/bin/python3
 
 import re
+import pygit2
 import sys
 import bleach
 import markdown
 
+import aurweb.config
 import aurweb.db
 
+repo_path = aurweb.config.get('serve', 'repo-path')
+commit_uri = aurweb.config.get('options', 'commit_uri')
+
 
 class LinkifyPreprocessor(markdown.preprocessors.Preprocessor):
     _urlre = re.compile(r'(\b(?:https?|ftp):\/\/[\w\/\#~:.?+=&%@!\-;,]+?'
@@ -21,10 +26,53 @@ class LinkifyExtension(markdown.extensions.Extension):
         md.preprocessors.add('linkify', LinkifyPreprocessor(md), '_end')
 
 
+class GitCommitsPreprocessor(markdown.preprocessors.Preprocessor):
+    _oidre = re.compile(r'(\b)([0-9a-f]{7,40})(\b)')
+    _repo = pygit2.Repository(repo_path)
+    _head = None
+
+    def __init__(self, md, head):
+        self._head = head
+        super(markdown.preprocessors.Preprocessor, self).__init__(md)
+
+    def handleMatch(self, m):
+        oid = m.group(2)
+        if oid not in self._repo:
+            return oid
+
+        prefixlen = 12
+        while prefixlen < 40:
+            if oid[:prefixlen] in self._repo:
+                break
+            prefixlen += 1
+
+        html = '[`' + oid[:prefixlen] + '`]'
+        html += '(' + commit_uri % (self._head, oid[:prefixlen]) + ')'
+
+        return html
+
+    def run(self, lines):
+        return [self._oidre.sub(self.handleMatch, line) for line in lines]
+
+
+class GitCommitsExtension(markdown.extensions.Extension):
+    _head = None
+
+    def __init__(self, head):
+        self._head = head
+        super(markdown.extensions.Extension, self).__init__()
+
+    def extendMarkdown(self, md, md_globals):
+        preprocessor = GitCommitsPreprocessor(md, self._head)
+        md.preprocessors.add('git-commits', preprocessor, '_end')
+
+
 def get_comment(conn, commentid):
-    cur = conn.execute('SELECT Comments FROM PackageComments WHERE ID = ?',
-                       [commentid])
-    return cur.fetchone()[0]
+    cur = conn.execute('SELECT PackageComments.Comments, PackageBases.Name '
+                       'FROM PackageComments INNER JOIN PackageBases '
+                       'ON PackageBases.ID = PackageComments.PackageBaseID '
+                       'WHERE PackageComments.ID = ?', [commentid])
+    return cur.fetchone()
 
 
 def save_rendered_comment(conn, commentid, html):
@@ -37,8 +85,9 @@ def main():
 
     conn = aurweb.db.Connection()
 
-    text = get_comment(conn, commentid)
-    html = markdown.markdown(text, extensions=['nl2br', LinkifyExtension()])
+    text, pkgbase = get_comment(conn, commentid)
+    html = markdown.markdown(text, extensions=['nl2br', LinkifyExtension(),
+                                               GitCommitsExtension(pkgbase)])
     allowed_tags = bleach.sanitizer.ALLOWED_TAGS + ['p', 'br']
     html = bleach.clean(html, tags=allowed_tags)
     save_rendered_comment(conn, commentid, html)

conf/config.proto

@@ -30,6 +30,7 @@ auto_orphan_age = 15552000
 auto_delete_age = 86400
 source_file_uri =  https://aur.archlinux.org/cgit/aur.git/tree/%s?h=%s
 log_uri = https://aur.archlinux.org/cgit/aur.git/log/?h=%s
+commit_uri = https://aur.archlinux.org/cgit/aur.git/commit/?h=%s&id=%s
 snapshot_uri = /cgit/aur.git/snapshot/%s.tar.gz
 enable-maintenance = 1
 maintenance-exceptions = 127.0.0.1

test/setup.sh

@@ -29,6 +29,7 @@ aur_location = https://aur.archlinux.org
 aur_request_ml = aur-requests@archlinux.org
 enable-maintenance = 0
 maintenance-exceptions = 127.0.0.1
+commit_uri = https://aur.archlinux.org/cgit/aur.git/log/?h=%s&id=%s
 
 [notifications]
 notify-cmd = $NOTIFY

test/t2600-rendercomment.sh

@@ -6,6 +6,7 @@ test_description='rendercomment tests'
 
 test_expect_success 'Test comment rendering.' '
 	cat <<-EOD | sqlite3 aur.db &&
+	INSERT INTO PackageBases (ID, Name, PackagerUID, SubmittedTS, ModifiedTS, FlaggerComment) VALUES (1, "foobar", 1, 0, 0, "");
 	INSERT INTO PackageComments (ID, PackageBaseID, Comments, RenderedComment) VALUES (1, 1, "Hello world!
 	This is a comment.", "");
 	EOD