From c1cd290d1f83d3d1c2d081d734e8d213f12cc06b Mon Sep 17 00:00:00 2001
From: Jeff Smith <whydoubt@gmail.com>
Date: Sun, 1 Oct 2017 23:39:08 -0500
Subject: ui-blame: add blame UI

Implement a page which provides the blame view of a specified file.

This feature is controlled by a new config variable, "enable-blame",
which is disabled by default.

Signed-off-by: Jeff Smith <whydoubt@gmail.com>
Reviewed-by: John Keeping <john@keeping.me.uk>
---
 cgit.c       |   2 +
 cgit.css     |   8 +++
 cgit.h       |   1 +
 cgit.mk      |   1 +
 cgitrc.5.txt |   9 +++
 cmd.c        |  12 +++-
 ui-blame.c   | 227 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 ui-blame.h   |   6 ++
 8 files changed, 265 insertions(+), 1 deletion(-)
 create mode 100644 ui-blame.c
 create mode 100644 ui-blame.h

diff --git a/cgit.c b/cgit.c
index 1dae4b8..972a67e 100644
--- a/cgit.c
+++ b/cgit.c
@@ -167,6 +167,8 @@ static void config_cb(const char *name, const char *value)
 		ctx.cfg.enable_index_links = atoi(value);
 	else if (!strcmp(name, "enable-index-owner"))
 		ctx.cfg.enable_index_owner = atoi(value);
+	else if (!strcmp(name, "enable-blame"))
+		ctx.cfg.enable_blame = atoi(value);
 	else if (!strcmp(name, "enable-commit-graph"))
 		ctx.cfg.enable_commit_graph = atoi(value);
 	else if (!strcmp(name, "enable-log-filecount"))
diff --git a/cgit.css b/cgit.css
index 1dc2c11..836f8ae 100644
--- a/cgit.css
+++ b/cgit.css
@@ -329,6 +329,14 @@ div#cgit table.ssdiff td.lineno a:hover {
 	color: black;
 }
 
+div#cgit table.blame tr:nth-child(even) {
+	background: #eee;
+}
+
+div#cgit table.blame tr:nth-child(odd) {
+	background: white;
+}
+
 div#cgit table.bin-blob {
 	margin-top: 0.5em;
 	border: solid 1px black;
diff --git a/cgit.h b/cgit.h
index fbc6c6a..0b88dcd 100644
--- a/cgit.h
+++ b/cgit.h
@@ -228,6 +228,7 @@ struct cgit_config {
 	int enable_http_clone;
 	int enable_index_links;
 	int enable_index_owner;
+	int enable_blame;
 	int enable_commit_graph;
 	int enable_log_filecount;
 	int enable_log_linecount;
diff --git a/cgit.mk b/cgit.mk
index 90a2346..3fcc1ca 100644
--- a/cgit.mk
+++ b/cgit.mk
@@ -77,6 +77,7 @@ CGIT_OBJ_NAMES += parsing.o
 CGIT_OBJ_NAMES += scan-tree.o
 CGIT_OBJ_NAMES += shared.o
 CGIT_OBJ_NAMES += ui-atom.o
+CGIT_OBJ_NAMES += ui-blame.o
 CGIT_OBJ_NAMES += ui-blob.o
 CGIT_OBJ_NAMES += ui-clone.o
 CGIT_OBJ_NAMES += ui-commit.o
diff --git a/cgitrc.5.txt b/cgitrc.5.txt
index 9fcf445..4da166c 100644
--- a/cgitrc.5.txt
+++ b/cgitrc.5.txt
@@ -141,6 +141,11 @@ embedded::
 	suitable for embedding in other html pages. Default value: none. See
 	also: "noheader".
 
+enable-blame::
+	Flag which, when set to "1", will allow cgit to provide a "blame" page
+	for files, and will make it generate links to that page in appropriate
+	places. Default value: "0".
+
 enable-commit-graph::
 	Flag which, when set to "1", will make cgit print an ASCII-art commit
 	history graph to the left of the commit messages in the repository
@@ -799,6 +804,10 @@ enable-http-clone=1
 enable-index-links=1
 
 
+# Enable blame page and create links to it from tree page
+enable-blame=1
+
+
 # Enable ASCII art commit history graph on the log pages
 enable-commit-graph=1
 
diff --git a/cmd.c b/cmd.c
index d280e95..63f0ae5 100644
--- a/cmd.c
+++ b/cmd.c
@@ -1,6 +1,6 @@
 /* cmd.c: the cgit command dispatcher
  *
- * Copyright (C) 2006-2014 cgit Development Team <cgit@lists.zx2c4.com>
+ * Copyright (C) 2006-2017 cgit Development Team <cgit@lists.zx2c4.com>
  *
  * Licensed under GNU General Public License v2
  *   (see COPYING for full license text)
@@ -11,6 +11,7 @@
 #include "cache.h"
 #include "ui-shared.h"
 #include "ui-atom.h"
+#include "ui-blame.h"
 #include "ui-blob.h"
 #include "ui-clone.h"
 #include "ui-commit.h"
@@ -63,6 +64,14 @@ static void about_fn(void)
 		cgit_print_site_readme();
 }
 
+static void blame_fn(void)
+{
+	if (ctx.cfg.enable_blame)
+		cgit_print_blame();
+	else
+		cgit_print_error_page(403, "Forbidden", "Blame is disabled");
+}
+
 static void blob_fn(void)
 {
 	cgit_print_blob(ctx.qry.sha1, ctx.qry.path, ctx.qry.head, 0);
@@ -164,6 +173,7 @@ struct cgit_cmd *cgit_get_cmd(void)
 		def_cmd(HEAD, 1, 0, 1),
 		def_cmd(atom, 1, 0, 0),
 		def_cmd(about, 0, 0, 0),
+		def_cmd(blame, 1, 1, 0),
 		def_cmd(blob, 1, 0, 0),
 		def_cmd(commit, 1, 1, 0),
 		def_cmd(diff, 1, 1, 0),
diff --git a/ui-blame.c b/ui-blame.c
new file mode 100644
index 0000000..62cf431
--- /dev/null
+++ b/ui-blame.c
@@ -0,0 +1,227 @@
+/* ui-blame.c: functions for blame output
+ *
+ * Copyright (C) 2006-2017 cgit Development Team <cgit@lists.zx2c4.com>
+ *
+ * Licensed under GNU General Public License v2
+ *   (see COPYING for full license text)
+ */
+
+#include "cgit.h"
+#include "ui-blame.h"
+#include "html.h"
+#include "ui-shared.h"
+#include "argv-array.h"
+#include "blame.h"
+
+
+static char *emit_suspect_detail(struct blame_origin *suspect)
+{
+	struct commitinfo *info;
+	struct strbuf detail = STRBUF_INIT;
+
+	info = cgit_parse_commit(suspect->commit);
+
+	strbuf_addf(&detail, "author  %s", info->author);
+	if (!ctx.cfg.noplainemail)
+		strbuf_addf(&detail, " %s", info->author_email);
+	strbuf_addf(&detail, "  %s\n",
+		    show_date(info->author_date, info->author_tz,
+				    cgit_date_mode(DATE_ISO8601)));
+
+	strbuf_addf(&detail, "committer  %s", info->committer);
+	if (!ctx.cfg.noplainemail)
+		strbuf_addf(&detail, " %s", info->committer_email);
+	strbuf_addf(&detail, "  %s\n\n",
+		    show_date(info->committer_date, info->committer_tz,
+				    cgit_date_mode(DATE_ISO8601)));
+
+	strbuf_addstr(&detail, info->subject);
+
+	cgit_free_commitinfo(info);
+	return strbuf_detach(&detail, NULL);
+}
+
+static void emit_blame_entry(struct blame_scoreboard *sb,
+			     struct blame_entry *ent)
+{
+	struct blame_origin *suspect = ent->suspect;
+	struct object_id *oid = &suspect->commit->object.oid;
+	const char *numberfmt = "<a id='n%1$d' href='#n%1$d'>%1$d</a>\n";
+	const char *cp, *cpend;
+
+	char *detail = emit_suspect_detail(suspect);
+
+	html("<tr><td class='sha1 lines'>");
+	cgit_commit_link(find_unique_abbrev(oid->hash, DEFAULT_ABBREV), detail,
+			 NULL, ctx.qry.head, oid_to_hex(oid), suspect->path);
+	html("</td>\n");
+
+	free(detail);
+
+	if (ctx.cfg.enable_tree_linenumbers) {
+		unsigned long lineno = ent->lno;
+		html("<td class='linenumbers'><pre>");
+		while (lineno < ent->lno + ent->num_lines)
+			htmlf(numberfmt, ++lineno);
+		html("</pre></td>\n");
+	}
+
+	cp = blame_nth_line(sb, ent->lno);
+	cpend = blame_nth_line(sb, ent->lno + ent->num_lines);
+
+	html("<td class='lines'><pre><code>");
+	html_ntxt(cp, cpend - cp);
+	html("</code></pre></td></tr>\n");
+}
+
+struct walk_tree_context {
+	char *curr_rev;
+	int match_baselen;
+	int state;
+};
+
+static void print_object(const unsigned char *sha1, const char *path,
+			 const char *basename, const char *rev)
+{
+	enum object_type type;
+	unsigned long size;
+	struct argv_array rev_argv = ARGV_ARRAY_INIT;
+	struct rev_info revs;
+	struct blame_scoreboard sb;
+	struct blame_origin *o;
+	struct blame_entry *ent = NULL;
+
+	type = sha1_object_info(sha1, &size);
+	if (type == OBJ_BAD) {
+		cgit_print_error_page(404, "Not found", "Bad object name: %s",
+				      sha1_to_hex(sha1));
+		return;
+	}
+
+	argv_array_push(&rev_argv, "blame");
+	argv_array_push(&rev_argv, rev);
+	init_revisions(&revs, NULL);
+	DIFF_OPT_SET(&revs.diffopt, ALLOW_TEXTCONV);
+	setup_revisions(rev_argv.argc, rev_argv.argv, &revs, NULL);
+	init_scoreboard(&sb);
+	sb.revs = &revs;
+	setup_scoreboard(&sb, path, &o);
+	o->suspects = blame_entry_prepend(NULL, 0, sb.num_lines, o);
+	prio_queue_put(&sb.commits, o->commit);
+	blame_origin_decref(o);
+	sb.ent = NULL;
+	sb.path = path;
+	assign_blame(&sb, 0);
+	blame_sort_final(&sb);
+	blame_coalesce(&sb);
+
+	cgit_set_title_from_path(path);
+
+	cgit_print_layout_start();
+	htmlf("blob: %s (", sha1_to_hex(sha1));
+	cgit_plain_link("plain", NULL, NULL, ctx.qry.head, rev, path);
+	html(") (");
+	cgit_tree_link("tree", NULL, NULL, ctx.qry.head, rev, path);
+	html(")\n");
+
+	if (ctx.cfg.max_blob_size && size / 1024 > ctx.cfg.max_blob_size) {
+		htmlf("<div class='error'>blob size (%ldKB)"
+		      " exceeds display size limit (%dKB).</div>",
+		      size / 1024, ctx.cfg.max_blob_size);
+		return;
+	}
+
+	html("<table class='blame blob'>");
+	for (ent = sb.ent; ent; ) {
+		struct blame_entry *e = ent->next;
+		emit_blame_entry(&sb, ent);
+		free(ent);
+		ent = e;
+	}
+	html("</table>\n");
+	free((void *)sb.final_buf);
+
+	cgit_print_layout_end();
+}
+
+static int walk_tree(const unsigned char *sha1, struct strbuf *base,
+		     const char *pathname, unsigned mode, int stage,
+		     void *cbdata)
+{
+	struct walk_tree_context *walk_tree_ctx = cbdata;
+
+	if (base->len == walk_tree_ctx->match_baselen) {
+		if (S_ISREG(mode)) {
+			struct strbuf buffer = STRBUF_INIT;
+			strbuf_addbuf(&buffer, base);
+			strbuf_addstr(&buffer, pathname);
+			print_object(sha1, buffer.buf, pathname,
+				     walk_tree_ctx->curr_rev);
+			strbuf_release(&buffer);
+			walk_tree_ctx->state = 1;
+		} else if (S_ISDIR(mode)) {
+			walk_tree_ctx->state = 2;
+		}
+	} else if (base->len < INT_MAX
+			&& (int)base->len > walk_tree_ctx->match_baselen) {
+		walk_tree_ctx->state = 2;
+	} else if (S_ISDIR(mode)) {
+		return READ_TREE_RECURSIVE;
+	}
+	return 0;
+}
+
+static int basedir_len(const char *path)
+{
+	char *p = strrchr(path, '/');
+	if (p)
+		return p - path + 1;
+	return 0;
+}
+
+void cgit_print_blame(void)
+{
+	const char *rev = ctx.qry.sha1;
+	struct object_id oid;
+	struct commit *commit;
+	struct pathspec_item path_items = {
+		.match = ctx.qry.path,
+		.len = ctx.qry.path ? strlen(ctx.qry.path) : 0
+	};
+	struct pathspec paths = {
+		.nr = 1,
+		.items = &path_items
+	};
+	struct walk_tree_context walk_tree_ctx = {
+		.state = 0
+	};
+
+	if (!rev)
+		rev = ctx.qry.head;
+
+	if (get_oid(rev, &oid)) {
+		cgit_print_error_page(404, "Not found",
+			"Invalid revision name: %s", rev);
+		return;
+	}
+	commit = lookup_commit_reference(&oid);
+	if (!commit || parse_commit(commit)) {
+		cgit_print_error_page(404, "Not found",
+			"Invalid commit reference: %s", rev);
+		return;
+	}
+
+	walk_tree_ctx.curr_rev = xstrdup(rev);
+	walk_tree_ctx.match_baselen = (path_items.match) ?
+				       basedir_len(path_items.match) : -1;
+
+	read_tree_recursive(commit->tree, "", 0, 0, &paths, walk_tree,
+		&walk_tree_ctx);
+	if (!walk_tree_ctx.state)
+		cgit_print_error_page(404, "Not found", "Not found");
+	else if (walk_tree_ctx.state == 2)
+		cgit_print_error_page(404, "No blame for folders",
+			"Blame is not available for folders.");
+
+	free(walk_tree_ctx.curr_rev);
+}
diff --git a/ui-blame.h b/ui-blame.h
new file mode 100644
index 0000000..5b97e03
--- /dev/null
+++ b/ui-blame.h
@@ -0,0 +1,6 @@
+#ifndef UI_BLAME_H
+#define UI_BLAME_H
+
+extern void cgit_print_blame(void);
+
+#endif /* UI_BLAME_H */
-- 
cgit