Blame view: add guesstimation of line number when blaming parent commit

... by looking through the commit's diff for the hunk which introduced
the line. Also, try to set the filename properly.

diff --git a/tig.c b/tig.c
index fb6231f256fbbfbcbb1545dc7caaa6d0a69dd3c1..04a44db37ec0d11dfe33e5bda4be1b83fb3da151 100644 (file)
--- a/tig.c
+++ b/tig.c
@@ -4413,6 +4413,42 @@ check_blame_commit(struct blame *blame)
        return FALSE;
 }
 
+static void
+setup_blame_parent_line(struct view *view, struct blame *blame)
+{
+       const char *diff_tree_argv[] = {
+               "git", "diff-tree", "-U0", blame->commit->id,
+                       "--", blame->commit->filename, NULL
+       };
+       struct io io = {};
+       int parent_lineno = -1;
+       int blamed_lineno = -1;
+       char *line;
+
+       if (!run_io(&io, diff_tree_argv, NULL, IO_RD))
+               return;
+
+       while ((line = io_get(&io, '\n', TRUE))) {
+               if (*line == '@') {
+                       char *pos = strchr(line, '+');
+
+                       parent_lineno = atoi(line + 4);
+                       if (pos)
+                               blamed_lineno = atoi(pos + 1);
+
+               } else if (*line == '+' && parent_lineno != -1) {
+                       if (blame->lineno == blamed_lineno - 1 &&
+                           !strcmp(blame->text, line + 1)) {
+                               view->lineno = parent_lineno ? parent_lineno - 1 : 0;
+                               break;
+                       }
+                       blamed_lineno++;
+               }
+       }
+
+       done_io(&io);
+}
+
 static enum request
 blame_request(struct view *view, enum request request, struct line *line)
 {
@@ -4432,8 +4468,11 @@ blame_request(struct view *view, enum request request, struct line *line)
 
        case REQ_PARENT:
                if (check_blame_commit(blame) &&
-                   select_commit_parent(blame->commit->id, opt_ref))
+                   select_commit_parent(blame->commit->id, opt_ref)) {
+                       string_copy(opt_file, blame->commit->filename);
+                       setup_blame_parent_line(view, blame);
                        open_view(view, REQ_VIEW_BLAME, OPEN_REFRESH);
+               }
                break;
 
        case REQ_ENTER: