command: add playlist-next-playlist and playlist-prev-playlist

playlist-prev-playlist goes to the beginning of the previous playlist
because this seems more useful and symmetrical to
playlist-next-playlist. It does not go to the beginning when the current
playlist-path starts with the previous playlist-path, e.g. with mpv
--loop-playlist foo/, which expands to foo/{1..9}.zip, the current
playlist path foo/1.zip beings with the playlist-path foo/ of {2..9}.zip
and thus playlist-prev-playlist goes to 9.zip rather than to 2.zip.

Closes #12495.

1 files changed, 68 insertions, 0 deletions

diff --git a/common/playlist.c b/common/playlist.c
index 78a7713462..e79a96b402 100644
--- a/common/playlist.c
+++ b/common/playlist.c
@@ -214,6 +214,74 @@ struct playlist_entry *playlist_entry_get_rel(struct playlist_entry *e,
     return playlist_entry_from_index(e->pl, e->pl_index + direction);
 }
 
+struct playlist_entry *playlist_get_first_in_next_playlist(struct playlist *pl,
+                                                           int direction)
+{
+    struct playlist_entry *entry = playlist_get_next(pl, direction);
+    if (!entry)
+        return NULL;
+
+    while (entry && entry->playlist_path &&
+           strcmp(entry->playlist_path, pl->current->playlist_path) == 0)
+        entry = playlist_entry_get_rel(entry, direction);
+
+    if (direction < 0)
+        entry = playlist_get_first_in_same_playlist(entry,
+                                                    pl->current->playlist_path);
+
+    return entry;
+}
+
+struct playlist_entry *playlist_get_first_in_same_playlist(
+    struct playlist_entry *entry, char *current_playlist_path)
+{
+    void *tmp = talloc_new(NULL);
+
+    if (!entry || !entry->playlist_path)
+        goto exit;
+
+    // Don't go to the beginning of the playlist when the current playlist-path
+    // starts with the previous playlist-path, e.g. with mpv --loop-playlist
+    // archive_dir/, which expands to archive_dir/{1..9}.zip, the current
+    // playlist path "archive_dir/1.zip" begins with the playlist-path
+    // "archive_dir/" of {2..9}.zip, so go to 9.zip instead of 2.zip. But
+    // playlist-prev-playlist from e.g. the directory "foobar" to the directory
+    // "foo" should still go to the first entry in "foo/", and this should all
+    // work whether mpv's arguments have trailing slashes or not, e.g. in the
+    // first example:
+    // mpv archive_dir results in the playlist-paths "archive_dir/1.zip" and
+    // "archive_dir"
+    // mpv archive_dir/ in "archive_dir/1.zip" and "archive_dir/"
+    // mpv archive_dir// in "archive_dir//1.zip" and "archive_dir//"
+    // Always adding a separator to entry->playlist_path to fix the foobar foo
+    // case would break the previous 2 cases instead. Stripping the separator
+    // from entry->playlist_path if present and appending it again makes this
+    // work in all cases.
+    char* playlist_path = talloc_strdup(tmp, entry->playlist_path);
+    mp_path_strip_trailing_separator(playlist_path);
+    if (bstr_startswith(bstr0(current_playlist_path),
+                        bstr0(talloc_strdup_append(playlist_path, "/")))
+#if HAVE_DOS_PATHS
+        ||
+        bstr_startswith(bstr0(current_playlist_path),
+                        bstr0(talloc_strdup_append(playlist_path, "\\")))
+#endif
+       )
+        goto exit;
+
+    struct playlist_entry *prev = playlist_entry_get_rel(entry, -1);
+
+    while (prev && prev->playlist_path &&
+           strcmp(prev->playlist_path, entry->playlist_path) == 0) {
+        entry = prev;
+        prev = playlist_entry_get_rel(entry, -1);
+    }
+
+exit:
+    talloc_free(tmp);
+    return entry;
+}
+
 void playlist_add_base_path(struct playlist *pl, bstr base_path)
 {
     if (base_path.len == 0 || bstrcmp0(base_path, ".") == 0)