1 files changed, 60 insertions, 6 deletions
diff --git a/emacs/.emacs.d/lisp/my/my-emms.el b/emacs/.emacs.d/lisp/my/my-emms.el
index cdbe57a..054d3d9 100644
--- a/emacs/.emacs.d/lisp/my/my-emms.el
+++ b/emacs/.emacs.d/lisp/my/my-emms.el
@@ -421,12 +421,66 @@ under /zzz-seren/."
 (defun my-emms-playlist-random-album ()
   (interactive)
   (with-current-emms-playlist
-    (goto-line (1+ (random (count-lines (point-min) (point-max)))))
-    (let ((album-name (my-emms-playlist-album-name-at-point)))
-      (goto-char (point-min))
-      (search-forward album-name)
-      (beginning-of-line)
-      (emms-playlist-mode-play-current-track))))
+   (goto-line (1+ (random (count-lines (point-min) (point-max)))))
+   (let ((album-name (my-emms-playlist-album-name-at-point)))
+     (goto-char (point-min))
+     (search-forward album-name)
+     (beginning-of-line)
+     (emms-playlist-mode-play-current-track))))
+
+(defvar my-emms-playlist-group-length 20
+  "Length of a track group in an album.")
+
+(defvar my-emms-playlist-tail-group-length 10
+  "Min length of a tail track group in an album.")
+
+(defun my-emms-playlist-group-bounds ()
+  "Return (GROUP-START . GROUP-END) of the group the current track belongs to."
+  (save-excursion
+    (let* ((album-name (my-emms-playlist-album-name-at-point))
+           (current-ln (line-number-at-pos))
+           (start-ln (progn (goto-char (point-min))
+                            (re-search-forward (concat "^" (regexp-quote album-name)))
+                            (line-number-at-pos)))
+           (end-ln (progn (goto-char (point-max))
+                          (re-search-backward (concat "^" (regexp-quote album-name)))
+                          (1+ (line-number-at-pos))))
+           ;; How many tracks have been from the start of the album
+           ;; (exclusive)
+           (past (- current-ln start-ln))
+           ;; How many tracks to go (inclusive)
+           (remain (- end-ln current-ln))
+           (idx (/ past my-emms-playlist-group-length))
+           (maybe-group-start (+ start-ln (* idx my-emms-playlist-group-length)))
+           (group-start
+            (if (< (- end-ln maybe-group-start) my-emms-playlist-tail-group-length)
+                ;; Too close to the end of the album
+                (max start-ln (- maybe-group-start my-emms-playlist-group-length))
+              maybe-group-start))
+           (group-end
+            (if (<= remain my-emms-playlist-tail-group-length)
+                end-ln
+              (min end-ln (+ group-start my-emms-playlist-group-length)))))
+      (cons group-start group-end))))
+
+(defun my-emms-playlist-random-group ()
+  (interactive)
+  (with-current-emms-playlist
+   (goto-line (1+ (random (count-lines (point-min) (point-max)))))
+   (pcase-let ((`(,group-start . ,group-end) (my-emms-playlist-group-bounds)))
+     (goto-line group-start)
+     (emms-playlist-mode-play-current-track))))
+
+(defun my-emms-next-track-or-random-group ()
+  (interactive)
+  (with-current-buffer emms-playlist-buffer
+    (emms-playlist-mode-center-current)
+    (pcase-let ((`(,group-start . ,group-end) (my-emms-playlist-group-bounds)))
+      (when emms-player-playing-p (emms-stop))
+      (if (>= (1+ (line-number-at-pos)) group-end)
+          (my-emms-playlist-random-group)
+        (emms-playlist-current-select-next)
+        (emms-start)))))
 
 ;;; override the minor mode
 ;;;###autoload