;;; test-music-config--renumber-rows.el --- Tests for playlist row numbering -*- coding: utf-8; lexical-binding: t; -*-
;;
;; Author: Craig Jennings <c@cjennings.net>
;;
;;; Commentary:
;; Playlist rows carry a numeric overlay prefix so the cursor stays visible
;; when it sits on a cover-art thumbnail and each row's position in the list
;; is readable.  The renumber walks the buffer and rebuilds the overlays; a
;; buffer-local after-change hook debounces it behind an idle timer.  Overlays
;; leave the buffer text untouched (EMMS owns it), so these tests drive plain
;; temp buffers.

;;; Code:

(require 'ert)
(require 'cl-lib)

(defvar cj/custom-keymap (make-sparse-keymap)
  "Stub keymap for testing.")

(require 'music-config)

(defun test-music-renumber--numbers (buffer)
  "Return the overlay number strings in BUFFER, in position order."
  (with-current-buffer buffer
    (mapcar (lambda (ov) (overlay-get ov 'before-string))
            (sort (seq-filter (lambda (ov) (overlay-get ov 'cj-music-row-number))
                              (overlays-in (point-min) (point-max)))
                  (lambda (a b) (< (overlay-start a) (overlay-start b)))))))

;;; Normal Cases

(ert-deftest test-music-renumber-rows-numbers-each-line ()
  "Normal: every non-blank line gets a sequential number overlay."
  (with-temp-buffer
    (insert "track one\ntrack two\ntrack three\n")
    (cj/music--renumber-rows (current-buffer))
    (should (equal (mapcar #'substring-no-properties
                           (test-music-renumber--numbers (current-buffer)))
                   '("  1 " "  2 " "  3 ")))))

(ert-deftest test-music-renumber-rows-idempotent ()
  "Normal: renumbering twice leaves one overlay per line, not two."
  (with-temp-buffer
    (insert "track one\ntrack two\n")
    (cj/music--renumber-rows (current-buffer))
    (cj/music--renumber-rows (current-buffer))
    (should (= 2 (length (test-music-renumber--numbers (current-buffer)))))))

(ert-deftest test-music-renumber-rows-number-carries-cursor-property ()
  "Normal: the number string carries a cursor property.  Point is pinned at
the row start, and without the property redisplay draws the cursor after
the before-string -- on the album-art thumbnail, where it's invisible."
  (with-temp-buffer
    (insert "track one\n")
    (cj/music--renumber-rows (current-buffer))
    (let ((s (car (test-music-renumber--numbers (current-buffer)))))
      (should (get-text-property 0 'cursor s)))))

;;; Boundary Cases

(ert-deftest test-music-renumber-rows-skips-blank-lines ()
  "Boundary: blank lines are not numbered and don't advance the count."
  (with-temp-buffer
    (insert "track one\n\ntrack two\n")
    (cj/music--renumber-rows (current-buffer))
    (should (equal (mapcar #'substring-no-properties
                           (test-music-renumber--numbers (current-buffer)))
                   '("  1 " "  2 ")))))

(ert-deftest test-music-renumber-rows-empty-buffer-no-overlays ()
  "Boundary: an empty buffer gets no overlays and no error."
  (with-temp-buffer
    (cj/music--renumber-rows (current-buffer))
    (should-not (test-music-renumber--numbers (current-buffer)))))

;;; Error Cases

(ert-deftest test-music-renumber-rows-dead-buffer-noop ()
  "Error: renumbering a killed buffer is a silent no-op (the debounce timer
can fire after the playlist buffer is gone)."
  (let ((buf (generate-new-buffer " *test-renumber-dead*")))
    (kill-buffer buf)
    (should-not (cj/music--renumber-rows buf))))

(ert-deftest test-music-renumber-rows-number-outranks-header-overlay ()
  "Normal: number overlays carry a priority above the header overlay's 100.
The header block is a same-position overlay string at the buffer start;
without the higher priority, row 1's number renders above the header
instead of next to its own track."
  (with-temp-buffer
    (insert "track one\n")
    (cj/music--renumber-rows (current-buffer))
    (let ((ov (car (seq-filter (lambda (o) (overlay-get o 'cj-music-row-number))
                               (overlays-in (point-min) (point-max))))))
      (should (> (or (overlay-get ov 'priority) 0) 100)))))

(ert-deftest test-music-ensure-playlist-buffer-logical-line-motion ()
  "Normal: the playlist moves by logical lines, not screen lines.  The
multi-line header overlay string at position 1 otherwise absorbs every
next-line from the top row -- vertical motion steps through the header's
display and maps back to the same buffer position, so arrows look dead."
  (let (created)
    (cl-letf (((symbol-function 'emms-playlist-mode) #'ignore))
      (unwind-protect
          (progn
            (setq created (cj/music--ensure-playlist-buffer))
            (with-current-buffer created
              (should (local-variable-p 'line-move-visual))
              (should-not line-move-visual)))
        (when (buffer-live-p created) (kill-buffer created))))))

;;; Current-row indicator

(ert-deftest test-music-highlight-current-number-marks-current-row ()
  "Normal: the current row's number renders inverse-video; moving to another
row restores the old one and marks the new one.  The block cursor only
draws in the selected window, so the number itself carries the mark."
  (with-temp-buffer
    (insert "track one\ntrack two\ntrack three\n")
    (cj/music--renumber-rows (current-buffer))
    (goto-char (point-min))
    (forward-line 1)
    (cj/music--highlight-current-number)
    (let ((numbers (test-music-renumber--numbers (current-buffer))))
      (should-not (plist-get (get-text-property 0 'face (nth 0 numbers)) :inverse-video))
      (should (plist-get (get-text-property 0 'face (nth 1 numbers)) :inverse-video)))
    (forward-line 1)
    (cj/music--highlight-current-number)
    (let ((numbers (test-music-renumber--numbers (current-buffer))))
      (should-not (plist-get (get-text-property 0 'face (nth 1 numbers)) :inverse-video))
      (should (plist-get (get-text-property 0 'face (nth 2 numbers)) :inverse-video)))))

(ert-deftest test-music-highlight-current-number-survives-renumber ()
  "Boundary: a renumber rebuilds the overlays; the highlight re-applies to
the current row rather than pointing at a dead overlay."
  (with-temp-buffer
    (insert "track one\ntrack two\n")
    (cj/music--renumber-rows (current-buffer))
    (goto-char (point-min))
    (forward-line 1)
    (cj/music--highlight-current-number)
    (cj/music--renumber-rows (current-buffer))
    (let ((numbers (test-music-renumber--numbers (current-buffer))))
      (should (plist-get (get-text-property 0 'face (nth 1 numbers)) :inverse-video)))))

(ert-deftest test-music-highlight-current-number-keeps-cursor-property ()
  "Boundary: re-facing a number keeps the cursor property intact."
  (with-temp-buffer
    (insert "track one\n")
    (cj/music--renumber-rows (current-buffer))
    (goto-char (point-min))
    (cj/music--highlight-current-number)
    (let ((s (car (test-music-renumber--numbers (current-buffer)))))
      (should (get-text-property 0 'cursor s)))))

(ert-deftest test-music-ensure-playlist-buffer-sticky-hl-line ()
  "Normal: hl-line in the playlist stays visible when the window isn't
selected -- the dock is glanced at from other windows constantly."
  (let (created)
    (cl-letf (((symbol-function 'emms-playlist-mode) #'ignore))
      (unwind-protect
          (progn
            (setq created (cj/music--ensure-playlist-buffer))
            (should (buffer-local-value 'hl-line-sticky-flag created)))
        (when (buffer-live-p created) (kill-buffer created))))))

;;; Sticky header

(ert-deftest test-music-stick-header-moves-overlay-to-window-start ()
  "Normal: a scroll re-anchors the header overlay at the new window start,
so the header block stays at the top of the window while the list scrolls."
  (with-temp-buffer
    (insert "track one\ntrack two\ntrack three\ntrack four\n")
    (setq cj/music--header-overlay (make-overlay (point-min) (point-min)))
    (save-window-excursion
      (set-window-buffer (selected-window) (current-buffer))
      (let ((start (save-excursion (goto-char (point-min)) (forward-line 2) (point))))
        (cj/music--stick-header (selected-window) start)
        (should (= (overlay-start cj/music--header-overlay) start))
        ;; Converges: the same start again is a no-op, not a loop.
        (cj/music--stick-header (selected-window) start)
        (should (= (overlay-start cj/music--header-overlay) start))))))

(ert-deftest test-music-stick-header-no-overlay-noop ()
  "Boundary: no header overlay yet -- the scroll handler is a silent no-op."
  (with-temp-buffer
    (insert "track one\n")
    (setq cj/music--header-overlay nil)
    (save-window-excursion
      (set-window-buffer (selected-window) (current-buffer))
      (should-not (cj/music--stick-header (selected-window) (point-min))))))

(ert-deftest test-music-header-anchor-position-displayed-vs-not ()
  "Normal: the header anchors at the displaying window's start; an
undisplayed buffer anchors at the top."
  (with-temp-buffer
    (insert "track one\ntrack two\ntrack three\ntrack four\n")
    (save-window-excursion
      (set-window-buffer (selected-window) (current-buffer))
      (let ((start (save-excursion (goto-char (point-min)) (forward-line 2) (point))))
        (set-window-start (selected-window) start)
        (should (= (cj/music--header-anchor-position) start))))
    ;; Not displayed after the excursion restores the old config.
    (should (= (cj/music--header-anchor-position) (point-min)))))

(ert-deftest test-music-ensure-playlist-buffer-wires-scroll-hook ()
  "Normal: the playlist buffer re-sticks its header on every window scroll."
  (let (created)
    (cl-letf (((symbol-function 'emms-playlist-mode) #'ignore))
      (unwind-protect
          (progn
            (setq created (cj/music--ensure-playlist-buffer))
            (with-current-buffer created
              (should (member #'cj/music--stick-header window-scroll-functions))))
        (when (buffer-live-p created) (kill-buffer created))))))

;;; Hook wiring

(ert-deftest test-music-renumber-ensure-playlist-buffer-wires-hook ()
  "Normal: the playlist buffer gets the debounced renumber on after-change."
  (let (created)
    (cl-letf (((symbol-function 'emms-playlist-mode) #'ignore))
      (unwind-protect
          (progn
            (setq created (cj/music--ensure-playlist-buffer))
            (with-current-buffer created
              (should (member #'cj/music--schedule-renumber after-change-functions))))
        (when (buffer-live-p created) (kill-buffer created))))))

(provide 'test-music-config--renumber-rows)
;;; test-music-config--renumber-rows.el ends here