;;; livie-playlist.el --- Auxiliary mode to display playlist results

;; Copyright (C) 2018 - 2021

;;; Authors:

;; Charlie Ritter <chewzerita@posteo.net>
;; Jesus E. <heckyel@hyperbola.info>
;; Gabriele Rastello <gabriele.rastello@edu.unito.it>
;; Pablo BC <pablo.barraza@protonmail.com>

;;; Commentary:

;; livie grabs a list of youtube videos based on a search.
;; the user can then select a video to watch through `livie-player'

;;; Code:

(defvar livie-playlist-mode-map
  (let ((map (make-sparse-keymap)))
    (set-keymap-parent map text-mode-map)
    (define-key map "h" #'describe-mode)
    (define-key map "q" #'livie--quit-playlist-buffer)
    (define-key map ">" #'livie-playlist-next-page)
    (define-key map "<" #'livie-playlist-previous-page)
    (define-key map (kbd "<tab>") #'next-line)
    (define-key map (kbd "<backtab>") #'previous-line)
    (define-key map "A" #'livie--open-channel)
    (define-key map (kbd "RET") #'livie-open-entry)
    (define-key map "y" #'livie-watch-this-video)
    map)
  "Keymap for `livie-playlist-mode'.")

(define-derived-mode livie-playlist-mode livie-mode
  "livie-playlist-mode"
  "Mode for displaying livie-playlists.
\\{livie-playlist-mode-map}"
  (buffer-disable-undo)
  (make-local-variable 'livie-videos)
  (make-local-variable 'livie-playlist-title)
  (make-local-variable 'livie-playlistId)
  (setq-local livie-type-of-results "video")
  (setf buffer-read-only t))

(defun livie--process-playlist-videos (videos)
  "Process VIDEOS fetched from a playlist."
  (dotimes (i (length videos))
    (let* ((v (aref videos i)))
      (aset videos i  (livie-video--create
                       :title     (assoc-default 'title v)
		       :author    (assoc-default 'author v)
		       :authorId  (assoc-default 'authorId v)
		       :length    (assoc-default 'lengthSeconds v)
		       :id        (assoc-default 'videoId v)))))
  videos)

(defun livie-playlist--insert-entry (video)
  "Insert VIDEO into the playlist buffer."
  (insert (livie--format-author (livie-video-author video))
	  " "
	  (livie--format-video-length (livie-video-length video))
	  " "
	  (livie--format-title (livie-video-title video))))

(defun livie--get-playlist-videos ()
  "Fetch the videos of the current playlist."
  (let* ((entry (livie-get-current-video)))
    (if (livie-playlist-p entry)
	(progn
	  (switch-to-buffer (livie-playlist-title entry))
	  (unless (eq major-mode 'livie-playlist-mode)
	    (livie-playlist-mode))
	  (setf livie-playlistId (livie-playlist-playlistId entry))
	  (setf livie-playlist-title (livie-playlist-title entry))
	  (livie-playlist--query livie-playlistId livie-current-page)
	  (livie-playlist--draw-buffer)))))

(defun livie-playlist-previous-page ()
  "Go to the previous page of playlist."
  (interactive)
  (setf livie-current-page (1- livie-current-page))
  (livie-playlist--query livie-playlistId livie-current-page)
  (livie-playlist--draw-buffer))

(defun livie-playlist-next-page ()
  "Go to the next page of playlist."
  (interactive)
  (setf livie-current-page (1+ livie-current-page))
  (livie-playlist--query livie-playlistId livie-current-page)
  (livie-playlist--draw-buffer))

(defun livie-playlist--draw-buffer ()
  "Draw buffer for the current playlist."
  (let ((inhibit-read-only t))
    (erase-buffer)
    (setq header-line-format (concat "Displaying videos from " (propertize livie-playlist-title 'face 'livie-parameter-face)
				     ", page "
				     (propertize (number-to-string livie-current-page) 'face 'livie-parameter-face)))
    (seq-do (lambda (v)
	      (livie-playlist--insert-entry v)
	      (insert "\n"))
	    livie-videos)
    (goto-char (point-min))))

(defun livie-playlist--query (playlistID page)
  "Query Invidious for videos from PLAYLISTID on PAGE."
  (let* ((results (livie--API-call (concat "playlists/" livie-playlistId) '(("fields" "videos")
									    ("page" ,livie-current-page)))))
    (setf livie-videos (livie--process-playlist-videos (assoc-default 'videos results)))))

(defun livie--quit-playlist-buffer ()
  "Deletes the current buffer."
  (interactive)
  (kill-buffer (current-buffer)))


(provide 'livie-playlist)

;;; livie-playlist.el ends here