;;; acdw-erc.el -*- lexical-binding: t; coding: utf-8-unix -*-

;; Author: Case Duckworth <(rot13-string "npqj@npqj.arg")>
;; Created: 24 May 2021
;; Keywords: configuration
;; URL: https://tildegit.org/acdw/emacs

;; This file is NOT part of GNU Emacs.

;;; License:
;; Everyone is permitted to do whatever with this software, without
;; limitation.  This software comes without any warranty whatsoever,
;; but with two pieces of advice:
;; - Don't hurt yourself.
;; - Make good choices.

;;; Commentary:
;; `acdw-erc' is a dumping ground for functions and stuff for ERC, so they
;; don't clutter up `init.el'.

;;; Code:

(defgroup acdw-erc nil
  "Customizations for ERC."
  :group 'erc)


;;; Show a different header-line face when ERC is disconnected.
;; https://www.emacswiki.org/emacs/ErcModeline#h5o-1

(defface erc/header-line-disconnected
  '((t (:foreground "black" :background "indianred")))
  "Face to use when ERC has been disconnected.")

(defun erc/update-header-line-show-disconnected ()
  "Use a different face in the header-line when disconnected."
  (erc-with-server-buffer
    (cond ((erc-server-process-alive) 'erc-header-line)
          (t 'erc/header-line-disconnected))))


;;; Convenience functions
;; from Prelude:
;; https://github.com/bbatsov/prelude/blob/master/modules/prelude-erc.el#L114

(defcustom erc/servers nil
  "The list of IRC servers to connect to with `erc/connect'."
  :type '(list string))

(defcustom erc/bye-message "See You Space Cowpokes."
  "Quit message sent when calling `erc/disconnect'."
  :type 'string)

(defun connect-to-erc (server &optional use-tls port nick)
  "Connects to IRC SERVER at PORT with NICK.
If USE-TLS is non-nil, use TLS."
  (let* ((use-tls (or use-tls t))
         (erc-fn (if use-tls #'erc-tls #'erc))
         (port (or port (if use-tls 6697 6667)))
         (nick (or nick erc-nick)))
    (funcall erc-fn
             :server server
             :port port
             :nick nick)))

(defun erc/connect ()
  "Connect to all the servers in `erc/servers'."
  (interactive)
  (require 'erc)
  (mapcar #'connect-to-erc erc/servers))

(defun filter-server-buffers ()
  (delq nil (mapcar (lambda (x)
                      (and (erc-server-buffer-p x) x))
                    (buffer-list))))

(defun erc/reconnect ()
  "Reconnect to all IRC servers."
  (interactive)
  (dolist (buffer (filter-server-buffers))
    (with-current-buffer buffer
      (ignore-errors
        (erc-cmd-RECONNECT)))))

(defun erc/disconnect ()
  "Disconnect from all IRC servers."
  (interactive)
  (dolist (buffer (filter-server-buffers))
    (with-message (format "Killing server buffer: %s" (buffer-name buffer))
      (with-current-buffer buffer
        (erc-quit-server erc/bye-message))))
  ;; TODO: kill all channel buffers
  (force-mode-line-update))

(defun acdw-erc/prompt ()
  "The prompt to show for ERC."
  ;; Rewrite s-truncate to avoid dependency.
  (let ((name (buffer-name))
        (ellipsis "~")
        (len erc-fill-static-center))
    (if (and len (> (length name) (- len 2)))
        (format "%s%s>"
                (substring name 0 (- len 2 (length ellipsis)))
                ellipsis)
      (propertize
       (format "%s%s>"
               name
               (let ((ss)               ; Rewrite s-repeat to avoid dependency.
                     (num (- len 2 (length name))))
                 (while (> num 0)
                   (setq ss (cons " " ss))
                   (setq num (1- num)))
                 (apply #'concat ss)))
       'read-only t
       'intangible t
       'cursor-intangible t))))

(defcustom erc-nick-truncate nil
  "The width at which to truncate a nick with `erc-format-truncate-@nick'."
  :group 'erc
  :type 'integer)

(defalias 'erc-propertize 'propertize)  ; I guess...taken out in 28 ?

(defun erc-format-truncate-@nick (&optional user channel-data)
  "Format the nickname of USER as in `erc-format-@nick', with truncation.
Truncation is customized using the `erc-nick-truncate' variable.
See also `erc-format-nick-function'."
  (when user
    (let* ((nick (erc-server-user-nickname user))
           (prefix (erc-get-user-mode-prefix nick))
           (ellipsis "~")
           (max-len (- erc-nick-truncate 2 ; one each for < and >
                       (length ellipsis)
                       (length prefix))))
      (concat (erc-propertize
               prefix
               'font-lock-face 'erc-nick-prefix-face)
              (if (and max-len (> (length nick) max-len))
                  (format "%s%s" (substring nick 0 max-len)
                          ellipsis)
                nick)))))


;;; Uh

(defun acdw-erc/erc-switch-to-buffer (&optional arg)
  "Prompt for ERC buffer to switch to.
Reverse prefix argument from `erc-switch-to-buffer'."
  (interactive "P")
  (erc-switch-to-buffer (not arg)))


;;; ERC-Bar
;; NEEDS MUCH WORK

(defun erc-bar-move-back (n)
  "Moves back n message lines. Ignores wrapping, and server messages."
  (interactive "nHow many lines ? ")
  (re-search-backward "^.*<.*>" nil t n))

(defun erc-bar-update-overlay ()
  "Update the overlay for current buffer, based on the content of
erc-modified-channels-alist. Should be executed on window change."
  (interactive)
  (let* ((info (assq (current-buffer) erc-modified-channels-alist))
         (count (cadr info)))
    (if (and info (> count erc-bar-threshold))
        (save-excursion
          (end-of-buffer)
          (when (erc-bar-move-back count)
            (let ((inhibit-field-text-motion t))
              (move-overlay erc-bar-overlay
                            (line-beginning-position)
                            (line-end-position)
                            (current-buffer)))))
      (delete-overlay erc-bar-overlay))))

(defvar erc-bar-threshold 0
  "Display bar when there are more than erc-bar-threshold unread messages.")

(defvar erc-bar-overlay nil
  "Overlay used to set bar")

(setq erc-bar-overlay (make-overlay 0 0))
(overlay-put erc-bar-overlay 'face '(:overline "gray"))

(with-eval-after-load 'erc-track
  ;;put the hook before erc-modified-channels-update
  (defadvice erc-track-mode (after erc-bar-setup-hook
                                   (&rest args) activate)
    (add-hook 'window-configuration-change-hook 'erc-bar-update-overlay -90))

  (add-hook 'erc-send-completed-hook (lambda (str)
                                       (erc-bar-update-overlay))))


;;; ZNC babeee
;; needed variables are stored in private.el
(defun znc/connect (znc-server znc-port znc-nick irc-servers)
  (interactive (let ((zserv (or znc/server
                                (read-string "ZNC Server: ")))
                     (zport (or znc/port
                                (read-number "ZNC Port: ")))
                     (znick (or znc/nick
                                (read-string "ZNC Nick: ")))
                     (servers (or znc/irc-servers
                                  (list
                                   (cons
                                    (read-string "IRC Server to connect to: ")
                                    (read-passwd "Password: "))))))
                 (list zserv zport znick servers)))
  (let ((si 0))
    (dolist (server irc-servers)
      (run-at-time si nil
                   (lambda ()
                     (erc-tls :server znc-server
                              :port znc-port
                              :nick znc-nick
                              :password (format "%s/%s:%s"
                                                znc-nick
                                                (car server)
                                                (cdr server)))))
      (setq si (1+ si)))))


(provide 'acdw-erc)
;;; acdw-erc.el ends here