;;; echistory.el --- Electric Command History Mode  -*- lexical-binding: t -*-

;; Copyright (C) 1985, 2001-2021 Free Software Foundation, Inc.

;; Author: K. Shane Hartman
;; Maintainer: emacs-devel@gnu.org

;; This file is part of GNU Emacs.

;; GNU Emacs is free software: you can redistribute it and/or modify
;; it under the terms of the GNU General Public License as published by
;; the Free Software Foundation, either version 3 of the License, or
;; (at your option) any later version.

;; GNU Emacs is distributed in the hope that it will be useful,
;; but WITHOUT ANY WARRANTY; without even the implied warranty of
;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
;; GNU General Public License for more details.

;; You should have received a copy of the GNU General Public License
;; along with GNU Emacs.  If not, see <https://www.gnu.org/licenses/>.

;;; Commentary:

;;; Code:

(require 'electric)			; command loop
(require 'chistory)			; history lister

;; Dynamically bound in electric-command-history
(defvar electric-history-in-progress)

;;;###autoload
(defun Electric-command-history-redo-expression (&optional noconfirm)
  "Edit current history line in minibuffer and execute result.
With prefix arg NOCONFIRM, execute current line as-is without editing."
  (interactive "P")
  (let (todo)
    (with-current-buffer "*Command History*"
      (beginning-of-line)
      (setq todo (read (current-buffer)))
      (if (boundp 'electric-history-in-progress)
	  (if todo (throw 'electric-history-quit (list noconfirm todo)))))))

(defvar electric-history-map
  (let ((map (make-sparse-keymap)))
    (define-key map [t] #'Electric-history-undefined)
    (define-key map "\e" (make-sparse-keymap))
    (define-key map [?\e t] #'Electric-history-undefined)
    (define-key map "\C-u" #'universal-argument)
    (define-key map " " #'Electric-command-history-redo-expression)
    (define-key map "!" #'Electric-command-history-redo-expression)
    (define-key map "\e\C-d" #'down-list)
    (define-key map "\e\C-u" #'backward-up-list)
    (define-key map "\e\C-b" #'backward-sexp)
    (define-key map "\e\C-f" #'forward-sexp)
    (define-key map "\e\C-a" #'beginning-of-defun)
    (define-key map "\e\C-e" #'end-of-defun)
    (define-key map "\e\C-n" #'forward-list)
    (define-key map "\e\C-p" #'backward-list)
    (define-key map "q" #'Electric-history-quit)
    (define-key map "\C-c" nil)
    (define-key map "\C-c\C-c" #'Electric-history-quit)
    (define-key map "\C-]" #'Electric-history-quit)
    (define-key map "\C-z" #'suspend-frame)
    (define-key map (char-to-string help-char) #'Helper-help)
    (define-key map "?" #'Helper-describe-bindings)
    (define-key map "\e>" #'end-of-buffer)
    (define-key map "\e<" #'beginning-of-buffer)
    (define-key map "\n" #'next-line)
    (define-key map "\r" #'next-line)
    (define-key map "\177" #'previous-line)
    (define-key map "\C-n" #'next-line)
    (define-key map "\C-p" #'previous-line)
    (define-key map "\ev" #'scroll-down)
    (define-key map "\C-v" #'scroll-up)
    (define-key map [home] #'beginning-of-buffer)
    (define-key map [down] #'next-line)
    (define-key map [up] #'previous-line)
    (define-key map [prior] #'scroll-down)
    (define-key map [next] #'scroll-up)
    (define-key map "\C-l" #'recenter)
    (define-key map "\e\C-v" #'scroll-other-window)
    map)
  "Keymap for Electric Command History mode.")

(defvar electric-command-history-hook nil
  "If non-nil, its value is called by `electric-command-history'.")

(defvar Helper-return-blurb) ; from helper.el

(defun electric-command-history ()
  "\\<electric-history-map>Major mode for examining and redoing commands from `command-history'.
This pops up a window with the Command History listing.
The number of command listed is controlled by `list-command-history-max'.
The command history is filtered by `list-command-history-filter' if non-nil.
Combines typeout Command History list window with menu like selection
of an expression from the history for re-evaluation in the *original* buffer.

The history displayed is filtered by `list-command-history-filter' if non-nil.

Like Emacs-Lisp mode except that characters do not insert themselves and
Tab and Linefeed do not indent.  Instead these commands are provided:
\\{electric-history-map}

Calls the value of `electric-command-history-hook' if that is non-nil.
The Command History listing is recomputed each time this mode is invoked."
  (interactive)
  (let ((electric-history-in-progress t)
	(old-buffer (current-buffer))
	(todo))
    (unwind-protect
	(setq todo
	      (catch 'electric-history-quit
		(save-window-excursion
		  (save-window-excursion
		    (list-command-history)
		    (set-buffer "*Command History*")
		    (setq major-mode 'electric-command-history)
		    (setq mode-name "Electric History")
		    (use-local-map electric-history-map))
		  (Electric-pop-up-window "*Command History*")
		  (run-hooks 'electric-command-history-hook)
		  (if (eobp)
		      (progn (ding)
			     (message "No command history.")
			     (throw 'electric-history-quit nil))
		    (let ((Helper-return-blurb "return to History"))
		      (Electric-command-loop 'electric-history-quit
					     "->" t))))))
      (set-buffer "*Command History*")
      (command-history-mode)
      (bury-buffer (current-buffer)))
    (if (consp todo)
	(progn (set-buffer old-buffer)
	       (if (car todo)
		   (apply (car (car (cdr todo))) (cdr (car (cdr todo))))
		 (edit-and-eval-command "Redo: " (car (cdr todo))))))))

(defun Electric-history-undefined ()
  (interactive)
  (ding)
  (message "%s" (substitute-command-keys "Type \\[Helper-help] for help, \
\\[Helper-describe-bindings] for commands, \\[Electric-history-quit] to quit, \
\\[Electric-command-history-redo-expression] to execute"))
  (sit-for 4))

(defun Electric-history-quit ()
  "Quit Electric Command History, restoring previous window configuration."
  (interactive)
  (if (boundp 'electric-history-in-progress)
      (progn (message "")
	     (throw 'electric-history-quit nil))))

(provide 'echistory)

;;; echistory.el ends here