;;; em-cmpl.el --- completion using the TAB key  -*- lexical-binding:t -*-

;; Copyright (C) 1999-2023 Free Software Foundation, Inc.

;; Author: John Wiegley <johnw@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:

;; Eshell, by using the pcomplete package, provides a full
;; programmable completion facility that is comparable to shells like
;; tcsh or zsh.
;;
;; Completions are context-sensitive, which means that pressing <TAB>
;; after the command 'rmdir' will result in a list of directories,
;; while doing so after 'rm' will result in a list of all file
;; entries.
;;
;; Many builtin completion rules are provided, for commands such as
;; `cvs', or RedHat's `rpm' utility.  Adding new completion rules is
;; no more difficult than writing a plain Lisp functions, and they can
;; be debugged, profiled, and compiled using exactly the same
;; facilities (since in fact, they *are* just Lisp functions).  See
;; the definition of the function `pcomplete/make' for an example of
;; how to write a completion function.
;;
;; The completion facility is very easy to use.  Just press TAB.  If
;; there are a large number of possible completions, a buffer will
;; appear showing a list of them.  Completions may be selected from
;; that buffer using the mouse.  If no completion is selected, and the
;; user starts doing something else, the display buffer will
;; automatically disappear.
;;
;; If the list of possible completions is very small, Eshell will
;; "cycle" through them, selecting a different entry each time <TAB>
;; is pressed.  <S-TAB> may be used to cycle in the opposite
;; direction.
;;
;; Glob patterns can also be cycled.  For example, entering 'echo
;; x*<tab>' will cycle through all the filenames beginning with 'x'.
;; This is done because the glob list is treated as though it were a
;; list of possible completions.  Pressing <C-c SPC> will insert all
;; of the matching glob patterns at point.
;;
;; If a Lisp form is being entered, <TAB> will complete the Lisp
;; symbol name, in exactly the same way that <M-TAB> does in Emacs
;; Lisp mode.
;;
;; The list of possible completions can be viewed at any point by
;; pressing <M-?>.
;;
;; Finally, context-related help can be accessed by pressing <C-c M-h>.
;; This only works well if the completion function has provided Eshell
;; with sufficient pointers to locate the relevant help text.

;;; Code:
(require 'pcomplete)

(require 'esh-mode)
(require 'esh-util)
(require 'em-dirs)

(eval-when-compile (require 'cl-lib))

;;;###autoload
(progn
(defgroup eshell-cmpl nil
  "This module provides a programmable completion function bound to
the TAB key, which allows for completing command names, file names,
variable names, arguments, etc."
  :tag "Argument completion"
  :group 'eshell-module))

;;; Internal variables:

;; FIXME: Instead of using a dynamic variable for this, it might be
;; better to pass `eshell-parse-argument-hook' functions a parsing
;; context.  This could also be useful for restructuring parsing more
;; generally, e.g. to fix bug#59752.
(defvar eshell-parsing-for-completion nil
  "This is bound to t when calling `eshell-parse-arguments' for completion.
Functions added to `eshell-parse-argument-hook' should consult this to
adjust their behavior when parsing a command for completion, if
necessary.

When parsing for completion, we need to ensure that the resulting
Lisp form has no side effects, and returns quickly.  For example,
this means that Eshell subcommands should return some stub value
when this is set so that the completion code doesn't try to
invoke the subcommand (see `eshell-parse-subcommand-argument').")

;;; User Variables:

(defcustom eshell-cmpl-load-hook nil
  "A list of functions to run when `eshell-cmpl' is loaded."
  :version "24.1"			; removed eshell-cmpl-initialize
  :type 'hook)

(defcustom eshell-show-lisp-completions nil
  "If non-nil, include Lisp functions in the command completion list.
If this variable is nil, Lisp completion can still be done in command
position by using M-TAB instead of TAB."
  :type 'boolean)

(defcustom eshell-show-lisp-alternatives t
  "If non-nil, and no other completions found, show Lisp functions.
Setting this variable means nothing if `eshell-show-lisp-completions'
is non-nil."
  :type 'boolean)

(defcustom eshell-no-completion-during-jobs t
  "If non-nil, don't allow completion while a process is running."
  :type 'boolean)

(defcustom eshell-command-completions-alist
  '(("acroread" . "\\.pdf\\'")
    ("xpdf"     . "\\.pdf\\'")
    ("gunzip"   . "\\.t?gz\\'")
    ("bunzip2"  . "\\.t?bz2\\'")
    ("unxz"     . "\\.t?xz\\'")
    ("ar"       . "\\.[ao]\\'")
    ("gcc"      . "\\.[Cc]\\([Cc]\\|[Pp][Pp]\\)?\\'")
    ("g++"      . "\\.[Cc]\\([Cc]\\|[Pp][Pp]\\)?\\'")
    ("cc"       . "\\.[Cc]\\([Cc]\\|[Pp][Pp]\\)?\\'")
    ("CC"       . "\\.[Cc]\\([Cc]\\|[Pp][Pp]\\)?\\'")
    ("acc"      . "\\.[Cc]\\([Cc]\\|[Pp][Pp]\\)?\\'")
    ("bcc"      . "\\.[Cc]\\([Cc]\\|[Pp][Pp]\\)?\\'")
    ("readelf"  . "\\(\\`[^.]*\\|\\.\\([ao]\\|so\\)\\)\\'")
    ("objdump"  . "\\(\\`[^.]*\\|\\.\\([ao]\\|so\\)\\)\\'")
    ("nm"       . "\\(\\`[^.]*\\|\\.\\([ao]\\|so\\)\\)\\'")
    ("gdb"      . "\\`\\([^.]*\\|a\\.out\\)\\'")
    ("dbx"      . "\\`\\([^.]*\\|a\\.out\\)\\'")
    ("sdb"      . "\\`\\([^.]*\\|a\\.out\\)\\'")
    ("adb"      . "\\`\\([^.]*\\|a\\.out\\)\\'"))
  "An alist that defines simple argument type correlations.
This is provided for common commands, as a simplistic alternative
to writing a completion function."
  :type '(repeat (cons string regexp)))

(defun eshell-cmpl--custom-variable-docstring (pcomplete-var)
  "Generate the docstring of a variable derived from a pcomplete-* variable."
  (format "%s\n\nIts value is assigned to `%s' locally after eshell starts."
          (documentation-property pcomplete-var
                                  'variable-documentation t)
          (symbol-name pcomplete-var)))

(defcustom eshell-cmpl-file-ignore "~\\'"
  (eshell-cmpl--custom-variable-docstring 'pcomplete-file-ignore)
  :type (get 'pcomplete-file-ignore 'custom-type))

(defcustom eshell-cmpl-dir-ignore "\\`\\(\\.\\.?\\|CVS\\)/\\'"
  (eshell-cmpl--custom-variable-docstring 'pcomplete-dir-ignore)
  :type (get 'pcomplete-dir-ignore 'custom-type))

(defcustom eshell-cmpl-ignore-case (eshell-under-windows-p)
  (eshell-cmpl--custom-variable-docstring 'completion-ignore-case)
  :type (get 'completion-ignore-case 'custom-type))

(defcustom eshell-cmpl-autolist nil
  (eshell-cmpl--custom-variable-docstring 'pcomplete-autolist)
  :type (get 'pcomplete-autolist 'custom-type))

(defcustom eshell-cmpl-recexact nil
  (eshell-cmpl--custom-variable-docstring 'pcomplete-recexact)
  :type (get 'pcomplete-recexact 'custom-type))

(defcustom eshell-cmpl-man-function #'man
  (eshell-cmpl--custom-variable-docstring 'pcomplete-man-function)
  :type (get 'pcomplete-man-function 'custom-type))

(defcustom eshell-cmpl-compare-entry-function #'file-newer-than-file-p
  (eshell-cmpl--custom-variable-docstring 'pcomplete-compare-entry-function)
  :type (get 'pcomplete-compare-entry-function 'custom-type))

(defcustom eshell-cmpl-expand-before-complete nil
  (eshell-cmpl--custom-variable-docstring 'pcomplete-expand-before-complete)
  :type (get 'pcomplete-expand-before-complete 'custom-type))

(defcustom eshell-cmpl-cycle-completions t
  (eshell-cmpl--custom-variable-docstring 'pcomplete-cycle-completions)
  :type (get 'pcomplete-cycle-completions 'custom-type))

(defcustom eshell-cmpl-cycle-cutoff-length 5
  (eshell-cmpl--custom-variable-docstring 'pcomplete-cycle-cutoff-length)
  :type (get 'pcomplete-cycle-cutoff-length 'custom-type))

(defcustom eshell-cmpl-restore-window-delay 1
  (eshell-cmpl--custom-variable-docstring 'pcomplete-restore-window-delay)
  :type (get 'pcomplete-restore-window-delay 'custom-type))

(defcustom eshell-command-completion-function
  (lambda ()
    (pcomplete-here (eshell--complete-commands-list)))
  (eshell-cmpl--custom-variable-docstring 'pcomplete-command-completion-function)
  :type (get 'pcomplete-command-completion-function 'custom-type))

(defcustom eshell-cmpl-command-name-function
  #'eshell-completion-command-name
  (eshell-cmpl--custom-variable-docstring 'pcomplete-command-name-function)
  :type (get 'pcomplete-command-name-function 'custom-type))

(defcustom eshell-default-completion-function
  (lambda ()
    (while (pcomplete-here
            (pcomplete-dirs-or-entries
             (cdr (assoc (funcall eshell-cmpl-command-name-function)
                         eshell-command-completions-alist))))))
  (eshell-cmpl--custom-variable-docstring 'pcomplete-default-completion-function)
  :type (get 'pcomplete-default-completion-function 'custom-type))

(defcustom eshell-cmpl-use-paring t
  (eshell-cmpl--custom-variable-docstring 'pcomplete-use-paring)
  :type (get 'pcomplete-use-paring 'custom-type))

;;; Functions:

(defun eshell-complete-lisp-symbol ()
  "Try to complete the text around point as a Lisp symbol."
  (interactive)
  (let ((completion-at-point-functions '(elisp-completion-at-point)))
    (completion-at-point)))

(defvar-keymap eshell-cmpl-mode-map
  "C-i"       #'completion-at-point
  ;; jww (1999-10-19): Will this work on anything but X?
  "<backtab>" #'pcomplete-reverse
  "M-?"       #'completion-help-at-point
  "C-M-i"     #'eshell-complete-lisp-symbol
  ;; C-c prefix:
  "C-c M-h"   #'eshell-completion-help
  "C-c TAB"   #'pcomplete-expand-and-complete
  "C-c C-i"   #'pcomplete-expand-and-complete
  "C-c SPC"   #'pcomplete-expand)

(define-minor-mode eshell-cmpl-mode
  "Minor mode that provides a keymap when `eshell-cmpl' active.

\\{eshell-cmpl-mode-map}"
  :keymap eshell-cmpl-mode-map)

(defun eshell-cmpl-initialize ()    ;Called from `eshell-mode' via intern-soft!
  "Initialize the completions module."
  (setq-local pcomplete-command-completion-function
              eshell-command-completion-function)
  (setq-local pcomplete-command-name-function
              eshell-cmpl-command-name-function)
  (setq-local pcomplete-default-completion-function
              eshell-default-completion-function)
  (setq-local pcomplete-parse-arguments-function
              #'eshell-complete-parse-arguments)
  (setq-local pcomplete-file-ignore
              eshell-cmpl-file-ignore)
  (setq-local pcomplete-dir-ignore
              eshell-cmpl-dir-ignore)
  (setq-local completion-ignore-case
              eshell-cmpl-ignore-case)
  (setq-local pcomplete-autolist
              eshell-cmpl-autolist)
  (setq-local pcomplete-recexact
              eshell-cmpl-recexact)
  (setq-local pcomplete-man-function
              eshell-cmpl-man-function)
  (setq-local pcomplete-compare-entry-function
              eshell-cmpl-compare-entry-function)
  (setq-local pcomplete-expand-before-complete
              eshell-cmpl-expand-before-complete)
  (setq-local pcomplete-cycle-completions
              eshell-cmpl-cycle-completions)
  (setq-local pcomplete-cycle-cutoff-length
              eshell-cmpl-cycle-cutoff-length)
  (setq-local pcomplete-restore-window-delay
              eshell-cmpl-restore-window-delay)
  (setq-local pcomplete-use-paring
              eshell-cmpl-use-paring)
  ;; `comint-file-name-quote-list' should only be set after all the
  ;; load-hooks for any other extension modules have been run, which
  ;; is true at the time `eshell-mode-hook' is run
  (add-hook 'eshell-mode-hook
            (lambda ()
              (setq-local comint-file-name-quote-list
                          eshell-special-chars-outside-quoting))
            nil t)
  (add-hook 'pcomplete-quote-arg-hook #'eshell-quote-backslash nil t)
  (add-hook 'completion-at-point-functions
            #'pcomplete-completions-at-point nil t)
  (eshell-cmpl-mode))

(defun eshell-completion-command-name ()
  "Return the command name, possibly sans globbing."
  (let ((cmd (file-name-nondirectory (pcomplete-arg 'first))))
    (setq cmd (if (and (> (length cmd) 0)
		       (eq (aref cmd 0) eshell-explicit-command-char))
		  (substring cmd 1)
		cmd))
    (if (eshell-under-windows-p)
	(file-name-sans-extension cmd)
      cmd)))

(defun eshell-completion-help ()
  (interactive)
  (if (= (point) eshell-last-output-end)
      (describe-prefix-bindings)
    (call-interactively 'pcomplete-help)))

(defun eshell--pcomplete-insert-tab ()
  (if (not pcomplete-allow-modifications)
      (throw 'pcompleted nil)
    (insert-and-inherit "\t")
    (throw 'pcompleted t)))

(defun eshell-complete--eval-argument-form (arg)
  "Evaluate a single Eshell argument form ARG for the purposes of completion."
  (let ((result (eshell-do-eval `(eshell-commands ,arg) t)))
    (cl-assert (eq (car result) 'quote))
    (cadr result)))

(defun eshell-complete-parse-arguments ()
  "Parse the command line arguments for `pcomplete-argument'."
  (when (and eshell-no-completion-during-jobs
	     (eshell-interactive-process-p))
    (eshell--pcomplete-insert-tab))
  (let ((end (point-marker))
	(begin (save-excursion (beginning-of-line) (point)))
	args posns delim incomplete-arg)
    (when (and pcomplete-allow-modifications
	       (memq this-command '(pcomplete-expand
			            pcomplete-expand-and-complete)))
      (run-hook-with-args 'eshell-expand-input-functions begin end)
      (if (= begin end)
	  (end-of-line))
      (setq end (point-marker)))
    (if (setq delim
	      (catch 'eshell-incomplete
		(ignore
                 (setq args (let ((eshell-parsing-for-completion t))
                              (eshell-parse-arguments begin end))))))
        (cond ((member (car delim) '("{" "${" "$<"))
	       (setq begin (1+ (cadr delim))
		     args (eshell-parse-arguments begin end)))
              ((member (car delim) '("$'" "$\"" "#<"))
               ;; Add the (incomplete) argument to our arguments, and
               ;; note its position.
               (setq args (append (nth 2 delim) (list (car delim)))
                     incomplete-arg t)
               (push (- (nth 1 delim) 2) posns))
              ((member (car delim) '("(" "$("))
	       (throw 'pcompleted (elisp-completion-at-point)))
	      (t
	       (eshell--pcomplete-insert-tab))))
    (when (get-text-property (1- end) 'comment)
      (eshell--pcomplete-insert-tab))
    (let ((pos (1- end)))
      (while (>= pos begin)
        (when (get-text-property pos 'arg-begin)
          (push pos posns))
        (setq pos (1- pos))))
    (cl-assert (= (length args) (length posns)))
    (let ((a args) (i 0) new-start)
      (while a
        ;; If there's an unreplaced `eshell-operator' sigil, consider
        ;; the token after it the new start of our arguments.
        (when (and (consp (car a))
                   (eq (caar a) 'eshell-operator))
          (setq new-start i))
        (setq a (cdr a)
              i (1+ i)))
      (when new-start
	(setq args (nthcdr (1+ new-start) args)
	      posns (nthcdr (1+ new-start) posns))))
    (cl-assert (= (length args) (length posns)))
    (when (and args (not incomplete-arg)
               (eq (char-syntax (char-before end)) ? )
	       (not (eq (char-before (1- end)) ?\\)))
      (nconc args (list ""))
      (nconc posns (list (point))))
    ;; Evaluate and expand Eshell forms.
    (let (evaled-args evaled-posns)
      (cl-mapc
       (lambda (arg posn)
         (pcase arg
           (`(eshell-splice-args ,val)
            (dolist (subarg (eshell-complete--eval-argument-form val))
              (push subarg evaled-args)
              (push posn evaled-posns)))
           ((pred listp)
            (push (eshell-complete--eval-argument-form arg) evaled-args)
            (push posn evaled-posns))
           (_
            (push arg evaled-args)
            (push posn evaled-posns))))
       args posns)
      (setq args (nreverse evaled-args)
            posns (nreverse evaled-posns)))
    ;; Convert arguments to forms that Pcomplete can understand.
    (cons (mapcar
           (lambda (arg)
             (pcase arg
               ;; Expand ".../" etc that only Eshell understands to
               ;; the standard "../../".
               ((rx ".." (+ ".") "/")
                (propertize (eshell-expand-multiple-dots arg)
                            'pcomplete-arg-value arg))
               ((pred stringp)
                arg)
               ('nil
                (propertize "" 'pcomplete-arg-value arg))
               (_
                (propertize (eshell-stringify arg)
                            'pcomplete-arg-value arg))))
	   args)
	  posns)))

(defun eshell--complete-commands-list ()
  "Generate list of applicable, visible commands."
  ;; Building the commands list can take quite a while, especially over Tramp
  ;; (bug#41423), so do it lazily.
  (let ((glob-name
	 ;; When a command is specified using `eshell-explicit-command-char',
         ;; that char is not part of the command and hence not part of what
         ;; we complete.  Adjust `pcomplete-stub' accordingly!
	 (if (and (> (length pcomplete-stub) 0)
	          (eq (aref pcomplete-stub 0) eshell-explicit-command-char))
             (setq pcomplete-stub (substring pcomplete-stub 1))))
        (filename (pcomplete-arg)))
    ;; Do not use `completion-table-dynamic' when completing a command file
    ;; name since it doesn't know about boundaries and would end up doing silly
    ;; things like adding a SPC char when completing to "/usr/sbin/".
    ;;
    ;; If you work on this function, be careful not to reintroduce bug#48995.
    (if (file-name-directory filename)
        (if eshell-force-execution
            (pcomplete-dirs-or-entries nil #'file-readable-p)
          (pcomplete-executables))
      (completion-table-dynamic
       (lambda (filename)
	 (let* ((paths (eshell-get-path))
		(cwd (file-name-as-directory
		      (expand-file-name default-directory)))
		(filepath "") (completions ()))
	   ;; Go thru each path in the search path, finding completions.
	   (dolist (path paths)
	     (setq path (file-name-as-directory
		         (expand-file-name (or path "."))))
	     ;; Go thru each completion found, to see whether it should
	     ;; be used.
	     (dolist (file (and (file-accessible-directory-p path)
		                (file-name-all-completions filename path)))
	       (setq filepath (concat path file))
	       (if (and (not (member file completions)) ;
			(or (string-equal path cwd)
			    (not (file-directory-p filepath)))
			;; FIXME: Those repeated file tests end up
			;; very costly over Tramp, we should cache the result.
			(if eshell-force-execution
                            (file-readable-p filepath)
                          (file-executable-p filepath)))
		   (push file completions))))
	   ;; Add aliases which are currently visible, and Lisp functions.
	   (pcomplete-uniquify-list
	    (if glob-name
	        completions
	      (setq completions
		    (append (if (fboundp 'eshell-alias-completions)
			        (eshell-alias-completions filename))
			    (eshell-winnow-list
			     (mapcar
                              (lambda (name)
                                (substring name 7))
			      (all-completions (concat "eshell/" filename)
					       obarray #'functionp))
			     nil '(eshell-find-alias-function))
			    completions))
	      (append (and (or eshell-show-lisp-completions
			       (and eshell-show-lisp-alternatives
				    (null completions)))
			   (all-completions filename obarray #'functionp))
		      completions)))))))))

(define-obsolete-function-alias 'eshell-pcomplete #'completion-at-point "27.1")

(provide 'em-cmpl)

;; Local Variables:
;; generated-autoload-file: "esh-groups.el"
;; End:

;;; em-cmpl.el ends here