;;; hmoccur.el --- Multi-buffer or multi-file regexp occurrence location.  -*- lexical-binding: t; -*-
;;
;; Author:       Markus Freericks <Mfx@cs.tu-berlin.de> / Bob Weiner
;;
;; Orig-Date:     1-Aug-91
;; Last-Mod:     25-Jul-22 at 20:00:01 by Mats Lidell
;;
;; SPDX-License-Identifier: GPL-3.0-or-later
;;
;; Copyright (C) 1991-2022  Free Software Foundation, Inc.
;; See the "HY-COPY" file for license information.
;;
;; This file is part of GNU Hyperbole.

;;; Commentary:
;;
;; Modified by Bob Weiner to allow selection of a set of files within a
;; single directory to search.  By default, {M-x moccur RET} searches
;; current buffers with files attached.
;;
;; Date: 1 Aug 91 15:47:27 GMT
;; From: mfx@cs.tu-berlin.de (Markus Freericks)
;; Subject: moccur - multibuffer occurences
;;
;; While editing some dozen or so files, i had the dire need for
;; something like 'occur' that can cope with multiple buffers.  This has
;; probably been done before; but still, here is my try at it.  It seems
;; to be very useful.
;; 
;; How to use it: simple say
;; 	M-x moccur <regexp>
;; moccur then searches through *all buffers* currently existing that are
;; bound to files and displays the occurences in a buffer that runs in
;; Moccur-mode.  Change to that buffer, scroll around, and say C-c C-c
;; to jump to the occurrence.  Quite simple.
;; 
;; Incompatibilites to Occur mode:
;; a) it browses through *all* buffers that have a file name
;; associated with them; those may or may not include the current
;; buffer.  Especially, while standard occur works
;; on 'all lines following point', Moccur does not.
;; b) there is no support for the 'NLINE' argument.
;;
;; Usage:
;; moccur <regexp> shows all occurences of <regexp> in all buffers
;; currently existing that refer to files.
;; the occurences are displayed in a buffer running in Moccur mode;
;; C-c C-c gets you to the occurence

;;; Code:
;;; ************************************************************************
;;; Public variables
;;; ************************************************************************

(defconst moccur-source-prefix "@loc> "
  "Prefix for lines indicating source of matches.")

;;; ************************************************************************
;;; Public functions
;;; ************************************************************************

(defun moccur (regexp &optional file-regexp no-fold-search)
  "Show all lines of all buffers containing a match for REGEXP.
With optional FILE-REGEXP (a pattern which matches to files in a
single directory), search matching files rather than current
buffers.  The lines are shown in a buffer named *Moccur* which
serves as a menu to find any of the occurrences in this buffer.

\\{moccur-mode-map}"
  (interactive "sRegexp to find occurrences of: \nsFiles to search (default current file buffers): ")
  (if (equal file-regexp "") (setq file-regexp nil))
  (let*  ((buffers (if file-regexp (directory-files
				    (expand-file-name
				     (or (file-name-directory
					  file-regexp)
					 "."))
				    'full (file-name-nondirectory file-regexp))
		     (buffer-list)))
	  (occbuf (get-buffer-create "*Moccur*"))
	  (matches 0)
	  (firstmatch t))
    (set-buffer occbuf)
    (setq buffer-read-only nil)
    (widen)
    (erase-buffer)
    (insert "Lines matching '" regexp "':\n\n")
    (let ((currbuf) (currfile) (kill-buf)
	  ;; Disable syntax highlighting of new buffers created by this command.
	  (font-lock-global-modes))
      (while buffers
	(setq currbuf (car buffers)
	      currfile (if (stringp currbuf) currbuf)
	      kill-buf (and currfile (not (get-file-buffer currfile)))
	      buffers (cdr buffers))
	(if currfile
	    (setq currbuf (find-file-noselect currfile))
	  (setq currfile (buffer-file-name currbuf)))
	(if (or (not currfile) (not currbuf))
	    nil
	  (set-buffer currbuf)
	  (let ((case-fold-search (not no-fold-search)))
	    (save-excursion
	      (goto-char (point-min))
	      (setq firstmatch t)
	      (while (re-search-forward regexp nil t)
		(setq matches (+ matches 1))
		(let* ((linenum (count-lines (point-min)(point)))
		       (tag (format "\n%5d:" linenum)))
		  (set-buffer occbuf)
		  (if firstmatch
		      (progn
			(insert moccur-source-prefix currfile "\n")
			(setq firstmatch nil)))
		  (insert tag)
		  (set-buffer currbuf)
		  (forward-word -1) ;; needed if match goes to eoline
		  (beginning-of-line)
		  (let ((beg (point)))
		    (end-of-line)
		    (append-to-buffer occbuf beg (point)))
		  (forward-line 1)))))
	  (with-current-buffer occbuf
	    (if (not firstmatch) (insert "\n\n"))
	    (if kill-buf (kill-buffer currbuf))))))
    (if (> matches 0)
	(progn
	  (set-buffer occbuf)
	  (moccur-mode)
	  (if (fboundp 'outline-minor-mode)
	      (and (progn (goto-char 1)
			  (search-forward "\C-m" nil t))
		   (outline-minor-mode 1)))
	  (goto-char (point-min))
	  (pop-to-buffer occbuf)
	  (message "%d matches." matches)
	  t)
      (message "No matches.")
      nil)))

(defun moccur-to ()
  "Go to the line where this occurrence was found."
  (interactive)
  (let* ((result (moccur-noselect))
	 (buffer (car result))
	 (lineno (cadr result))
	 (occur-match (car (cddr result))))
    (when result
      (message "Selection <%s> line %d." occur-match lineno)
      (hpath:display-buffer buffer)
      (goto-char (point-min))
      (forward-line (1- lineno)))))

(defalias 'moccur-mode-goto-occurrence 'moccur-to)

(defun moccur-mode-display-occurrence ()
  "Display in another window the occurrence the current line describes."
  (interactive)
  (let* ((result (moccur-noselect))
	 (buffer (car result))
	 (lineno (cadr result)))
    (when result
      ;; This is the way to set point in the proper window.
      (save-selected-window
	(hpath:display-buffer buffer)
	(goto-char (point-min))
	(forward-line (1- lineno))))))

;;; ************************************************************************
;;; Private functions
;;; ************************************************************************

(put 'moccur-mode 'mode-class 'special)
(define-derived-mode moccur-mode special-mode "Moccur"
  "Major mode for output from \\[moccur].
\\<moccur-mode-map>Move point to one of the items in this buffer, then use
\\[moccur-to] to go to the occurrence on the current line.
\\[moccur-mode-display-occurrence] displays but does not select the occurrence.

\\{moccur-mode-map}"
  (kill-all-local-variables)
  (use-local-map moccur-mode-map)
  (setq major-mode 'moccur-mode)
  (setq mode-name "Moccur"))

(defun moccur-noselect ()
  "Return match data for the current moccur buffer line.
Match data is returned as a list (destination-buffer line-number
occur-match-text).  Signal an error if not on a valid occurrence
line."
  (if (not (eq major-mode 'moccur-mode))
      (error "'moccur-to' must be called within a moccur buffer")
    (let (beg file-path lineno dstbuf occur-match)
      (save-excursion
	(beginning-of-line)
	(setq beg (point))
	(end-of-line)
	(setq occur-match (buffer-substring beg (point)))
	(if (string-match "^[ ]*[0-9]+:" occur-match)
	    (progn
	      (setq lineno (string-to-number (substring
					      occur-match 0 (match-end 0))))
	      (if (re-search-backward
		   (concat "^" moccur-source-prefix
			   "\"?\\([^\" \n\r]+\\)\"?") nil t)
		  (progn
		    (setq file-path (buffer-substring
				     (match-beginning 1) (match-end 1))
			  dstbuf (find-file-noselect file-path))
		    (if (not dstbuf)
			(message
			 "moccur-to: file '%s' is not readable" file-path)))
		(error "No moccur header line for file")))
	  (error "Not an moccur occurrence line")))
      (if (and dstbuf lineno)
	  (list dstbuf lineno occur-match)))))

;;; ************************************************************************
;;; Private variables
;;; ************************************************************************

(defvar moccur-mode-map nil)
(unless moccur-mode-map
  (setq moccur-mode-map (make-sparse-keymap))
  (define-key moccur-mode-map "\C-c\C-c" 'moccur-to)
  (define-key moccur-mode-map "\C-o" 'moccur-mode-display-occurrence)
  (define-key moccur-mode-map " " 'moccur-to)
  (define-key moccur-mode-map "\C-m" 'moccur-to))

(provide 'hmoccur)

;;; hmoccur.el ends here