;;; ag.el --- Ag frontend

;;; Commentary:

;;

(defun my/ag-goto ()

  (interactive)

  (save-excursion

    (let ( lineno end )

      (forward-line 1)

      (backward-char 1)

      (setq end (point))

      (forward-line 0)

      (if (not (search-forward-regexp "^\\([1-9][0-9]*\\):" end t))

          (message "Not at line number...")

        (setq lineno (string-to-int (match-string 1)))

        (if (search-backward-regexp "^$" nil t)

            (forward-char)

          (goto-char (point-min)))

        (search-forward-regexp "^.*")

        (find-file-other-window (match-string 0))

        (goto-line lineno)))))

(defun my/ag-kill-process ()

  (interactive)

  (let ( (proc (get-buffer-process (current-buffer))) )

    (if proc

	(interrupt-process proc)

      (error "The %s process is not running" (downcase mode-name)))))

(defvar my/ag-mode-map (make-sparse-keymap))

(define-key my/ag-mode-map (kbd "RET") 'my/ag-goto)

(define-key my/ag-mode-map (kbd "C-c C-k") 'my/ag-kill-process)

(defface my/ag-lineno-face

  '((t :inherit warning))

  "Face for line number.")

(defface my/ag-path-face

  '((t :inherit success))

  "Face for line number.")

(defvar my/ag-keywords

  '(("^[1-9][0-9]\\{0,5\\}:" . (0 'my/ag-lineno-face))

    ("^[^:]\\{6\\}.*" . (0 'my/ag-path-face))))

(defun my/ag-font-lock-extend-region ()

  (save-excursion

    (goto-char font-lock-beg)

    (forward-line 2)

    (setq font-lock-beg (point))))

(define-derived-mode my/ag-mode fundamental-mode "Ag"

  "Major mode for Ag parsing."

  (setq font-lock-defaults '(my/ag-keywords t nil nil)) ;  (font-lock-multiline . t)

  ;; (add-hook 'font-lock-extend-region-functions 'my/ag-font-lock-extend-region)

  (use-local-map my/ag-mode-map))

(defvar my/ag-buffer-name "*ag*")

(defvar my/ag-buffer nil)

(defun my/ag-filter (proc str)

  (when (buffer-live-p (process-buffer proc))

    (with-current-buffer (process-buffer proc)

      (save-excursion

        (goto-char (process-mark proc))

        (insert str)

        (set-marker (process-mark proc) (point)))

      )))

(defvar my/ag-regex-history nil)

(defun my/ag-setup-buffer (dir)

  (setq my/ag-buffer (get-buffer-create my/ag-buffer-name))

  (with-current-buffer my/ag-buffer

    (setq default-directory dir)

    (erase-buffer)

    (my/ag-mode))

  (display-buffer my/ag-buffer))

(defun my/ag-run (regex)

  (let ( (default-directory (buffer-local-value 'default-directory my/ag-buffer)) )

    (make-process

     :name "ag"

     :buffer my/ag-buffer

     :filter 'my/ag-filter

     :command (list "ag" "--group" "--nocolor" regex))))

(defun my/ag-project-root ()

  (condition-case err

      (let ( backend )

        (setq backend (vc-responsible-backend default-directory))

        (if backend

            (vc-call-backend backend 'root default-directory)

          default-directory))

    (error default-directory)))

;;;###autoload

(defun my/ag (regex)

  (my/ag-setup-buffer (if current-prefix-arg default-directory (my/ag-project-root)))

  (my/ag-run regex))

(provide 'ag)

;;; ag.el ends here