;; ---------------------------------------------------------------------------
;; Author:       Stuart Robinson
;; Date:         19 June 2008
;; Description:  This file provides a lexc mode for emacs
;; Versions:     0.1 -- initial implementation
;; ---------------------------------------------------------------------------

(defvar lexc-mode-hook nil)

(defvar lexc-mode-map
  (let ((lexc-mode-map (make-keymap)))
    (define-key lexc-mode-map "\C-j" 'newline-and-indent)
    lexc-mode-map)
  "Keymap for lexc major mode")

;; built-ins & variables

(defconst lexc-font-lock-keywords-1
  (list
   ;; NOTE: The regex is wrapped in \\< and \\> to ensure that it only matches words 
   ;;       (i.e., it doesn't match substrings). It is generated by running the program 
   ;;       keyword-list-to-emacs-regex.rb on the file lexc-keywords-no-spaces.txt.
   '("\\<\\(LEXICON\\)\\>" . font-lock-builtin-face)
   '("\\(+\\w*\\)"        . font-lock-variable-name-face))
  "Minimal highlighting expressions for LEXC mode")

;; keywords and constants

(defconst lexc-font-lock-keywords-2
  (append lexc-font-lock-keywords-1
		  (list
		   '("\\(;\\|:\\|>\\|<\\|@\\)" . font-lock-keyword-face)
		   '("\\<\\(ON\\|OFF\\|NONE\\)\\>"   . font-lock-constant-face)))
  "Additional Keywords to highlight in LEXC mode")

;; don't understand why this is necessary...

(defconst lexc-font-lock-keywords-3
  (append lexc-font-lock-keywords-2
		  (list
		   '("" . font-lock-constant-face)))
  "Balls-out highlighting in LEXC mode")

(defvar lexc-font-lock-keywords lexc-font-lock-keywords-3
  "Default highlighting expressions for LEXC mode")

;; Indentation not being handled properly--needs to be updated
(defun lexc-indent-line ()
  "Indent current line as LEXC code"
  (interactive)
  (beginning-of-line)
  ; Check for rule 1
  (if (bobp)  
      (indent-line-to 0)
    (let ((not-indented t) cur-indent)
      ; Check for rule 2
      (if (looking-at "^[ \t]*END_") 
	  (progn
	    (save-excursion
	      (forward-line -1)
	      (setq cur-indent (- (current-indentation) default-tab-width)))
	    (if (< cur-indent 0)
		(setq cur-indent 0)))
        (save-excursion 
          (while not-indented
            (forward-line -1)
	    ; Check for rule 3
            (if (looking-at "^[ \t]*END_") 
                (progn
                  (setq cur-indent (current-indentation))
                  (setq not-indented nil))
	      ; Check for rule 4
              (if (looking-at "^[ \t]*\\(PARTICIPANT\\|MODEL\\|APPLICATION\\|WORKFLOW\\|ACTIVITY\\|DATA\\|TOOL_LIST\\|TRANSITION\\)")
                  (progn
                    (setq cur-indent (+ (current-indentation) default-tab-width))
                    (setq not-indented nil))
                ; Check for rule 5
                (if (bobp) 
                    (setq not-indented nil)))))))
      ; If we didn't see an indentation hint, then allow no indentation
      (if cur-indent
          (indent-line-to cur-indent)
        (indent-line-to 0))))) 


;; Change the interpretation of particular chars in Emacs' syntax table
(defvar lexc-mode-syntax-table
  (let ( (lexc-mode-syntax-table (make-syntax-table) ) )
    (modify-syntax-entry  ?!   "<"   lexc-mode-syntax-table)  ; start comment
    (modify-syntax-entry  ?\n  ">"   lexc-mode-syntax-table)  ; end comment
    (modify-syntax-entry  ?\\  "_"   lexc-mode-syntax-table)  ; don't escape quote
    (modify-syntax-entry  ?%   "/"   lexc-mode-syntax-table)  ; functions as escape char
    lexc-mode-syntax-table )
  "Syntax table for lexc-mode" )


(defun lexc-mode ()
  "Major mode for editing lexc scripts"
  (interactive)
  (kill-all-local-variables)
  (set-syntax-table lexc-mode-syntax-table)
  (use-local-map lexc-mode-map)
  (set (make-local-variable 'font-lock-defaults) '(lexc-font-lock-keywords))
  (set (make-local-variable 'indent-line-function) 'lexc-indent-line)  
  (setq major-mode 'lexc-mode)
  (setq mode-name "LEXC")
  (run-hooks 'lexc-mode-hook))


;; Make LEXC mode available for .infile and .script files
(provide 'lexc-mode)
(add-to-list 'auto-mode-alist '("\\.lexc\\'" . lexc-mode))