;;; -*-scheme-*-

;;; Mes --- Maxwell Equations of Software
;;; Copyright © 2016 Jan Nieuwenhuizen <janneke@gnu.org>
;;;
;;; compiler.mes: This file is part of Mes.
;;;
;;; Mes 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.
;;;
;;; Mes 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 Mes.  If not, see <http://www.gnu.org/licenses/>.

;;; Commentary:

;;; compiler.mes produces an i386 binary from the C produced by
;;; c-parser.

;;; Code:

(mes-use-module (mes elf))
(mes-use-module (mes libc-i386))
(mes-use-module (mes match))
(mes-use-module (srfi srfi-1))
(mes-use-module (language c lexer))
(mes-use-module (language c parser))

(define mescc
  (let ((errorp
         (lambda args
           (for-each display args)
             (newline))))
    (lambda ()
      (c-parser (c-lexer errorp) errorp))))

(define (write-any x) (write-char (if (char? x) x (integer->char (if (>= x 0) x (+ x 256))))))

(define (ast:function? o)
  (and (pair? o) (eq? (car o) 'function)))

(define (.name o)
  (cadr o))

;; (define (.statement o)
;;   (match o
;;     (('function name signature statement) statement)
;;     (_ #f)))

;; (define (statement->data o)
;;   (match o
;;     (('call 'puts ('arguments string)) (string->list string))
;;     (_ '())))

;; (define (statement->text o)
;;   (match o
;;     (('call 'puts ('arguments string)) (list (lambda (data) (i386:puts data (string-length string)))))
;;     (('return code) (list (lambda (data) (i386:exit code))))
;;     (_ '())))

(define (.statement o)
  (and (pair? o)
       (eq? (car o) 'function)
       (cadddr o)))

(define (statement->data o)
  (or (and (pair? o)
           (eq? (car o) 'call)
           (string->list (cadr (caddr o))))
      (and (pair? o) (eq? (car o) 'for)
           (let ((statement (cadr (cdddr o))))
             (statement->data statement)))
      '()))

(define (statement->text data o)
  (cond
   ((and (pair? o) (eq? (car o) 'call))
    (let ((string (cadr (caddr o)))
          (offset (length data)))
      (list (lambda (data) (i386:puts (+ data offset) (string-length string))))))
   ((and (pair? o) (eq? (car o) 'for))
    (let ((start (cadr o))
          (test (caddr o))
          (step (cadddr o))
          (statement (cadr (cdddr o))))
      (display "start:" (current-error-port))
      (display start (current-error-port))
      (newline (current-error-port))

      (display "test:" (current-error-port))
      (display test (current-error-port))
      (newline (current-error-port))

      (display "step:" (current-error-port))
      (display step (current-error-port))
      (newline (current-error-port))

      (display "for-statement:" (current-error-port))
      (display statement (current-error-port))
      (newline (current-error-port))

      (let ((start (cadr (cdadr start)))
            (test (cadr (cdadr test)))
            ;;(step (cadr (cdadr step)))
            (step 1)
            (statement (car (statement->text data statement)))
            )
        (display "2start:" (current-error-port))
        (display start (current-error-port))
        (newline (current-error-port))

      (display "2for-statement:" (current-error-port))
      (display statement (current-error-port))
      (newline (current-error-port))

        (list (lambda (d) (i386:for start test step (statement d)))))))
   ((and (pair? o) (eq? (car o) 'return))
    (list (lambda (data) (i386:exit (cadr o)))))
   (else '())))

(define (compile)
  (let* ((ast (mescc))
         (functions (filter ast:function? (cdr ast)))
         (main (find (lambda (x) (eq? (.name x) 'main)) functions))
         (statements (cdr (.statement main))))
    (display "program: " (current-error-port))
    (display ast (current-error-port))
    (newline (current-error-port))
    (let loop ((statements statements) (text '()) (data '()))
      (display "text:" (current-error-port))
      (display text (current-error-port))
      (newline (current-error-port))
      (if (null? statements)
          (begin
            (display "dumping to a.out:\n" (current-error-port))
            (map write-any (make-elf (lambda (data)
                                       (append-map (lambda (f) (f data)) text)) data)))
          (let* ((statement (car statements)))
            (display "statement:" (current-error-port))
            (display statement (current-error-port))
            (newline (current-error-port))
            (loop (cdr statements)
                  (append text (statement->text data statement))
                  (append data (statement->data statement))))))))