(in-package :cl-forth)

(defun make-token (sym? line col &optional (type nil))
  (when (null type)
    (setf type
          (cond ((numberp sym?) :number)
                ((stringp sym?) :string)
                ((is-identifier sym?) :identifier)
                (t
                 ;; temporary hack...
                 (return-from make-token
                   (values (list sym? :line line :col col :error t) t))))))
  (values (list sym? :line line :col col :type type) nil))

(defun token-op (token)
  (car token))

;;; LEXER
(defun read-string (stream)
  ;; TODO: Handle unmatched " and give proper error message
  (with-output-to-string (str)
    (iter (for ch = (read-char stream))
          (cond ((char= ch #\")
                 (finish))
                ((and (char= ch #\\) (char= (peek-char nil stream) #\n))
                 (read-char stream)
                 (write-char #\Newline str))
                (t (write-char ch str))))))

(defun lex-line (line &optional (line-num 0))
  (iter (with line-stream = (make-string-input-stream line))
        (with col = 0)
        (with has-err = nil)
        (for next-char = (peek-char nil line-stream nil nil))
        (until (null next-char))
        (let ((flag t))
          (cond ;; ((char= #\. next-char)
            ;;  (collect (make-token '|.| line-num col) into tokens)
            ;;  (read-char line-stream))
            ((char= #\|  next-char)
             (read-char line-stream)
             (collect (make-token "|" line-num col :identifier) into tokens))
            ((char= #\Space next-char) (read-char line-stream))
            ((char= #\; next-char) ;; and not in string
             (finish))
            ((char= #\" next-char)
             (read-char line-stream)
             (collect (make-token (read-string line-stream)
                                  line-num col)
               into tokens))
            (t (setf flag nil)))
          (when flag
            (incf col)
            (next-iteration)))
        (for next-sym in-stream line-stream
             using #'read-preserving-whitespace)
        (multiple-value-bind (token err)
            (make-token next-sym line-num col)
          (collect token into tokens)
          (when err ;; skip line on error and continue lexing
            (setf has-err t)
            (finish))
          (incf col (length (princ-to-string next-sym))))
        (finally (return (values tokens has-err)))))

(defun lex-file (file-name &optional report-errors)
  (let ((has-error nil))
    (values
     (with-open-file (str file-name :external-format :utf-8)
       (iter outer
             (for line = (read-line str nil nil))
             (until (null line))
             (for line-num from 1)
             (multiple-value-bind (tokens has-err)
                 (lex-line line line-num)
               (when has-err
                 (setf has-error t)
                 (when report-errors
                   (let ((err-token (find-if (lambda (tok) (find :error tok))
                                             tokens)))
                     (format t "~5@a ~a~%"
                             (format nil "~a:" (getf (cdr err-token) :line))
                             line)
                     (format t "      ~a^~%"
                             (make-string (getf (cdr err-token) :col)
                                          :initial-element #\Space)))))
               (appending tokens))))
     has-error)))

(defun lex-string (string &optional report-errors)
  (let ((has-error nil))
    (values
     (let ((str (make-string-input-stream string)))
       (iter outer
             (for line = (read-line str nil nil))
             (until (null line))
             (for line-num from 1)
             (multiple-value-bind (tokens has-err)
                 (lex-line line line-num)
               (when has-err
                 (setf has-error t)
                 (when report-errors
                   (format t "~a~%" line)
                   (let ((err-token (find-if (lambda (tok) (find :error tok))
                                             tokens)))
                     (format t "~a^"
                             (make-string (getf (cdr err-token) :col)
                                          :initial-element #\Space)))))
               (appending tokens))))
     has-error)))

;;; PARSER
(defun parse-tokens (tokens)
  (iter (with ops = (make-array (length tokens) :fill-pointer 0
                                                :adjustable t))
        (with stack = ())
        (for i from 0)
        (for token in tokens)
        (let ((op (token-op token))
              (op-type (getf (cdr token) :type)))
          (cond ((eq :number op-type)
                 (vector-push-extend `(push-int ,op) ops))
                ((eq :string op-type)
                 (vector-push-extend `(push-str ,(length op) ,i ,op)
                                     ops))
                ((string= 'ise op)
                 (push (list 'ise i) stack)
                 (vector-push-extend (list 'ise nil) ops))
                ((string= 'yoksa op)
                 (let ((top (pop stack)))
                   (assert (string= 'ise (car top)))
                   (setf (second (aref ops (cadr top))) i)
                   (push (list 'yoksa i) stack)
                   (vector-push-extend (list 'yoksa nil i) ops)))
                ((string= 'yap op)
                 (let ((top (pop stack)))
                   (cond ((find (car top) (list 'yoksa 'ise))
                          (setf (second (aref ops (cadr top))) i)
                          (vector-push-extend (list 'yap i) ops))
                         ((string= 'iken (car top))
                          (setf (second (aref ops (cadr top))) i)
                          (vector-push-extend (list 'yap i (third top)) ops))
                         (t (error "yap cannot reference: ~a" (car top))))))
                ((string= 'döngü op)
                 (push (list 'döngü i) stack)
                 (vector-push-extend (list 'döngü i) ops))
                ((string= 'iken op)
                 (let ((top (pop stack)))
                   (assert (string= 'döngü (car top)))
                   (push (list 'iken i (cadr top)) stack)
                   (vector-push-extend (list 'iken nil) ops)))
                ((search "syscall" (string-downcase (string op)))
                 (let ((syscall-num (parse-integer (subseq (string op) 8))))
                   (vector-push-extend (list 'syscall syscall-num) ops)))
                (t (vector-push-extend (list op) ops))))
        (finally (return ops))))

(defun make-program (file-name)
  (multiple-value-bind (tokens has-error)
      (lex-file file-name t)
    (when has-error
      (error "Can't generate program due to error during lexing"))
    (parse-tokens tokens)))

;;; COMPILER
(defun write-program (program out &key (mem-cap 640000))
  (format out "~a~%" "segment .text")
  (gen-dump out)
  (format out "~{~a~%~}" '("global _start"
                           "_start:"))
  (let ((strs nil))
    (iter (for op in-sequence program)
          (let ((gen-val (gen-code op out)))
            (when (and (consp gen-val) (eq :string (car gen-val)))
              (push (cdr gen-val) strs))))
         (gen-code '(exit 0) out)
         (unless (null strs)
           (format out "segment .data~%")
           (dolist (str strs)
             (format out "str_~a: db ~{0x~x~^,~}~%"
                     (first str)
                     (map 'list #'char-code (second str))))))
  (format out "~a~%" "segment .bss")
  (format out "~a ~a~%" "bel: resb" mem-cap))

(defun generate-program (program &key (path "output.asm") (compile nil)
                                   (mem-cap 640000) (silence nil))
  (with-open-file (out path :direction :output
                            :if-exists :supersede)
    (write-program program out :mem-cap mem-cap))
  (when compile
    (run `("nasm" "-felf64" ,path) :output t :silence silence)
    (let ((name (first (uiop:split-string path :separator '(#\.)))))
      (run `("ld" "-o" ,name ,(concatenate 'string name ".o"))
           :output t :silence silence))))

(defun compile-program (path)
  (generate-program (make-program path) :compile t))