;;; Utils

(defmacro while (condition &body body)
  `(do ()
       ((not ,condition))
     ,@body))

;;; simplify me, please
(defun concat (&rest strs)
  (reduce (lambda (s1 s2) (concatenate 'string s1 s2))
          strs
          :initial-value ""))


(let ((counter 0))
  (defun make-var-binding (symbol)
    (cons symbol (format nil "v~d" (incf counter)))))

(let ((counter 0))
  (defun make-func-binding (symbol)
    (cons symbol (format nil "f~d" (incf counter)))))


;;; Concatenate a list of strings, with a separator
(defun join (list separator)
  (cond
    ((null list)
     "")
    ((null (cdr list))
     (car list))
    (t
     (concat (car list)
             separator
             (join (cdr list) separator)))))

;;; Compiler

(defvar *compilations* nil)

(defun ls-compile-sexps (sexps env fenv)
  (concat (join (mapcar (lambda (x)
                          (concat (ls-compile x env fenv) ";"))
                        sexps)
                ";
")))

(defun ls-compile-block (sexps env fenv)
  (concat (ls-compile-sexps (butlast sexps) env fenv)
          "return " (ls-compile (car (last sexps)) env fenv) ";"))


(defun extend-env (args env)
  (append (mapcar #'make-var-binding args) env))

(defparameter *env* '())
(defparameter *fenv* '())

(defun ls-lookup (symbol env)
  (let ((binding (assoc symbol env)))
    (and binding (format nil "~a" (cdr binding)))))

(defun lookup-variable (symbol env)
  (or (ls-lookup symbol env)
      (ls-lookup symbol *env*)
      (error "Undefined variable `~a'"  symbol)))

(defun lookup-function (symbol env)
  (or (ls-lookup symbol env)
      (ls-lookup symbol *fenv*)
      (error "Undefined function `~a'"  symbol)))

(defmacro define-compilation (name args &body body)
  ;; Creates a new primitive `name' with parameters args and
  ;; @body. The body can access to the local environment through the
  ;; variable ENV.
  `(push (list ',name (lambda (env fenv ,@args) ,@body))
         *compilations*))

(define-compilation if (condition true false)
  (format nil "((~a)? (~a) : (~a))"
          (ls-compile condition env fenv)
          (ls-compile true env fenv)
          (ls-compile false env fenv)))

(define-compilation lambda (args &rest body)
  (let ((new-env (extend-env args env)))
    (concat "(function ("
	    (join (mapcar (lambda (x) (lookup-variable x new-env))
                          args)
                  ",")
	    "){
"
	    (ls-compile-block body new-env fenv)
	    "
})")))

(define-compilation fsetq (var val)
  (format nil "~a = ~a" (lookup-function var fenv) (ls-compile val env fenv)))

(define-compilation setq (var val)
  (format nil "~a = ~a" (lookup-variable var env) (ls-compile val env fenv)))

(defun lisp->js (sexp)
  (cond
    ((integerp sexp) (format nil "~a" sexp))
    ((stringp sexp) (format nil "\"~a\"" sexp))
    ((listp sexp)   (concat "[" (join (mapcar 'lisp->js sexp) ",") "]"))))

(define-compilation quote (sexp)
  (lisp->js sexp))

(define-compilation debug (form)
  (format nil "console.log(~a)" (ls-compile form env fenv)))

(define-compilation while (pred &rest body)
  (format nil "(function(){while(~a){~a}})() "
	  (ls-compile pred env fenv)
	  (ls-compile-sexps body env fenv)))

(defmacro eval-when-compile (&body body)
  `(eval-when (:compile-toplevel :execute)
     ,@body))

(define-compilation eval-when-compile (&rest body)
  (eval (cons 'progn body)))

;;; aritmetic primitives
(define-compilation + (x y)
  (concat "((" (ls-compile x env fenv) ") + (" (ls-compile y env fenv) "))"))

(define-compilation - (x y)
  (concat "((" (ls-compile x env fenv) ") - (" (ls-compile y env fenv) "))"))

(define-compilation * (x y)
  (concat "((" (ls-compile x env fenv) ") * (" (ls-compile y env fenv) "))"))

(define-compilation / (x y)
  (concat "((" (ls-compile x env fenv) ") / (" (ls-compile y env fenv) "))"))

(define-compilation = (x y)
  (concat "((" (ls-compile x env fenv) ") == (" (ls-compile y env fenv) "))"))


(defun %compile-defvar (name)
  (push (make-var-binding name) *env*)
  (format nil "var ~a" (lookup-variable name *env*)))

(defun %compile-defun (name)
  (push (make-func-binding name) *fenv*)
  (format nil "var ~a" (lookup-variable name *fenv*)))

(defun compile-funcall (name args env fenv)
  (format nil "~a(~{~a~^, ~})"
          (lookup-function name fenv)
          (mapcar (lambda (x) (ls-compile x env fenv)) args)))

(defun ls-compile (sexp &optional env fenv)
  (cond
    ((symbolp sexp) (lookup-variable sexp env))
    ((integerp sexp) (format nil "~a" sexp))
    ((stringp sexp) (format nil "\"~a\"" sexp))
    ((listp sexp)
     (let ((compiler-func (second (assoc (car sexp) *compilations*))))
       (if compiler-func
           (apply compiler-func env fenv (cdr sexp))
           (compile-funcall (car sexp) (cdr sexp) env fenv))))))


;;; Testing

(defun compile-test ()
  (with-open-file (in "test.lisp")
    (with-open-file (out "test.js" :direction :output :if-exists :supersede)
      (loop
         for x = (read in nil) while x
         do (write-line (concat (ls-compile x) "; ") out)))))