(in-package #:mulk.objective-cl)


;;; (@* "Low-level Data Conversion")
(declaim (ftype (function (*)
                          (values foreign-pointer &rest nil))
                obj-data->lisp))
(defun lisp->obj-data (value)
  (let ((obj-data (foreign-alloc 'obj-data))
        (type-name (lisp-value->type-name value)))
    (with-foreign-slots ((type data) obj-data obj-data)
      (setf (foreign-slot-value data
                                'obj-data-union
                                (type-name->slot-name type-name))
            (typecase value
              (symbol (selector value))
              ((or id objc-class selector exception)
               (pointer-to value))
              (string (foreign-string-alloc value))
              (otherwise value)))
      (setf type
            (foreign-string-alloc (type-name->type-id type-name))))
    obj-data))


(declaim (ftype (function (foreign-pointer)
                          (values (or number string symbol selector id
                                      objc-class boolean foreign-pointer)
                                  &rest nil))
                obj-data->lisp))
(defun obj-data->lisp (obj-data)
  (with-foreign-slots ((type data) obj-data obj-data)
    (let* ((type-name (type-id->type-name (foreign-string-to-lisp type)))
           (lisp-type (type-name->lisp-type type-name))
           (value     (if (eq 'void type-name)
                          (values)
                          (foreign-slot-value data
                                              'obj-data-union
                                              (type-name->slot-name type-name)))))
      (case lisp-type
        ((id objc-class selector exception)
         (make-instance lisp-type :pointer value))
        ((string) (foreign-string-to-lisp value))
        (otherwise value)))))


(defmacro with-foreign-conversion (bindings &body body)
  `(with-foreign-objects
       ,(mapcar #'(lambda (name-value-pair)
                     (destructuring-bind (name value)
                         name-value-pair
                       `(,name (lisp->obj-data ,value))))
                bindings)
     ,@body))


(defmacro with-foreign-objects (bindings &body body)
  `(let ,(mapcar #'(lambda (name-value-pair)
                     (destructuring-bind (name value)
                         name-value-pair
                       `(,name ,value)))
                 bindings)
     (unwind-protect
          (progn ,@body)
       ,@(mapcar #'(lambda (name-value-pair)
                     `(dealloc-obj-data ,(first name-value-pair)))
                 bindings))))


(declaim (ftype (function (foreign-pointer) (values string &rest nil))
                foreign-string-to-lisp/dealloc))
(defun foreign-string-to-lisp/dealloc (foreign-string)
  "Convert a (possibly freshly allocated) C string into a Lisp string
and free the C string afterwards."

  (unwind-protect
       (foreign-string-to-lisp foreign-string)
    (foreign-string-free foreign-string)))


(defun parse-typespec (typestring &optional (start 0))
  "Parse a typestring like \"@0:4{_NSRange=II}8\" into something like (ID ()).

\"rn{_NSRange=II}8\" is parsed into (STRUCT (CONST IN)
\"_NSRange\" :INTEGER :INTEGER).

Returns: (VALUES typespec byte-position string-position)"

  (let ((init-char (char typestring start))
        (string-position start)
        (qualifiers (list)))
    (loop do (setq init-char (char typestring string-position))
          while (let ((qualifier (case init-char
                                   (#\r 'const)
                                   (#\n 'in)
                                   (#\N 'inout)
                                   (#\o 'out)
                                   (#\O 'bycopy)
                                   (#\V 'oneway)
                                   (#\R 'byref))))
                  (and qualifier
                       (incf string-position)
                       (push qualifier qualifiers))))
    (values (case init-char
              ((#\{ #\()
               (let* ((=-token (position #\= typestring :start start))
                      (name-end (or =-token
                                    ;; An opaque struct whose contents
                                    ;; we don't know.
                                    (position (ecase init-char
                                               (#\{ #\})
                                               (#\( #\)))
                                              typestring
                                              :start start)
                                    (error "Premature end of file in~
                                            typespec: ~A."
                                           typestring)))
                      (struct-name (subseq typestring
                                           (1+ string-position)
                                           name-end)))
                 (list* (ecase init-char
                          (#\{ 'struct)
                          (#\( 'union))
                        (if =-token
                            qualifiers
                            (cons 'opaque qualifiers))
                        struct-name
                        (progn
                          (setq string-position
                                (if =-token
                                    (1+ name-end) ; skip #\=
                                    name-end))
                          (loop until (char= (char typestring string-position)
                                             (ecase init-char
                                               (#\{ #\})
                                               (#\( #\))))
                                collect (multiple-value-bind (typespec
                                                              byte-position
                                                              new-string-pos)
                                            (parse-typespec
                                             typestring
                                             string-position)
                                          (declare (ignore byte-position))
                                          (setq string-position new-string-pos)
                                          typespec)
                                ;; Skip end marker (right brace/paren).
                                finally (incf string-position))))))
              (#\^ (list 'pointer
                         qualifiers
                         (multiple-value-bind (typespec byte-pos new-str-pos)
                             (parse-typespec typestring (1+ string-position))
                           (declare (ignore byte-pos))
                           (prog1 typespec
                             (setq string-position new-str-pos)))))
              (#\[ (list 'array
                         qualifiers
                         (multiple-value-bind (count new-str-pos)
                             (parse-integer typestring
                                            :start (1+ string-position)
                                            :junk-allowed t)
                           (prog1 count
                             (setq string-position new-str-pos)))
                         (multiple-value-bind (typespec byte-pos new-str-pos)
                             (parse-typespec typestring string-position)
                           (declare (ignore byte-pos))
                           ;; Skip end marker (right bracket).
                           (prog1 typespec
                             (setq string-position (1+ new-str-pos))))))
              (#\j
               (list 'complex
                     qualifiers
                     (multiple-value-bind (typespec byte-pos new-str-pos)
                         (parse-typespec typestring (1+ string-position))
                       (declare (ignore byte-pos))
                       (prog1 typespec
                         (setq string-position new-str-pos)))))
              (#\b
               (let (bit-field-starting-pos
                     bit-field-typespec
                     bit-field-length
                     byte-position)
                 (multiple-value-setq (bit-field-starting-pos string-position)
                     (parse-integer typestring
                                    :start (1+ string-position)
                                    :junk-allowed t))
                 (multiple-value-setq (bit-field-typespec
                                       byte-position
                                       string-position)
                     (parse-typespec typestring string-position))
                 (multiple-value-setq (bit-field-length string-position)
                     (parse-integer typestring
                                    :start string-position
                                    :junk-allowed t))
                 (list 'bit-field
                       qualifiers
                       bit-field-starting-pos
                       bit-field-length
                       bit-field-typespec)))
              (otherwise
               (prog1 (list (case init-char
                              (#\B :boolean)
                              (#\c :char)
                              (#\C :unsigned-char)
                              (#\s :short)
                              (#\S :unsigned-short)
                              (#\i :int)
                              (#\I :unsigned-int)
                              (#\l :long)
                              (#\L :unsigned-long)
                              (#\q :long-long)
                              (#\Q :unsigned-long-long)
                              (#\f :float)
                              (#\d :double)
                              (#\v :void)
                              (#\@ 'id)
                              (#\# 'objc-class)
                              (#\: 'selector)
                              (#\* :string)
                              (#\? :unknown))
                            qualifiers)
                 (incf string-position))))
            #+(or)  ; too greedy (=> bit-fields can't see their length!)
            (multiple-value-bind (byte-position new-string-pos)
                (parse-integer typestring
                               :start string-position
                               :junk-allowed t)
              (setq string-position new-string-pos)
              byte-position)
            #-(or) nil
            string-position)))


;;; (@* "High-level Data Conversion")
(eval-when (:compile-toplevel :load-toplevel)
  ;; In order to be able to dispatch over pointer types, we need to
  ;; define an alias of the implementation's own pointer class.  Note
  ;; that this may be T (in GNU CLISP, for example), so it's a good idea
  ;; to use CHECK-TYPE in the method body.
  (unless (find-class 'foreign-pointer nil)
    (setf (find-class 'foreign-pointer nil)
          (class-of (make-pointer 0))))
  (deftype foreign-pointer ()
    '(satisfies cffi:pointerp)))


(defun objc-typep (x class-designator)
  (objc-eql (invoke x 'class)
            (etypecase x
              (class x)
              (id (invoke x 'class))
              ((or string symbol) (find-objc-class class-designator t)))))


(defgeneric ->id (x))
(defgeneric ->class (x))
(defgeneric ->integer (x))
(defgeneric ->selector (x))
(defgeneric ->exception (x))
(defgeneric ->character (x))
(defgeneric ->float (x))
(defgeneric ->double (x))
(defgeneric ->bool (x))
(defgeneric ->string (x))
(defgeneric ->pointer (x))


(defmethod ->id ((x id))
  x)

(defmethod ->id ((x class))
  (invoke x 'self))

(defmethod ->id ((x exception))
  (invoke x 'self))

(defmethod ->id ((x integer))
  (let ((id (invoke (find-class 'ns-number)
                    :number-with-long x)))
    (invoke id 'retain)
    (invoke id 'autorelease)
    id))

(defmethod ->id ((x float))
  (let ((id (invoke (find-class 'ns-number)
                    :number-with-double x)))
    (invoke id 'retain)
    (invoke id 'autorelease)
    id))

(defmethod ->id ((x string))
  (let ((id (invoke (find-class 'ns-string)
                    :string-with-c-string x)))
    (invoke id 'retain)
    (invoke id 'autorelease)
    id))


(defmethod ->class ((x id))
  (invoke x 'class))

(defmethod ->class ((x exception))
  (invoke x 'class))

(defmethod ->class ((x class))
  x)

(defmethod ->class ((x string))
  (find-objc-class x t))

(defmethod ->class ((x symbol))
  (find-objc-class x t))


(defmethod ->integer ((x id))
  (assert (objc-typep x 'ns-number))
  (invoke x 'long-value))

(defmethod ->integer ((x number))
  (truncate x))

(defmethod ->integer ((x null))
  0)

(defmethod ->integer ((x symbol))
  (assert (eq 't x))
  1)


(defmethod ->selector ((x selector))
  x)

(defmethod ->selector ((x symbol))
  (selector x))

(defmethod ->selector ((x string))
  (selector x))

(defmethod ->selector ((x cons))
  (selector x))


(defmethod ->exception ((x exception))
  x)


(defmethod ->character ((x character))
  x)

(defmethod ->character ((x integer))
  x)


(defmethod ->float ((x number))
  (float x))


(defmethod ->double ((x number))
  (float x))


(defmethod ->bool ((x null))
  x)

(defmethod ->bool ((x symbol))
  (assert (eq 't x))
  x)

(defmethod ->bool ((x integer))
  x)


(defmethod ->string ((x string))
  x)

(defmethod ->string ((x foreign-pointer))
  (check-type x foreign-pointer)
  x)


(defmethod ->pointer ((x foreign-pointer))
  (check-type x foreign-pointer)
  x)

(defmethod ->pointer ((x exception))
  (pointer-to x))

(defmethod ->pointer ((x c-pointer-wrapper))
  (pointer-to x))

(defmethod ->pointer ((x number))
  (pointer-to (->id x)))