(import scheme)
(import (chicken base))
(import (chicken format))
(import (chicken pathname))
(import (chicken process-context))
(import gtk-server)

(define gtk-server (start-gtk-server!))
(define (gtk #!rest args) (apply gtk-send! gtk-server args))

(gtk "gtk_init" 'NULL 'NULL)
(gtk "gtk_server_define gtk_builder_new_from_file NONE WIDGET 1 STRING")
(gtk "gtk_server_define gtk_builder_get_object NONE WIDGET 2 WIDGET STRING")
(define widget #f)

;; Get GUI definition
(define ui-file (pathname-replace-extension (program-name) ".ui"))
(define xml (gtk "gtk_builder_new_from_file" ui-file))

;; Get main window ID and connect signal
(set! widget (gtk "gtk_builder_get_object" xml "window"))
(gtk "gtk_server_connect" widget "delete-event" "window")

;; Get button ID's and connect signals
(set! widget (gtk "gtk_builder_get_object" xml "button0"))
(gtk "gtk_server_connect" widget "clicked" "button0")
(set! widget (gtk "gtk_builder_get_object" xml "button1"))
(gtk "gtk_server_connect" widget "clicked" "button1")
(set! widget (gtk "gtk_builder_get_object" xml "button2"))
(gtk "gtk_server_connect" widget "clicked" "button2")
(set! widget (gtk "gtk_builder_get_object" xml "button3"))
(gtk "gtk_server_connect" widget "clicked" "button3")
(set! widget (gtk "gtk_builder_get_object" xml "button4"))
(gtk "gtk_server_connect" widget "clicked" "button4")
(set! widget (gtk "gtk_builder_get_object" xml "button5"))
(gtk "gtk_server_connect" widget "clicked" "button5")
(set! widget (gtk "gtk_builder_get_object" xml "button6"))
(gtk "gtk_server_connect" widget "clicked" "button6")
(set! widget (gtk "gtk_builder_get_object" xml "button7"))
(gtk "gtk_server_connect" widget "clicked" "button7")
(set! widget (gtk "gtk_builder_get_object" xml "button8"))
(gtk "gtk_server_connect" widget "clicked" "button8")
(set! widget (gtk "gtk_builder_get_object" xml "button9"))
(gtk "gtk_server_connect" widget "clicked" "button9")
;; Operators
(set! widget (gtk "gtk_builder_get_object" xml "buttonC"))
(gtk "gtk_server_connect" widget "clicked" "buttonC")
(set! widget (gtk "gtk_builder_get_object" xml "buttonCE"))
(gtk "gtk_server_connect" widget "clicked" "buttonCE")
(set! widget (gtk "gtk_builder_get_object" xml "buttonAdd"))
(gtk "gtk_server_connect" widget "clicked" "buttonAdd")
(set! widget (gtk "gtk_builder_get_object" xml "buttonMinus"))
(gtk "gtk_server_connect" widget "clicked" "buttonMinus")
(set! widget (gtk "gtk_builder_get_object" xml "buttonMul"))
(gtk "gtk_server_connect" widget "clicked" "buttonMul")
(set! widget (gtk "gtk_builder_get_object" xml "buttonDiv"))
(gtk "gtk_server_connect" widget "clicked" "buttonDiv")
(set! widget (gtk "gtk_builder_get_object" xml "buttonEq"))
(gtk "gtk_server_connect" widget "clicked" "buttonEq")
;; Memory buttons
(set! widget (gtk "gtk_builder_get_object" xml "buttonMemadd"))
(gtk "gtk_server_connect" widget "clicked" "buttonMemadd")
(set! widget (gtk "gtk_builder_get_object" xml "buttonMemread"))
(gtk "gtk_server_connect" widget "clicked" "buttonMemread")
;; Get entry ID
(define entry (gtk "gtk_builder_get_object" xml "entry"))
;; Calculator starts with 0
(gtk "gtk_entry_set_text" entry 0)

;;; Init variables

(define state 0) ; Initialize calculator state
(define cache 0) ; Initialize temp calculator cache
(define action 0) ; Initialize last calculator action
(define total 0) ; Initialize calculator total result
(define mem 0) ; Initialize MEM function

;;; Functions

;; Define action when +, -, *, or / is pressed
(define (operator-key)
  (define (// a b) (inexact->exact (floor (/ a b))))
  (when (= state 0)
    (case action
      ((1)
       (set! cache (+ cache (string->number (gtk "gtk_entry_get_text" entry))))
       (gtk "gtk_entry_set_text" entry cache))
      ((2)
       (set! cache (- cache (string->number (gtk "gtk_entry_get_text" entry))))
       (gtk "gtk_entry_set_text" entry cache))
      ((3)
       (set! cache (* cache (string->number (gtk "gtk_entry_get_text" entry))))
       (gtk "gtk_entry_set_text" entry cache))
      ((4)
       (if (zero? (string->number (gtk "gtk_entry_get_text" entry)))
           (gtk "gtk_entry_set_text" entry "ERROR")
           (begin
             (set! cache (// cache (string->number
                                    (gtk "gtk_entry_get_text" entry))))
             (gtk "gtk_entry_set_text" entry cache)))))))

;; Define action when 0 1 2 3 4 5 6 7 8 9 is pressed; requires argument
(define (number-key arg)
  (let ((number (gtk "gtk_entry_get_text" entry)))
    (if (or (equal? number "0") (> state 0))
        (begin
          (set! cache (string->number number))
          (gtk "gtk_entry_set_text" entry arg))
        (gtk "gtk_entry_set_text" entry (string-append number arg)))
    (set! state 0)))

;; Mainloop
(let loop ()
  (let ((event (gtk "gtk_server_callback wait")))
    (when (not (equal? event "window"))
      (cond
       ((equal? event "buttonMemread")
        (set! state 0)
        (set! cache (string->number (gtk "gtk_entry_get_text" entry)))
        (gtk "gtk_entry_set_text" entry mem))
       ((equal? event "buttonMemadd")
        (set! mem (gtk "gtk_entry_get_text" entry)))
       ((equal? event "buttonC")
        (gtk "gtk_entry_set_text" entry 0))
       ((equal? event "buttonCE")
        (set! total 0)
        (set! state 0)
        (set! action 0)
        (set! cache 0)
        (set! mem 0)
        (gtk "gtk_entry_set_text" entry 0))
       ((equal? event "buttonAdd")
        (operator-key)
        (set! action 1)
        (set! state (+ state 1)))
       ((equal? event "buttonMinus")
        (operator-key)
        (set! action 2)
        (set! state (+ state 1)))
       ((equal? event "buttonMul")
        (operator-key)
        (set! action 3)
        (set! state (+ state 1)))
       ((equal? event "buttonDiv")
        (operator-key)
        (set! action 4)
        (set! state (+ state 1)))
       ((equal? event "buttonEq")
        (operator-key)
        (set! action 0)
        (set! state (+ state 1)))
       ((member event '("button0" "button1" "button2" "button3" "button4"
                        "button5" "button6" "button7" "button8" "button9"))
        (number-key (string (string-ref event 6)))))
      (loop))))

;; Exit GTK
(gtk "gtk_server_exit")
(stop-gtk-server! gtk-server)