/*
   ooRexx (FOSS):   <http://www.ooRexx.org>
   BSF4Rexx (FOSS): <http://wi.wu-wien.ac.at/rgf/rexx/bsf4rexx/current/> or
                    eventually at <https://sourceforge.net/projects/bsf4rexx>

    ------------------------ Apache Version 2.0 license -------------------------
       Copyright (C) 2001-2006 Rony G. Flatscher

       Licensed under the Apache License, Version 2.0 (the "License");
       you may not use this file except in compliance with the License.
       You may obtain a copy of the License at

           http://www.apache.org/licenses/LICENSE-2.0

       Unless required by applicable law or agreed to in writing, software
       distributed under the License is distributed on an "AS IS" BASIS,
       WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
       See the License for the specific language governing permissions and
       limitations under the License.
    -----------------------------------------------------------------------------
*/

/*********************************************************
 * A simple four function calculator, written in REXX    *
 *********************************************************/

/* *** create a res window                   */
res = .bsf~new("java.awt.TextField", 0)


/* *** create a panel of buttons                */
panel = .bsf~new("java.awt.Panel")
panel~setLayout(.bsf~new("java.awt.GridLayout", 4, 4))

buttons = "789*456/123-C0.+"
do i=1 to buttons~length
   label=buttons~substr(i, 1)
   button=.bsf~new("java.awt.Button", label)
   panel~add(button)

   if "*/-+"~pos(label)>0 then
      button~bsf.addEventListener("action", "", "call op '" ||label||"'")

   else if label="C" then
      button~bsf.addEventListener("action", "", "call clear")

   else
      button~bsf.addEventListener("action", "", "call press" label)
end


/* *** Place everything in the frame            */
frame = .bsf~bsf.lookupBean("frame")
frame~~setTitle("Object Rexx Calc") ~~resize(130, 200)
frame~~add("North", res) ~~add("Center", panel) ~~validate ~~show
frame~bsf.addEventListener("window", "windowClosing", "call bsf 'exit'")

/* *** Initialize the state of the calculator   */
mem = 0
nextOp = "+"
autoClear = 1                   /* true         */

do forever      /* get eventText and execute it as a Rexx program       */
   interpret .bsf~bsf.pollEventText
end
exit


press:                          /* handle data entry keys       */
   parse arg key

   if autoClear  then
      res~bsf.invokestrict("setText", "str", 0)

   if res~getText=="0" & key<>"." then
      res~bsf.invokeStrict("setText", "str", "")
      -- res~setText("str", "")

   if key="." then
      if pos(".", res~getText)>0 then
         key=""

   -- res~setText("str", res~getText || key)
   res~bsf.invokeStrict("setText", "str", res~getText || key)

   autoClear=0                  /* set it to false              */
   return

/*  *** handle arithmetic keys  */
op:
   parse arg key
   num=res~getText
   if      nextOp="+" then mem=mem+num
   else if nextOp="-" then mem=mem-num
   else if nextOp="*" then mem=mem*num
   else if nextOp="/" & num<>0 then mem=mem/num
   nextOp=key
   -- res~setText("str", mem)
   res~bsf.invokeStrict("setText", "str", mem)
   autoClear=1          /* set to true          */
   return

/* handle the "C" key   */
clear:
   mem=0
   nextOp=""
   -- res~setText("str", 0)
   res~bsf.invokeStrict("setText", "str", 0)
   return

::requires BSF.CLS    -- add Object Rexx proxy support