/* -*- mode: JavaScript; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
/* Copyright 2010-2013 Will Scullin <scullin@scullinsteel.com>
 *
 * Permission to use, copy, modify, distribute, and sell this software and its
 * documentation for any purpose is hereby granted without fee, provided that
 * the above copyright notice appear in all copies and that both that
 * copyright notice and this permission notice appear in supporting
 * documentation.  No representations are made about the suitability of this
 * software for any purpose.  It is provided "as is" without express or
 * implied warranty.
 */

/*globals debug: false, toHex: false, each: false */
/*exported Apple2IO */

function Apple2IO(cpu, callbacks)
{
    var SAMPLE_RATE = 64;

    var _buffer = [];
    var _key = 0;
    var _keyDown = false;
    var _button = [false, false, false];
    var _paddle = [0.0, 0.0, 0.0, 0,0];
    var _phase = -1;
    var _sample = [];
    var _oldSample = [];
    var _sampleTime = 0;

    var _high = "%A0";
    var _low = "%60";

    var _trigger = 0;

    var LOC = {
        KEYBOARD: 0x00, // keyboard data (latched) (Read), 
        CLR80VID: 0x0C, // clear 80 column mode
        SET80VID: 0x0D, // set 80 column mode
        CLRALTCH: 0x0E, // clear 80 column mode
        SETALTCH: 0x0F, // set 80 column mode
        STROBE:   0x10, // clear bit 7 of keyboard data ($C000)

        RDTEXT:   0x1A, // using text mode
        RDMIXED:  0x1B, // using mixed mode
        RDPAGE2:  0x1C, // using text/graphics page2
        RDHIRES:  0x1D, // using Hi-res graphics mode
        RDALTCH:  0x1E, // using alternate character set
        RD80VID:  0x1F, // using 80-column display mode

        TAPEOUT:  0x20, // toggle the cassette output.
        SPEAKER:  0x30, // toggle speaker diaphragm
        CLRTEXT:  0x50, // display graphics
        SETTEXT:  0x51, // display text
        CLRMIXED: 0x52, // clear mixed mode- enable full graphics
        SETMIXED: 0x53, // enable graphics/text mixed mode
        PAGE1:    0x54, // select text/graphics page1
        PAGE2:    0x55, // select text/graphics page2
        CLRHIRES: 0x56, // select Lo-res
        SETHIRES: 0x57, // select Hi-res
        CLRAN0:   0x58, // Set annunciator-0 output to 0
        SETAN0:   0x59, // Set annunciator-0 output to 1
        CLRAN1:   0x5A, // Set annunciator-1 output to 0
        SETAN1:   0x5B, // Set annunciator-1 output to 1
        CLRAN2:   0x5C, // Set annunciator-2 output to 0
        SETAN2:   0x5D, // Set annunciator-2 output to 1
        CLRAN3:   0x5E, // Set annunciator-3 output to 0
        SETAN3:   0x5F, // Set annunciator-3 output to 1
        TAPEIN:   0x60, // bit 7: data from cassette
        PB0:      0x61, // game Pushbutton 0 / open apple (command) key data
        PB1:      0x62, // game Pushbutton 1 / closed apple (option) key data
        PB2:      0x63, // game Pushbutton 2 (read)
        PADDLE0:  0x64, // bit 7: status of pdl-0 timer (read)
        PADDLE1:  0x65, // bit 7: status of pdl-1 timer (read)
        PADDLE2:  0x66, // bit 7: status of pdl-2 timer (read)
        PADDLE3:  0x67, // bit 7: status of pdl-3 timer (read)
        PDLTRIG:  0x70, // trigger paddles
        SETIOUDIS:0x7E, // Enable double hires
        CLRIOUDIS:0x7F  // Disable double hires
    };
    
    function _debug() {
        // debug.apply(arguments);
    }

    var _locs = [];

    function _access(off) {
        var result = 0;
        var now = cpu.cycles();
        var delta = now - _trigger;
        switch (off) {
        case LOC.CLR80VID:
            // _debug("80 Column Mode off");
            if ('_80col' in callbacks) callbacks._80col(false);
            break;
        case LOC.SET80VID:
            // _debug("80 Column Mode on");
            if ('_80col' in callbacks) callbacks._80col(true);
            break;
        case LOC.CLRALTCH:
            // _debug("Alt Char off");
            if ('altchar' in callbacks) callbacks.altchar(false);
            break;
        case LOC.SETALTCH:
            // _debug("Alt Char on");
            if ('altchar' in callbacks) callbacks.altchar(true);
            break;
        case LOC.CLRTEXT:
            _debug("Graphics Mode");
            callbacks.text(false);
            break;
        case LOC.SETTEXT:
            _debug("Text Mode");
            callbacks.text(true);
            break;
        case LOC.CLRMIXED:
            _debug("Mixed Mode off");
            callbacks.mixed(false);
            break;
        case LOC.SETMIXED:
            _debug("Mixed Mode on");
            callbacks.mixed(true);
            break;
        case LOC.CLRHIRES:
            _debug("LoRes Mode");
            callbacks.hires(false);
            break;
        case LOC.SETHIRES:
            _debug("HiRes Mode");
            callbacks.hires(true);
            break;
        case LOC.PAGE1:
            callbacks.page(1);
            break;
        case LOC.PAGE2:
            callbacks.page(2);
            break;
        case LOC.RDTEXT:
            if ('isText' in callbacks) 
                result = callbacks.isText() ? 0x80 : 0x0;
            break;
        case LOC.RDMIXED:
            if ('isMixed' in callbacks) 
                result = callbacks.isMixed() ? 0x80 : 0x0;
            break;
        case LOC.RDPAGE2:
            if ('isPage2' in callbacks) 
                result = callbacks.isPage2() ? 0x80 : 0x0;
            break;
        case LOC.RDHIRES:
            if ('isHires' in callbacks) 
                result = callbacks.isHires() ? 0x80 : 0x0;
            break;
        case LOC.RD80VID:
            if ('is80Col' in callbacks) 
                result = callbacks.is80Col() ? 0x80 : 0x0;
            break;
        case LOC.RDALTCH:
            if ('isAltChar' in callbacks) 
                result = callbacks.isAltChar() ? 0x80 : 0x0;
            break;
        case LOC.SETAN0:
            _debug('Annunciator 0 on');
            if ('annunciator' in callbacks) callbacks.annunicator(0, true);
            break;
        case LOC.SETAN1:
            _debug('Annunciator 1 on');
            if ('annunciator' in callbacks) callbacks.annunicator(1, true);
            break;
        case LOC.SETAN2:
            _debug('Annunciator 2 on');
            if ('annunciator' in callbacks) callbacks.annunicator(2, true);
            break;
        case LOC.SETAN3:
            _debug('Annunciator 3 on');
            if ('annunciator' in callbacks) callbacks.annunicator(3, true);
            if ('doublehires' in callbacks) callbacks.doublehires(false);
            break;
        case LOC.CLRAN0:
            _debug('Annunciator 0 off');
            if ('annunciator' in callbacks) callbacks.annunicator(0, false);
            break;
        case LOC.CLRAN1:
            _debug('Annunciator 1 off');
            if ('annunciator' in callbacks) callbacks.annunicator(1, false);
            break;
        case LOC.CLRAN2:
            _debug('Annunciator 2 off');
            if ('annunciator' in callbacks) callbacks.annunicator(2, false);
            break;
        case LOC.CLRAN3:
            _debug('Annunciator 3 off');
            if ('annunciator' in callbacks) callbacks.annunicator(3, false);
            if ('doublehires' in callbacks) callbacks.doublehires(true);
            break;
        case LOC.SPEAKER:
            if (_sampleTime) {
                var phase = _phase > 0 ? _high : _low;
                for (; _sampleTime < now; _sampleTime += SAMPLE_RATE) {
                    _sample.push(phase);
                }
                _phase = -_phase;
            }
            break;
        case LOC.STROBE:
            _key &= 0x7f;
            if (_buffer.length > 0) {
                _key = _buffer.shift().charCodeAt(0) | 0x80;
            }
            result = _keyDown ? 0x80 : 0x00;
            break;
        case LOC.KEYBOARD:
            result = _key;
            break;
        case LOC.PB0:
            result = _button[0] ? 0x80 : 0;
            break;
        case LOC.PB1:
            result = _button[1] ? 0x80 : 0;
            break;
        case LOC.PB2:
            result = _button[2] ? 0x80 : 0;
            break;
        case LOC.PADDLE0:
            result = (delta < (_paddle[0] * 2560) ? 0x80 : 0x00);
            break;
        case LOC.PADDLE1:
            result = (delta < (_paddle[1] * 2560) ? 0x80 : 0x00);
            break;
        case LOC.PADDLE2:
            result = (delta < (_paddle[2] * 2560) ? 0x80 : 0x00);
            break;
        case LOC.PADDLE3:
            result = (delta < (_paddle[3] * 2560) ? 0x80 : 0x00);
            break;
        case LOC.PDLTRIG:
            _trigger = cpu.cycles();
            break;
        }
        return result;       
    }
    
    return {
        registerSwitches: function apple2io_registerSwitches(a, locs) {
            each(locs, function(key) {
                var val = locs[key];
                if (_locs[val]) {
                    debug('duplicate switch! ' + toHex(val));
                }
                _locs[val] = a;
            });
        },
        start: function apple2io_start() {
            this.registerSwitches(this, LOC);
            return 0xc0;
        },
        end: function apple2io_end() {
            return 0xc0;
        },
        read: function apple2io_read(page, off) { 
            var result = 0;
            if (_locs[off]) {
                result = _locs[off].ioSwitch(off);
            } else {
                debug("I/O read: C0" + toHex(off));
            }
            return result;
        },
        write: function apple2io_write(page, off, val) {
            if (_locs[off]) {
                _locs[off].ioSwitch(off, val);
            } else {
                debug("I/O write: C0" + toHex(off));
            }
        },
        getState: function apple2io_getState() { return {}; },
        setState: function apple2io_setState() { },
        ioSwitch: function apple2io_ioSwitch(off, val) {
            return _access(off, val);
        },
        keyDown: function apple2io_keyDown(ascii) {
            _keyDown = true;
            _key = ascii | 0x80;
        },
        keyUp: function apple2io_keyUp() { 
            _keyDown = false;
            _key = 0;
        },

        buttonDown: function apple2io_buttonDown(b) {
            _button[b] = true;
        },
        buttonUp: function apple2io_buttonUp(b) {
            _button[b] = false;
        },
        paddle: function apple2io_paddle(p, v) {
            _paddle[p] = v;
        },
        getSample: function apple2io_getSample(stop) {
            var result = _sample;
            var now = cpu.cycles();

            //if (_sampleTime) {
            //    var phase = _phase > 0 ? _high : _low;
            //    for (; _sampleTime < now; _sampleTime += SAMPLE_RATE)
            //        _sample.push(phase);
            //}

            _sample = _oldSample;
            _sample.length = 0;
            _sampleTime = stop ? 0 : now;

            _oldSample = result;

            return result;
        },
        floatAudio: function apple2io_floatAudio(rate) {
            _low = -0.5;
            _high = 0.5;

            SAMPLE_RATE = 1023000.0 / rate;
        },
        byteAudio: function apple2io_floatAudio(rate) {
            _low = 0xa0;
            _high = 0x60;

            SAMPLE_RATE = 1023000.0 / rate;
        },
        setKeyBuffer: function apple2io_setKeyBuffer(buffer) {
            _buffer = buffer.split("");
            if (_buffer.length > 0) {
                _keyDown = true;
                _key = _buffer.shift().charCodeAt(0) | 0x80;
            }
        }
    };
}