#include "pia.h"

namespace pia
{
    uint8_t ram[128];
    bool timer_interrupt = false;
    uint8_t timer_value = 0;
    uint16_t prescaler = 0;
    uint16_t divider = 0;
    bool timer_underflow = false;

    void reset()
    {

    }

    void tick()
    {
        prescaler++;

        if (!timer_underflow) {
            if (prescaler >= divider) {
                prescaler = 0;
                if (timer_value == 0) {
                    timer_underflow = true;
                    timer_interrupt = true;
                    timer_value = 0xff;
                } else {
                    timer_value--;
                }
            }
        } else {
            timer_value--;
        }
    }

    uint8_t read(uint16_t address)
    {
        if (address & 0x200) {
            if ( (address & 0x04) ) {
                // Timer functions
                if (address & 0x01) {
                    uint8_t flags = timer_interrupt ? 0x80 : 0x00;
                    timer_interrupt = false;
                    return flags;
                } else {
                    return timer_value;
                }
            } else {
                // I/O Ports
                switch( address & 0x03) {
                    case 0x00: // [TODO] SWCHA
                        return 0xff;
                    case 0x01: // [TODO] DDRA
                        return 0x00;
                    case 0x02: // [TODO] SWCHB
                        return 0x03;
                    case 0x03: // [TODO] DDRB
                        return 0x00;
                    default:
                        return 0x00;
                }
            }
        } else {
            return ram[address & 0x7f];
        }
    }

    void write(uint16_t address, uint8_t value)
    {
        if (address & 0x200) {
            if ( (address & 0x04) ) {
                if ( (address & 0x10) ) {
                    // Timer functions
                    switch( address & 0x03) {
                        case 0x00: // [TODO] TIM1T
                            divider = 1;
                            timer_value = value;
                            prescaler = 0;
                            timer_underflow = false;
                            timer_interrupt = false;
                            break;
                        case 0x01: // [TODO] TIM8T
                            divider = 8;
                            timer_value = value;
                            prescaler = 0;
                            timer_underflow = false;
                            timer_interrupt = false;
                            break;
                        case 0x02: // [TODO] TIM64T
                            divider = 64;
                            timer_value = value;
                            prescaler = 0;
                            timer_underflow = false;
                            timer_interrupt = false;
                            break;
                        case 0x03: // [TODO] TIM1024T
                            divider = 1024;
                            timer_value = value;
                            prescaler = 0;
                            timer_underflow = false;
                            timer_interrupt = false;
                            break;
                    }
                } else {
                    // Funcionalitat relacionada amb les interrupcions. Ignorar per a la Atari 2600
                }
            } else {
                // I/O Ports
                switch( address & 0x03) {
                    case 0x00: // [TODO] SWCHA
                        break;
                    case 0x01: // [TODO] DDRA
                        break;
                    case 0x02: // [TODO] SWCHB
                        break;
                    case 0x03: // [TODO] DDRB
                        break;
                }
            }
        } else {
            ram[address & 0x7f] = value;
        }
    }

    namespace debug
    {
        const memDebugInfo getInfo(uint16_t address)
        {
            if (address & 0x200) {
                return {"PIA", mdtRegister, address};
            } else {
                return {"RAM", mdtRAM, address & 0xff};
            }
        }
    }

}