/*
 * Copyright (c) 2018-19 Marco Maccaferri and others.
 *
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/epl-v10.html
 */

package com.maccasoft.tools;

import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.RandomAccessFile;

import com.maccasoft.tools.internal.Utility;

import z80core.MemIoOps;
import z80core.Z80;

public class Machine extends MemIoOps {

    public final static int SIOA_C = 0x80;
    public final static int SIOA_D = 0x81;
    public final static int SIOB_C = 0x82;
    public final static int SIOB_D = 0x83;

    public final static int CF_DATA = 0x10;
    public final static int CF_FEATURES = 0x11;
    public final static int CF_ERROR = 0x11;
    public final static int CF_SECCOUNT = 0x12;
    public final static int CF_SECTOR = 0x13;
    public final static int CF_CYL_LOW = 0x14;
    public final static int CF_CYL_HI = 0x15;
    public final static int CF_HEAD = 0x16;
    public final static int CF_STATUS = 0x17;
    public final static int CF_COMMAND = 0x17;
    public final static int CF_LBA0 = 0x13;
    public final static int CF_LBA1 = 0x14;
    public final static int CF_LBA2 = 0x15;
    public final static int CF_LBA3 = 0x16;

    public final static byte CF_READ_SEC = 0x20;
    public final static byte CF_WRITE_SEC = 0x30;
    public final static byte CF_IDENTIFY = (byte) 0xEC;

    boolean rom_paged;
    byte[] rom;
    byte[] ram;

    byte cfCommand;
    byte[] cfLBA = new byte[4];
    byte cfSecCount;
    File cfFile;
    RandomAccessFile cf;
    byte[] cfIdentifyBuffer = new byte[512];
    int cfDataCount;

    Z80 proc;
    Thread thread;
    long clockPeriodNs;
    long clockTimeNs;

    int tmsRam;
    int tmsReg;
    TMS9918 tms9918;

    public Machine() {
        rom = new byte[16384];
        ram = new byte[65536];

        clockPeriodNs = (long) (1000.0 / 7.3728);
        clockTimeNs = 0;

        proc = new Z80(this, null);

        tms9918 = new TMS9918() {

            @Override
            protected void onVSync() {
                Machine.this.onTMS9918VSync();
            }

        };
        tmsRam = 0x40;
        tmsReg = 0x41;

        thread = new Thread(new Runnable() {

            @Override
            public void run() {
                Machine.this.run();
            }
        });
    }

    public void setRom(int address, File file) throws IOException {
        InputStream is = new FileInputStream(file);
        is.read(rom, address, rom.length - address);
        is.close();
    }

    public void setRom(int address, byte[] rom) throws IOException {
        System.arraycopy(rom, 0, this.rom, address, Math.min(this.rom.length - address, rom.length));
    }

    public void setClock(double freq) {
        clockPeriodNs = (long) (1000.0 / freq);
    }

    public void setCompactFlash(File file) {
        this.cfFile = file;
    }

    public void start() {
        try {
            System.arraycopy("EM-CF-00000001      ".getBytes(), 0, cfIdentifyBuffer, 20, 20); // Serial number
            System.arraycopy(Utility.getSwappedBytes("1.00    "), 0, cfIdentifyBuffer, 46, 8); // Firmware version
            System.arraycopy(Utility.getSwappedBytes("EMULATED CF CARD                        "), 0, cfIdentifyBuffer, 54, 40); // Card model

            if (cfFile != null && cfFile.exists()) {
                cf = new RandomAccessFile(cfFile, "rw");

                long size = cf.length() >> 9;
                cfIdentifyBuffer[14] = (byte) (size >> 16);
                cfIdentifyBuffer[15] = (byte) (size >> 24);
                cfIdentifyBuffer[16] = (byte) (size);
                cfIdentifyBuffer[17] = (byte) (size >> 8);

            }
        } catch (IOException e) {
            e.printStackTrace();
        }
        thread.start();
    }

    protected void run() {
        long ns = System.nanoTime();

        while (!Thread.interrupted()) {
            synchronized (proc) {
                int runTstates = (int) ((System.nanoTime() - ns) / clockPeriodNs);
                if (runTstates >= 4) {
                    long prevTstates = tstates;
                    long prevClockTime = clockTimeNs;
                    while (tstates < (prevTstates + runTstates)) {
                        proc.execute();
                    }
                    long elapsed = clockTimeNs - prevClockTime;
                    tms9918.processFrame(elapsed);
                    onElapsedTime(elapsed);
                    ns += elapsed;
                }
            }

            try {
                Thread.sleep(1L);
            } catch (InterruptedException e) {
                break;
            }
        }
    }

    protected void onElapsedTime(long elapsedNs) {
        // Do nothing
    }

    @Override
    public void reset() {
        synchronized (proc) {
            rom_paged = true;
            tstates = 0;
            clockTimeNs = 0;
            if (tms9918 != null) {
                tms9918.reset();
            }
            proc.reset();
            super.reset();
        }
    }

    @Override
    public int fetchOpcode(int address) {
        tstates += 4; // 3 clocks to fetch opcode from RAM and 1 execution clock
        clockTimeNs += clockPeriodNs * 4;
        address &= 0xFFFF;
        if (rom_paged && address < rom.length) {
            return rom[address] & 0xff;
        }
        return ram[address] & 0xff;
    }

    @Override
    public int inPort(int port) {
        tstates += 4; // 4 clocks for read byte from bus
        clockTimeNs += clockPeriodNs * 4;

        port &= 0xFF;

        if (port == tmsRam) {
            return tms9918.inRam();
        }
        if (port == tmsReg) {
            return tms9918.inReg();
        }

        if (cf != null) {
            switch (port) {
                case CF_DATA:
                    if (cfCommand == CF_READ_SEC) {
                        if (cfDataCount < 512 * cfSecCount) {
                            cfDataCount++;
                            try {
                                if (cf != null) {
                                    return (byte) cf.read();
                                }
                            } catch (IOException e) {
                                e.printStackTrace();
                            }
                            return 0x00;
                        }
                    }
                    else if (cfCommand == CF_IDENTIFY) {
                        if (cfDataCount < cfIdentifyBuffer.length) {
                            return cfIdentifyBuffer[cfDataCount++];
                        }
                        return 0x00;
                    }
                    return 0x00;
                case CF_SECCOUNT:
                    return cfSecCount & 0xFF;
                case CF_STATUS:
                    if (cfCommand == CF_WRITE_SEC || cfCommand == CF_READ_SEC) {
                        return 0x48; // CF Ready, DRQ
                    }
                    else if (cfCommand == CF_IDENTIFY) {
                        if (cfDataCount < cfIdentifyBuffer.length) {
                            return 0x48; // CF Ready, DRQ
                        }
                    }
                    return 0x40; // CF Ready
                case CF_ERROR:
                    return 0x01; // No error
                case CF_SECTOR:
                case CF_CYL_LOW:
                case CF_CYL_HI:
                case CF_HEAD:
                    return 0x00;
            }
        }

        return port;
    }

    @Override
    public void outPort(int port, int value) {
        tstates += 4; // 4 clocks for write byte to bus
        clockTimeNs += clockPeriodNs * 4;

        port &= 0xFF;
        value &= 0xFF;

        if (port == tmsRam) {
            tms9918.outRam(value);
        }
        if (port == tmsReg) {
            tms9918.outReg(value);
        }

        if (cf != null) {
            switch (port) {
                case CF_DATA:
                    if (cfCommand == CF_WRITE_SEC) {
                        if (cfDataCount < 512 * cfSecCount) {
                            cfDataCount++;
                            try {
                                if (cf != null) {
                                    cf.write(value & 0xFF);
                                }
                            } catch (IOException e) {
                                e.printStackTrace();
                            }
                        }
                    }
                    break;
                case CF_COMMAND:
                    cfCommand = (byte) value;
                    if (cfCommand == CF_WRITE_SEC || cfCommand == CF_READ_SEC) {
                        try {
                            long addr = ((cfLBA[3] & 0x0F) << 24) | ((cfLBA[2] & 0xFF) << 16) | ((cfLBA[1] & 0xFF) << 8) | (cfLBA[0] & 0xFF);
                            if (cf != null) {
                                cf.seek(addr << 9);
                            }
                        } catch (IOException e) {
                            e.printStackTrace();
                        }
                        cfDataCount = 0;
                    }
                    else if (cfCommand == CF_IDENTIFY) {
                        cfDataCount = 0;
                    }
                    break;
                case CF_LBA0:
                    cfLBA[0] = (byte) value;
                    break;
                case CF_LBA1:
                    cfLBA[1] = (byte) value;
                    break;
                case CF_LBA2:
                    cfLBA[2] = (byte) value;
                    break;
                case CF_LBA3: {
                    cfLBA[3] = (byte) value;
                    break;
                }
                case CF_SECCOUNT:
                    cfSecCount = (byte) value;
                    break;
            }
        }

        switch (port) {
            case 0x38: // ROM page
                rom_paged = value != 0x01;
                break;
        }
    }

    @Override
    public int peek8(int address) {
        tstates += 3; // 3 clocks for read byte from RAM
        clockTimeNs += clockPeriodNs * 3;
        address &= 0xFFFF;
        if (rom_paged && address < rom.length) {
            return rom[address] & 0xff;
        }
        return ram[address] & 0xff;
    }

    @Override
    public void poke8(int address, int value) {
        tstates += 3; // 3 clocks for write byte to RAM
        clockTimeNs += clockPeriodNs * 3;
        address &= 0xFFFF;
        if (!rom_paged || address >= rom.length) {
            ram[address] = (byte) value;
        }
    }

    @Override
    public long getTstates() {
        return tstates;
    }

    public void stop() {
        try {
            thread.interrupt();
        } catch (Exception e) {
            // Do nothing
        }
        try {
            if (cf != null) {
                cf.close();
            }
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    protected void onTMS9918VSync() {
        // Do nothing
    }

}