package cn.org.hentai.jtt1078.server;

import cn.org.hentai.jtt1078.util.ByteHolder;
import cn.org.hentai.jtt1078.util.ByteUtils;
import cn.org.hentai.jtt1078.util.Packet;

import java.time.Instant;
import java.time.ZoneOffset;
import java.time.ZonedDateTime;
import java.time.format.DateTimeFormatter;
import java.util.Arrays;

/**
 * JTT1078 Protocol Decoder
 */

public class Jtt1078Decoder {
    private ByteHolder buffer = new ByteHolder(4096);
    private int simLen = 0;
    private String sim = "";
    private byte channel = 0;
    private static final byte[] HEAD1078 = {0x30, 0x31, 0x63, 0x64};

    public void write(byte[] block) {
        buffer.write(block);
    }

    public void write(byte[] block, int startIndex, int length) {
        byte[] buff = new byte[length];
        System.arraycopy(block, startIndex, buff, 0, length);
        write(buff);
    }

    public Packet decode() {
        if (buffer.size() < 4) return null;

        // Check header
        if (!Arrays.equals(buffer.array(4), HEAD1078)) {
//            log.warn("Invalid protocol header, expected:30316364, actual:{}",
//                    ByteUtils.toHexString(buffer.array(4)));
            buffer.clear();
            return null;
        }

        // Try to determine protocol version if not set
        if (simLen == 0) {
            // Try version 16 (2013 protocol)
            Packet packet = decodePacket(16);
            if (packet != null) {
                Analyze analyze = parse16(packet.getBytes());
                sim = analyze.getSim();
                channel = analyze.getCh();
                simLen = 6;
                System.out.printf("%s-%d device started output%n", sim, channel);
                return packet;
            }

            // Try version 19 (2019 protocol)
            packet = decodePacket(19);
            if (packet != null) {
                Analyze analyze = parse19(packet.getBytes());
                sim = analyze.getSim();
                channel = analyze.getCh();
                simLen = 10;
                System.out.printf("%s-%d device started output%n", sim, channel);
                return packet;
            }

            return null;
        } else {
            return decodePacket(simLen == 6 ? 16 : 19);
        }
    }

    private Packet decodePacket(int version) {
        int dataTypeIndex = version == 16 ? 15 : 19;
        if (buffer.size() < dataTypeIndex + 1) return null;

        byte dataType = (byte) ((buffer.get(dataTypeIndex) >> 4) & 0x0F);
        int dataLenIndex;

        switch (dataType) {
            case 3:
                dataLenIndex = dataTypeIndex + 9;
                break;
            case 4:
                dataLenIndex = dataTypeIndex + 1;
                break;
            default:
                dataLenIndex = dataTypeIndex + 13;
        }
        //log.info("dataType:"+dataType);
        if (buffer.size() < dataLenIndex + 2) return null;
        int dataLen = buffer.getShort(dataLenIndex) & 0xFFFF;
        int packetLength = dataLenIndex + 2 + dataLen;

        if (buffer.size() < packetLength) return null;

        // Check next packet header
        if (buffer.size() >= packetLength + 4) {
            byte[] nextHeader = new byte[4];
            for (int i = 0; i < 4; i++) {
                nextHeader[i] = buffer.get(packetLength + i);
            }
            if (!Arrays.equals(nextHeader, HEAD1078)) {
               // log.warn("Invalid data type: {}", dataType);
                buffer.clear();
                return null;
            }
        }

        byte[] packetData = new byte[packetLength];
        buffer.sliceInto(packetData, packetLength);
        // printPacketInfo(packetData, version);
        return Packet.create(packetData);
    }

    private Analyze parse16(byte[] data) {
        Analyze analyze = new Analyze();
        analyze.setPt((byte) (data[5] & 0x7F));
        analyze.setSn((short) (((data[6] & 0xFF) << 8) | (data[7] & 0xFF)));

        StringBuilder simBuilder = new StringBuilder();
        for (int i = 0; i < 6; i++) {
            simBuilder.append(nextBcd(data, 8 + i));
        }
        analyze.setSim(simBuilder.toString());

        analyze.setCh(data[14]);
        analyze.setDt((byte) ((data[15] >> 4) & 0x0F));
        analyze.setFi((byte) (data[15] & 0x0F));

        int dataLenIndex;
        switch (analyze.getDt()) {
            case 3:
                analyze.setTimestamp(setTimestamp(data, 16));
                dataLenIndex = 24;
                break;
            case 4:
                dataLenIndex = 16;
                break;
            default:
                analyze.setTimestamp(setTimestamp(data, 16));
                analyze.setLastIInterval((short) (((data[24] & 0xFF) << 8) | (data[25] & 0xFF)));
                analyze.setLastInterval((short) (((data[26] & 0xFF) << 8) | (data[27] & 0xFF)));
                dataLenIndex = 28;
        }

        analyze.setDataLen((short) (((data[dataLenIndex] & 0xFF) << 8) | (data[dataLenIndex + 1] & 0xFF)));
        byte[] payload = new byte[analyze.getDataLen()];
        System.arraycopy(data, dataLenIndex + 2, payload, 0, payload.length);
        analyze.setData(payload);

        return analyze;
    }

    private Analyze parse19(byte[] data) {
        Analyze analyze = new Analyze();
        analyze.setPt((byte) (data[5] & 0x7F));
        analyze.setSn((short) (((data[6] & 0xFF) << 8) | (data[7] & 0xFF)));

        StringBuilder simBuilder = new StringBuilder();
        for (int i = 0; i < 10; i++) {
            simBuilder.append(nextBcd(data, 8 + i));
        }
        analyze.setSim(simBuilder.toString());

        analyze.setCh(data[18]);
        analyze.setDt((byte) ((data[19] >> 4) & 0x0F));
        analyze.setFi((byte) (data[19] & 0x0F));

        int dataLenIndex;
        switch (analyze.getDt()) {
            case 3:
                analyze.setTimestamp(setTimestamp(data, 20));
                dataLenIndex = 28;
                break;
            case 4:
                dataLenIndex = 20;
                break;
            default:
                analyze.setTimestamp(setTimestamp(data, 20));
                analyze.setLastIInterval((short) (((data[28] & 0xFF) << 8) | (data[29] & 0xFF)));
                analyze.setLastInterval((short) (((data[30] & 0xFF) << 8) | (data[31] & 0xFF)));
                dataLenIndex = 32;
        }

        analyze.setDataLen((short) (((data[dataLenIndex] & 0xFF) << 8) | (data[dataLenIndex + 1] & 0xFF)));
        byte[] payload = new byte[analyze.getDataLen()];
        System.arraycopy(data, dataLenIndex + 2, payload, 0, payload.length);
        analyze.setData(payload);

        return analyze;
    }

    private long setTimestamp(byte[] data, int offset) {
        long timestamp = 0;
        for (int i = 0; i < 8; i++) {
            timestamp = (timestamp << 8) | (data[offset + i] & 0xFF);
        }
        return timestamp;
    }

    private String nextBcd(byte[] data, int offset) {
        byte val = data[offset];
        int ch1 = (val >> 4) & 0x0F;
        int ch2 = val & 0x0F;
        return String.format("%d%d", ch1, ch2);
    }

    private void printPacketInfo(byte[] packet, int version) {
        System.out.println("\n=== JTT1078 " + (version == 16 ? "2013" : "2019") + " Protocol Packet ===");
        System.out.println("Header: " + ByteUtils.toHexString(packet, 0, 4));

        Analyze analyze = version == 16 ? parse16(packet) : parse19(packet);
        System.out.println("Payload Type: " + analyze.getPt());
        System.out.println("Sequence Number: " + analyze.getSn());
        System.out.println("SIM: " + analyze.getSim());
        System.out.println("Channel: " + analyze.getCh());
        System.out.println("Data Type: " + getDataTypeDescription(analyze.getDt()));
        System.out.println("Frame Info: " + getFrameInfoDescription(analyze.getFi()));

        if (analyze.getTimestamp() != 0) {
            Instant instant = Instant.ofEpochMilli(analyze.getTimestamp());
            ZonedDateTime beijingTime = instant.atZone(ZoneOffset.ofHours(8));
            DateTimeFormatter formatter = DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm:ss");
            System.out.println("Timestamp: " + formatter.format(beijingTime));
        }

        if (analyze.getLastIInterval() != 0) {
            System.out.println("Last I Frame Interval: " + analyze.getLastIInterval());
        }
        if (analyze.getLastInterval() != 0) {
            System.out.println("Last Frame Interval: " + analyze.getLastInterval());
        }

        System.out.println("Data Length: " + analyze.getDataLen());
        System.out.println("=================================\n");
    }

    private String getDataTypeDescription(int dataType) {
        switch (dataType) {
            case 0: return "Video I Frame";
            case 1: return "Video P Frame";
            case 2: return "Video B Frame";
            case 3: return "Audio Frame";
            case 4: return "Transparent Data";
            default: return "Unknown (" + dataType + ")";
        }
    }

    private String getFrameInfoDescription(int fi) {
        switch (fi) {
            case 0: return "Atomic Packet";
            case 1: return "First Packet";
            case 2: return "Last Packet";
            case 3: return "Middle Packet";
            default: return "Unknown (" + fi + ")";
        }
    }
}

class Analyze {
    private byte pt;
    private short sn;
    private String sim;
    private byte ch;
    private byte dt;
    private byte fi;
    private long timestamp;
    private short lastIInterval;
    private short lastInterval;
    private short dataLen;
    private byte[] data;

    // Getters and setters
    public byte getPt() { return pt; }
    public void setPt(byte pt) { this.pt = pt; }

    public short getSn() { return sn; }
    public void setSn(short sn) { this.sn = sn; }

    public String getSim() { return sim; }
    public void setSim(String sim) { this.sim = sim; }

    public byte getCh() { return ch; }
    public void setCh(byte ch) { this.ch = ch; }

    public byte getDt() { return dt; }
    public void setDt(byte dt) { this.dt = dt; }

    public byte getFi() { return fi; }
    public void setFi(byte fi) { this.fi = fi; }

    public long getTimestamp() { return timestamp; }
    public void setTimestamp(long timestamp) { this.timestamp = timestamp; }

    public short getLastIInterval() { return lastIInterval; }
    public void setLastIInterval(short lastIInterval) { this.lastIInterval = lastIInterval; }

    public short getLastInterval() { return lastInterval; }
    public void setLastInterval(short lastInterval) { this.lastInterval = lastInterval; }

    public short getDataLen() { return dataLen; }
    public void setDataLen(short dataLen) { this.dataLen = dataLen; }

    public byte[] getData() { return data; }
    public void setData(byte[] data) { this.data = data; }
}