package com.xiaopeng.map.utils;

import com.google.protobuf.CodedOutputStream;
import com.xiaopeng.map.dto.MapAreaDataDto;
import com.xiaopeng.map.dto.OddAreaDto;
import com.xiaopeng.map.dto.OddPointDto;

import java.io.FileOutputStream;
import java.io.IOException;
import java.io.OutputStream;
import java.util.List;

/**
 * 将 MapAreaDataDto 序列化为与 map_area_data.proto 兼容的 Protobuf 二进制格式。
 */
public final class MapAreaDataProtoWriter {

    private MapAreaDataProtoWriter() {
    }

    public static void writeTo(MapAreaDataDto data, OutputStream out) throws IOException {
        byte[] bytes = toByteArray(data);
        out.write(bytes);
    }

    public static byte[] toByteArray(MapAreaDataDto data) throws IOException {
        int size = computeSize(data);
        byte[] buf = new byte[size];
        CodedOutputStream cos = CodedOutputStream.newInstance(buf);
        writeMapAreaData(cos, data);
        cos.checkNoSpaceLeft();
        return buf;
    }

    private static int computeSize(MapAreaDataDto data) {
        int size = 0;
        if (data.getVersion() != 0) {
            size += CodedOutputStream.computeUInt32Size(1, data.getVersion());
        }
        for (OddAreaDto area : data.getOddAreas()) {
            int areaSize = computeOddAreaSize(area);
            size += CodedOutputStream.computeTagSize(2) + CodedOutputStream.computeRawVarint32Size(areaSize) + areaSize;
        }
        return size;
    }

    private static int computeOddAreaSize(OddAreaDto area) {
        int size = 0;
        if (area.getOddId() != 0) {
            size += CodedOutputStream.computeUInt32Size(1, area.getOddId());
        }
        for (OddPointDto pt : area.getOddPoints()) {
            int ptSize = computeOddPointSize(pt);
            size += CodedOutputStream.computeTagSize(2) + CodedOutputStream.computeRawVarint32Size(ptSize) + ptSize;
        }
        if (area.isBlacklist()) {
            size += CodedOutputStream.computeBoolSize(3, true);
        }
        return size;
    }

    private static int computeOddPointSize(OddPointDto pt) {
        int size = 0;
        if (pt.getLatitude() != 0.0) {
            size += CodedOutputStream.computeDoubleSize(1, pt.getLatitude());
        }
        if (pt.getLongitude() != 0.0) {
            size += CodedOutputStream.computeDoubleSize(2, pt.getLongitude());
        }
        return size;
    }

    private static void writeMapAreaData(CodedOutputStream cos, MapAreaDataDto data) throws IOException {
        cos.writeUInt32(1, data.getVersion());
        for (OddAreaDto area : data.getOddAreas()) {
            cos.writeTag(2, 2); // field 2, wire type length-delimited
            int areaSize = computeOddAreaSize(area);
            cos.writeRawVarint32(areaSize);
            writeOddArea(cos, area);
        }
    }

    private static void writeOddArea(CodedOutputStream cos, OddAreaDto area) throws IOException {
        cos.writeUInt32(1, area.getOddId());
        List<OddPointDto> points = area.getOddPoints();
        for (OddPointDto pt : points) {
            cos.writeTag(2, 2);
            int ptSize = computeOddPointSize(pt);
            cos.writeRawVarint32(ptSize);
            writeOddPoint(cos, pt);
        }
        if (area.isBlacklist()) {
            cos.writeBool(3, true);
        }
    }

    private static void writeOddPoint(CodedOutputStream cos, OddPointDto pt) throws IOException {
        cos.writeDouble(1, pt.getLatitude());
        cos.writeDouble(2, pt.getLongitude());
    }

    /**
     * 测试入口：使用 XngpAreaRTreeFbsUtil 的示例 GCL 数据生成 map_area_data 文件。
     */
    public static void main(String[] args) {
        String gcl = "104.06249657558965_30.583221674855963," +
                "104.06244328689024_30.58049965528362," +
                "104.06640444191817_30.580606702069797," +
                "104.06496563619123_30.58420035984882," +
                "104.06249657558965_30.583221674855963";

        List<XngpAreaRTreeFbsUtil.LonLat> points = XngpAreaRTreeFbsUtil.parseGcl(gcl);
        if (points.isEmpty()) {
            System.err.println("parseGcl failed: no points");
            return;
        }

        OddAreaDto oddArea = OddAreaDto.builder()
                .oddId(1)
                .isBlacklist(false)
                .build();
        for (XngpAreaRTreeFbsUtil.LonLat p : points) {
            oddArea.getOddPoints().add(OddPointDto.builder()
                    .latitude(p.getLat())
                    .longitude(p.getLon())
                    .build());
        }

        MapAreaDataDto data = MapAreaDataDto.builder()
                .version(1)
                .oddAreas(java.util.Collections.singletonList(oddArea))
                .build();

        String outFile = "map_area_data_test.bin";
        try (FileOutputStream fos = new FileOutputStream(outFile)) {
            MapAreaDataProtoWriter.writeTo(data, fos);
            System.out.println("MapAreaDataProtoWriter success, outFile=" + outFile);
        } catch (IOException e) {
            System.err.println("MapAreaDataProtoWriter failed: " + e.getMessage());
        }
    }
}