using System;
using System.Buffers.Binary;
using System.Collections.Generic;
using System.IO;
using System.IO.Compression;
using System.Text;

namespace SmartNav.Model.Navigation;

public static class WaterCacheFormat
{
	public const uint FileMagic = 1129469015u;

	public const int FileFormatVersion = 1;

	public const string FileName = "water-cache.bin";

	private const int MaxTerritoryCount = 65536;

	private const int ClassBytes = 65536;

	private const int SurfaceBytes = 131072;

	private const int PayloadBytes = 196608;

	public static void Write(Stream stream, string gameVersion, IReadOnlyList<TerritoryWaterMap> maps)
	{
		ArgumentNullException.ThrowIfNull(stream, "stream");
		ArgumentNullException.ThrowIfNull(gameVersion, "gameVersion");
		ArgumentNullException.ThrowIfNull(maps, "maps");
		List<TerritoryWaterMap> list = new List<TerritoryWaterMap>(maps.Count);
		foreach (TerritoryWaterMap map in maps)
		{
			if (map.HasWater)
			{
				list.Add(map);
			}
		}
		list.Sort((TerritoryWaterMap left, TerritoryWaterMap right) => left.TerritoryId.CompareTo(right.TerritoryId));
		using BinaryWriter binaryWriter = new BinaryWriter(stream, Encoding.UTF8, leaveOpen: true);
		binaryWriter.Write(1129469015u);
		binaryWriter.Write(1);
		binaryWriter.Write(gameVersion);
		binaryWriter.Write(list.Count);
		foreach (TerritoryWaterMap item in list)
		{
			byte[] array = new byte[196608];
			item.Classes.CopyTo(array.AsSpan(0, 65536));
			ReadOnlySpan<ushort> surfaceYRaw = item.SurfaceYRaw;
			for (int num = 0; num < surfaceYRaw.Length; num++)
			{
				BinaryPrimitives.WriteUInt16LittleEndian(array.AsSpan(65536 + num * 2), surfaceYRaw[num]);
			}
			using MemoryStream memoryStream = new MemoryStream();
			using (DeflateStream deflateStream = new DeflateStream(memoryStream, CompressionLevel.Optimal, leaveOpen: true))
			{
				deflateStream.Write(array);
			}
			binaryWriter.Write(item.TerritoryId);
			binaryWriter.Write((int)memoryStream.Length);
			binaryWriter.Write(memoryStream.GetBuffer(), 0, (int)memoryStream.Length);
		}
	}

	public static (string GameVersion, List<TerritoryWaterMap> Maps) Read(Stream stream)
	{
		ArgumentNullException.ThrowIfNull(stream, "stream");
		using BinaryReader binaryReader = new BinaryReader(stream, Encoding.UTF8, leaveOpen: true);
		uint num = binaryReader.ReadUInt32();
		if (num != 1129469015)
		{
			throw new InvalidDataException($"water cache has magic 0x{num:X8}, expected 0x{1129469015:X8}");
		}
		int num2 = binaryReader.ReadInt32();
		if (num2 != 1)
		{
			throw new InvalidDataException($"water cache has format version {num2}, expected {1}");
		}
		string item = binaryReader.ReadString();
		int num3 = binaryReader.ReadInt32();
		if (num3 < 0 || num3 > 65536)
		{
			throw new InvalidDataException($"water cache declares {num3} territories");
		}
		List<TerritoryWaterMap> list = new List<TerritoryWaterMap>(num3);
		for (int i = 0; i < num3; i++)
		{
			ushort num4 = binaryReader.ReadUInt16();
			int num5 = binaryReader.ReadInt32();
			if (num5 < 0)
			{
				throw new InvalidDataException($"territory {num4} declares {num5} compressed bytes");
			}
			byte[] array = binaryReader.ReadBytes(num5);
			if (array.Length != num5)
			{
				throw new InvalidDataException($"territory {num4} is truncated: {array.Length} of {num5} bytes");
			}
			byte[] array2 = new byte[196608];
			using (DeflateStream deflateStream = new DeflateStream(new MemoryStream(array, writable: false), CompressionMode.Decompress))
			{
				deflateStream.ReadExactly(array2);
			}
			byte[] subArray = array2[..65536];
			byte[] array3 = subArray;
			foreach (byte b in array3)
			{
				if (b > 2)
				{
					throw new InvalidDataException($"territory {num4} has cell class {b}, expected 0..{2}");
				}
			}
			ushort[] array4 = new ushort[65536];
			for (int k = 0; k < array4.Length; k++)
			{
				array4[k] = BinaryPrimitives.ReadUInt16LittleEndian(array2.AsSpan(65536 + k * 2));
			}
			list.Add(new TerritoryWaterMap(num4, subArray, array4));
		}
		return (GameVersion: item, Maps: list);
	}
}