using SourceFormatParser.Common;
using System;
using System.Collections;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Text;
using UnityEngine;

public class VPKFile
{
    public struct Header {
        public uint Magic;
        public uint Version;
        public uint TreeSizeInBytes;
        public uint FileDataSectionSize;
        public uint ArchiveMD5SectionSize;
        public uint OtherMD5SectionSize;
        public uint SignatureSectionSize;
        //Assert(0x55aa1234 == Magic, "WTF");
    }

    public struct FileDescription {
        public uint CRC;
        public ushort PreloadBytes;
        public ushort ArchiveId;
        public uint EntryOffset;
        public uint EntryLength;
        public ushort ConstFooter;
    }

    public class FileRecord {
        public string Name;
        public FileDescription Description;
        public byte[] PreloadData;
    }

    public class DirectoryRecord {
        public string Name;
        public List<FileRecord> Files = new List<FileRecord>();
    }

    public class ExtensionRecord
    {
        public string Name;
        public List<DirectoryRecord> Directories = new List<DirectoryRecord>();
    }


    public static string ReadSZString(BinaryReader reader)
    {
        var result = new StringBuilder();
        while (true) {
            byte b = reader.ReadByte();
            if (0 == b)
                break;
            result.Append((char)b);
        }
        return result.ToString();
    }



    public static FileRecord FindFile(List<ExtensionRecord> tree, string path)
    {
        var fileNameSeparator = path.LastIndexOf('/');
        var dir = path.Substring(0, fileNameSeparator);
        var fileNameWithExtension = path.Substring(fileNameSeparator + 1);

        var extSeparator = fileNameWithExtension.LastIndexOf('.');
        var fileName = fileNameWithExtension.Substring(0, extSeparator);
        var ext = fileNameWithExtension.Substring(extSeparator + 1);

        var extRecord = tree.FirstOrDefault(x => x.Name == ext);
        if (extRecord == null) {
            return null;
        }

        var dirRecord = extRecord.Directories.FirstOrDefault(x => x.Name == dir);
        if (dirRecord == null) {
            return null;
        }

        var fileRecord = dirRecord.Files.FirstOrDefault(x => x.Name == fileName);
        return fileRecord;
    }

    public static byte[] ReadFile(string vpkDirectory, string pakNamePrefix, FileRecord record)
    {
        var archiveId = record.Description.ArchiveId;
        var archiveFileName = pakNamePrefix + "_" + archiveId.ToString("D3") + ".vpk";

        var archiveFilePath = System.IO.Path.Combine(vpkDirectory, archiveFileName);

        var stream = System.IO.File.OpenRead(archiveFilePath);
        stream.Seek(record.Description.EntryOffset, SeekOrigin.Begin);

        var reader = new BinaryReader(stream);
        var result = reader.ReadBytes((int)record.Description.EntryLength);

        reader.Close();
        return result;
    }

    //pak01_dir.vpk
    public static List<ExtensionRecord> ReadDirTree(string dirVpkFile)
    {
        var stream = File.OpenRead(dirVpkFile);

        BinaryReader br = new BinaryReader(stream, Encoding.ASCII, false);

        Header header = new Header();
        header.Magic = br.ReadUInt32();
        if(header.Magic != 0x55aa1234) {
            throw new Exception("Invalid magic number");
        }

        header.Version = br.ReadUInt32();
        if(header.Version != 2) {
            throw new Exception($"Version {header.Version} is not supported");
        }

        header.TreeSizeInBytes = br.ReadUInt32();
        header.FileDataSectionSize = br.ReadUInt32();
        header.ArchiveMD5SectionSize = br.ReadUInt32();
        header.OtherMD5SectionSize = br.ReadUInt32();
        header.SignatureSectionSize = br.ReadUInt32();


        List<ExtensionRecord> result = new List<ExtensionRecord>();

        while (true) {
            string extName = ReadSZString(br);
            if (string.IsNullOrEmpty(extName)) {
                break;
            }

            ExtensionRecord extRecord = new ExtensionRecord();
            extRecord.Name = extName;

            while (true) {
                string dirName = ReadSZString(br);
                if (string.IsNullOrEmpty(dirName)) {
                    break;
                }

                DirectoryRecord dirRecord = new DirectoryRecord();
                dirRecord.Name = dirName;

                while (true) {
                    string fileName = ReadSZString(br);
                    if (string.IsNullOrEmpty(fileName)) {
                        break;
                    }

                    FileRecord fileRecord = new FileRecord();
                    fileRecord.Name = fileName;

                    //read file desc
                    FileDescription desc = new FileDescription();
                    desc.CRC = br.ReadUInt32();
                    desc.PreloadBytes = br.ReadUInt16();
                    desc.ArchiveId = br.ReadUInt16();
                    desc.EntryOffset = br.ReadUInt32();
                    desc.EntryLength = br.ReadUInt32();
                    desc.ConstFooter = br.ReadUInt16();

                    fileRecord.Description = desc;

                    if(desc.PreloadBytes != 0) {
                        fileRecord.PreloadData = br.ReadBytes(desc.PreloadBytes);
                    }

                    dirRecord.Files.Add(fileRecord);
                }

                extRecord.Directories.Add(dirRecord);
            }

            result.Add(extRecord);
        }

        return result;
    }

}