using System;
using System.Collections.Generic;
using System.IO;
using System.IO.Abstractions;
using System.Linq;
using System.Text;
using CommandLine;
using COM3D2.Toolkit.Arc;
using Ganss.IO;

namespace ArcToolkitCLI
{
    internal interface IOptions
    {
        [Value(0, MetaName = "input", HelpText = "Input ARC files")]
        IEnumerable<string> Input { get; set; }
    }

    internal interface IDecryptionOptions
    {
        [Option("arc-search-dir", Required = false, HelpText = "Directory where to search ARC file to decrypt the WARP file")]
        string ArcDirectory { get; set; }

        [Option('k', "key", HelpText = "Decryption key as a base64 string (applied to all inputs)", Required = false)]
        string DecryptionKey { get; set; }

        [Option("key-file",
                HelpText = "A file with decryption keys on each line. Format of the file is <decryption arc name>:<key in base64>.",
                Required = false)]
        string KeyFile { get; set; }

        [Option("warc", Required = false, HelpText = "WARC file to use for decryption")]
        string WarcFile { get; set; }
    }

    [Verb("extract", HelpText = "Extract the contents of the given ARC files")]
    internal class ExtractOptions : IOptions, IDecryptionOptions
    {
        [Option('o', "output", HelpText = "Output directory", Required = true)]
        public string Output { get; set; }

        public string ArcDirectory { get; set; }
        public string DecryptionKey { get; set; }
        public string KeyFile { get; set; }

        public string WarcFile { get; set; }
        public IEnumerable<string> Input { get; set; }
    }

    [Verb("info", HelpText = "Display information about the given ARC files")]
    internal class InfoOptions : IOptions
    {
        [Option("only-key",
                HelpText = "If the archive is a WARC file, output only the decryption key as a base64 string",
                Required = false)]
        public bool OnlyKey { get; set; }

        public IEnumerable<string> Input { get; set; }
    }

    [Verb("decrypt", HelpText = "Decrypts the provided WARP files")]
    internal class DecryptOptions : IOptions, IDecryptionOptions
    {
        [Option('o', "output", HelpText = "Output directory", Default = ".")]
        public string Output { get; set; }

        public string ArcDirectory { get; set; }
        public string DecryptionKey { get; set; }
        public string KeyFile { get; set; }
        public string WarcFile { get; set; }
        public IEnumerable<string> Input { get; set; }
    }

    internal static class Errors
    {
        public enum ErrorCodes
        {
            NotAFile = 100,
            UnknownArcType,
            KeyNotFound,
            InvalidKeyFile,
            NoCorrectKey
        }

        public static readonly string[] ErrorMessages =
        {
                "{0} is not a file",
                "{0} is not a known ARC file",
                "No key specified or the key file does not exist",
                "The provided keyfile is not valid",
                "The ARC {0} needs a key from {1}"
        };

        public static int Error(ErrorCodes code, params object[] args)
        {
            Console.Error.WriteLine(ErrorMessages[code - ErrorCodes.NotAFile], args);
            return (int) code;
        }
    }

    internal static class Util
    {
        private static readonly char[] GlobCharacters = {'*', '{', '}', '[', ']', '?'};

        public static IEnumerable<FileSystemInfoBase> EnumerateFiles(IEnumerable<string> patterns)
        {
            foreach (string pattern in patterns)
                if (IsGlob(pattern))
                    foreach (var fileSystemInfoBase in Glob.Expand(pattern))
                        yield return fileSystemInfoBase;
                else
                    yield return new FileInfoWrapper(new FileSystem(), new FileInfo(pattern));
        }

        private static bool IsGlob(string path)
        {
            return path.IndexOfAny(GlobCharacters) >= 0;
        }
    }

    internal class Program
    {
        private static int Main(string[] args)
        {
            return Parser.Default.ParseArguments<InfoOptions, ExtractOptions, DecryptOptions>(args)
                         .MapResult((InfoOptions opts) => DisplayInfo(opts),
                                    (ExtractOptions opts) => Extract(opts),
                                    (DecryptOptions opts) => Decrypt(opts),
                                    errs => 1);
        }

        private static int DisplayInfo(InfoOptions opts)
        {
            bool first = true;
            foreach (var file in Util.EnumerateFiles(opts.Input))
            {
                if (!file.Exists)
                    return Errors.Error(Errors.ErrorCodes.NotAFile, file.Name);

                if (!first && !opts.OnlyKey)
                    Console.WriteLine();
                first = false;

                using (var stream = File.OpenRead(file.FullName))
                {
                    var header = new byte[4];
                    stream.Read(header, 0, header.Length);
                    string headerString = Encoding.ASCII.GetString(header);
                    stream.Position = 0;

                    if (headerString == "warc")
                    {
                        var key = new byte[2048];
                        stream.Read(key, 0, key.Length);
                        string keyBase64 = Convert.ToBase64String(key);
                        if (opts.OnlyKey)
                        {
                            Console.WriteLine($"{Path.GetFileName(file.FullName)}:{keyBase64}");
                            continue;
                        }

                        stream.Position = 0;
                        using (var warc = new WarcArc(stream))
                        {
                            Console.WriteLine($"File name: {file.Name}");
                            Console.WriteLine("ARC type: WARC");
                            Console.WriteLine($"ARC Name: {warc.Name}");
                            Console.WriteLine($"File count: {warc.Entries.Count()}");
                            Console.WriteLine($"Decryption key: {keyBase64}");
                        }
                    }
                    else if (headerString == "warp")
                    {
                        if (opts.OnlyKey)
                            continue;

                        Console.WriteLine($"File name: {file.Name}");
                        Console.WriteLine("ARC type: WARP");
                        using (var br = new BinaryReader(stream))
                            Console.WriteLine($"Needs a decryption key from the following ARC: {WarpArc.GetKeyWarpName(br)}");
                    }
                    else
                    {
                        return Errors.Error(Errors.ErrorCodes.UnknownArcType, file.Name);
                    }
                }
            }

            return 0;
        }

        private static int Extract(ExtractOptions opts)
        {
            return 0;
        }

        private static byte[] ReadKeyFromFile(string filename)
        {
            using (var br = new BinaryReader(File.OpenRead(filename)))
                return br.ReadBytes(2048);
        }

        private static int Decrypt(DecryptOptions opts)
        {
            var keysDict = new Dictionary<string, byte[]>(StringComparer.InvariantCultureIgnoreCase);
            if (!string.IsNullOrWhiteSpace(opts.KeyFile))
            {
                if (!File.Exists(opts.KeyFile))
                    return Errors.Error(Errors.ErrorCodes.KeyNotFound);

                foreach (string line in File.ReadAllLines(opts.KeyFile))
                {
                    var parts = line.Split(':');
                    if (parts.Length != 2)
                        return Errors.Error(Errors.ErrorCodes.InvalidKeyFile);
                    keysDict[parts[0].Trim()] = Convert.FromBase64String(parts[1].Trim());
                }
            }
            else if (!string.IsNullOrWhiteSpace(opts.DecryptionKey))
            {
                keysDict["*"] = Convert.FromBase64String(opts.DecryptionKey);
            }
            else if (string.IsNullOrWhiteSpace(opts.ArcDirectory) && string.IsNullOrWhiteSpace(opts.WarcFile))
            {
                return Errors.Error(Errors.ErrorCodes.KeyNotFound);
            }

            Directory.CreateDirectory(opts.Output);

            foreach (var file in Util.EnumerateFiles(opts.Input))
            {
                if (!file.Exists)
                    return Errors.Error(Errors.ErrorCodes.NotAFile, file.Name);

                using (var stream = File.OpenRead(file.FullName))
                {
                    var header = new byte[4];
                    stream.Read(header, 0, header.Length);
                    string headerString = Encoding.ASCII.GetString(header);
                    stream.Position = 0;
                    if (headerString == "warc")
                    {
                        Console.WriteLine($"{file.Name} is a WARC file, skipping...");
                    }
                    else if (headerString == "warp")
                    {
                        try
                        {
                            var arcStream = WarpArc.DecryptWarp(stream,
                                                                requestedFile =>
                                                                {
                                                                    if (keysDict.TryGetValue("*", out var key))
                                                                        return key;
                                                                    if (keysDict.TryGetValue(requestedFile, out key))
                                                                        return key;
                                                                    if (Directory.Exists(opts.ArcDirectory)
                                                                     && File.Exists(Path.Combine(opts.ArcDirectory, requestedFile)))
                                                                        return ReadKeyFromFile(Path.Combine(opts.ArcDirectory, requestedFile));
                                                                    if (File.Exists(opts.WarcFile))
                                                                        return ReadKeyFromFile(opts.WarcFile);
                                                                    throw new FileNotFoundException("No key found for the requested ARC",
                                                                                                    requestedFile);
                                                                });

                            using (var output =
                                    File.Create(Path.Combine(Path.GetDirectoryName(opts.Output), Path.GetFileNameWithoutExtension(file.Name))))
                                arcStream.CopyTo(output);
                        }
                        catch (FileNotFoundException fe)
                        {
                            return Errors.Error(Errors.ErrorCodes.NoCorrectKey, file.Name, fe.FileName);
                        }
                    }
                    else
                    {
                        return Errors.Error(Errors.ErrorCodes.UnknownArcType, file.Name);
                    }
                }
            }

            return 0;
        }
    }
}