using System.IO.Compression;
using System.Text.Json.Serialization;
using LibGit.Extensions;
using LibGit.Interfaces;

namespace LibGit;

public class CommitObject
{
    [JsonIgnore]
    public IRepoSource RepoSource { get; }
    public string CommitId { get; }

    public CommitObject(IRepoSource repoSource, string commitId)
    {
        RepoSource = repoSource;
        CommitId = commitId;
    }

    private const bool _debug = false;

    public string Length { get; set; }
    public string TreeId { get; set; }
    public List<string> ParentIds { get; set; } = new();

    public string Author { get; set; }

    //The Arcane Brony <myrainbowdash949@gmail.com> 1682901812 +0200
    public string Committer { get; set; }
    public string GpgSignature { get; set; }
    public string Message { get; set; }
    public string Description { get; set; }

    public List<CommitObject> Children { get; set; } = new();

    [JsonIgnore]
    public DateTime CommitDate => new DateTime(long.Parse(Committer.Split(" ").TakeLast(2).First())*TimeSpan.TicksPerSecond)
        .AddHours(long.Parse(Committer.Split(" ").TakeLast(1).First()[1..3]))
        .AddMinutes(long.Parse(Committer.Split(" ").TakeLast(1).First()[3..]))
        .AddYears(1970);

    [JsonIgnore]
    public DateTime AuthorDate => new DateTime(long.Parse(Author.Split(" ").TakeLast(2).First())*TimeSpan.TicksPerSecond)
        .AddHours(long.Parse(Committer.Split(" ").TakeLast(1).First()[1..3]))
        .AddMinutes(long.Parse(Committer.Split(" ").TakeLast(1).First()[3..]))
        .AddYears(1970);

    [JsonIgnore]
    public string AuthorEmail => Author.Split(" <").Last().Split("> ").First();

    [JsonIgnore]
    public string AuthorName => Author.Split(" <").First();

    [JsonIgnore]
    public string CommitterEmail => Committer.Split(" <").Last().Split("> ").First();

    [JsonIgnore]
    public string CommitterName => Committer.Split(" <").First();

    public async Task<TreeObject> GetTreeAsync() => new TreeObject(RepoSource, TreeId).ReadFromZlibCompressedObjFile(await RepoSource.GetObjectStreamById(TreeId));

    public CommitObject ReadFromZlibCompressedObjFile(Stream bytes)
    {
        if (_debug)
        {
            Console.WriteLine($"Decompressing {this.GetType().Name}");
            Console.WriteLine($"File header:");
            // bytes.Peek(64).HexDump(16);
        }
        using ZLibStream stream = new ZLibStream(bytes, CompressionMode.Decompress);
        using var result = new MemoryStream();
        stream.CopyTo(result);
        stream.Flush();
        stream.Close();
        return ReadFromDecompressedObjFile(result);
    }

    public CommitObject ReadFromDecompressedObjFile(Stream data)
    {
        if(_debug) Console.WriteLine("Parsing commit object");
        // var data = new Queue<byte>(bytes.ToArray());
        int iters = 0;
        data.Seek(0, SeekOrigin.Begin);
        if(_debug)Console.WriteLine($"Iteration {iters}: starting pos: {data.Position}/+{data.Remaining()}/{data.Length}");
        Length = data.ReadNullTerminatedField(asciiPrefix: "commit ").AsString();
        while (data.Position < data.Length)
        {
            if(_debug) Console.WriteLine($"Iteration {iters} ({data.Position}/+{data.Remaining()}/{data.Length})");
            if (data.StartsWith("tree "))
                TreeId = data.ReadTerminatedField((byte)'\n', asciiPrefix: "tree ").AsString();
            while (data.StartsWith("parent "))
                ParentIds.Add(data.ReadTerminatedField((byte)'\n', asciiPrefix: "parent ").AsString());
            if (data.StartsWith("author "))
                Author = data.ReadTerminatedField((byte)'\n', asciiPrefix: "author ").AsString();
            if (data.StartsWith("committer "))
                Committer = data.ReadTerminatedField((byte)'\n', asciiPrefix: "committer ").AsString();;
            if (data.StartsWith("gpgsig "))
                GpgSignature = GetGpgSignature(data);
            if(data.Remaining() >= 1 && (data.Peek() == (byte)'\n' || data.Peek() == (byte)'\r'))
                data.Skip(1);
            if(data.Peek() != (byte)'\n')
                Message = GetMessage(data);
            while(data.Remaining() >= 1 && (data.Peek() == (byte)'\n' || data.Peek() == (byte)'\r'))
                data.Skip(1);
            if(data.Remaining() >= 1 && data.Peek() != (byte)'\n')
                Description = GetDescription(data);
            
            if (data.Remaining() > 0)
            {
                Console.WriteLine($"--Unparsed data after {++iters} iteration(s) of parsing CommitObject--");
                Console.WriteLine(this.ToJson());
                Console.WriteLine("--HexDump of remaining data--");
                data.Peek(data.Remaining()).HexDump();
                //Console.WriteLine($"Unparsed data: {Encoding.UTF8.GetString(data.ToArray())}");
            }
            if(iters > 100) throw new Exception("Too many iterations");
        }
        
        data.Close();
        return this;
    }

    //parsing
    private string GetMessage(Stream data)
    {
        if(_debug) Console.WriteLine($"--commit.GetMessage--");
        var message = "";
        while (data.Remaining() > 0 && data.Peek() != (byte)'\n')
        {
            if(_debug) Console.WriteLine($"Commit.GetMessage -- pos: {data.Position}/+{data.Remaining()}/{data.Length} | next: {(char)data.Peek()} | Message: {message}");
            message += (char)data.ReadByte();
            
        }

        // if(data.Count > 0 && data.Peek() == (byte)'\n')
        // data.Dequeue();
        return message.Trim();
    }

    private string GetDescription(Stream data)
    {
        if(_debug) Console.WriteLine($"--commit.GetDescription--");
        var message = "";
        while (data.Remaining() > 0)
        {
            message += (char)data.ReadByte();
        }

        // if(data.Count > 0 && data.Peek() == (byte)'\n')
        // data.Dequeue();
        return message.Trim();
    }

    private string GetGpgSignature(Stream data)
    {
        if(_debug) Console.WriteLine($"--commit.GetGpgSignature--");
        data.Seek(7, SeekOrigin.Current);
        var signature = "";
        while (
            !signature.EndsWith("-----END PGP SIGNATURE-----\n\n") 
               && !signature.EndsWith("-----END PGP SIGNATURE-----\n \n")
               && !signature.EndsWith("-----END SSH SIGNATURE-----\n\n")
            )
        {
            // Console.Write((char)data.Peek());
            signature += (char)data.ReadByte();
        }

        return signature;
    }
}