// Bootleg MIDI bridge for the Vajcsi soundboard: plays MIDI pads on the Discord bot without a browser.
// Build with desktop\bootleg\build.cmd, which uses the .NET Framework compiler that ships with Windows.
// C# 5 only: that compiler predates string interpolation and other newer syntax.
using System;
using System.Collections.Concurrent;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Net;
using System.Reflection;
using System.Runtime.InteropServices;
using System.Text;
using System.Text.RegularExpressions;
using System.Threading;
using System.Web.Script.Serialization;

[assembly: AssemblyTitle("bootleg-do-not-click")]
[assembly: AssemblyProduct("Vajcsi soundboard MIDI bridge")]
[assembly: AssemblyVersion("1.0.0.0")]

class Binding
{
    public string Type;
    public int Channel;
    public int Number;
    public string ClipId;
    public string Name;

    public bool Matches(Binding other)
    {
        return other != null && Type == other.Type && Channel == other.Channel && Number == other.Number;
    }

    public string Label()
    {
        string[] notes = { "C", "C#", "D", "D#", "E", "F", "F#", "G", "G#", "A", "A#", "B" };
        string channel = " ch " + (Channel + 1);
        if (Type == "note") return "Note " + notes[Number % 12] + (Number / 12 - 1) + " (" + Number + ")" + channel;
        if (Type == "cc") return "CC " + Number + channel;
        return "Program " + (Number + 1) + channel;
    }
}

static class Bootleg
{
    delegate void MidiInProc(IntPtr handle, uint message, IntPtr instance, IntPtr param1, IntPtr param2);

    [StructLayout(LayoutKind.Sequential, CharSet = CharSet.Unicode)]
    struct MidiInCaps
    {
        public ushort Manufacturer;
        public ushort Product;
        public uint DriverVersion;
        [MarshalAs(UnmanagedType.ByValTStr, SizeConst = 32)] public string Name;
        public uint Support;
    }

    [DllImport("winmm.dll")] static extern uint midiInGetNumDevs();
    [DllImport("winmm.dll", CharSet = CharSet.Unicode, EntryPoint = "midiInGetDevCapsW")] static extern uint midiInGetDevCaps(UIntPtr device, out MidiInCaps caps, uint size);
    [DllImport("winmm.dll")] static extern uint midiInOpen(out IntPtr handle, uint device, MidiInProc callback, IntPtr instance, uint flags);
    [DllImport("winmm.dll")] static extern uint midiInStart(IntPtr handle);
    [DllImport("winmm.dll")] static extern uint midiInStop(IntPtr handle);
    [DllImport("winmm.dll")] static extern uint midiInClose(IntPtr handle);

    const uint CallbackFunction = 0x30000;
    const uint MimData = 0x3C3;
    static readonly MidiInProc Callback = OnMidi; // Kept in a field so the GC never collects it.
    static readonly BlockingCollection<int> Messages = new BlockingCollection<int>();
    static readonly List<IntPtr> Inputs = new List<IntPtr>();
    static readonly Dictionary<int, int> ControlValues = new Dictionary<int, int>();
    static readonly object ConsoleLock = new object();
    static readonly string SetupDirectory = Path.Combine(Environment.GetFolderPath(Environment.SpecialFolder.ApplicationData), "VajcsiBootleg");
    static readonly string SavedSetup = Path.Combine(SetupDirectory, "setup.json");

    static string apiBase;
    static string guildId;
    static List<Binding> bindings = new List<Binding>();
    static Binding stopBinding;

    static int Main(string[] args)
    {
        Console.Title = "bootleg-do-not-click";
        Console.OutputEncoding = Encoding.UTF8;
        ServicePointManager.SecurityProtocol = (SecurityProtocolType)3072; // TLS 1.2
        Say(ConsoleColor.Yellow, "  bootleg-do-not-click.exe  --  you clicked it anyway.");
        Say(ConsoleColor.DarkGray, "  Vajcsi soundboard MIDI bridge. Keep this window open; close it to stop.\n");
        try
        {
            List<string> simulated = new List<string>();
            string setupArgument = null;
            for (int index = 0; index < args.Length; index++)
            {
                if (args[index] == "--simulate" && index + 1 < args.Length) simulated.Add(args[++index]);
                else setupArgument = args[index];
            }
            LoadSetup(setupArgument);
            RefreshGuild();
            if (simulated.Count > 0)
            {
                foreach (string message in simulated) Handle(ParseHex(message), true);
                return 0;
            }
            OpenInputs();
            new Thread(WatchDevices) { IsBackground = true }.Start();
            foreach (int message in Messages.GetConsumingEnumerable()) Handle(message, false);
            return 0;
        }
        catch (Exception error)
        {
            Say(ConsoleColor.Red, "\n  " + error.Message);
            Console.WriteLine("\n  Press Enter to close.");
            Console.ReadLine();
            return 1;
        }
    }

    static void Say(ConsoleColor color, string text)
    {
        lock (ConsoleLock)
        {
            Console.ForegroundColor = color;
            Console.WriteLine(text);
            Console.ResetColor();
        }
    }

    // Setup comes from the MIDI panel's "Download setup file": the soundboard link plus pad bindings.
    static void LoadSetup(string argument)
    {
        string path = null;
        if (argument != null)
        {
            if (!File.Exists(argument)) throw new Exception("Setup file not found: " + argument);
            path = argument;
        }
        else
        {
            string downloads = Path.Combine(Environment.GetFolderPath(Environment.SpecialFolder.UserProfile), "Downloads");
            FileInfo newest = Directory.Exists(downloads)
                ? new DirectoryInfo(downloads).GetFiles("bootleg-setup*.json").OrderByDescending(file => file.LastWriteTimeUtc).FirstOrDefault()
                : null;
            if (newest != null && (!File.Exists(SavedSetup) || newest.LastWriteTimeUtc > File.GetLastWriteTimeUtc(SavedSetup))) path = newest.FullName;
            else if (File.Exists(SavedSetup)) path = SavedSetup;
        }
        if (path == null)
            throw new Exception("No setup yet. Open your soundboard link in Chrome or Edge, click MIDI, then \"Download setup file\". Run me again afterwards (or drag the file onto me).");
        var setup = new JavaScriptSerializer().DeserializeObject(File.ReadAllText(path, Encoding.UTF8)) as Dictionary<string, object>;
        if (setup == null || !setup.ContainsKey("link")) throw new Exception("That setup file is not from the soundboard.");
        Match link = Regex.Match(Convert.ToString(setup["link"]), @"^(https?://[^/\s]+)/soundboard/bot/([0-9]{1,10}\.[A-Za-z0-9_-]{43})/?$");
        if (!link.Success) throw new Exception("The setup file has no valid soundboard bot link. Download it again from the MIDI panel.");
        apiBase = link.Groups[1].Value + "/api/soundboard/bot/" + link.Groups[2].Value;
        Say(ConsoleColor.Gray, "  Setup file: " + path);
        Say(ConsoleColor.Gray, "  I only talk to " + link.Groups[1].Value + " and print a line for every request.");
        Say(ConsoleColor.Gray, "  I read MIDI input and this setup file, nothing else: no keyboard, microphone or other files.\n");
        bindings = new List<Binding>();
        object[] list = setup.ContainsKey("bindings") ? setup["bindings"] as object[] : null;
        if (list != null)
            foreach (object item in list)
            {
                Binding binding = ReadBinding(item as Dictionary<string, object>);
                if (binding != null && binding.ClipId != null && Regex.IsMatch(binding.ClipId, "^[a-f0-9]{32}$")) bindings.Add(binding);
            }
        stopBinding = setup.ContainsKey("stop") ? ReadBinding(setup["stop"] as Dictionary<string, object>) : null;
        if (path != SavedSetup)
        {
            Directory.CreateDirectory(SetupDirectory);
            File.Copy(path, SavedSetup, true);
            File.SetLastWriteTimeUtc(SavedSetup, DateTime.UtcNow);
        }
        Say(ConsoleColor.Gray, "  Loaded " + bindings.Count + " pad" + (bindings.Count == 1 ? "" : "s") + (stopBinding != null ? " and a Stop all pad" : "") + ".");
        foreach (Binding binding in bindings) Say(ConsoleColor.DarkGray, "    " + binding.Label() + "  ->  " + binding.Name);
        if (bindings.Count == 0 && stopBinding == null)
            Say(ConsoleColor.Yellow, "  No pads assigned yet. Use Learn in a sound's Edit panel, then download the setup file again.");
    }

    static Binding ReadBinding(Dictionary<string, object> item)
    {
        if (item == null || !item.ContainsKey("type") || !item.ContainsKey("channel") || !item.ContainsKey("number")) return null;
        var binding = new Binding
        {
            Type = Convert.ToString(item["type"]),
            Channel = Convert.ToInt32(item["channel"]),
            Number = Convert.ToInt32(item["number"]),
            ClipId = item.ContainsKey("clipId") ? Convert.ToString(item["clipId"]) : null,
            Name = item.ContainsKey("name") ? Convert.ToString(item["name"]) : "",
        };
        bool valid = (binding.Type == "note" || binding.Type == "cc" || binding.Type == "program")
            && binding.Channel >= 0 && binding.Channel <= 15 && binding.Number >= 0 && binding.Number <= 127;
        return valid ? binding : null;
    }

    static void RefreshGuild()
    {
        var data = Request("GET", apiBase, null);
        var discord = data.ContainsKey("discord") ? data["discord"] as Dictionary<string, object> : null;
        var guilds = discord != null && discord.ContainsKey("guilds") ? discord["guilds"] as object[] : null;
        var guild = guilds != null && guilds.Length > 0 ? guilds[0] as Dictionary<string, object> : null;
        if (guild == null) throw new Exception("The soundboard link works, but the Discord bot is offline.");
        guildId = Convert.ToString(guild["id"]);
        bool connected = guild.ContainsKey("channelId") && Convert.ToString(guild["channelId"]) != "";
        Say(ConsoleColor.Green, "  Soundboard reached: " + guild["name"] + (connected ? "" : " (bot is not in a voice channel yet: press Join on the page)"));
    }

    static Dictionary<string, object> Request(string method, string url, Dictionary<string, object> body)
    {
        var request = (HttpWebRequest)WebRequest.Create(url);
        request.Method = method;
        request.UserAgent = "bootleg-do-not-click/1.0";
        request.Timeout = 12000;
        if (body != null)
        {
            byte[] bytes = Encoding.UTF8.GetBytes(new JavaScriptSerializer().Serialize(body));
            request.ContentType = "application/json";
            request.ContentLength = bytes.Length;
            using (Stream stream = request.GetRequestStream()) stream.Write(bytes, 0, bytes.Length);
        }
        try
        {
            using (var response = (HttpWebResponse)request.GetResponse())
                return ReadJson(response);
        }
        catch (WebException error)
        {
            var response = error.Response as HttpWebResponse;
            if (response == null) throw new Exception("Could not reach the soundboard: " + error.Message);
            using (response)
            {
                if (response.StatusCode == HttpStatusCode.NotFound)
                    throw new Exception("This soundboard link no longer works. Get a fresh setup file from the MIDI panel.");
                var data = ReadJson(response);
                throw new Exception(data.ContainsKey("error") ? Convert.ToString(data["error"]) : "The soundboard answered " + (int)response.StatusCode);
            }
        }
    }

    static Dictionary<string, object> ReadJson(HttpWebResponse response)
    {
        using (var reader = new StreamReader(response.GetResponseStream(), Encoding.UTF8))
            return new JavaScriptSerializer { MaxJsonLength = 8 * 1024 * 1024 }.DeserializeObject(reader.ReadToEnd()) as Dictionary<string, object>
                ?? new Dictionary<string, object>();
    }

    static void OnMidi(IntPtr handle, uint message, IntPtr instance, IntPtr param1, IntPtr param2)
    {
        if (message == MimData) Messages.Add((int)(param1.ToInt64() & 0xFFFFFF));
    }

    static void OpenInputs()
    {
        uint count = midiInGetNumDevs();
        if (count == 0) Say(ConsoleColor.Yellow, "  No MIDI devices found. Plug one in; I'll pick it up automatically.");
        for (uint device = 0; device < count; device++)
        {
            MidiInCaps caps;
            string name = midiInGetDevCaps(new UIntPtr(device), out caps, (uint)Marshal.SizeOf(typeof(MidiInCaps))) == 0 ? caps.Name : "MIDI device " + device;
            IntPtr handle;
            if (midiInOpen(out handle, device, Callback, IntPtr.Zero, CallbackFunction) != 0)
            {
                Say(ConsoleColor.Yellow, "  " + name + " is busy. Close the soundboard tab (Windows lets one app use a MIDI device).");
                continue;
            }
            midiInStart(handle);
            lock (Inputs) Inputs.Add(handle);
            Say(ConsoleColor.Green, "  Listening to " + name);
        }
    }

    static void CloseInputs()
    {
        lock (Inputs)
        {
            foreach (IntPtr handle in Inputs)
            {
                midiInStop(handle);
                midiInClose(handle);
            }
            Inputs.Clear();
        }
    }

    // Reopens everything when a device is plugged in or removed.
    static void WatchDevices()
    {
        uint known = midiInGetNumDevs();
        while (true)
        {
            Thread.Sleep(3000);
            uint count = midiInGetNumDevs();
            if (count == known) continue;
            known = count;
            Say(ConsoleColor.Gray, "  MIDI devices changed; reconnecting.");
            CloseInputs();
            OpenInputs();
        }
    }

    // Same rules as the web page: note-ons with velocity, program changes, and CCs crossing 64 fire.
    static Binding Trigger(int message)
    {
        int status = message & 0xFF, kind = status & 0xF0, channel = status & 0x0F;
        int number = (message >> 8) & 0x7F, value = (message >> 16) & 0x7F;
        if (kind == 0x90 && value > 0) return new Binding { Type = "note", Channel = channel, Number = number };
        if (kind == 0xC0) return new Binding { Type = "program", Channel = channel, Number = number };
        if (kind != 0xB0) return null;
        int key = channel * 128 + number, previous;
        if (!ControlValues.TryGetValue(key, out previous)) previous = 0;
        ControlValues[key] = value;
        return value >= 64 && previous < 64 ? new Binding { Type = "cc", Channel = channel, Number = number } : null;
    }

    static void Handle(int message, bool wait)
    {
        Binding pressed = Trigger(message);
        if (pressed == null) return;
        Binding target = pressed.Matches(stopBinding) ? stopBinding : bindings.FirstOrDefault(binding => binding.Matches(pressed));
        if (target == null)
        {
            Say(ConsoleColor.DarkGray, "  " + pressed.Label() + " is not assigned");
            return;
        }
        bool stop = target == stopBinding;
        var command = new Dictionary<string, object> { { "action", stop ? "stop" : "play" } };
        if (!stop) command["clipId"] = target.ClipId;
        Thread sender = new Thread(() => Send(command, stop ? "Stop all" : target.Name)) { IsBackground = !wait };
        sender.Start();
        if (wait) sender.Join();
    }

    static void Send(Dictionary<string, object> command, string label)
    {
        for (int attempt = 0; attempt < 2; attempt++)
        {
            try
            {
                command["guildId"] = guildId;
                Request("POST", apiBase + "/discord", command);
                Say(ConsoleColor.Cyan, "  > " + label);
                return;
            }
            catch (Exception error)
            {
                if (attempt == 0 && error.Message.Contains("cannot control that server"))
                {
                    try { RefreshGuild(); continue; } catch (Exception) { }
                }
                Say(ConsoleColor.Red, "  " + label + ": " + error.Message);
                return;
            }
        }
    }

    static int ParseHex(string text)
    {
        string[] parts = text.Split(new[] { ' ', ',' }, StringSplitOptions.RemoveEmptyEntries);
        int message = 0;
        for (int index = 0; index < parts.Length && index < 3; index++)
            message |= Convert.ToInt32(parts[index], 16) << (8 * index);
        return message;
    }
}