// ReSharper disable MemberCanBePrivate.Global
// ReSharper disable UnusedMember.Global

using System;
using System.Collections.Generic;
using System.Collections.ObjectModel;
using System.Diagnostics;
using System.Linq;

namespace RGB.NET.Core;

/// <inheritdoc cref="AbstractBindable" />
/// <inheritdoc cref="IDisposable" />
/// <summary>
/// Represents a RGB-surface containing multiple devices.
/// </summary>
public sealed class RGBSurface : AbstractBindable, IDisposable
{
    #region Properties & Fields

    private readonly Stopwatch _deltaTimeCounter;

    private readonly IList<IRGBDevice> _devices = [];
    private readonly IList<IUpdateTrigger> _updateTriggers = [];
    private readonly List<ILedGroup> _ledGroups = [];

    /// <summary>
    /// Gets a readonly list containing all loaded <see cref="IRGBDevice"/>.
    /// This collection should be locked when enumerated in a multi-threaded application.
    /// </summary>
    public IReadOnlyList<IRGBDevice> Devices { get; }

    /// <summary>
    /// Gets a readonly list containing all registered <see cref="IUpdateTrigger"/>.
    /// This collection should be locked when enumerated in a multi-threaded application.
    /// </summary>
    public IReadOnlyList<IUpdateTrigger> UpdateTriggers { get; }

    /// <summary>
    /// Gets a copy of the <see cref="Rectangle"/> representing this <see cref="RGBSurface"/>.
    /// </summary>
    public Rectangle Boundary { get; private set; } = new(new Point(0, 0), new Size(0, 0));

    /// <summary>
    /// Gets a list of all <see cref="Led"/> on this <see cref="RGBSurface"/>.
    /// </summary>
    public IEnumerable<Led> Leds
    {
        get
        {
            lock (Devices)
                return _devices.SelectMany(x => x);
        }
    }

    #endregion

    #region EventHandler

    /// <summary>
    /// Represents the event-handler of the <see cref="Exception"/>-event.
    /// </summary>
    /// <param name="args">The arguments provided by the event.</param>
    public delegate void ExceptionEventHandler(ExceptionEventArgs args);

    /// <summary>
    /// Represents the event-handler of the <see cref="Updating"/>-event.
    /// </summary>
    /// <param name="args">The arguments provided by the event.</param>
    public delegate void UpdatingEventHandler(UpdatingEventArgs args);

    /// <summary>
    /// Represents the event-handler of the <see cref="Updated"/>-event.
    /// </summary>
    /// <param name="args">The arguments provided by the event.</param>
    public delegate void UpdatedEventHandler(UpdatedEventArgs args);

    /// <summary>
    /// Represents the event-handler of the <see cref="SurfaceLayoutChanged"/>-event.
    /// </summary>
    /// <param name="args">The arguments provided by the event.</param>
    public delegate void SurfaceLayoutChangedEventHandler(SurfaceLayoutChangedEventArgs args);

    #endregion

    #region Events

    // ReSharper disable EventNeverSubscribedTo.Global

    /// <summary>
    /// Occurs when a catched exception is thrown inside the <see cref="RGBSurface"/>.
    /// </summary>
    public event ExceptionEventHandler? Exception;

    /// <summary>
    /// Occurs when the <see cref="RGBSurface"/> starts updating.
    /// </summary>
    public event UpdatingEventHandler? Updating;

    /// <summary>
    /// Occurs when the <see cref="RGBSurface"/> update is done.
    /// </summary>
    public event UpdatedEventHandler? Updated;

    /// <summary>
    /// Occurs when the layout of this <see cref="RGBSurface"/> changed.
    /// </summary>
    public event SurfaceLayoutChangedEventHandler? SurfaceLayoutChanged;

    // ReSharper restore EventNeverSubscribedTo.Global

    #endregion

    #region Constructors

    /// <summary>
    /// Initializes a new instance of the <see cref="RGBSurface"/> class.
    /// </summary>
    public RGBSurface()
    {
        _deltaTimeCounter = Stopwatch.StartNew();

        Devices = new ReadOnlyCollection<IRGBDevice>(_devices);
        UpdateTriggers = new ReadOnlyCollection<IUpdateTrigger>(_updateTriggers);
    }

    #endregion

    #region Methods

    /// <summary>
    /// Perform a full update for all devices. Updates only dirty <see cref="Led"/> by default, or all <see cref="Led"/>, if flushLeds is set to true.
    /// </summary>
    /// <param name="flushLeds">Specifies whether all <see cref="Led"/>, (including clean ones) should be updated.</param>
    //public void Update(bool flushLeds = false) => Update(null, new CustomUpdateData((CustomUpdateDataIndex.FLUSH_LEDS, flushLeds)));
    public void Update(bool flushLeds = false) => Update(null, flushLeds ? DefaultCustomUpdateData.FLUSH : DefaultCustomUpdateData.NO_FLUSH);

    private void Update(object? updateTrigger, ICustomUpdateData customData) => Update(updateTrigger as IUpdateTrigger, customData);

    private void Update(IUpdateTrigger? updateTrigger, ICustomUpdateData customData)
    {
        try
        {
            bool flushLeds = customData[CustomUpdateDataIndex.FLUSH_LEDS] as bool? ?? false;
            bool render = customData[CustomUpdateDataIndex.RENDER] as bool? ?? true;
            bool updateDevices = customData[CustomUpdateDataIndex.UPDATE_DEVICES] as bool? ?? true;

            lock (UpdateTriggers)
                lock (Devices)
                {
                    OnUpdating(updateTrigger, customData);

                    // ReSharper disable ForCanBeConvertedToForeach - 'for' has a performance benefit (no enumerator allocation) here and since 'Update' is considered a hot path it's optimized
                    if (render)
                        lock (_ledGroups)
                        {
                            // Render brushes
                            for (int i = 0; i < _ledGroups.Count; i++)
                            {
                                try { Render(_ledGroups[i]); }
                                catch (Exception ex) { OnException(ex); }
                            }
                        }

                    if (updateDevices)
                        for (int i = 0; i < _devices.Count; i++)
                        {
                            try { _devices[i].Update(flushLeds); }
                            catch (Exception ex) { OnException(ex); }
                        }
                    // ReSharper restore ForCanBeConvertedToForeach

                    OnUpdated();
                }
        }
        catch (Exception ex)
        {
            OnException(ex);
        }
    }

    /// <inheritdoc />
    public void Dispose()
    {
        List<IRGBDevice> devices;
        lock (Devices)
            devices = [.._devices];

        foreach (IRGBDevice device in devices)
            try { Detach(device); }
            catch { /* We do what we can */}

        foreach (IUpdateTrigger updateTrigger in _updateTriggers)
            try { updateTrigger.Dispose(); }
            catch { /* We do what we can */}

        _ledGroups.Clear();
    }

    /// <summary>
    /// Renders a ledgroup.
    /// </summary>
    /// <param name="ledGroup">The led group to render.</param>
    /// <exception cref="ArgumentException">Thrown if the <see cref="IBrush.CalculationMode"/> of the Brush is not valid.</exception>
    private void Render(ILedGroup ledGroup)
    {
        IBrush? brush = ledGroup.Brush;

        if ((brush == null) || !brush.IsEnabled) return;

        using (ledGroup.ToListUnsafe(out IList<Led> leds))
        {
            IEnumerable<(RenderTarget renderTarget, Color color)> render;
            switch (brush.CalculationMode)
            {
                case RenderMode.Relative:
                    Rectangle brushRectangle = new(leds);
                    Point offset = new(-brushRectangle.Location.X, -brushRectangle.Location.Y);
                    brushRectangle = brushRectangle.SetLocation(new Point(0, 0));
                    render = brush.Render(brushRectangle, leds.Select(led => new RenderTarget(led, led.AbsoluteBoundary.Translate(offset))));
                    break;
                case RenderMode.Absolute:
                    render = brush.Render(Boundary, leds.Select(led => new RenderTarget(led, led.AbsoluteBoundary)));
                    break;
                default:
                    throw new ArgumentException($"The CalculationMode '{brush.CalculationMode}' is not valid.");
            }

            foreach ((RenderTarget renderTarget, Color c) in render)
                renderTarget.Led.Color = c;
        }
    }

    /// <summary>
    /// Attaches the specified <see cref="ILedGroup"/>.
    /// </summary>
    /// <param name="ledGroup">The <see cref="ILedGroup"/> to attach.</param>
    /// <returns><c>true</c> if the <see cref="ILedGroup"/> could be attached; otherwise, <c>false</c>.</returns>
    public bool Attach(ILedGroup ledGroup)
    {
        lock (_ledGroups)
        {
            if (ledGroup.Surface != null) return false;

            ledGroup.Surface = this;
            _ledGroups.Add(ledGroup);
            _ledGroups.Sort((group1, group2) => group1.ZIndex.CompareTo(group2.ZIndex));
            ledGroup.OnAttach();

            return true;
        }
    }

    /// <summary>
    /// Detaches the specified <see cref="ILedGroup"/>.
    /// </summary>
    /// <param name="ledGroup">The <see cref="ILedGroup"/> to detache.</param>
    /// <returns><c>true</c> if the <see cref="ILedGroup"/> could be detached; <c>false</c> otherwise.</returns>
    public bool Detach(ILedGroup ledGroup)
    {
        lock (_ledGroups)
        {
            if (!_ledGroups.Remove(ledGroup)) return false;
            ledGroup.OnDetach();
            ledGroup.Surface = null;

            return true;
        }
    }

    /// <summary>
    /// Attaches the specified <see cref="IRGBDevice"/>.
    /// </summary>
    /// <param name="device">The <see cref="IRGBDevice"/> to attach.</param>
    public void Attach(IRGBDevice device)
    {
        lock (Devices)
        {
            if (string.IsNullOrWhiteSpace(device.DeviceInfo.DeviceName)) throw new RGBDeviceException($"The device '{device.DeviceInfo.Manufacturer} {device.DeviceInfo.Model}' has no valid name.");
            if (device.Surface != null) throw new RGBSurfaceException($"The device '{device.DeviceInfo.DeviceName}' is already attached to a surface.");

            device.Surface = this;
            device.BoundaryChanged += DeviceOnBoundaryChanged;

            _devices.Add(device);
            OnSurfaceLayoutChanged(SurfaceLayoutChangedEventArgs.FromAddedDevice(device));
        }
    }

    /// <summary>
    /// Detaches the specified <see cref="IRGBDevice"/>.
    /// </summary>
    /// <param name="device">The <see cref="IRGBDevice"/> to detache.</param>
    /// <returns><c>true</c> if the <see cref="IRGBDevice"/> could be detached; <c>false</c> otherwise.</returns>
    public void Detach(IRGBDevice device)
    {
        lock (Devices)
        {
            if (!_devices.Contains(device)) throw new RGBSurfaceException($"The device '{device.DeviceInfo.DeviceName}' is not attached to this surface.");

            device.BoundaryChanged -= DeviceOnBoundaryChanged;
            device.Surface = null;

            _devices.Remove(device);

            OnSurfaceLayoutChanged(SurfaceLayoutChangedEventArgs.FromRemovedDevice(device));
        }
    }

    // ReSharper restore UnusedMember.Global

    private void DeviceOnBoundaryChanged(object? sender, EventArgs args)
        => OnSurfaceLayoutChanged((sender is IRGBDevice device) ? SurfaceLayoutChangedEventArgs.FromChangedDevice(device) : SurfaceLayoutChangedEventArgs.Misc());

    private void OnSurfaceLayoutChanged(SurfaceLayoutChangedEventArgs args)
    {
        UpdateSurfaceRectangle();

        SurfaceLayoutChanged?.Invoke(args);
    }

    private void UpdateSurfaceRectangle()
    {
        lock (Devices)
        {
            Rectangle devicesRectangle = new(_devices.Select(d => d.Boundary));
            Boundary = Boundary.SetSize(new Size(devicesRectangle.Location.X + devicesRectangle.Size.Width, devicesRectangle.Location.Y + devicesRectangle.Size.Height));
        }
    }

    /// <summary>
    /// Registers the provided <see cref="IUpdateTrigger"/>.
    /// </summary>
    /// <param name="updateTrigger">The <see cref="IUpdateTrigger"/> to register.</param>
    public void RegisterUpdateTrigger(IUpdateTrigger updateTrigger)
    {
        if (!_updateTriggers.Contains(updateTrigger))
        {
            _updateTriggers.Add(updateTrigger);
            updateTrigger.Update += Update;
        }
    }

    /// <summary>
    /// Unregisters the provided <see cref="IUpdateTrigger"/>.
    /// </summary>
    /// <param name="updateTrigger">The <see cref="IUpdateTrigger"/> to unregister.</param>
    public void UnregisterUpdateTrigger(IUpdateTrigger updateTrigger)
    {
        if (_updateTriggers.Remove(updateTrigger))
            updateTrigger.Update -= Update;
    }

    /// <summary>
    /// Handles the needed event-calls for an exception.
    /// </summary>
    /// <param name="ex">The exception previously thrown.</param>
    private void OnException(Exception ex)
    {
        try
        {
            Exception?.Invoke(new ExceptionEventArgs(ex));
        }
        catch { /* Well ... that's not my fault */ }
    }

    /// <summary>
    /// Handles the needed event-calls before updating.
    /// </summary>
    private void OnUpdating(IUpdateTrigger? trigger, ICustomUpdateData customData)
    {
        try
        {
            double deltaTime = _deltaTimeCounter.Elapsed.TotalSeconds;
            _deltaTimeCounter.Restart();
            Updating?.Invoke(new UpdatingEventArgs(deltaTime, trigger, customData));
        }
        catch { /* Well ... that's not my fault */ }
    }

    /// <summary>
    /// Handles the needed event-calls after an update.
    /// </summary>
    private void OnUpdated()
    {
        try
        {
            Updated?.Invoke(new UpdatedEventArgs());
        }
        catch { /* Well ... that's not my fault */ }
    }

    #endregion
}