using System.Collections.Generic;
using System.Diagnostics.CodeAnalysis;
using System.Linq;
using System.Text.RegularExpressions;
using ADOFAIRenderer.Data;
using ADOFAIRenderer.Util.FFmpeg;
using ADOFAIRenderer.Util.OS;
using MelonLoader;
using UnityEngine;

namespace ADOFAIRenderer.Util;

/// <summary>
/// GPU vendor, used to try the hardware encoders of the active GPU first (VideoEncoder.Vendor). <c>Unknown</c> is
/// also the vendor of the software encoders.
/// </summary>
[SuppressMessage("ReSharper", "InconsistentNaming")]
internal enum GPUVendor
{
    Unknown, NVIDIA, AMD, Intel, Apple
}
    
/// <summary>
/// Detection of the active GPU vendor and the NVIDIA driver version, and the encoder try order derived from the vendor.
/// Results are cached for the game session. Main thread (SystemInfo is read on first use).
/// </summary>
internal static class GPUUtil
{
    // Device name patterns (SystemInfo.graphicsDeviceName) of the GPU families recognized per vendor. A name that matches
    // none of them gives GPUVendor.Unknown (Apple on macOS), which only affects the encoder try order.
    // NVIDIA: "NVIDIA GeForce RTX/GTX <number>" with optional SUPER / Ti / Ti SUPER, memory size, "Laptop GPU" and a
    // "/PCIe/SSE2" suffix.
    private const string NvidiaPattern = 
        @"^NVIDIA GeForce [RG]TX [0-9]+(?> SUPER| Ti(?> SUPER)?)?(?> [0-9]+GB)?(?> Laptop GPU)?(?>/PCIe/SSE2)?$";

    // Intel: "Intel(R) UHD/HD Graphics <number>" or "Intel(R) Arc(TM) <A-C><number> Graphics", with an optional
    // parenthesized suffix.
    private const string IntelPattern =
        @"^Intel(?>\(R\))? (?>U?HD Graphics [0-9]+|Arc\(TM\) [A-C][0-9]+ Graphics)(?> \([^)]+\))?$";

    // AMD: "AMD Radeon RX <number>" with an optional " XT".
    // ReSharper disable once InconsistentNaming
    private const string AMDPattern =
        @"^AMD Radeon RX [0-9]+(?> XT)?$";

    /// <summary>Vendor found by the first GetActiveGPUVendor call.</summary>
    private static GPUVendor _cachedVendor = GPUVendor.Unknown;
    /// <summary>True once _cachedVendor is set.</summary>
    private static bool _hasCachedVendor;

    /// <summary>
    /// Vendor of the GPU Unity renders with: the device name is matched against the NVIDIA, Intel and AMD patterns in
    /// that order; on macOS an unmatched name gives Apple; otherwise Unknown. Logs the device name once.
    /// </summary>
    private static GPUVendor GetActiveGPUVendor()
    {
        if (_hasCachedVendor) return _cachedVendor;

        var gpuName = SystemInfo.graphicsDeviceName;
        Melon<RenderMod>.Logger.Msg($"Active GPU: {gpuName}");
            
        _cachedVendor = GPUVendor.Unknown;
        foreach (Match unused in Regex.Matches(gpuName, NvidiaPattern))
        {
            _cachedVendor = GPUVendor.NVIDIA;
            break;
        }
            
        if (_cachedVendor == GPUVendor.Unknown)
        {
            foreach (Match unused in Regex.Matches(gpuName, IntelPattern))
            {
                _cachedVendor = GPUVendor.Intel;
                break;
            }
        }
            
        if (_cachedVendor == GPUVendor.Unknown)
        {
            foreach (Match unused in Regex.Matches(gpuName, AMDPattern))
            {
                _cachedVendor = GPUVendor.AMD;
                break;
            }
        }

        if (_cachedVendor == GPUVendor.Unknown && Application.platform == RuntimePlatform.OSXPlayer)
        {
            _cachedVendor = GPUVendor.Apple;
        }
            
        _hasCachedVendor = true;
        return _cachedVendor;
    }

    /// <summary>Result of the first GetNvidiaDriverVersion call (null when not available).</summary>
    private static double? _cachedNvidiaVersion;
    /// <summary>True once _cachedNvidiaVersion is set.</summary>
    private static bool _hasCachedNvidiaVersion;

    /// <summary>
    /// NVIDIA driver version in NVIDIA's numbering (for example 561.09), or null when the active GPU is not detected as
    /// NVIDIA or no version can be found. The result is cached.
    /// <para>
    /// The version is derived from a four-part Windows driver version a.b.c.d as ((c mod 10) x 10000 + d) / 100,
    /// for example 31.0.15.6109 gives 561.09. It is read from SystemInfo.graphicsDeviceVersion when that string contains a
    /// four-part number, otherwise (Windows only) from the DriverVersion value of the first display adapter entry whose
    /// ProviderName contains "NVIDIA" under the display adapter class key of the registry.
    /// </para>
    /// </summary>
    public static double? GetNvidiaDriverVersion()
    {
        if (_hasCachedNvidiaVersion) return _cachedNvidiaVersion;

        _hasCachedNvidiaVersion = true;
        _cachedNvidiaVersion = null;

        if (GetActiveGPUVendor() != GPUVendor.NVIDIA) return null;

        // 1. Try parsing from UnityEngine.SystemInfo.graphicsDeviceVersion
        var deviceVersion = SystemInfo.graphicsDeviceVersion;
        if (!string.IsNullOrEmpty(deviceVersion))
        {
            var match = Regex.Match(deviceVersion, @"\b(\d+)\.(\d+)\.(\d+)\.(\d+)\b");
            if (match.Success)
            {
                if (int.TryParse(match.Groups[3].Value, out var sub) && int.TryParse(match.Groups[4].Value, out int build))
                {
                    var nvidiaVerInt = sub % 10 * 10000 + build;
                    _cachedNvidiaVersion = nvidiaVerInt / 100.0;
                    Melon<RenderMod>.Logger.Msg($"Parsed NVIDIA Driver Version from SystemInfo: {_cachedNvidiaVersion:F2}");
                    return _cachedNvidiaVersion;
                }
            }
        }

        // 2. Fallback to Windows Registry (only on Windows NT platforms via RegistryUtil)
        if (System.Environment.OSVersion.Platform != System.PlatformID.Win32NT) return null;
        // Device class key of display adapters (class GUID {4d36e968-e325-11ce-bfc1-08002be10318}); each numbered subkey is
        // one installed adapter driver.
        // Reference: https://learn.microsoft.com/en-us/windows-hardware/drivers/install/system-defined-device-setup-classes-available-to-vendors
        const string classKey = @"SYSTEM\CurrentControlSet\Control\Class\{4d36e968-e325-11ce-bfc1-08002be10318}";
        var subkeys = RegistryUtil.GetHKLMSubKeyNames(classKey);
        if (subkeys == null) return null;
            
        foreach (var subkey in subkeys)
        {
            var subkeyPath = classKey + "\\" + subkey;
            var provider = RegistryUtil.GetHKLMValue(subkeyPath, "ProviderName");
            if (provider == null || !provider.Contains("NVIDIA")) continue;
                    
            var driverVersionStr = RegistryUtil.GetHKLMValue(subkeyPath, "DriverVersion");
            if (string.IsNullOrEmpty(driverVersionStr)) continue;
                        
            var regMatch = Regex.Match(driverVersionStr, @"\b(\d+)\.(\d+)\.(\d+)\.(\d+)\b");
            if (!regMatch.Success) continue;
            if (!int.TryParse(regMatch.Groups[3].Value, out var sub) ||
                !int.TryParse(regMatch.Groups[4].Value, out var build)) continue;
                            
            var nvidiaVerInt = sub % 10 * 10000 + build;
            _cachedNvidiaVersion = nvidiaVerInt / 100.0;
            Melon<RenderMod>.Logger.Msg($"Parsed NVIDIA Driver Version from Registry (RegistryUtil): {_cachedNvidiaVersion:F2}");
            return _cachedNvidiaVersion;
        }

        return null;
    }

    /// <summary>
    /// Encoders for <paramref name="codec"/> in the order they are tried: the encoders of the active GPU vendor first,
    /// then all others in VideoEncoder.All order (hardware encoders of other vendors and the software encoders).
    /// </summary>
    /// <param name="codec">Video codec.</param>
    /// <param name="forceSoftware">When true, only the software encoders of the codec are returned.</param>
    public static List<VideoEncoder> GetPrioritizedEncoders(Codec codec, bool forceSoftware = false)
    {
        var encoders = VideoEncoder.All.Where(e => e.Codec == codec).ToList();
        if (forceSoftware)
        {
            return encoders.Where(e => !e.IsHardware).ToList();
        }

        var vendor = GetActiveGPUVendor();
        var prioritized = new List<VideoEncoder>();
        var others = new List<VideoEncoder>();

        foreach (var item in encoders)
        {
            if (item.Vendor == vendor) prioritized.Add(item);
            else others.Add(item);
        }

        prioritized.AddRange(others);
        return prioritized;
    }
}