using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using ADOFAIRenderer.Core.Data;
using ADOFAIRenderer.Data;
using MelonLoader;
using MelonLoader.Utils;
using Newtonsoft.Json;
using Newtonsoft.Json.Linq;

namespace ADOFAIRenderer.Core;

/// <summary>A named render configuration, stored as one JSON file in the presets directory.</summary>
public class RenderPreset
{
    /// <summary>Display name of the preset. A file without a name uses the file name (without extension).</summary>
    public string Name { get; set; } = string.Empty;

    /// <summary>Render configuration of the preset.</summary>
    public RenderConfig Config { get; set; } = null!;

    /// <summary>Returns a copy with a copied configuration.</summary>
    public RenderPreset Clone()
    {
        return new RenderPreset
        {
            Name = Name,
            Config = Config.Clone()
        };
    }
}

/// <summary>
/// Loads, saves and deletes render presets. Presets are JSON files (one per preset, file name derived from the preset
/// name) in &lt;game root&gt;/UserData/ADOFAIRenderer/Presets. The built-in presets are written once, on first use
/// (GlobalConfig.DefaultPresetsInitialized), so the user can edit or delete them. Main thread.
/// </summary>
public static class PresetManager
{
    /// <summary>
    /// Built-in presets (H.264 CBR, 48 kHz stereo AAC at 256 kbps, mkv): 1080p, 1440p and 2160p at 60 FPS video.
    /// "(4x)" presets render 240 game frames per second (4 per video frame); "(1x)" renders 60.
    /// Video bitrates are in kbps.
    /// </summary>
    private static readonly List<RenderPreset> DefaultPresets = new()
    {
        new RenderPreset
        {
            Name = "FHD 60fps (1x)",
            Config = new RenderConfig
            {
                RenderWidth = 1920,
                RenderHeight = 1080,
                RenderFPS = 60,
                VideoFPS = 60,
                DelayAfterEnd = 15,
                ShowJudgementText = false,
                VideoConfig = new VideoEncodingConfig { Codec = Codec.H264, RateControlMode = RateControlMode.CBR, Bitrate = 20000, MaxBitrate = 35000, QP = 18, KeyframeInterval = 2.0 },
                AudioConfig = new AudioEncodingConfig { RenderAudio = true, AudioSampleRate = 48000, AudioChannels = 2, AudioBitrate = 256000 },
                AdvancedConfig = new AdvancedConfig { ProcessAudio = true, NonTile = false, FileExtension = "mkv" }
            }
        },
        new RenderPreset
        {
            Name = "FHD 60fps (4x)",
            Config = new RenderConfig
            {
                RenderWidth = 1920,
                RenderHeight = 1080,
                RenderFPS = 240,
                VideoFPS = 60,
                DelayAfterEnd = 15,
                ShowJudgementText = false,
                VideoConfig = new VideoEncodingConfig { Codec = Codec.H264, RateControlMode = RateControlMode.CBR, Bitrate = 30000, MaxBitrate = 50000, QP = 18, KeyframeInterval = 2.0 },
                AudioConfig = new AudioEncodingConfig { RenderAudio = true, AudioSampleRate = 48000, AudioChannels = 2, AudioBitrate = 256000 },
                AdvancedConfig = new AdvancedConfig { ProcessAudio = true, NonTile = false, FileExtension = "mkv" }
            }
        },
        new RenderPreset
        {
            Name = "QHD 60fps (4x)",
            Config = new RenderConfig
            {
                RenderWidth = 2560,
                RenderHeight = 1440,
                RenderFPS = 240,
                VideoFPS = 60,
                DelayAfterEnd = 15,
                ShowJudgementText = false,
                VideoConfig = new VideoEncodingConfig { Codec = Codec.H264, RateControlMode = RateControlMode.CBR, Bitrate = 35000, MaxBitrate = 60000, QP = 18, KeyframeInterval = 2.0 },
                AudioConfig = new AudioEncodingConfig { RenderAudio = true, AudioSampleRate = 48000, AudioChannels = 2, AudioBitrate = 256000 },
                AdvancedConfig = new AdvancedConfig { ProcessAudio = true, NonTile = false, FileExtension = "mkv" }
            }
        },
        new RenderPreset
        {
            Name = "4K 60fps (4x)",
            Config = new RenderConfig
            {
                RenderWidth = 3840,
                RenderHeight = 2160,
                RenderFPS = 240,
                VideoFPS = 60,
                DelayAfterEnd = 15,
                ShowJudgementText = false,
                VideoConfig = new VideoEncodingConfig { Codec = Codec.H264, RateControlMode = RateControlMode.CBR, Bitrate = 60000, MaxBitrate = 100000, QP = 18, KeyframeInterval = 2.0 },
                AudioConfig = new AudioEncodingConfig { RenderAudio = true, AudioSampleRate = 48000, AudioChannels = 2, AudioBitrate = 256000 },
                AdvancedConfig = new AdvancedConfig { ProcessAudio = true, NonTile = false, FileExtension = "mkv" }
            }
        }
    };

    /// <summary>
    /// &lt;root&gt;/UserData/ADOFAIRenderer/Presets, where root is MelonLoader's game root directory, or the application
    /// base directory when that is unavailable.
    /// </summary>
    private static string GetPresetsDirectory()
    {
        string? root = null;
        try
        {
            root = MelonEnvironment.GameRootDirectory;
        }
        catch
        {
            // Outside MelonLoader host environment (e.g. tests)
        }

        if (string.IsNullOrEmpty(root))
        {
            root = AppDomain.CurrentDomain.BaseDirectory;
        }

        return Path.Combine(root, "UserData", "ADOFAIRenderer", "Presets");
    }

    /// <summary>
    /// File name (without extension) of the preset file for the given preset name: every character that is invalid
    /// in a file name is replaced with '_'. Different preset names can map to the same file name (e.g. "a/b" and "a_b").
    /// </summary>
    internal static string GetSafeFileName(string name)
    {
        return Path.GetInvalidFileNameChars().Aggregate(name, (current, c) => current.Replace(c, '_'));
    }

    /// <summary>
    /// Creates the presets directory and, once per installation (GlobalConfig.DefaultPresetsInitialized), writes the
    /// built-in presets whose files do not exist yet, then saves the flag. Errors are logged, not thrown.
    /// </summary>
    public static void EnsureDefaultPresetsCreated()
    {
        try
        {
            var dir = GetPresetsDirectory();
            if (!Directory.Exists(dir))
            {
                Directory.CreateDirectory(dir);
            }

            if (!GlobalSettings.Current.DefaultPresetsInitialized)
            {
                var settings = new JsonSerializerSettings
                {
                    Formatting = Formatting.Indented
                };
                settings.Converters.Add(new ColorJsonConverter());

                foreach (var def in DefaultPresets)
                {
                    var safeName = GetSafeFileName(def.Name);
                    var filePath = Path.Combine(dir, safeName + ".json");
                    if (!File.Exists(filePath))
                    {
                        var json = JsonConvert.SerializeObject(def, settings);
                        File.WriteAllText(filePath, json);
                    }
                }

                GlobalSettings.Current.DefaultPresetsInitialized = true;
                GlobalSettings.Save();
            }
        }
        catch (Exception ex)
        {
            MelonLogger.Warning($"Error initializing default presets: {ex.Message}");
        }
    }

    /// <summary>
    /// Saves a copy of <paramref name="config"/> as preset <paramref name="name"/>, overwriting the file of the same
    /// safe file name (see GetSafeFileName).
    /// </summary>
    /// <exception cref="ArgumentException">The name is empty or white space.</exception>
    /// <exception cref="IOException">The directory or file cannot be written (not caught).</exception>
    public static void SavePreset(string name, RenderConfig config)
    {
        if (string.IsNullOrWhiteSpace(name))
        {
            throw new ArgumentException("Preset name cannot be empty.");
        }

        string dir = GetPresetsDirectory();
        if (!Directory.Exists(dir))
        {
            Directory.CreateDirectory(dir);
        }

        var preset = new RenderPreset
        {
            Name = name,
            Config = config.Clone()
        };

        var settings = new JsonSerializerSettings
        {
            Formatting = Formatting.Indented
        };
        settings.Converters.Add(new ColorJsonConverter());

        string json = JsonConvert.SerializeObject(preset, settings);
        string safeName = GetSafeFileName(name);
        string filePath = Path.Combine(dir, safeName + ".json");
        File.WriteAllText(filePath, json);
    }

    /// <summary>
    /// Loads every *.json preset file (after creating the built-in presets on first use). Files written by older
    /// versions are migrated in memory (old key names and flat properties moved into the nested configs); the files are
    /// not rewritten. A file that cannot be read is logged and skipped. When two files have the same preset name
    /// (case-insensitive), the first one in directory order is used. Returns copies of the built-in presets when the
    /// directory does not exist.
    /// </summary>
    public static List<RenderPreset> GetPresets()
    {
        EnsureDefaultPresetsCreated();

        var presets = new List<RenderPreset>();
        var dir = GetPresetsDirectory();
        if (!Directory.Exists(dir))
        {
            foreach (var b in DefaultPresets)
            {
                presets.Add(b.Clone());
            }
            return presets;
        }

        try
        {
            var files = Directory.GetFiles(dir, "*.json");
            var serializerSettings = new JsonSerializerSettings();
            serializerSettings.Converters.Add(new ColorJsonConverter());
            var serializer = JsonSerializer.Create(serializerSettings);

            foreach (var file in files)
            {
                try
                {
                    var json = File.ReadAllText(file);
                    var jObject = JsonConvert.DeserializeObject<JObject>(json);
                    if (jObject == null) continue;
                        
                    var configToken = jObject["Config"];
                    if (configToken is JObject configObj)
                    {
                        TryChangeKey(configObj, "DelayAfterLevelEnd", "DelayAfterEnd");
                            
                        // 1. legacy EncodingConfig -> VideoConfig
                        if (configObj["EncodingConfig"] is JObject oldEncodingConfigObj)
                        {
                            configObj["VideoConfig"] ??= oldEncodingConfigObj;
                            configObj.Remove("EncodingConfig");
                        }

                        // 2. legacy top-level Codec -> VideoConfig.Codec
                        var legacyCodecToken = configObj["Codec"];
                        if (legacyCodecToken != null && legacyCodecToken.Type != JTokenType.Null)
                        {
                            if (configObj["VideoConfig"] == null || configObj["VideoConfig"]!.Type == JTokenType.Null)
                            {
                                configObj["VideoConfig"] = new JObject();
                            }
                                    
                            var videoConfigObj = (JObject)configObj["VideoConfig"]!;
                            videoConfigObj["Codec"] ??= legacyCodecToken;
                                    
                            configObj.Remove("Codec");
                        }

                        // 3. legacy top-level Audio properties -> AudioConfig
                        string[] legacyAudioProps = { "RenderAudio", "AudioSampleRate", "AudioChannels", "AudioBitrate" };
                        foreach (var prop in legacyAudioProps)
                        {
                            var legacyToken = configObj[prop];
                            if (legacyToken != null && legacyToken.Type != JTokenType.Null)
                            {
                                if (configObj["AudioConfig"] == null || configObj["AudioConfig"]!.Type == JTokenType.Null)
                                {
                                    configObj["AudioConfig"] = new JObject();
                                }

                                var audioConfigObj = (JObject)configObj["AudioConfig"]!;
                                audioConfigObj[prop] ??= legacyToken;
                            }

                            configObj.Remove(prop);
                        }

                        if (configObj["AudioConfig"] != null && configObj["AudioConfig"]!.Type == JTokenType.Null)
                        {
                            configObj.Remove("AudioConfig");
                        }

                        // 4. legacy top-level Advanced properties -> AdvancedConfig
                        string[] legacyAdvancedProps = { "RandomSeed", "ProcessAudio", "NonTile" };
                        foreach (var prop in legacyAdvancedProps)
                        {
                            var legacyToken = configObj[prop];
                            if (legacyToken != null && legacyToken.Type != JTokenType.Null)
                            {
                                if (configObj["AdvancedConfig"] == null || configObj["AdvancedConfig"]!.Type == JTokenType.Null)
                                {
                                    configObj["AdvancedConfig"] = new JObject();
                                }

                                var advancedConfigObj = (JObject)configObj["AdvancedConfig"]!;
                                advancedConfigObj[prop] ??= legacyToken;
                            }

                            configObj.Remove(prop);
                        }

                        if (configObj["AdvancedConfig"] != null && configObj["AdvancedConfig"]!.Type == JTokenType.Null)
                        {
                            configObj.Remove("AdvancedConfig");
                        }
                    }
                            
                    var preset = jObject.ToObject<RenderPreset>(serializer);
                    if (preset != null)
                    {
                        var fileBaseName = Path.GetFileNameWithoutExtension(file);
                        if (string.IsNullOrWhiteSpace(preset.Name))
                        {
                            preset.Name = fileBaseName;
                        }

                        if (presets.Any(p => string.Equals(p.Name, preset.Name, StringComparison.OrdinalIgnoreCase)))
                        {
                            continue;
                        }

                        presets.Add(preset);
                    }
                }
                catch (Exception ex)
                {
                    MelonLogger.Warning($"Error loading preset file '{Path.GetFileName(file)}': {ex.Message}");
                }
            }
        }
        catch (Exception ex)
        {
            MelonLogger.Error($"Error retrieving preset list: {ex.Message}");
        }

        return presets;
    }

    /// <summary>
    /// Renames key <paramref name="keyBefore"/> to <paramref name="targetKey"/>: a non-null old value overwrites the target
    /// key, and the old key is always removed.
    /// </summary>
    private static void TryChangeKey(JObject configObj, string keyBefore, string targetKey)
    {
        var legacyToken = configObj[keyBefore];
        if (legacyToken != null && legacyToken.Type != JTokenType.Null)
            configObj[targetKey] = legacyToken;

        configObj.Remove(keyBefore);
    }

    /// <summary>
    /// Deletes the file of preset <paramref name="name"/>: first the file with the safe file name; otherwise the first
    /// file whose base name or stored "Name" matches (case-insensitive). Does nothing for an empty name or when no file
    /// matches.
    /// </summary>
    /// <exception cref="IOException">The file with the safe file name exists but cannot be deleted (not caught).</exception>
    public static void DeletePreset(string name)
    {
        if (string.IsNullOrWhiteSpace(name)) return;

        var dir = GetPresetsDirectory();
        if (!Directory.Exists(dir)) return;

        var safeName = GetSafeFileName(name);
        var filePath = Path.Combine(dir, safeName + ".json");

        if (File.Exists(filePath))
        {
            File.Delete(filePath);
            return;
        }

        foreach (var file in Directory.GetFiles(dir, "*.json"))
        {
            try
            {
                var fileBaseName = Path.GetFileNameWithoutExtension(file);
                if (string.Equals(fileBaseName, name, StringComparison.OrdinalIgnoreCase))
                {
                    File.Delete(file);
                    return;
                }

                var json = File.ReadAllText(file);
                var jObject = JsonConvert.DeserializeObject<JObject>(json);
                var pName = (string?)jObject?["Name"];
                if (string.Equals(pName, name, StringComparison.OrdinalIgnoreCase))
                {
                    File.Delete(file);
                    return;
                }
            }
            catch
            {
                // Ignore read errors during cleanup search
            }
        }
    }
}