using System.Text.Json;
using System.Text.Json.Serialization;
using MBN_STOCK_WEBVIEW.Core.Playout;
using MBN_STOCK_WEBVIEW.Core.Playout.Scenes;

namespace MBN_STOCK_WEBVIEW.Playout.Configuration;

public static class PlayoutOptionsLoader
{
    public const string LiveAuthorizationEnvironmentVariable =
        "MBN_STOCK_PLAYOUT_AUTHORIZE_LIVE_OUTPUT";

    public const string RequiredLiveAuthorizationValue =
        "I_AUTHORIZE_LIVE_PROGRAM_OUTPUT_FOR_THIS_LAUNCH";

    public static string DefaultPath => Path.Combine(
        Environment.GetFolderPath(Environment.SpecialFolder.LocalApplicationData),
        "MBN_STOCK_WEBVIEW",
        "Config",
        "playout.local.json");

    public static PlayoutOptions Load(string? path = null)
    {
        var options = LoadJson(path ?? DefaultPath);
        ApplyEnvironment(options);
        ApplyExecutableAssetDefaults(options, AppContext.BaseDirectory);
        return options;
    }

    /// <summary>
    /// Loads only the specified JSON file and deliberately ignores all environment
    /// overrides. Intended for explicit, reproducible diagnostic commands.
    /// </summary>
    public static PlayoutOptions LoadFileOnly(string path)
    {
        ArgumentException.ThrowIfNullOrWhiteSpace(path);
        return LoadJson(path);
    }

    internal static bool IsLiveAuthorizedForThisLaunch() =>
        string.Equals(
            Environment.GetEnvironmentVariable(LiveAuthorizationEnvironmentVariable),
            RequiredLiveAuthorizationValue,
            StringComparison.Ordinal);

    internal static void ApplyExecutableAssetDefaults(
        PlayoutOptions options,
        string? baseDirectory)
    {
        ArgumentNullException.ThrowIfNull(options);
        if (!string.IsNullOrWhiteSpace(options.SceneDirectory) ||
            string.IsNullOrWhiteSpace(baseDirectory))
        {
            return;
        }

        try
        {
            var cutsDirectory = Path.Combine(
                Path.GetFullPath(baseDirectory),
                "Cuts");
            if (Directory.Exists(cutsDirectory))
            {
                options.SceneDirectory = cutsDirectory;
            }
        }
        catch (Exception exception) when (
            exception is ArgumentException or IOException or NotSupportedException or
                System.Security.SecurityException)
        {
            // A missing or invalid executable asset root leaves the existing safe
            // configuration unchanged; validation reports it if a command needs it.
        }
    }

    private static PlayoutOptions LoadJson(string path)
    {
        if (!File.Exists(path))
        {
            return new PlayoutOptions();
        }

        try
        {
            var json = File.ReadAllText(path);
            return JsonSerializer.Deserialize<PlayoutOptions>(json, JsonOptions())
                ?? new PlayoutOptions();
        }
        catch (JsonException exception)
        {
            throw new PlayoutConfigurationException(
                "송출 설정 파일 형식이 올바르지 않습니다.", exception);
        }
        catch (IOException exception)
        {
            throw new PlayoutConfigurationException(
                "송출 설정 파일을 읽을 수 없습니다.", exception);
        }
        catch (UnauthorizedAccessException exception)
        {
            throw new PlayoutConfigurationException(
                "송출 설정 파일에 접근할 수 없습니다.", exception);
        }
    }

    private static void ApplyEnvironment(PlayoutOptions options)
    {
        ApplyEnum(
            "MBN_STOCK_PLAYOUT_MODE",
            (PlayoutMode value) => options.Mode = value);
        ApplyString("MBN_STOCK_PLAYOUT_HOST", value => options.Host = value);
        ApplyInt("MBN_STOCK_PLAYOUT_PORT", value => options.Port = value);
        ApplyInt("MBN_STOCK_PLAYOUT_TCP_MODE", value => options.TcpMode = value);
        ApplyInt("MBN_STOCK_PLAYOUT_CLIENT_PORT", value => options.ClientPort = value);
        ApplyNullableInt("MBN_STOCK_PLAYOUT_OUTPUT_CHANNEL", value => options.OutputChannel = value);
        ApplyInt("MBN_STOCK_PLAYOUT_LAYOUT_INDEX", value => options.LayoutIndex = value);
        ApplyInt(
            "MBN_STOCK_PLAYOUT_LEGACY_FADE_DURATION",
            value => options.LegacySceneFadeDuration = value);
        ApplyEnum(
            "MBN_STOCK_PLAYOUT_LEGACY_BACKGROUND_KIND",
            (LegacySceneBackgroundKind value) => options.LegacySceneBackgroundKind = value);
        ApplyString(
            "MBN_STOCK_PLAYOUT_LEGACY_BACKGROUND_ASSET",
            value => options.LegacySceneBackgroundAssetPath = value);
        ApplyInt(
            "MBN_STOCK_PLAYOUT_LEGACY_BACKGROUND_VIDEO_LOOP_COUNT",
            value => options.LegacySceneBackgroundVideoLoopCount = value);
        ApplyBool(
            "MBN_STOCK_PLAYOUT_LEGACY_BACKGROUND_VIDEO_LOOP_INFINITE",
            value => options.LegacySceneBackgroundVideoLoopInfinite = value);
        ApplyString(
            "MBN_STOCK_PLAYOUT_LEGACY_BACKGROUND_DIRECTORY",
            value => options.LegacyBackgroundDirectory = value);
        ApplyString("MBN_STOCK_PLAYOUT_SCENE_DIRECTORY", value => options.SceneDirectory = value);
        ApplyString(
            "MBN_STOCK_PLAYOUT_TEST_WINDOW_TITLE_PATTERN",
            value => options.TestProcessWindowTitlePattern = value);
        ApplyInt("MBN_STOCK_PLAYOUT_QUEUE_CAPACITY", value => options.QueueCapacity = value);
        ApplyInt(
            "MBN_STOCK_PLAYOUT_CONNECT_TIMEOUT_MS",
            value => options.ConnectTimeoutMilliseconds = value);
        ApplyInt(
            "MBN_STOCK_PLAYOUT_OPERATION_TIMEOUT_MS",
            value => options.OperationTimeoutMilliseconds = value);
        ApplyInt(
            "MBN_STOCK_PLAYOUT_DISCONNECT_TIMEOUT_MS",
            value => options.DisconnectTimeoutMilliseconds = value);
        ApplyInt(
            "MBN_STOCK_PLAYOUT_PROCESS_POLL_INTERVAL_MS",
            value => options.ProcessPollIntervalMilliseconds = value);
        ApplyInt(
            "MBN_STOCK_PLAYOUT_RECONNECT_DELAY_MS",
            value => options.ReconnectDelayMilliseconds = value);
        ApplyInt(
            "MBN_STOCK_PLAYOUT_MAXIMUM_RECONNECT_ATTEMPTS",
            value => options.MaximumReconnectAttempts = value);
        ApplyBool(
            "MBN_STOCK_PLAYOUT_RECONNECT_ENABLED",
            value => options.ReconnectEnabled = value);
    }

    private static JsonSerializerOptions JsonOptions()
    {
        var result = new JsonSerializerOptions
        {
            PropertyNameCaseInsensitive = true,
            ReadCommentHandling = JsonCommentHandling.Skip,
            AllowTrailingCommas = true
        };
        result.Converters.Add(new JsonStringEnumConverter());
        return result;
    }

    private static void ApplyString(string name, Action<string> apply)
    {
        var value = Environment.GetEnvironmentVariable(name);
        if (!string.IsNullOrWhiteSpace(value))
        {
            apply(value.Trim());
        }
    }

    private static void ApplyInt(string name, Action<int> apply)
    {
        var text = Environment.GetEnvironmentVariable(name);
        if (string.IsNullOrWhiteSpace(text))
        {
            return;
        }

        if (!int.TryParse(text, out var value))
        {
            throw InvalidEnvironment(name);
        }

        apply(value);
    }

    private static void ApplyNullableInt(string name, Action<int?> apply)
    {
        var text = Environment.GetEnvironmentVariable(name);
        if (string.IsNullOrWhiteSpace(text))
        {
            return;
        }

        if (!int.TryParse(text, out var value))
        {
            throw InvalidEnvironment(name);
        }

        apply(value);
    }

    private static void ApplyBool(string name, Action<bool> apply)
    {
        var text = Environment.GetEnvironmentVariable(name);
        if (string.IsNullOrWhiteSpace(text))
        {
            return;
        }

        if (!bool.TryParse(text, out var value))
        {
            throw InvalidEnvironment(name);
        }

        apply(value);
    }

    private static void ApplyEnum<TEnum>(string name, Action<TEnum> apply)
        where TEnum : struct, Enum
    {
        var text = Environment.GetEnvironmentVariable(name);
        if (string.IsNullOrWhiteSpace(text))
        {
            return;
        }

        if (!Enum.TryParse<TEnum>(text, true, out var value) || !Enum.IsDefined(value))
        {
            throw InvalidEnvironment(name);
        }

        apply(value);
    }

    private static PlayoutConfigurationException InvalidEnvironment(string name) =>
        new($"환경 변수 {name} 값이 올바르지 않습니다.");
}

public sealed class PlayoutConfigurationException : Exception
{
    public PlayoutConfigurationException(string message)
        : base(message)
    {
    }

    public PlayoutConfigurationException(string message, Exception innerException)
        : base(message, innerException)
    {
    }
}