namespace PKHeX.Core;

/// <summary>
/// Settings for Parsing Legality
/// </summary>
/// <remarks><see cref="LegalityAnalysis"/></remarks>
public static class ParseSettings
{
    /// <summary>
    /// Current Trainer of the active Save Data.
    /// </summary>
    /// <remarks>
    /// Used for legality checks to determine if the data is from the active save file.
    /// Defaults to a blank trainer with no data to prevent matching unless another reference (save file) is loaded.
    /// </remarks>
    internal static ITrainerInfo? ActiveTrainer { get; private set; }

    /// <summary>
    /// Resets active trainer to null, disabling any legality checks that compare to a currently loaded trainer.
    /// </summary>
    /// <remarks>Shouldn't need to use this unless you want to undo any loading of save data to revert to an uninitialized state.</remarks>
    public static void ClearActiveTrainer() => ActiveTrainer = null;

    /// <summary>
    /// Master settings configuration for legality analysis.
    /// </summary>
    /// <remarks>Allows configuring severities away from the default settings for users who want to deviate.</remarks>
    public static LegalitySettings Settings { get; set; } = new();

    /// <summary>
    /// Setting to specify if an analysis should permit data sourced from the physical cartridge era of Game Boy games.
    /// </summary>
    /// <remarks>If false, indicates to use Virtual Console rules (which are transferable to Gen7+)</remarks>
    public static bool AllowEraCartGB { private get; set; }

    /// <summary>
    /// Setting to specify if an analysis should permit data sourced from the physical cartridge era of Game Boy Advance games.
    /// </summary>
    public static bool AllowEraCartGBA { private get; set; } = true;

    /// <summary>
    /// Setting to specify if an analysis should permit data sourced from the Nintendo Switch Virtual Console era of Game Boy Advance games.
    /// </summary>
    public static bool AllowEraSwitchGBA { private get; set; }

    /// <summary>
    /// Setting to specify if an analysis should permit trading a Generation 1 origin file to Generation 2, then back. Useful for checking RBY Metagame rules.
    /// </summary>
    public static bool AllowGen1Tradeback => Settings.Tradeback.AllowGen1Tradeback;

    public static void Initialize(LegalitySettings settings) => Settings = settings;

    /// <summary>
    /// Checks to see if Crystal is available to visit/originate from.
    /// </summary>
    /// <param name="pk">Data being checked</param>
    /// <returns>True if Crystal data is allowed</returns>
    public static bool AllowGen2Crystal(PKM pk) => !pk.Korean;

    /// <summary>
    /// Checks to see if the Move Reminder (Relearner) is available.
    /// </summary>
    /// <remarks> Pokémon Stadium 2 was never released in Korea.</remarks>
    /// <param name="pk">Data being checked</param>
    /// <returns>True if Crystal data is allowed</returns>
    public static bool AllowGen2MoveReminder(PKM pk) => !pk.Korean && AllowGBStadium2;

    public static bool AllowGen2OddEgg(PKM pk) => !pk.Japanese || AllowEraCartGB;

    public static bool AllowGBVirtualConsole3DS => !AllowEraCartGB;
    public static bool AllowGBEraEvents => AllowEraCartGB;
    public static bool AllowGBStadium2 => AllowEraCartGB;

    // This logic will likely need to change (format check): TODO HOME FR/LG
    public static bool AllowGBACrossTransferXD(PKM pk) => AllowEraCartGBA;
    public static bool AllowGBACrossTransferRSE(PKM pk) => AllowEraCartGBA;
    public static bool AllowGen3EventTicketsAll(PKM pk) => AllowEraSwitchGBA;

    /// <summary>
    /// Initializes certain settings
    /// </summary>
    /// <param name="sav">Newly loaded save file</param>
    /// <returns>Save file is Physical GB cartridge save file (not Virtual Console)</returns>
    public static void InitFromSaveFileData(SaveFile sav)
    {
        ActiveTrainer = sav;
        AllowEraCartGB = sav switch
        {
            SAV1 { IsVirtualConsole: true } => false,
            SAV2 { IsVirtualConsole: true } => false,
            { Generation: 1 or 2 } => true,
            _ => false,
        };
        var isVirtual3 = sav is SAV3 { IsVirtualConsole: true };
        AllowEraSwitchGBA = isVirtual3;
        AllowEraCartGBA = !isVirtual3; // sav.Generation >= 8; TODO HOME FR/LG
    }

    internal static bool IgnoreTransferIfNoTracker => Settings.HOMETransfer.HOMETransferTrackerNotPresent == Severity.Invalid;
}