using System;
using System.Collections.Generic;
using System.Linq;
using static PKHeX.Core.GameVersion;

namespace PKHeX.Core;

/// <summary>
/// Utility class for <see cref="GameVersion"/> logic.
/// </summary>
public static class GameUtil
{
    /// <summary>
    /// All possible <see cref="GameVersion"/> values a <see cref="PKM.Version"/> can have.
    /// </summary>
    /// <remarks>Ordered roughly by most recent games first.</remarks>
    public static readonly GameVersion[] GameVersions = GetValidGameVersions();

    private static GameVersion[] GetValidGameVersions()
    {
        var all = (GameVersion[])Enum.GetValues(typeof(GameVersion));
        var valid = Array.FindAll(all, IsValidSavedVersion);
        Array.Reverse(valid);
        return valid;
    }

    /// <summary>
    /// Indicates if the <see cref="GameVersion"/> value is a value used by the games or is an aggregate indicator.
    /// </summary>
    /// <param name="game">Game to check</param>
    public static bool IsValidSavedVersion(this GameVersion game) => game is > 0 and <= HighestGameID;

    /// <summary>
    /// Most recent game ID utilized by official games.
    /// </summary>
    internal const GameVersion HighestGameID = RB - 1;

    /// <summary>Determines the Version Grouping of an input Version ID</summary>
    /// <param name="version">Version of which to determine the group</param>
    /// <returns>Version Group Identifier or Invalid if type cannot be determined.</returns>
    public static GameVersion GetMetLocationVersionGroup(GameVersion version) => version switch
    {
        // Side games
        CXD => CXD,
        GO => GO,

        // VC Transfers
        RD or BU or YW or GN or GD or SI or C => USUM,

        // Gen2 -- PK2
        GS or GSC => GSC,

        // Gen3
        R or S => RS,
        E => E,
        FR or LG => FR,

        // Gen4
        D or P => DP,
        Pt => Pt,
        HG or SS => HGSS,

        // Gen5
        B or W => BW,
        B2 or W2 => B2W2,

        // Gen6
        X or Y => XY,
        OR or AS => ORAS,

        // Gen7
        SN or MN => SM,
        US or UM => USUM,
        GP or GE => GG,

        // Gen8
        SW or SH => SWSH,
        BD or SP => BDSP,
        PLA => PLA,

        // Gen9
        SL or VL => SV,
        _ => Invalid,
    };

    /// <summary>
    /// Gets a Version ID from the end of that Generation
    /// </summary>
    /// <param name="generation">Generation ID</param>
    /// <returns>Version ID from requested generation. If none, return <see cref="Invalid"/>.</returns>
    public static GameVersion GetVersion(int generation) => generation switch
    {
        1 => RBY,
        2 => C,
        3 => E,
        4 => SS,
        5 => W2,
        6 => AS,
        7 => UM,
        8 => SH,
        9 => VL,
        _ => Invalid,
    };

    /// <summary>
    /// Gets the Generation the <see cref="GameVersion"/> belongs to.
    /// </summary>
    /// <param name="game">Game to retrieve the generation for</param>
    /// <returns>Generation ID</returns>
    public static int GetGeneration(this GameVersion game)
    {
        if (Gen1.Contains(game)) return 1;
        if (Gen2.Contains(game)) return 2;
        if (Gen3.Contains(game)) return 3;
        if (Gen4.Contains(game)) return 4;
        if (Gen5.Contains(game)) return 5;
        if (Gen6.Contains(game)) return 6;
        if (Gen7.Contains(game)) return 7;
        if (Gen7b.Contains(game)) return 7;
        if (Gen8.Contains(game)) return 8;
        if (Gen9.Contains(game)) return 9;
        return -1;
    }

    /// <summary>
    /// Gets the Generation the <see cref="GameVersion"/> belongs to.
    /// </summary>
    /// <param name="game">Game to retrieve the generation for</param>
    /// <returns>Generation ID</returns>
    public static ushort GetMaxSpeciesID(this GameVersion game)
    {
        if (Gen1.Contains(game)) return Legal.MaxSpeciesID_1;
        if (Gen2.Contains(game)) return Legal.MaxSpeciesID_2;
        if (Gen3.Contains(game)) return Legal.MaxSpeciesID_3;
        if (Gen4.Contains(game)) return Legal.MaxSpeciesID_4;
        if (Gen5.Contains(game)) return Legal.MaxSpeciesID_5;
        if (Gen6.Contains(game)) return Legal.MaxSpeciesID_6;
        if (Gen7b.Contains(game)) return Legal.MaxSpeciesID_7b;
        if (Gen7.Contains(game))
        {
            if (SM.Contains(game))
                return Legal.MaxSpeciesID_7;
            if (USUM.Contains(game))
                return Legal.MaxSpeciesID_7_USUM;
            return Legal.MaxSpeciesID_7_USUM;
        }
        if (PLA == game) return Legal.MaxSpeciesID_8a;
        if (BDSP.Contains(game)) return Legal.MaxSpeciesID_8b;
        if (Gen8.Contains(game)) return Legal.MaxSpeciesID_8;
        if (Gen9.Contains(game)) return Legal.MaxSpeciesID_9;
        return 0;
    }

    /// <summary>
    /// Checks if the <see cref="g1"/> version (or subset versions) is equivalent to <see cref="g2"/>.
    /// </summary>
    /// <param name="g1">Version (set)</param>
    /// <param name="g2">Individual version</param>
    public static bool Contains(this GameVersion g1, int g2) => g1.Contains((GameVersion) g2);

    /// <summary>
    /// Checks if the <see cref="g1"/> version (or subset versions) is equivalent to <see cref="g2"/>.
    /// </summary>
    /// <param name="g1">Version (set)</param>
    /// <param name="g2">Individual version</param>
    public static bool Contains(this GameVersion g1, GameVersion g2)
    {
        if (g1 == g2 || g1 == Any)
            return true;

        return g1 switch
        {
            RB => g2 is RD or BU or GN,
            RBY or Stadium => RB.Contains(g2) || g2 == YW,
            Gen1 => RBY.Contains(g2) || g2 == Stadium,

            GS => g2 is GD or SI,
            GSC or Stadium2 => GS.Contains(g2) || g2 == C,
            Gen2 => GSC.Contains(g2) || g2 == Stadium2,

            RS => g2 is R or S,
            RSE => RS.Contains(g2) || g2 == E,
            FRLG => g2 is FR or LG,
            COLO or XD => g2 == CXD,
            CXD => g2 is COLO or XD,
            RSBOX => RS.Contains(g2) || g2 == E || FRLG.Contains(g2),
            Gen3 => RSE.Contains(g2) || FRLG.Contains(g2) || CXD.Contains(g2) || g2 == RSBOX,

            DP => g2 is D or P,
            HGSS => g2 is HG or SS,
            DPPt => DP.Contains(g2) || g2 == Pt,
            BATREV => DP.Contains(g2) || g2 == Pt || HGSS.Contains(g2),
            Gen4 => DPPt.Contains(g2) || HGSS.Contains(g2) || g2 == BATREV,

            BW => g2 is B or W,
            B2W2 => g2 is B2 or W2,
            Gen5 => BW.Contains(g2) || B2W2.Contains(g2),

            XY => g2 is X or Y,
            ORAS => g2 is OR or AS,

            Gen6 => XY.Contains(g2) || ORAS.Contains(g2),
            SM => g2 is SN or MN,
            USUM => g2 is US or UM,
            GG => g2 is GP or GE,
            Gen7 => SM.Contains(g2) || USUM.Contains(g2),
            Gen7b => GG.Contains(g2) || GO == g2,

            SWSH => g2 is SW or SH,
            BDSP => g2 is BD or SP,
            Gen8 => SWSH.Contains(g2) || BDSP.Contains(g2) || PLA == g2,

            SV => g2 is SL or VL,
            Gen9 => SV.Contains(g2),
            _ => false,
        };
    }

    /// <summary>
    /// List of possible <see cref="GameVersion"/> values within the provided <see cref="generation"/>.
    /// </summary>
    /// <param name="generation">Generation to look within</param>
    /// <param name="pkVersion"></param>
    public static GameVersion[] GetVersionsInGeneration(int generation, int pkVersion)
    {
        if (Gen7b.Contains(pkVersion))
            return new[] {GO, GP, GE};
        return Array.FindAll(GameVersions, z => z.GetGeneration() == generation);
    }

    /// <summary>
    /// List of possible <see cref="GameVersion"/> values within the provided <see cref="IGameValueLimit"/> criteria.
    /// </summary>
    /// <param name="obj">Criteria for retrieving versions</param>
    /// <param name="generation">Generation format minimum (necessary for the CXD/Gen4 swap etc)</param>
    public static IEnumerable<GameVersion> GetVersionsWithinRange(IGameValueLimit obj, int generation = -1)
    {
        var max = obj.MaxGameID;
        if (max == Legal.MaxGameID_7b) // edge case
            return new[] {GO, GP, GE};
        if (max == Legal.MaxGameID_8)
            max = Legal.MaxGameID_8a;
        var versions = GameVersions
            .Where(version => (GameVersion)obj.MinGameID <= version && version <= (GameVersion)max);
        if (generation < 0)
            return versions;
        if (max == Legal.MaxGameID_7 && generation == 7)
            versions = versions.Where(version => version != GO);
        return versions.Where(version => version.GetGeneration() <= generation);
    }
}