using System;
using System.Collections.Generic;

namespace PKHeX.Core;

/// <summary>
/// Bundles raw string inputs into lists that can be used in data binding.
/// </summary>
public sealed class GameDataSource
{
    /// <summary>
    /// List of <see cref="Region3DSIndex"/> values to display.
    /// </summary>
    public readonly IReadOnlyList<ComboItem> Regions;

    /// <summary>
    /// List of <see cref="LanguageID"/> values to display.
    /// </summary>
    private readonly ComboItem[] LanguageList;

    private static ReadOnlySpan<byte> LanguageIDs =>
    [
        (byte)LanguageID.Japanese,
        (byte)LanguageID.English,
        (byte)LanguageID.French,
        (byte)LanguageID.Italian,
        (byte)LanguageID.German,
        (byte)LanguageID.Spanish,
        (byte)LanguageID.Korean,
        (byte)LanguageID.ChineseS,
        (byte)LanguageID.ChineseT,
        (byte)LanguageID.SpanishL,
    ];

    /// <summary>
    /// Gets a list of languages to display based on the generation.
    /// </summary>
    /// <param name="generation">Generation to get the language list for.</param>
    /// <param name="context">Entity context as a sub-generation specifier.</param>
    /// <returns>List of languages to display.</returns>
    public IReadOnlyList<ComboItem> LanguageDataSource(byte generation, EntityContext context) => generation switch
    {
          3 => LanguageList[..6], // No Korean+
        < 7 => LanguageList[..7], // No Chinese+
        _ when context is EntityContext.Gen9a => [.. LanguageList],
        _ => [.. LanguageList.AsSpan(0, LanguageList.Length - 1)],
    };

    public GameDataSource(GameStrings s)
    {
        Strings = s;
        BallDataSource = GetBalls(s.itemlist);
        SpeciesDataSource = Util.GetCBList(s.specieslist);
        NatureDataSource = Util.GetCBList(s.natures);
        AbilityDataSource = Util.GetCBList(s.abilitylist);
        GroundTileDataSource = Util.GetUnsortedCBList(s.groundtiletypes, GroundTileTypeExtensions.ValidTileTypes);
        Regions = Util.GetUnsortedCBList(s.console3ds, Locale3DS.DefinedLocales);
        LanguageList = Util.GetUnsortedCBList(s.languageNames, LanguageIDs);

        var moves = Util.GetCBList(s.movelist);
        HaXMoveDataSource = moves;
        var legal = new List<ComboItem>(moves.Count);
        foreach (var m in moves)
        {
            if (MoveInfo.IsMoveKnowable((ushort)m.Value))
                legal.Add(m);
        }
        LegalMoveDataSource = legal;

        var games = GetVersionList(s);
        VersionDataSource = games;

        Met = new MetDataSource(s);

        Empty = new ComboItem(s.itemlist[0], 0);
        games[^1] = Empty;
    }

    /// <summary> Strings that this object's lists were generated with. </summary>
    public readonly GameStrings Strings;

    /// <summary> Contains Met Data lists to source lists from. </summary>
    public readonly MetDataSource Met;

    /// <summary> Represents "(None)", localized to this object's language strings. </summary>
    public readonly ComboItem Empty;

    public readonly IReadOnlyList<ComboItem> SpeciesDataSource;
    public readonly IReadOnlyList<ComboItem> BallDataSource;
    public readonly IReadOnlyList<ComboItem> NatureDataSource;
    public readonly IReadOnlyList<ComboItem> AbilityDataSource;
    public readonly IReadOnlyList<ComboItem> VersionDataSource;
    public readonly IReadOnlyList<ComboItem> LegalMoveDataSource;
    public readonly IReadOnlyList<ComboItem> HaXMoveDataSource;
    public readonly IReadOnlyList<ComboItem> GroundTileDataSource;

    /// <summary>
    /// Preferentially ordered list of <see cref="GameVersion"/> values to display in a list.
    /// </summary>
    /// <remarks>Most recent games are at the top, loosely following Generation groups.</remarks>
    private static ReadOnlySpan<byte> OrderedVersionArray =>
    [
        52,     // 9 Z-A
        50, 51, // 9 S/V
        47,     // 8 PLA
        48, 49, // 8 BD/SP
        44, 45, // 8 SW/SH
        42, 43, // 7 LGP/E
        30, 31, // 7 S/M
        32, 33, // 7 US/UM
        24, 25, // 6 X/Y
        27, 26, // 6 OR/AS
        21, 20, // 5 B/W
        23, 22, // 5 B2/W2
        10, 11, 12, 16, // 4 D/P/Pt/PBR
        07, 08, // 4 HG/SS
        02, 01, 03, // 3 R/S/E
        04, 05, // 3 FR/LG
        15,     // 3 Colosseum & XD

        39, 40, 41, // 7vc2 (Gen2 VC)
        35, 36, 37, 38, // 7vc1 (Gen1 VC)
        34, // 7go

        00,
    ];

    private static ComboItem[] GetBalls(ReadOnlySpan<string> itemList) => Util.GetVariedCBListBall(itemList, BallStoredIndexes, BallItemIDs);

    // Since Poké Ball (and Great Ball / Ultra Ball) are most common, any list should have them at the top. The rest can be sorted alphabetically.
    private static ReadOnlySpan<byte> BallStoredIndexes => [ 004, 003, 002, 001, 005, 006, 007, 008, 009, 010, 011, 012, 013, 014, 015, 016, 017, 018, 019, 020, 021, 022, 023, 024, 025, 026, 0027, 0028, 0029, 0030, 0031, 0032, 0033, 0034, 0035, 0036, 0037 ];
    private static ReadOnlySpan<ushort> BallItemIDs     => [ 004, 003, 002, 001, 005, 006, 007, 008, 009, 010, 011, 012, 013, 014, 015, 016, 492, 493, 494, 495, 496, 497, 498, 499, 576, 851, 1785, 1710, 1711, 1712, 1713, 1746, 1747, 1748, 1749, 1750, 1771 ];

    private static ComboItem[] GetVersionList(GameStrings s)
    {
        var list = s.gamelist;
        return Util.GetUnsortedCBList(list, OrderedVersionArray);
    }

    public List<ComboItem> GetItemDataSource(GameVersion version, EntityContext context, ReadOnlySpan<ushort> allowed, bool HaX = false)
    {
        var items = Strings.GetItemStrings(context, version);
        return HaX ? Util.GetCBList(items) : Util.GetCBList(items, allowed);
    }
}