using System;

namespace PKHeX.Core;

/// <summary>
/// Logic for interacting with Pokédex Form flags
/// </summary>
public static class DexFormUtil
{
    public static int GetDexFormIndexSM(ushort species, byte formCount, int start) => GetDexFormBitIndex(species, formCount, start, formtable_SM);
    public static int GetDexFormIndexUSUM(ushort species, byte formCount, int start) => GetDexFormBitIndex(species, formCount, start, formtable_USUM);
    public static int GetDexFormIndexGG(ushort species, byte formCount, int start) => GetDexFormBitIndex(species, formCount, start, formtable_GG);
    public static int GetDexFormCountSM(ushort species) => GetDexFormCount(species, formtable_SM);
    public static int GetDexFormCountUSUM(ushort species) => GetDexFormCount(species, formtable_USUM);
    public static int GetDexFormCountGG(ushort species) => GetDexFormCount(species, formtable_GG);

    private static ReadOnlySpan<ushort> formtable_SM => new ushort[] // u16 species, u16 formcount
    {
        0x0003, 0x0002, 0x0006, 0x0003, 0x0009, 0x0002, 0x000F, 0x0002,
        0x0012, 0x0002, 0x0013, 0x0002, 0x0014, 0x0003, 0x0019, 0x0007,
        0x001A, 0x0002, 0x001B, 0x0002, 0x001C, 0x0002, 0x0025, 0x0002,
        0x0026, 0x0002, 0x0032, 0x0002, 0x0033, 0x0002, 0x0034, 0x0002,
        0x0035, 0x0002, 0x0041, 0x0002, 0x004A, 0x0002, 0x004B, 0x0002,
        0x004C, 0x0002, 0x0050, 0x0002, 0x0058, 0x0002, 0x0059, 0x0002,
        0x005E, 0x0002, 0x0067, 0x0002, 0x0069, 0x0002, 0x0073, 0x0002,
        0x007F, 0x0002, 0x0082, 0x0002, 0x008E, 0x0002, 0x0096, 0x0003,
        0x00B5, 0x0002, 0x00C9, 0x001C, 0x00D0, 0x0002, 0x00D4, 0x0002,
        0x00D6, 0x0002, 0x00E5, 0x0002, 0x00F8, 0x0002, 0x00FE, 0x0002,
        0x0101, 0x0002, 0x0104, 0x0002, 0x011A, 0x0002, 0x012E, 0x0002,
        0x012F, 0x0002, 0x0132, 0x0002, 0x0134, 0x0002, 0x0136, 0x0002,
        0x013F, 0x0002, 0x0143, 0x0002, 0x014E, 0x0002, 0x015F, 0x0004,
        0x0162, 0x0002, 0x0167, 0x0002, 0x016A, 0x0002, 0x0175, 0x0002,
        0x0178, 0x0002, 0x017C, 0x0002, 0x017D, 0x0002, 0x017E, 0x0002,
        0x017F, 0x0002, 0x0180, 0x0002, 0x0182, 0x0004, 0x019C, 0x0003,
        0x019D, 0x0003, 0x01A5, 0x0002, 0x01A6, 0x0002, 0x01A7, 0x0002,
        0x01AC, 0x0002, 0x01BD, 0x0002, 0x01C0, 0x0002, 0x01CC, 0x0002,
        0x01DB, 0x0002, 0x01DF, 0x0006, 0x01E7, 0x0002, 0x01EC, 0x0002,
        0x01ED, 0x0012, 0x0213, 0x0002, 0x0226, 0x0002, 0x022B, 0x0002,
        0x0249, 0x0004, 0x024A, 0x0004, 0x0281, 0x0002, 0x0282, 0x0002,
        0x0285, 0x0002, 0x0286, 0x0003, 0x0287, 0x0002, 0x0288, 0x0002,
        0x0289, 0x0005, 0x0292, 0x0003, 0x029A, 0x0014, 0x029D, 0x0005,
        0x029E, 0x0006, 0x029F, 0x0005, 0x02A4, 0x000A, 0x02A6, 0x0002,
        0x02A9, 0x0002, 0x02C6, 0x0004, 0x02C7, 0x0004, 0x02CC, 0x0002,
        0x02CE, 0x0005, 0x02CF, 0x0002, 0x02D0, 0x0002, 0x02DF, 0x0002,
        0x02E2, 0x0002, 0x02E5, 0x0004, 0x02E9, 0x0002, 0x02EA, 0x0002,
        0x02F2, 0x0002, 0x02F6, 0x0002, 0x0305, 0x0012, 0x0306, 0x000E,
        0x030A, 0x0004, 0x0310, 0x0002, 0x0321, 0x0002,
    };

    private static ReadOnlySpan<ushort> formtable_USUM => new ushort[] // u16 species, u16 formcount
    {
        0x0003, 0x0002, 0x0006, 0x0003, 0x0009, 0x0002, 0x000F, 0x0002,
        0x0012, 0x0002, 0x0013, 0x0002, 0x0014, 0x0003, 0x0019, 0x0008,
        0x001A, 0x0002, 0x001B, 0x0002, 0x001C, 0x0002, 0x0025, 0x0002,
        0x0026, 0x0002, 0x0032, 0x0002, 0x0033, 0x0002, 0x0034, 0x0002,
        0x0035, 0x0002, 0x0041, 0x0002, 0x004A, 0x0002, 0x004B, 0x0002,
        0x004C, 0x0002, 0x0050, 0x0002, 0x0058, 0x0002, 0x0059, 0x0002,
        0x005E, 0x0002, 0x0067, 0x0002, 0x0069, 0x0003, 0x0073, 0x0002,
        0x007F, 0x0002, 0x0082, 0x0002, 0x008E, 0x0002, 0x0096, 0x0003,
        0x00B5, 0x0002, 0x00C9, 0x001C, 0x00D0, 0x0002, 0x00D4, 0x0002,
        0x00D6, 0x0002, 0x00E5, 0x0002, 0x00F8, 0x0002, 0x00FE, 0x0002,
        0x0101, 0x0002, 0x0104, 0x0002, 0x011A, 0x0002, 0x012E, 0x0002,
        0x012F, 0x0002, 0x0132, 0x0002, 0x0134, 0x0002, 0x0136, 0x0002,
        0x013F, 0x0002, 0x0143, 0x0002, 0x014E, 0x0002, 0x015F, 0x0004,
        0x0162, 0x0002, 0x0167, 0x0002, 0x016A, 0x0002, 0x0175, 0x0002,
        0x0178, 0x0002, 0x017C, 0x0002, 0x017D, 0x0002, 0x017E, 0x0002,
        0x017F, 0x0002, 0x0180, 0x0002, 0x0182, 0x0004, 0x019C, 0x0003,
        0x019D, 0x0003, 0x019E, 0x0003, 0x01A5, 0x0002, 0x01A6, 0x0002,
        0x01A7, 0x0002, 0x01AC, 0x0002, 0x01BD, 0x0002, 0x01C0, 0x0002,
        0x01CC, 0x0002, 0x01DB, 0x0002, 0x01DF, 0x0006, 0x01E7, 0x0002,
        0x01EC, 0x0002, 0x01ED, 0x0012, 0x0213, 0x0002, 0x0226, 0x0002,
        0x022B, 0x0002, 0x0249, 0x0004, 0x024A, 0x0004, 0x0281, 0x0002,
        0x0282, 0x0002, 0x0285, 0x0002, 0x0286, 0x0003, 0x0287, 0x0002,
        0x0288, 0x0002, 0x0289, 0x0005, 0x0292, 0x0003, 0x0298, 0x0014,
        0x0299, 0x0014, 0x029A, 0x0014, 0x029D, 0x0005, 0x029E, 0x0006,
        0x029F, 0x0005, 0x02A4, 0x000A, 0x02A6, 0x0002, 0x02A9, 0x0002,
        0x02C6, 0x0004, 0x02C7, 0x0004, 0x02CC, 0x0002, 0x02CE, 0x0005,
        0x02CF, 0x0002, 0x02D0, 0x0002, 0x02DF, 0x0002, 0x02E2, 0x0002,
        0x02E5, 0x0004, 0x02E7, 0x0002, 0x02E8, 0x0002, 0x02E9, 0x0003,
        0x02EA, 0x0002, 0x02F0, 0x0002, 0x02F2, 0x0002, 0x02F6, 0x0002,
        0x0305, 0x0012, 0x0306, 0x000E, 0x0309, 0x0002, 0x030A, 0x0004,
        0x0310, 0x0002, 0x0320, 0x0004, 0x0321, 0x0002,
    };

    private static ReadOnlySpan<ushort> formtable_GG => new ushort[] // u16 species, u16 formcount
    {
        0x0003, 0x0002, 0x0006, 0x0003, 0x0009, 0x0002, 0x000F, 0x0002,
        0x0012, 0x0002, 0x0013, 0x0002, 0x0014, 0x0003, 0x0019, 0x0009,
        0x001A, 0x0002, 0x001B, 0x0002, 0x001C, 0x0002, 0x0025, 0x0002,
        0x0026, 0x0002, 0x0032, 0x0002, 0x0033, 0x0002, 0x0034, 0x0002,
        0x0035, 0x0002, 0x0041, 0x0002, 0x004A, 0x0002, 0x004B, 0x0002,
        0x004C, 0x0002, 0x0050, 0x0002, 0x0058, 0x0002, 0x0059, 0x0002,
        0x005E, 0x0002, 0x0067, 0x0002, 0x0069, 0x0003, 0x0073, 0x0002,
        0x007F, 0x0002, 0x0082, 0x0002, 0x008E, 0x0002, 0x0096, 0x0003,
    };

    private static int GetDexFormBitIndex(ushort species, byte formCount, int start, ReadOnlySpan<ushort> formTable)
    {
        int formIndex = start;
        for (int i = 0; i < formTable.Length; i += 2)
        {
            int s = formTable[i];
            int f = formTable[i + 1];
            if (s == species)
                return f > formCount ? -1 : formIndex;

            formIndex += f - 1;
        }
        return -1;
    }

    private static int GetDexFormCount(ushort species, ReadOnlySpan<ushort> formTable)
    {
        for (int i = 0; i < formTable.Length; i += 2)
        {
            if (formTable[i] == species)
                return formTable[i + 1];
        }
        return 0;
    }

    public static int GetDexFormIndexBW(ushort species, byte formCount)
    {
        if (formCount < 1 || species > Legal.MaxSpeciesID_5)
            return -1; // invalid
        return species switch
        {
            201 => 000, // 28 Unown
            386 => 028, // 4 Deoxys
            492 => 032, // 2 Shaymin
            487 => 034, // 2 Giratina
            479 => 036, // 6 Rotom
            422 => 042, // 2 Shellos
            423 => 044, // 2 Gastrodon
            412 => 046, // 3 Burmy
            413 => 049, // 3 Wormadam
            351 => 052, // 4 Castform
            421 => 056, // 2 Cherrim
            585 => 058, // 4 Deerling
            586 => 062, // 4 Sawsbuck
            648 => 066, // 2 Meloetta
            555 => 068, // 2 Darmanitan
            550 => 070, // 2 Basculin
            _ => -1,
        };
    }

    public static int GetDexFormIndexB2W2(ushort species, byte formCount)
    {
        if (formCount < 1 || species > Legal.MaxSpeciesID_5)
            return -1; // invalid
        return species switch
        {
            646 => 072, // 3 Kyurem
            647 => 075, // 2 Keldeo
            642 => 077, // 2 Thundurus
            641 => 079, // 2 Tornadus
            645 => 081, // 2 Landorus
            _ => GetDexFormIndexBW(species, formCount),
        };
    }

    public static int GetDexFormIndexXY(ushort species, byte formCount)
    {
        if (formCount < 1 || species > Legal.MaxSpeciesID_6)
            return -1; // invalid
        return species switch
        {
            666 => 083, // 20 Vivillion
            669 => 103, // 5 Flabébé
            670 => 108, // 6 Floette
            671 => 114, // 5 Florges
            710 => 119, // 4 Pumpkaboo
            711 => 123, // 4 Gourgeist
            681 => 127, // 2 Aegislash
            716 => 129, // 2 Xerneas
            003 => 131, // 2 Venusaur
            006 => 133, // 3 Charizard
            009 => 136, // 2 Blastoise
            065 => 138, // 2 Alakazam
            094 => 140, // 2 Gengar
            115 => 142, // 2 Kangaskhan
            127 => 144, // 2 Pinsir
            130 => 146, // 2 Gyarados
            142 => 148, // 2 Aerodactyl
            150 => 150, // 3 Mewtwo
            181 => 153, // 2 Ampharos
            212 => 155, // 2 Scizor
            214 => 157, // 2 Heracros
            229 => 159, // 2 Houndoom
            248 => 161, // 2 Tyranitar
            257 => 163, // 2 Blaziken
            282 => 165, // 2 Gardevoir
            303 => 167, // 2 Mawile
            306 => 169, // 2 Aggron
            308 => 171, // 2 Medicham
            310 => 173, // 2 Manetric
            354 => 175, // 2 Banette
            359 => 177, // 2 Absol
            380 => 179, // 2 Latias
            381 => 181, // 2 Latios
            445 => 183, // 2 Garchomp
            448 => 185, // 2 Lucario
            460 => 187, // 2 Abomasnow
            _ => GetDexFormIndexB2W2(species, formCount),
        };
    }

    public static int GetDexFormIndexORAS(ushort species, byte formCount)
    {
        if (formCount < 1 || species > Legal.MaxSpeciesID_6)
            return -1; // invalid
        return species switch
        {
            025 => 189, // 7 Pikachu
            720 => 196, // 2 Hoopa
            015 => 198, // 2 Beedrill
            018 => 200, // 2 Pidgeot
            080 => 202, // 2 Slowbro
            208 => 204, // 2 Steelix
            254 => 206, // 2 Sceptile
            260 => 208, // 2 Swampert
            302 => 210, // 2 Sableye
            319 => 212, // 2 Sharpedo
            323 => 214, // 2 Camerupt
            334 => 216, // 2 Altaria
            362 => 218, // 2 Glalie
            373 => 220, // 2 Salamence
            376 => 222, // 2 Metagross
            384 => 224, // 2 Rayquaza
            428 => 226, // 2 Lopunny
            475 => 228, // 2 Gallade
            531 => 230, // 2 Audino
            719 => 232, // 2 Diancie
            382 => 234, // 2 Kyogre
            383 => 236, // 2 Groudon
            493 => 238, // 18 Arceus
            649 => 256, // 5 Genesect
            676 => 261, // 10 Furfrou
            _ => GetDexFormIndexXY(species, formCount),
        };
    }
}