using System;
using static PKHeX.Core.Species;

namespace PKHeX.Core;

/// <summary>
/// Alternate form data has an associated value.
/// </summary>
/// <remarks>
/// <see cref="Furfrou"/> How long (days) the form can last before reverting to Form-0 (5 days max)
/// <see cref="Hoopa"/>: How long (days) the form can last before reverting to Form-0 (3 days max)
/// <see cref="Alcremie"/>: Topping (Strawberry, Star, etc); [0,7]
/// <see cref="Yamask"/> How much damage the Pokémon has taken as Yamask-1 [0,9999].
/// <see cref="Runerigus"/> How much damage the Pokémon has taken as Yamask-1 [0,9999].
/// <see cref="Stantler"/> How many times the Pokémon has used Psyshield Bash in the Agile Style [0,9999].
/// <see cref="Qwilfish"/> How many times the Pokémon has used Barb Barrage in the Strong Style as Qwilfish-1 [0,9999].
/// <see cref="Basculin"/> How much damage the Pokémon has taken through recoil as Basculin-2 [0,9999].
/// </remarks>
public interface IFormArgument
{
    /// <summary>
    /// Argument for the associated <see cref="PKM.Form"/>
    /// </summary>
    uint FormArgument { get; set; }

    /// <summary>
    /// Amount of days the timed <see cref="PKM.Form"/> will remain active for.
    /// </summary>
    byte FormArgumentRemain { get; set; }

    /// <summary>
    /// Amount of days the timed <see cref="PKM.Form"/> has been active for.
    /// </summary>
    byte FormArgumentElapsed { get; set; }

    /// <summary>
    /// Maximum amount of days the <see cref="Species.Furfrou"/> has maintained a <see cref="PKM.Form"/> without reverting to its base form.
    /// </summary>
    byte FormArgumentMaximum { get; set; }
}

/// <summary>
/// Logic for mutating an <see cref="IFormArgument"/> object.
/// </summary>
public static class FormArgumentUtil
{
    /// <summary>
    /// Sets the suggested Form Argument to the <see cref="pk"/>.
    /// </summary>
    public static void SetSuggestedFormArgument(this PKM pk, int originalSpecies = 0)
    {
        if (pk is not IFormArgument)
            return;
        if (!IsFormArgumentTypeDatePair(pk.Species, pk.Form))
        {
            uint suggest = originalSpecies switch
            {
                (int) Yamask when pk.Species == (int) Runerigus => 49u,
                (int) Qwilfish when pk.Species == (int) Overqwil => 20u,
                (int) Stantler when pk.Species == (int) Wyrdeer => 20u,
                (int) Basculin when pk.Species == (int) Basculegion => 294u,
                _ => 0u,
            };
            pk.ChangeFormArgument(suggest);
            return;
        }
        var max = GetFormArgumentMax(pk.Species, pk.Form, pk.Format);
        pk.ChangeFormArgument(max);
    }

    /// <summary>
    /// Modifies the <see cref="IFormArgument"/> values for the provided <see cref="pk"/> to the requested <see cref="value"/>.
    /// </summary>
    public static void ChangeFormArgument(this PKM pk, uint value)
    {
        if (pk is not IFormArgument f)
            return;
        f.ChangeFormArgument(pk.Species, pk.Form, pk.Format, value);
    }

    /// <summary>
    /// Modifies the <see cref="IFormArgument"/> values for the provided inputs to the requested <see cref="value"/>.
    /// </summary>
    /// <param name="f">Form Argument object</param>
    /// <param name="species">Entity Species</param>
    /// <param name="form">Entity Species</param>
    /// <param name="generation">Entity current format generation</param>
    /// <param name="value">Value to apply</param>
    public static void ChangeFormArgument(this IFormArgument f, int species, int form, int generation, uint value)
    {
        if (!IsFormArgumentTypeDatePair(species, form))
        {
            f.FormArgument = value;
            return;
        }

        var max = GetFormArgumentMax(species, form, generation);
        f.FormArgumentRemain = (byte)value;
        if (value == max)
        {
            f.FormArgumentElapsed = f.FormArgumentMaximum = 0;
            return;
        }

        byte elapsed = max < value ? (byte)0 : (byte)(max - value);
        f.FormArgumentElapsed = elapsed;
        if (species == (int)Furfrou)
            f.FormArgumentMaximum = Math.Max(f.FormArgumentMaximum, elapsed);
    }

    public static uint GetFormArgumentMax(int species, int form, int generation)
    {
        if (generation <= 5)
            return 0;

        return species switch
        {
            (int)Furfrou when form != 0 => 5,
            (int)Hoopa when form == 1 => 3,
            (int)Yamask when form == 1 => 9999,
            (int)Runerigus when form == 0 => 9999,
            (int)Alcremie => (uint)AlcremieDecoration.Ribbon,
            (int)Qwilfish when form == 1 && generation == 8 => 9999, // 20
            (int)Overqwil => 9999, // 20
            (int)Stantler or (int)Wyrdeer when generation == 8 => 9999, // 20
            (int)Basculin when form == 2 => 9999, // 294
            (int)Basculegion => 9999, // 294
            _ => 0,
        };
    }

    public static bool IsFormArgumentTypeDatePair(int species, int form) => species switch
    {
        (int)Furfrou when form != 0 => true,
        (int)Hoopa when form == 1 => true,
        _ => false,
    };
}