using System.Collections.Generic;
using System.IO;
using System.Linq;

using static PKHeX.Core.MessageStrings;

namespace PKHeX.Core;

/// <summary>
/// Utility logic for dealing with <see cref="MysteryGift"/> objects.
/// </summary>
public static class MysteryUtil
{
    /// <summary>
    /// Gets <see cref="MysteryGift"/> objects from a folder.
    /// </summary>
    /// <param name="folder">Folder path</param>
    /// <returns>Consumable list of gifts.</returns>
    public static IEnumerable<MysteryGift> GetGiftsFromFolder(string folder)
    {
        foreach (var file in Directory.EnumerateFiles(folder, "*", SearchOption.AllDirectories))
        {
            var fi = new FileInfo(file);
            if (!MysteryGift.IsMysteryGift(fi.Length))
                continue;

            var gift = MysteryGift.GetMysteryGift(File.ReadAllBytes(file), fi.Extension);
            if (gift != null)
                yield return gift;
        }
    }

    /// <summary>
    /// Gets a description of the <see cref="MysteryGift"/> using the current default string data.
    /// </summary>
    /// <param name="gift">Gift data to parse</param>
    /// <returns>List of lines</returns>
    public static IEnumerable<string> GetDescription(this MysteryGift gift) => gift.GetDescription(GameInfo.Strings);

    /// <summary>
    /// Gets a description of the <see cref="MysteryGift"/> using provided string data.
    /// </summary>
    /// <param name="gift">Gift data to parse</param>
    /// <param name="strings">String data to use</param>
    /// <returns>List of lines</returns>
    public static IEnumerable<string> GetDescription(this MysteryGift gift, IBasicStrings strings)
    {
        if (gift.Empty)
            return new[] { MsgMysteryGiftSlotEmpty };

        var result = new List<string> { gift.CardHeader };
        if (gift.IsItem)
        {
            AddLinesItem(gift, strings, result);
        }
        else if (gift.IsEntity)
        {
            try
            {
                AddLinesPKM(gift, strings, result);
            }
            catch { result.Add(MsgMysteryGiftParseFail); }
        }
        else
        {
            switch (gift)
            {
                case WC7 { IsBP: true } w7bp:
                    result.Add($"BP: {w7bp.BP}");
                    break;
                case WC7 { IsBean: true } w7bean:
                    result.Add($"Bean ID: {w7bean.Bean}");
                    result.Add($"Quantity: {w7bean.Quantity}");
                    break;
                default:
                    result.Add(MsgMysteryGiftParseTypeUnknown);
                    break;
            }
        }

        switch (gift)
        {
            case WC7 w7:
                result.Add($"Repeatable: {w7.GiftRepeatable}");
                result.Add($"Collected: {w7.GiftUsed}");
                result.Add($"Once Per Day: {w7.GiftOncePerDay}");
                break;
        }
        return result;
    }

    private static void AddLinesItem(MysteryGift gift, IBasicStrings strings, ICollection<string> result)
    {
        result.Add($"Item: {strings.Item[gift.ItemID]} (Quantity: {gift.Quantity})");
        if (gift is not WC7 wc7)
            return;

        for (var ind = 1; wc7.GetItem(ind) != 0; ind++)
        {
            result.Add($"Item: {strings.Item[wc7.GetItem(ind)]} (Quantity: {wc7.GetQuantity(ind)})");
        }
    }

    private static void AddLinesPKM(MysteryGift gift, IBasicStrings strings, ICollection<string> result)
    {
        var id = gift.Generation < 7 ? $"{gift.TID:D5}/{gift.SID:D5}" : $"[{gift.TrainerSID7:D4}]{gift.TrainerID7:D6}";

        var first =
            $"{strings.Species[gift.Species]} @ {strings.Item[gift.HeldItem >= 0 ? gift.HeldItem : 0]}  --- "
            + (gift.IsEgg ? strings.EggName : $"{gift.OT_Name} - {id}");
        result.Add(first);
        result.Add(string.Join(" / ", gift.Moves.Select(z => strings.Move[z])));

        if (gift is WC7 wc7)
        {
            var addItem = wc7.AdditionalItem;
            if (addItem != 0)
                result.Add($"+ {strings.Item[addItem]}");
        }
    }

    /// <summary>
    /// Checks if the <see cref="MysteryGift"/> data is compatible with the <see cref="SaveFile"/>. Sets appropriate data to the save file in order to receive the gift.
    /// </summary>
    /// <param name="g">Gift data to potentially insert to the save file.</param>
    /// <param name="sav">Save file receiving the gift data.</param>
    /// <param name="message">Error message if incompatible.</param>
    /// <returns>True if compatible, false if incompatible.</returns>
    public static bool IsCardCompatible(this MysteryGift g, SaveFile sav, out string message)
    {
        if (g.Generation != sav.Generation)
        {
            message = MsgMysteryGiftSlotSpecialReject;
            return false;
        }

        if (!sav.CanReceiveGift(g))
        {
            message = MsgMysteryGiftTypeDetails;
            return false;
        }

        if (g is WC6 && g.CardID == 2048 && g.ItemID == 726) // Eon Ticket (OR/AS)
        {
            if (sav is not SAV6AO)
            {
                message = MsgMysteryGiftSlotSpecialReject;
                return false;
            }
        }

        message = string.Empty;
        return true;
    }

    /// <summary>
    /// Checks if the gift values are receivable by the game.
    /// </summary>
    /// <param name="sav">Save file receiving the gift data.</param>
    /// <param name="gift">Gift data to potentially insert to the save file.</param>
    /// <returns>True if compatible, false if incompatible.</returns>
    public static bool CanReceiveGift(this SaveFile sav, MysteryGift gift)
    {
        if (gift.Species > sav.MaxSpeciesID)
            return false;
        if (gift.Moves.Any(move => move > sav.MaxMoveID))
            return false;
        if (gift.HeldItem > sav.MaxItemID)
            return false;
        return true;
    }
}