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

using static PKHeX.Core.MessageStrings;

namespace PKHeX.Core
{
    public static class SaveExtensions
    {
        /// <summary>
        /// Checks if the <see cref="PKM"/> is compatible with the input <see cref="SaveFile"/>, and makes any necessary modifications to force compatibility.
        /// </summary>
        /// <remarks>Should only be used when forcing a backwards conversion to sanitize the PKM fields to the target format.
        /// If the PKM is compatible, some properties may be forced to sanitized values.</remarks>
        /// <param name="SAV">Save File target that the PKM will be injected.</param>
        /// <param name="pk">PKM input that is to be injected into the Save File.</param>
        /// <returns>Indication whether or not the PKM is compatible.</returns>
        public static bool IsPKMCompatibleWithModifications(this SaveFile SAV, PKM pk) => PKMConverter.IsPKMCompatibleWithModifications(pk, SAV);

        /// <summary>
        /// Sets the details of a path to a <see cref="SaveFile"/> object.
        /// </summary>
        /// <param name="sav">Save File to set path details to.</param>
        /// <param name="path">Full Path of the file</param>
        public static void SetFileInfo(this SaveFile sav, string path)
        {
            if (!sav.Exportable) // Blank save file
            {
                sav.FileFolder = sav.FilePath = null;
                sav.FileName = "Blank Save File";
                return;
            }

            sav.FilePath = path;
            sav.FileFolder = Path.GetDirectoryName(path);
            sav.FileName = Path.GetFileName(path);
            if (!sav.FileName.EndsWith(".bak"))
                return;

            // trim off any bak details to get original file name
            int index = sav.FileName.LastIndexOf(" [", StringComparison.Ordinal);
            if (index < 0)
                return;
            sav.FileName = sav.FileName.Substring(0, index);
        }

        /// <summary>
        /// Checks a <see cref="PKM"/> file for compatibility to the <see cref="SaveFile"/>.
        /// </summary>
        /// <param name="SAV"><see cref="SaveFile"/> that is being checked.</param>
        /// <param name="pkm"><see cref="PKM"/> that is being tested for compatibility.</param>
        /// <returns></returns>
        public static IReadOnlyList<string> IsPKMCompatible(this SaveFile SAV, PKM pkm)
        {
            IBasicStrings strings = GameInfo.Strings;
            return SAV.GetSaveFileErrata(pkm, strings);
        }

        private static IReadOnlyList<string> GetSaveFileErrata(this SaveFile SAV, PKM pkm, IBasicStrings strings)
        {
            var errata = new List<string>();
            if (SAV.Generation > 1)
            {
                ushort held = (ushort)pkm.HeldItem;

                if (held > strings.Item.Count)
                    errata.Add($"{MsgIndexItemRange} {held}");
                else if (held > SAV.MaxItemID)
                    errata.Add($"{MsgIndexItemGame} {strings.Item[held]}");
                else if (!pkm.CanHoldItem(SAV.HeldItems))
                    errata.Add($"{MsgIndexItemHeld} {strings.Item[held]}");
            }

            if (pkm.Species > strings.Species.Count)
                errata.Add($"{MsgIndexSpeciesRange} {pkm.Species}");
            else if (SAV.MaxSpeciesID < pkm.Species)
                errata.Add($"{MsgIndexSpeciesGame} {strings.Species[pkm.Species]}");

            if (!SAV.Personal[pkm.Species].IsFormeWithinRange(pkm.AltForm) && !FormConverter.IsValidOutOfBoundsForme(pkm.Species, pkm.AltForm, pkm.GenNumber))
                errata.Add(string.Format(LegalityCheckStrings.V304, Math.Max(0, SAV.Personal[pkm.Species].FormeCount - 1), pkm.AltForm));

            if (pkm.Moves.Any(m => m > strings.Move.Count))
                errata.Add($"{MsgIndexMoveRange} {string.Join(", ", pkm.Moves.Where(m => m > strings.Move.Count).Select(m => m.ToString()))}");
            else if (pkm.Moves.Any(m => m > SAV.MaxMoveID))
                errata.Add($"{MsgIndexMoveGame} {string.Join(", ", pkm.Moves.Where(m => m > SAV.MaxMoveID).Select(m => strings.Move[m]))}");

            if (pkm.Ability > strings.Ability.Count)
                errata.Add($"{MsgIndexAbilityRange} {pkm.Ability}");
            else if (pkm.Ability > SAV.MaxAbilityID)
                errata.Add($"{MsgIndexAbilityGame} {strings.Ability[pkm.Ability]}");

            return errata;
        }

        public static int ImportPKMs(this SaveFile SAV, IEnumerable<PKM> compat, int boxStart, bool? noSetb)
        {
            int startCount = boxStart * SAV.BoxSlotCount;
            int maxCount = SAV.BoxCount * SAV.BoxSlotCount;
            int i = startCount;
            int getbox() => i / SAV.BoxSlotCount;
            int getslot() => i % SAV.BoxSlotCount;

            foreach (var pk in compat)
            {
                int box = getbox();
                int slot = getslot();
                while (SAV.IsSlotLocked(box, slot))
                {
                    ++i;
                    box = getbox();
                    slot = getslot();
                }

                int offset = SAV.GetBoxOffset(box) + (slot * SAV.SIZE_STORED);
                SAV.SetStoredSlot(pk, offset, noSetb);

                if (++i == maxCount) // Boxes full!
                    break;
            }
            i -= startCount; // actual imported count
            return i;
        }

        public static IEnumerable<PKM> GetCompatible(this SaveFile SAV, IEnumerable<PKM> pks)
        {
            var savtype = SAV.PKMType;
            foreach (var temp in pks)
            {
                var pk = PKMConverter.ConvertToType(temp, savtype, out string c);
                if (pk == null)
                {
                    Debug.WriteLine(c);
                    continue;
                }

                if (PKMConverter.IsIncompatibleGB(pk.Format, SAV.Japanese, pk.Japanese))
                {
                    c = PKMConverter.GetIncompatibleGBMessage(pk, SAV.Japanese);
                    Debug.WriteLine(c);
                    continue;
                }

                var compat = SAV.IsPKMCompatible(pk);
                if (compat.Count > 0)
                    continue;

                yield return pk;
            }
        }

        /// <summary>
        /// Removes the <see cref="PKM.HeldItem"/> for all <see cref="PKM"/> in the <see cref="SaveFile.BoxData"/>.
        /// </summary>
        /// <param name="SAV"><see cref="SaveFile"/> that is being operated on.</param>
        /// <param name="item"><see cref="PKM.HeldItem"/> to set. If no argument is supplied, the held item will be removed.</param>
        public static void SetBoxDataAllHeldItems(this SaveFile SAV, int item = 0)
        {
            var boxdata = SAV.BoxData;
            foreach (PKM pk in boxdata)
            {
                pk.HeldItem = item;
                pk.RefreshChecksum();
            }
            SAV.BoxData = boxdata;
        }
    }
}