namespace PKHeX.Core
{
    /// <summary>
    /// Facilitates interaction with a <see cref="SaveFile"/> or other data location's slot data.
    /// </summary>
    public sealed class SlotEditor<T>
    {
        private readonly SaveFile SAV;
        public readonly SlotChangelog Changelog;
        public readonly SlotPublisher<T> Publisher;

        public SlotEditor(SaveFile sav)
        {
            SAV = sav;
            Changelog = new SlotChangelog(sav);
            Publisher = new SlotPublisher<T>();
        }

        private void NotifySlotChanged(ISlotInfo slot, SlotTouchType type, PKM pkm) => Publisher.NotifySlotChanged(slot, type, pkm);

        /// <summary>
        /// Gets data from a slot.
        /// </summary>
        /// <param name="slot">Slot to retrieve from.</param>
        /// <returns>Operation succeeded or not via enum value.</returns>
        public PKM Get(ISlotInfo slot)
        {
            // Reading from a slot is always allowed.
            var pk = slot.Read(SAV);
            NotifySlotChanged(slot, SlotTouchType.Get, pk);
            return pk;
        }

        /// <summary>
        /// Sets data to a slot.
        /// </summary>
        /// <param name="slot">Slot to be set to.</param>
        /// <param name="pkm">Data to set.</param>
        /// <param name="type">Type of slot action</param>
        /// <returns>Operation succeeded or not via enum value.</returns>
        public SlotTouchResult Set(ISlotInfo slot, PKM pkm, SlotTouchType type = SlotTouchType.Set)
        {
            if (!slot.CanWriteTo(SAV))
                return SlotTouchResult.FailWrite;

            WriteSlot(slot, pkm, type);
            NotifySlotChanged(slot, type, pkm);

            return SlotTouchResult.Success;
        }

        /// <summary>
        /// Deletes a slot.
        /// </summary>
        /// <param name="slot">Slot to be deleted.</param>
        /// <returns>Operation succeeded or not via enum value.</returns>
        public SlotTouchResult Delete(ISlotInfo slot)
        {
            if (!slot.CanWriteTo(SAV))
                return SlotTouchResult.FailDelete;

            var pk = DeleteSlot(slot);
            NotifySlotChanged(slot, SlotTouchType.Delete, pk);

            return SlotTouchResult.Success;
        }

        /// <summary>
        /// Swaps two slots.
        /// </summary>
        /// <param name="source">Source slot to be switched with <see cref="dest"/>.</param>
        /// <param name="dest">Destination slot to be switched with <see cref="source"/>.</param>
        /// <returns>Operation succeeded or not via enum value.</returns>
        public SlotTouchResult Swap(ISlotInfo source, ISlotInfo dest)
        {
            if (!source.CanWriteTo(SAV))
                return SlotTouchResult.FailSource;
            if (!dest.CanWriteTo(SAV))
                return SlotTouchResult.FailDestination;

            NotifySlotChanged(source, SlotTouchType.None, source.Read(SAV));
            NotifySlotChanged(dest, SlotTouchType.Swap, dest.Read(SAV));

            return SlotTouchResult.Success;
        }

        private void WriteSlot(ISlotInfo slot, PKM pkm, SlotTouchType type = SlotTouchType.Set)
        {
            Changelog.AddNewChange(slot);
            var setDetail = type is SlotTouchType.Swap ? PKMImportSetting.Skip : PKMImportSetting.UseDefault;
            var result = slot.WriteTo(SAV, pkm, setDetail);
            if (result)
                NotifySlotChanged(slot, type, pkm);
        }

        private PKM DeleteSlot(ISlotInfo slot)
        {
            var pkm = SAV.BlankPKM;
            WriteSlot(slot, pkm, SlotTouchType.Delete);
            return pkm;
        }

        public void Undo()
        {
            if (!Changelog.CanUndo)
                return;
            var slot = Changelog.Undo();
            NotifySlotChanged(slot, SlotTouchType.Set, slot.Read(SAV));
        }

        public void Redo()
        {
            if (!Changelog.CanRedo)
                return;
            var slot = Changelog.Redo();
            NotifySlotChanged(slot, SlotTouchType.Set, slot.Read(SAV));
        }
    }
}
