using System.Collections.Generic;
using System.Diagnostics;

namespace PKHeX.Core
{
    /// <summary>
    /// Logic for rearranging pointers for Box Storage utility
    /// </summary>
    public static class SlotPointerUtil
    {
        private static bool WithinRange(int slot, int min, int max) => min <= slot && slot < max;

        public static void UpdateSwap(int b1, int b2, int slotsPerBox, params IList<int>[] ptrset)
        {
            int diff = (b1 - b2) * slotsPerBox;

            int b1s = b1 * slotsPerBox;
            int b1e = b1s + slotsPerBox;
            int b12 = b1 > b2 ? -diff : diff;

            int b2s = b2 * slotsPerBox;
            int b2e = b2s + slotsPerBox;
            int b21 = b2 > b1 ? -diff : diff;
            foreach (var list in ptrset)
            {
                for (int s = 0; s < list.Count; s++)
                {
                    if (WithinRange(b1s, b1e, list[s]))
                        list[s] += b12;
                    else if (WithinRange(b2s, b2e, list[s]))
                        list[s] += b21;
                }
            }
        }

        public static void UpdateRepointFrom(IList<PKM> result, IList<PKM> bd, int start, params IList<int>[] slotPointers)
        {
            foreach (var p in slotPointers)
            {
                for (int i = 0; i < p.Count; i++)
                {
                    var index = p[i];
                    if ((uint)index >= bd.Count)
                        continue;
                    var pk = bd[index];
                    var newIndex = result.IndexOf(pk);
                    if (newIndex < 0)
                        continue;

                    Debug.WriteLine($"Re-pointing {pk.Nickname} from {index} to {newIndex}");
                    Debug.WriteLine($"{result[newIndex]}");
                    p[i] = start + newIndex;
                }
            }
        }

        public static void UpdateRepointFrom(int newIndex, int oldIndex, params IList<int>[] slotPointers)
        {
            foreach (var p in slotPointers)
            {
                for (int s = 0; s < p.Count; s++)
                {
                    if (p[s] != oldIndex)
                        continue;
                    p[s] = newIndex;
                    break;
                }
            }
        }

        public static void UpdateMove(int bMove, int cMove, int slotsPerBox, params IList<int>[] ptrset)
        {
            int bStart = bMove * slotsPerBox;
            int cStart = cMove * slotsPerBox;
            int bEnd = bStart + slotsPerBox;
            int cEnd = cStart + slotsPerBox;
            int cShift;
            int bShift;
            if (bMove < cMove) // shift chunk down, shift box up
            {
                cShift = -slotsPerBox;
                bShift = (cStart - bStart);
            }
            else // shift box down, shift chunk up
            {
                cShift = slotsPerBox;
                bShift = -(bStart - cStart);
            }
            foreach (var list in ptrset)
            {
                for (int s = 0; s < list.Count; s++)
                {
                    if (WithinRange(cStart, cEnd, list[s]))
                        list[s] += cShift;
                    if (WithinRange(bStart, bEnd, list[s]))
                        list[s] += bShift;
                }
            }
        }
    }
}