using System.Collections.Generic;
using UnityEngine;

public class MateMgr : Singleton<MateMgr>
{
    [SerializeField] MateSkillCutSceneView skillCutSceneView;
    [SerializeField] MateSkillCoolTimeView skillCoolTimeView;

    bool isInitialized;
    Dictionary<uint, IVMate> mateInstanceGroup;
    SlotGroup<IVMate> settedMates;

    int currentMateSlotIndex;
    IVMate activeMate;

    public SlotGroup<IVMate> SettedMates => settedMates;
    public IVMate ActiveMate => activeMate;

    public void Init()
    {
        if (isInitialized) return;

        mateInstanceGroup = new Dictionary<uint, IVMate>();
        foreach (var prefab in MateDataGroup.Instance.MatePrefabs.Values)
        {
            IVMate mate = Instantiate(prefab);
            mate.gameObject.SetActive(false);
            mateInstanceGroup.Add(mate.Data.ID, mate);
        }

        settedMates = new SlotGroup<IVMate>(GameProperty.Instance.MateMaxCount);

        foreach (var row in MateDataGroup.Instance.GetMateDataMatrix(MateData.CompareByID))
        {
            settedMates.GetEmptySlots(out var emptySlots);
            foreach (var mate in row)
            {
                if(emptySlots.Count == 0) break;

                if(mate.IsSetted)
                {
                    SetMateAt(mate.ID, mate.SettedSlotIndex);
                    emptySlots.RemoveAt(0);
                }
            }
        }

        isInitialized = true;
    }

    private void Update()
    {
        if(!isInitialized || BattleMgr.Instance.BattlePause) return;

        for(int i = 0; i < settedMates.SlotCount; ++i)
        {
            var currentSlot = settedMates.GetSlot(i);

            if(!currentSlot.IsEmpty)
                currentSlot.item.UpdateSkillCoolTime();
        }

        if (activeMate is null) return;

        if (IsSafeToChangeCurrentMate() && activeMate.Skill.IsInCoolTime)
        {
            for (int i = currentMateSlotIndex + 1; true; ++i)
            {
                int nextIndex = i % settedMates.SlotCount;
                if (nextIndex == currentMateSlotIndex) break;

                var slot = settedMates.GetSlot(nextIndex);
                if (!slot.IsEmpty)
                {
                    if(!slot.item.Skill.IsInCoolTime)
                        ChangeActiveMate(slot.item, slot.slotIndex);
                    break;
                }
            }
        }

        if (activeMate.CastSkill())
        {
            skillCutSceneView.SetMate(activeMate);
            skillCutSceneView.Show();
        }
    }

    private void ChangeActiveMate(IVMate target, int slotIndex)
    {
        if(activeMate == target) return;

        var player = BattleMgr.Instance.GetPlayer();

        Transform spawnTrans = null;
        Vector2 lookDir = player.transform.position - target.transform.position;

        if (activeMate != null)
        {
            spawnTrans = activeMate.transform;
            lookDir = activeMate.LookDirection;
            activeMate.Dispose();
        }

        currentMateSlotIndex = slotIndex;
        activeMate = target;
        activeMate.Spawn(player, lookDir, spawnTrans);
    }

    public bool IsSafeToChangeCurrentMate() => activeMate?.IsSafeChange ?? true;

    public void SetMateAt(uint id, int slotIndex)
    {
        IVMate targetMate;

        if (!IsValidSpawnSlotIndex(slotIndex))
            throw new System.Exception("Invalid spawn position index");
        else if (!mateInstanceGroup.TryGetValue(id, out targetMate))
            throw new System.Exception("Invalid mate id");
        else if (settedMates.TryGetSlot(targetMate, out SlotGroup<IVMate>.Slot _))
            return;

        if (settedMates.TryGetItem(slotIndex, out IVMate existedMate))
        {
            existedMate.Data.RemoveSlotIndex();
            existedMate.Dispose();
            settedMates.ClearSlot(slotIndex);

            if(activeMate == existedMate)
                activeMate = null;
        }

        settedMates[slotIndex] = targetMate;
        targetMate.Data.SetSlotIndex(slotIndex);

        if (activeMate is null)
            ChangeActiveMate(targetMate, slotIndex);

        skillCoolTimeView?.SetMateAt(settedMates.GetSlot(slotIndex));
    }

    public void RemoveMateAt(int slotIndex)
    {
        if (!IsValidSpawnSlotIndex(slotIndex))
            throw new System.Exception("Invalid spawn position index");

        if (!settedMates.TryGetItem(slotIndex, out IVMate existedMate)) return;

        existedMate.Data.RemoveSlotIndex();
        existedMate.Dispose();
        settedMates.ClearSlot(slotIndex);

        if (activeMate == existedMate)
        {
            for(int i = currentMateSlotIndex + 1; true; ++i)
            {
                int nextIndex = i % settedMates.SlotCount;
                if (nextIndex == currentMateSlotIndex)
                {
                    currentMateSlotIndex = -1;
                    activeMate = null;
                    break;
                }

                var slot = settedMates.GetSlot(nextIndex);

                if(!slot.IsEmpty)
                {
                    ChangeActiveMate(slot.item, slot.slotIndex);
                    break;
                }
            }
        }

        skillCoolTimeView?.RemoveMateAt(slotIndex);
    }

    public bool IsValidSpawnSlotIndex(int slotIndex) => slotIndex >= 0 && slotIndex < GameProperty.Instance.MateMaxCount;
}