using System.Collections.Generic;
using GeometryTD.Definition;
using UnityEngine;

namespace GeometryTD.CustomUtility
{
    public static class InventoryParticipantUtility
    {
        public static ParticipantTowerAssignResult TryAddParticipantTower(
            BackpackInventoryData inventory,
            long towerInstanceId,
            int maxCount)
        {
            if (inventory == null || towerInstanceId <= 0)
            {
                return new ParticipantTowerAssignResult
                {
                    TowerInstanceId = towerInstanceId,
                    FailureReason = ParticipantTowerAssignFailureReason.TowerMissing,
                    ValidationFailureReason = CombatParticipantTowerValidationFailureReason.None
                };
            }

            int resolvedMaxCount = Mathf.Max(1, maxCount);
            NormalizeParticipantState(inventory, resolvedMaxCount);
            CombatParticipantTowerValidationResult validationResult =
                CombatParticipantTowerValidationService.ValidateTower(inventory, towerInstanceId);
            if (!validationResult.IsValid)
            {
                return new ParticipantTowerAssignResult
                {
                    TowerInstanceId = towerInstanceId,
                    FailureReason = validationResult.FailureReason == CombatParticipantTowerValidationFailureReason.TowerMissing
                        ? ParticipantTowerAssignFailureReason.TowerMissing
                        : ParticipantTowerAssignFailureReason.InvalidTower,
                    ValidationFailureReason = validationResult.FailureReason
                };
            }

            inventory.ParticipantTowerInstanceIds ??= new List<long>();
            if (inventory.ParticipantTowerInstanceIds.Contains(towerInstanceId))
            {
                if (validationResult.Tower != null)
                {
                    validationResult.Tower.IsParticipatingInCombat = true;
                }

                return new ParticipantTowerAssignResult
                {
                    TowerInstanceId = towerInstanceId,
                    FailureReason = ParticipantTowerAssignFailureReason.AlreadyAssigned,
                    ValidationFailureReason = CombatParticipantTowerValidationFailureReason.None
                };
            }

            if (inventory.ParticipantTowerInstanceIds.Count >= resolvedMaxCount)
            {
                return new ParticipantTowerAssignResult
                {
                    TowerInstanceId = towerInstanceId,
                    FailureReason = ParticipantTowerAssignFailureReason.ParticipantAreaFull,
                    ValidationFailureReason = CombatParticipantTowerValidationFailureReason.None
                };
            }

            inventory.ParticipantTowerInstanceIds.Add(towerInstanceId);
            if (validationResult.Tower != null)
            {
                validationResult.Tower.IsParticipatingInCombat = true;
            }

            return new ParticipantTowerAssignResult
            {
                TowerInstanceId = towerInstanceId,
                FailureReason = ParticipantTowerAssignFailureReason.None,
                ValidationFailureReason = CombatParticipantTowerValidationFailureReason.None
            };
        }

        public static bool TryRemoveParticipantTower(BackpackInventoryData inventory, long towerInstanceId, int maxCount)
        {
            if (inventory == null || towerInstanceId <= 0)
            {
                return false;
            }

            NormalizeParticipantState(inventory, maxCount);
            if (inventory.ParticipantTowerInstanceIds == null)
            {
                return false;
            }

            bool removed = inventory.ParticipantTowerInstanceIds.Remove(towerInstanceId);
            if (!removed)
            {
                return false;
            }

            if (TryGetTowerById(inventory, towerInstanceId, out TowerItemData tower))
            {
                tower.IsParticipatingInCombat = false;
            }

            return true;
        }

        public static void NormalizeParticipantState(BackpackInventoryData inventory, int maxCount)
        {
            if (inventory == null)
            {
                return;
            }

            int resolvedMaxCount = Mathf.Max(1, maxCount);
            inventory.ParticipantTowerInstanceIds ??= new List<long>();
            Dictionary<long, TowerItemData> towerMap = new Dictionary<long, TowerItemData>();
            if (inventory.Towers != null)
            {
                for (int i = 0; i < inventory.Towers.Count; i++)
                {
                    TowerItemData tower = inventory.Towers[i];
                    if (tower == null || tower.InstanceId <= 0)
                    {
                        continue;
                    }

                    tower.IsParticipatingInCombat = false;
                    towerMap[tower.InstanceId] = tower;
                }
            }

            HashSet<long> uniqueIds = new HashSet<long>();
            List<long> normalizedIds = new List<long>(inventory.ParticipantTowerInstanceIds.Count);
            for (int i = 0; i < inventory.ParticipantTowerInstanceIds.Count; i++)
            {
                if (normalizedIds.Count >= resolvedMaxCount)
                {
                    break;
                }

                long towerId = inventory.ParticipantTowerInstanceIds[i];
                if (towerId <= 0 || !uniqueIds.Add(towerId))
                {
                    continue;
                }

                if (!towerMap.TryGetValue(towerId, out TowerItemData tower))
                {
                    continue;
                }

                tower.IsParticipatingInCombat = true;
                normalizedIds.Add(towerId);
            }

            inventory.ParticipantTowerInstanceIds = normalizedIds;
        }

        public static bool TryGetTowerById(BackpackInventoryData inventory, long towerInstanceId, out TowerItemData tower)
        {
            tower = null;
            if (inventory?.Towers == null || towerInstanceId <= 0)
            {
                return false;
            }

            for (int i = 0; i < inventory.Towers.Count; i++)
            {
                TowerItemData candidate = inventory.Towers[i];
                if (candidate != null && candidate.InstanceId == towerInstanceId)
                {
                    tower = candidate;
                    return true;
                }
            }

            return false;
        }
    }
}