using System.Collections.Generic;

namespace GeometryTD.Definition
{
    public enum CombatParticipantTowerValidationFailureReason
    {
        None = 0,
        TowerMissing = 1,
        MissingMuzzleComponent = 2,
        MissingBearingComponent = 3,
        MissingBaseComponent = 4,
        BrokenMuzzleComponent = 5,
        BrokenBearingComponent = 6,
        BrokenBaseComponent = 7
    }

    public sealed class CombatParticipantTowerValidationResult
    {
        public long TowerInstanceId { get; set; }

        public bool IsValid => FailureReason == CombatParticipantTowerValidationFailureReason.None;

        public CombatParticipantTowerValidationFailureReason FailureReason { get; set; }

        public TowerItemData Tower { get; set; }
    }

    public sealed class CombatParticipantTowerValidationSummary
    {
        public IReadOnlyList<TowerItemData> ValidTowers { get; set; } = System.Array.Empty<TowerItemData>();

        public IReadOnlyList<CombatParticipantTowerValidationResult> InvalidResults { get; set; } =
            System.Array.Empty<CombatParticipantTowerValidationResult>();

        public bool HasAnyValidParticipantTower => ValidTowers != null && ValidTowers.Count > 0;
    }

    public static class CombatParticipantTowerValidationService
    {
        public static CombatParticipantTowerValidationResult ValidateTower(
            BackpackInventoryData inventory,
            long towerInstanceId)
        {
            if (!TryGetTowerById(inventory, towerInstanceId, out TowerItemData tower))
            {
                return new CombatParticipantTowerValidationResult
                {
                    TowerInstanceId = towerInstanceId,
                    FailureReason = CombatParticipantTowerValidationFailureReason.TowerMissing
                };
            }

            return ValidateTower(inventory, tower);
        }

        public static CombatParticipantTowerValidationResult ValidateTower(
            BackpackInventoryData inventory,
            TowerItemData tower)
        {
            if (tower == null || tower.InstanceId <= 0)
            {
                return new CombatParticipantTowerValidationResult
                {
                    TowerInstanceId = tower != null ? tower.InstanceId : 0,
                    Tower = tower,
                    FailureReason = CombatParticipantTowerValidationFailureReason.TowerMissing
                };
            }

            if (!TryGetComponentById(inventory?.MuzzleComponents, tower.MuzzleComponentInstanceId, out MuzzleCompItemData muzzleComponent))
            {
                return new CombatParticipantTowerValidationResult
                {
                    TowerInstanceId = tower.InstanceId,
                    Tower = tower,
                    FailureReason = CombatParticipantTowerValidationFailureReason.MissingMuzzleComponent
                };
            }

            if (muzzleComponent.Endurance <= 0f)
            {
                return new CombatParticipantTowerValidationResult
                {
                    TowerInstanceId = tower.InstanceId,
                    Tower = tower,
                    FailureReason = CombatParticipantTowerValidationFailureReason.BrokenMuzzleComponent
                };
            }

            if (!TryGetComponentById(inventory?.BearingComponents, tower.BearingComponentInstanceId, out BearingCompItemData bearingComponent))
            {
                return new CombatParticipantTowerValidationResult
                {
                    TowerInstanceId = tower.InstanceId,
                    Tower = tower,
                    FailureReason = CombatParticipantTowerValidationFailureReason.MissingBearingComponent
                };
            }

            if (bearingComponent.Endurance <= 0f)
            {
                return new CombatParticipantTowerValidationResult
                {
                    TowerInstanceId = tower.InstanceId,
                    Tower = tower,
                    FailureReason = CombatParticipantTowerValidationFailureReason.BrokenBearingComponent
                };
            }

            if (!TryGetComponentById(inventory?.BaseComponents, tower.BaseComponentInstanceId, out BaseCompItemData baseComponent))
            {
                return new CombatParticipantTowerValidationResult
                {
                    TowerInstanceId = tower.InstanceId,
                    Tower = tower,
                    FailureReason = CombatParticipantTowerValidationFailureReason.MissingBaseComponent
                };
            }

            if (baseComponent.Endurance <= 0f)
            {
                return new CombatParticipantTowerValidationResult
                {
                    TowerInstanceId = tower.InstanceId,
                    Tower = tower,
                    FailureReason = CombatParticipantTowerValidationFailureReason.BrokenBaseComponent
                };
            }

            return new CombatParticipantTowerValidationResult
            {
                TowerInstanceId = tower.InstanceId,
                Tower = tower,
                FailureReason = CombatParticipantTowerValidationFailureReason.None
            };
        }

        public static CombatParticipantTowerValidationSummary ValidateParticipantTowers(BackpackInventoryData inventory)
        {
            List<TowerItemData> validTowers = new List<TowerItemData>();
            List<CombatParticipantTowerValidationResult> invalidResults =
                new List<CombatParticipantTowerValidationResult>();
            HashSet<long> processedTowerIds = new HashSet<long>();

            if (inventory?.ParticipantTowerInstanceIds == null || inventory.ParticipantTowerInstanceIds.Count <= 0)
            {
                return new CombatParticipantTowerValidationSummary
                {
                    ValidTowers = validTowers,
                    InvalidResults = invalidResults
                };
            }

            for (int i = 0; i < inventory.ParticipantTowerInstanceIds.Count; i++)
            {
                long towerInstanceId = inventory.ParticipantTowerInstanceIds[i];
                if (towerInstanceId <= 0 || !processedTowerIds.Add(towerInstanceId))
                {
                    continue;
                }

                CombatParticipantTowerValidationResult result = ValidateTower(inventory, towerInstanceId);
                if (result.IsValid)
                {
                    validTowers.Add(result.Tower);
                }
                else
                {
                    invalidResults.Add(result);
                }
            }

            return new CombatParticipantTowerValidationSummary
            {
                ValidTowers = validTowers,
                InvalidResults = invalidResults
            };
        }

        private 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;
        }

        private static bool TryGetComponentById<TComponent>(
            IReadOnlyList<TComponent> components,
            long componentInstanceId,
            out TComponent resolvedComponent)
            where TComponent : TowerCompItemData
        {
            resolvedComponent = null;
            if (components == null || componentInstanceId <= 0)
            {
                return false;
            }

            for (int i = 0; i < components.Count; i++)
            {
                TComponent component = components[i];
                if (component != null && component.InstanceId == componentInstanceId)
                {
                    resolvedComponent = component;
                    return true;
                }
            }

            return false;
        }
    }
}