using System;
using System.Collections.Generic;
using Grid;
using UnityEngine;
using UnityEngine.Serialization;

namespace Actions {
    public class ShootAction : BaseAction
    {
        private enum State {
            Aiming,
            Shooting,
            Cooloff
        }

        public Unit TargetUnit { get; set; }
        public int maxShootDistance = 7;

        [SerializeField] private LayerMask obstaclesLayerMask;
        
        private State state;
        private float stateTimer;
        private bool canShootBullet;
        
        private const float rotationSpeed = 10f;
        private const float shootingStateTime = .2f;
        private const float coolOffStateTime = 1f;
        private const float aimingStateTime = 1.5f;
        private const float unitShoulderHeight = 1.7f;

        
        public event EventHandler<ShootEventArgs> OnShoot;
        public static event EventHandler<ShootEventArgs> OnAnyShoot;

        public class ShootEventArgs : EventArgs {
            public Unit TargetUnit;
            public Unit ShootingUnit;
        }

        protected override void Awake() {
            base.Awake();
            ActionName = "Shoot";
        }

        private void Update() {
            if (!IsActive) return;
            stateTimer -= Time.deltaTime;

            switch (state) {
                case State.Aiming:
                    Vector3 aimDirection = (TargetUnit.GetWorldPosition() - Unit.GetWorldPosition()).normalized;
                    transform.forward = Vector3.Lerp(transform.forward, aimDirection, rotationSpeed * Time.deltaTime);
                    break;
                case State.Shooting:
                    if (canShootBullet) {
                        Shoot();
                        canShootBullet = false;
                    }
                    break;
                case State.Cooloff:
                    break;
            }

            if (stateTimer <= 0f) NextState();
        }

        private void Shoot() {
            OnAnyShoot?.Invoke(this,new(){TargetUnit = TargetUnit, ShootingUnit = Unit});
            OnShoot?.Invoke(this,new(){TargetUnit = TargetUnit, ShootingUnit = Unit});
            TargetUnit.Damage(40);
        }

        private void NextState() {
            switch (state) {
                case State.Aiming:
                    state = State.Shooting;
                    stateTimer = shootingStateTime;
                    break;
                case State.Shooting:
                    state = State.Cooloff;
                    stateTimer = coolOffStateTime;
                    break;
                case State.Cooloff:
                    ActionComplete();
                    break;
            }
        }

        public override void TakeAction(GridPosition gridPosition, Action onActionComplete) {
            IsActive = true;

            TargetUnit = LevelGrid.Instance.GetUnitAtGridPosition(gridPosition);
            canShootBullet = true;
            
            state = State.Aiming;
            stateTimer = aimingStateTime;

            ActionStart(onActionComplete);
        }

        public override List<GridPosition> GetValidActionGridPositionList() => GetValidActionGridPositionList(Unit.GridPosition);

        private List<GridPosition> GetValidActionGridPositionList(GridPosition unitGridPosition) {
            List<GridPosition> validGridPositionList = new();
            for (int x = -maxShootDistance; x <= maxShootDistance; x++) {
                for (int z = -maxShootDistance; z <= maxShootDistance; z++) {
                    GridPosition offsetGridPosition = new(x, z);
                    GridPosition testGridPosition = unitGridPosition + offsetGridPosition;

                    if (!LevelGrid.Instance.IsValidGridPosition(testGridPosition)) continue; //Only return valid grid positions
                    if (Mathf.Abs(x) + Mathf.Abs(z) > maxShootDistance) continue; //Out of Range
                    
                    if (!LevelGrid.Instance.HasAnyUnitOnGridPosition(testGridPosition)) continue; //Grid position is empty, no unit

                    Unit unitAtGridPosition = LevelGrid.Instance.GetUnitAtGridPosition(testGridPosition);
                    if (unitAtGridPosition.IsEnemy == Unit.IsEnemy) continue; //Both units are on the same 'team'
                    TargetUnit = unitAtGridPosition;

                    Vector3 unitWorldPosition = LevelGrid.Instance.GetWorldPosition(unitGridPosition);
                    Vector3 shootDir = (TargetUnit.GetWorldPosition() - unitWorldPosition).normalized;
                    if (Physics.Raycast(
                        unitWorldPosition + Vector3.up * unitShoulderHeight, 
                        shootDir,
                        Vector3.Distance(unitWorldPosition, TargetUnit.GetWorldPosition()),
                        obstaclesLayerMask
                    )) continue; // Blocked by an obstacle
                    
                    validGridPositionList.Add(testGridPosition);
                }
            }
            return validGridPositionList;
        }

        protected override EnemyAIAction GetEnemyAIAction(GridPosition gridPosition) {
            Unit targetUnit = LevelGrid.Instance.GetUnitAtGridPosition(gridPosition);
            return new(gridPosition, 100 + Mathf.RoundToInt((1 - targetUnit.HealthSystem.HealthNormalized) * 100f));
        }

        public int GetTargetCountAtPosition(GridPosition gridPosition) => GetValidActionGridPositionList(gridPosition).Count;
    }
}