/*
*Author: Lin Hengrui Ryan
*Date:21/06/2024
*Description: a sript to make enemy move
*/
using System.Collections;
using System.Collections.Generic;
using System.Diagnostics.CodeAnalysis;
using UnityEngine;
using UnityEngine.AI;
using UnityEngine.UI;

public class EnemyAi : MonoBehaviour
{
    /// <summary>
    /// the navmesh agen to allow the enemy know where it can navigate
    /// </summary>
    public NavMeshAgent agent;

    /// <summary>
    /// to refrence the player to navigate the enemy to the player
    /// </summary>
    public Transform player;

    /// <summary>
    /// the physics layer of the ground so that the enemy knows where he can walk
    /// </summary>
    public LayerMask groundMask;

    /// <summary>
    /// the physic layer of the player to allow the enemy to checksphere
    /// </summary>
    public LayerMask playerMask;

    /// <summary>
    /// the health of the enemy
    /// </summary>
    public int health = 100;

    [Header("enemy stats")]
    /// <summary>
    /// the point that the enemy will walk to when they are patroling
    /// </summary>
    private Vector3 WalkPoint;
    /// <summary>
    /// to bool to allow the walkpoint to be reset
    /// </summary>
    private bool walkPointSet = false;
    /// <summary>
    /// the maximum range that the enemy will walk while patroling
    /// </summary>
    public float walkRange;
    /// <summary>
    /// how far the player is from the enemy to start chasing the player
    /// </summary>
    public float sightRange;
    /// <summary>
    /// how far the player is from the enemy to allow the enemy to start shooting
    /// </summary>
    public float attackRange;
    /// <summary>
    /// a bool to call the chase function
    /// </summary>
    private bool playerInSightRange;
    /// <summary>
    /// a bool to call the shoot function
    /// </summary>
    private bool playerInAttackRange;
    /// <summary>
    /// a variable to allow the enemy to refrence the gun to call its functions
    /// </summary>
    public GameObject gun;
    /// <summary>
    /// to show the enemy health in the world space ui
    /// </summary>
    private Slider healthbar;

    /// <summary>
    /// to calibrate the enemy health on load
    /// </summary>
    void Awake()
    {
        healthbar = GetComponentInChildren<Slider>();
        healthbar.maxValue = health;
    }
    /// <summary>
    /// to constantly check for the player in the sphere and do the nessasary action and to destroy the enemy dies after the heath reaches 0 or less
    /// </summary>
    void Update()
    {
        //Check for sight and attack range
        playerInSightRange = Physics.CheckSphere(transform.position, sightRange, playerMask);
        playerInAttackRange = Physics.CheckSphere(transform.position, attackRange, playerMask);

        if (!playerInSightRange && !playerInAttackRange)
            Patrol();
        if (playerInSightRange && !playerInAttackRange)
            Chase();
        if (playerInAttackRange && playerInSightRange)
            Attack();
        if (health <= 0)
        {
            Destroy(gameObject);
        }
        if (player == null)
        {
            player = GameObject.Find("PlayerCapsule").transform;
        }
        healthbar.value = health;
    }

    /// <summary>
    /// to set the enemy to go to a position specified 
    /// </summary>
    private void Patrol()
    {
        Debug.Log("Patroling");
        if (!walkPointSet)
        {
            SeachWalkPoint();
        }
        else
        {
            agent.SetDestination(WalkPoint);
        }
        ;
        Vector3 distaceToWalk = transform.position - WalkPoint;
        if (distaceToWalk.magnitude < 1f)
        {
            Invoke("changePoint", 4f);
        }
    }
    /// <summary>
    /// to allow the walkpoint to change
    /// </summary>
    public void changePoint()
    {
        walkPointSet = false;
    }
    /// <summary>
    /// seach for a new walk point to somewhere that is in the walk radius and is on the ground
    /// </summary>
    private void SeachWalkPoint()
    {
        float randomZ = Random.Range(-walkRange, walkRange);
        float randomX = Random.Range(-walkRange, walkRange);

        WalkPoint = new Vector3(
            transform.position.x + randomX,
            transform.position.y,
            transform.position.z + randomZ
        );

        if (Physics.Raycast(WalkPoint, -transform.up, 2f, groundMask))
        {
            walkPointSet = true;
        }
    }
    /// <summary>
    /// to make the enemy chase the player if it is not in the shooting range
    /// </summary>
    private void Chase()
    {
        Debug.Log("chasing");

        agent.SetDestination(player.position);
    }
    /// <summary>
    /// to make the enemy attack the player 
    /// </summary>
    private void Attack()
    {
        Debug.Log("Attacking");

        agent.SetDestination(transform.position);

        transform.LookAt(player);

        gun.GetComponent<enemyGun>().Shoot();
    }
    /// <summary>
    /// to see the ranges in the scene view
    /// </summary>
    private void OnDrawGizmosSelected()
    {
        Gizmos.color = Color.red;
        Gizmos.DrawWireSphere(transform.position, attackRange);
        Gizmos.color = Color.yellow;
        Gizmos.DrawWireSphere(transform.position, sightRange);
    }
}