using System.Collections;
using System.Collections.Generic;
using UnityEngine;
using Pathfinding;

public class Enemy : MonoBehaviour
{
    [Header("Health and Damage")] // Health and Damage enemy public variables
    [SerializeField] int enemyHealth = 100;
    [SerializeField] int playerDamageMult = 25;
    [SerializeField] GameObject skeletonRemains;
    [SerializeField] Color damageColor = Color.red;
    [SerializeField] float damageTime = 0.5f;
    [SerializeField] float knockbackStrength = 0.25f;

    [Header("Misc")] // Misc enemy public variables
    [SerializeField] AudioClip[] footstepFX;
    [SerializeField] float radius = 5f;
    
    // Enemy private variables
    LayerMask myLayerMask;
    Vector3 currentPosition;
    Vector3 lastPosition;
    bool isRunning;
    int facing = 1;
    bool hitWall = false;
    bool isDead = false;
    bool IFrames = false;
    bool isRunningFX = false;

    // Components
    Animator myAnimator;
    AIPath myAIPath;
    Renderer objectRenderer;
    AudioSource audioSource;
    ParticleSystem bloodParticleSystem;
    ParticleSystem footstepParticleSystem;
    Player player;
    Collider2D myCollider;

    [Header("GameObjects")] // Enemy GameObject public variables
    [SerializeField] GameObject potionObject;
    [SerializeField] GameObject playerObject;
    [SerializeField] GameObject footstepParticle;
    [SerializeField] GameObject bloodParticle;

    // Draws the enemy attack radius, just so I set it more accordingly
    void OnDrawGizmosSelected()
    {
        Gizmos.color = Color.yellow;
        Gizmos.DrawWireSphere(transform.position, radius);
    }

    // Method called on the first frame
    void Start()
    {
        // Get components
        myAnimator = GetComponent<Animator>();
        myCollider = GetComponent<Collider2D>();
        myAIPath = GetComponent<AIPath>();
        objectRenderer = GetComponent<Renderer>();
        audioSource = GetComponent<AudioSource>();
        footstepParticleSystem = footstepParticle.GetComponent<ParticleSystem>();
        bloodParticleSystem = bloodParticle.GetComponent<ParticleSystem>();
        player = playerObject.GetComponent<Player>();

        // Get layermask for player layer
        myLayerMask = LayerMask.GetMask("Player");

        // Start coroutines that run in the background
        StartCoroutine(RunningCheck());
        StartCoroutine(FootstepFunc());
    }

    // Method called every frame
    void Update()
    {
        // Run methods that run every frame 
        FlipSprite();
        AlertRadius();
        DashIFrames();
        Death();
    }

    // Wait for animation corutine
    IEnumerator WaitForAnimation()
    {
        // Wait for death animation to play
        yield return new WaitForSeconds(0.5f);

        // Instantiate skeleton remains where enemy died, with a 1/3 chance to instantiate a potion, then destroy itself
        GameObject newObject = Instantiate(skeletonRemains, transform.position, transform.rotation);
        newObject.transform.localScale = transform.localScale;
        int potionChance = Random.Range(0, 3);
        if (potionChance == 0)
        {
            Instantiate(potionObject, transform.position, Quaternion.identity);
        }
        Destroy(gameObject);
    }

    // Footstep sfx coroutine
    IEnumerator FootstepFunc()
    {
        // Runs forever as long as program is running
        while (true)
        {
            // If enemy is running play footstep sfx
            if (isRunningFX)
            {
                audioSource.PlayOneShot(footstepFX[Random.Range(0, 2)]);
            }
            yield return new WaitForSeconds(0.653f);
        }
    }

    // Check if enemy is running coroutine
    IEnumerator RunningCheck()
    {
        // Runs as long as the program is running
        while (true)
        {
            // currentPositon is set to the current position of enemy
            currentPosition = transform.position;

            // If the current postion is different from the last position the enemy has to be moving, so isRunning true
            if (currentPosition != lastPosition)
            {
                isRunning = true;
            }
            else // Otherwise not so false
            {
                isRunning = false;
            }

            // If the current position x is less than last position x the enemy must be running to the left, so flip sprite to left
            if (currentPosition.x < lastPosition.x)
            {
                transform.localScale = new Vector3(-1, transform.localScale.y, transform.localScale.z);
                facing = -1;
            }
            else if (currentPosition.x > lastPosition.x) // If the current position x is more than last position x the enemy must be running to the right, so flip sprite to right
            {
                transform.localScale = new Vector3(1, transform.localScale.y, transform.localScale.z);
                facing = 1;
            }

            // last position is set to the current position after all logic is finished
            lastPosition = currentPosition;

            yield return new WaitForSeconds(0.1f);
        }
    }

    // Coroutine for changing tint back to white after damaged
    IEnumerator DamageTint()
    {
        yield return new WaitForSeconds(damageTime);

        objectRenderer.material.color = Color.white;
    }
    
    // Damage knockback coroutine
    IEnumerator DamageKnockback()
    {
        // If damaged the enemy is invicible until knockback has been given
        IFrames = true;

        // If the enemy is facing to the right, give them knockback to the left. Stop knockback if they hit a wall
        if (facing == 1)
        {
            for (int i = 0; i < 15; i++)
            {
                if (hitWall == false)
                {
                    transform.position += new Vector3(-knockbackStrength, 0, 0);
                }
                yield return new WaitForSeconds(0.01f);
            }
        }
        // If the enemy is facing to the left, give them knockback to the right. Stop knockback if they hit a wall
        else if (facing == -1)
        {
            for (int i = 0; i < 15; i++)
            {
                if (hitWall == false)
                {
                    transform.position += new Vector3(knockbackStrength, 0, 0);
                }
                yield return new WaitForSeconds(0.01f);
            }
        }

        // Enemy is no longer invicible
        IFrames = false;
    }

    // DashIFrames method
    void DashIFrames()
    {
        // Disables enemy collider when players dashing
        if (player.isDashing && myCollider.enabled)
        {
            myCollider.enabled = false;
        }

        // Enables enemy collider when player is not dashing
        if (!player.isDashing && !myCollider.enabled)
        {
            myCollider.enabled = true;
        }
    }

    // Death method
    void Death()
    {
        // If enemy is not already dead and enemy health is 0 or below, isDead true, play death animation and start death coroutine
        if (!isDead && enemyHealth <= 0)
        {
            isDead = true;

            myAnimator.SetTrigger("isDead");
            StartCoroutine(WaitForAnimation());
        }
    }

    // Alert radius method
    void AlertRadius()
    {
        // Get array of colliders marked as layer "Player" in the radius circle around enemy
        Collider2D[] colliders = Physics2D.OverlapCircleAll(transform.position, radius, myLayerMask);

        // If there is a collider in the array (aka. the player) then the navigation library I used becomes active
        if (colliders.Length > 0)
        {
            isRunningFX = true;
            myAIPath.canMove = true;
        }
        // If there is no collider in the array then the enemy doesnt move
        else
        {
            isRunningFX = false;
            myAIPath.canMove = false;
        }
    }

    // Flip sprite method
    void FlipSprite()
    {
        // If enemy is running enable enemy footstep particles and set running animation
        if (isRunning)
        {
            if (!footstepParticleSystem.isPlaying)
            {
                footstepParticleSystem.Play();
            }
            myAnimator.SetBool("isRunning", true);
        }
        else // If enemy is not running disable enemy footstep particles and set idle animation
        {
            if (footstepParticleSystem.isPlaying)
            {
                footstepParticleSystem.Stop();
            }
            myAnimator.SetBool("isRunning", false);
        }
    }

    // If enemy enters any triggers
    void OnTriggerEnter2D(Collider2D col)
    {
        // If enemy enters weapon trigger and is not invicible
        if (col.gameObject.tag == "Weapon" && !IFrames)
        {

            // Spray blood particles, subtract health from enemy, tint enemy red and start the damagetint coroutine
            bloodParticleSystem.Emit(50);
            enemyHealth -= playerDamageMult;
            objectRenderer.material.color = damageColor;
            StartCoroutine(DamageTint());

            // Start damageknockback coroutine if enemy is not on wall
            if (!hitWall)
            {
                StartCoroutine(DamageKnockback());
            }
        }
    }

    // Enemy collides with anything
    void OnCollisionEnter2D(Collision2D col)
    {
        // If enemy hits wall hitWall true
        if (col.gameObject.tag == "Wall")
        {
            hitWall = true;
        }
    }

    // Enemy stops colliding with anything
    void OnCollisionExit2D(Collision2D col)
    {
        // If not colliding with wall anymore, hitWall false
        if (col.gameObject.tag == "Wall")
        {
            hitWall = false;
        }
    }
}