using System.Collections;
using System.Collections.Generic;
using UnityEngine;
using UnityEngine.Assertions;

public enum CurrentCommand { defend, moveForward, retreat }

// Left is Player, Enemy is right.
public enum Side { left = 1, right = -1 }

public class Unit : MonoBehaviour
{
    public string unitName;

    [SerializeField]
    private int basicAttack;
    private int finalAttack;

    [SerializeField]
    private int currentDefense;

    [SerializeField]
    private int basicMaxDefense;
    private int finalMaxDefense;

    [SerializeField]
    private CardTag[] cardTags;

    [SerializeField]
    private int attackRange = 1;
    [SerializeField]
    private int movement = 1;

    [SerializeField]
    private CurrentCommand currentCommand;

    [SerializeField]
    private Cell standingCell;
    private Cell destinationCell;
    private CellMap cellMap;

    [SerializeField]
    private Side side;

    public bool walkingToDestination = false;


    // Start is called before the first frame update
    void Start()
    {
        cellMap = FindObjectOfType<CellMap>();
        transform.position = standingCell.transform.position;
        transform.position = new Vector3(transform.position.x, transform.position.y, -1);
        standingCell.standingUnit = this;
    }

    // Update is called once per frame
    void Update()
    {
        if (walkingToDestination && destinationCell && transform.position != destinationCell.transform.position)
        {
            Vector3 moveVec = destinationCell.transform.position - transform.position;
            transform.position = new Vector3(transform.position.x + moveVec.x * 5.0f * Time.deltaTime, transform.position.y + moveVec.y * 5.0f * Time.deltaTime, -1);

            Debug.Log("Manitude: " + moveVec.magnitude);

            if ((Mathf.Approximately(transform.position.x, destinationCell.transform.position.x)
                && Mathf.Approximately(transform.position.y, destinationCell.transform.position.y))
                || moveVec.magnitude <= 1)
            {
                walkingToDestination = false;
                transform.position = new Vector3(destinationCell.transform.position.x, destinationCell.transform.position.y, -1);
                destinationCell = null;
                Debug.Log("Arrived.");
            }
        }
    }

    public void MoveAction()
    {
        if (walkingToDestination)
        {
            Debug.Log("Can start a new move action. Unit is still moving.");
            return;
        }

        Debug.Log("Call MoveAction().");
        switch (currentCommand)
        {
            case CurrentCommand.defend:
                break;
            case CurrentCommand.moveForward:
                Debug.Log("Try Move Forward.");
                if (checkDestinationCellEmpty())
                {
                    // Attack()
                    Debug.Log("Start Moving.");
                    MoveToCell(destinationCell);
                    walkingToDestination = true;
                }
                else
                {
                    Debug.Log("Can't Move.");
                    // Check the unit is facing the camp or unit.
                    if (destinationCell)
                    {
                        // Check the unit is Allie or Enemy.
                        if (destinationCell.standingUnit.side == side)
                        {
                            // Check the Allie is swappable or not.

                        }
                        else
                        {
                            // Can't move to cell this is standed by enemy.
                        }
                    }
                    else
                    {
                        // Facing the camp.
                    }
                }
                break;
            case CurrentCommand.retreat:
                break;
            default:
                break;
        }
    }

    bool checkDestinationCellEmpty(bool retreat = false)
    {
        int currentXPos = standingCell.xPos;
        int movePath = 0;

        if (retreat)
        {
            movePath = movement * -(int)side;
        }
        else
        {
            movePath = movement * (int)side;
        }

        int destinationXPos = standingCell.xPos + movePath;

        // Mean the destination cell is the Camp.
        if (destinationXPos < 0 || destinationXPos >= cellMap.column)
        {
            return false;
        }

        destinationCell = cellMap.GetCell(destinationXPos, standingCell.yPos);

        if (destinationCell.standingUnit == null)
        {
            return true;
        }
        else
        {
            return false;
        }
    }

    void MoveToCell(Cell cell)
    {
        Assert.IsTrue(destinationCell.standingUnit == null, "Trying to move a cell that is already be standing by another unit.");

        standingCell.standingUnit = null;
        standingCell = cell;
        cell.standingUnit = this;
    }
}