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

public class OrbitCamera : MonoBehaviour
{
    public GameObject target;
    public float speedX = 1000;
    public float speedY = 1000;

    public float minTheta = 0;
    public float maxTheta = 89;

    private float distance = 0;
    private float phi = 0;
    private float theta = 0;
    private float yOffset = 0;

    // Start is called before the first frame update
    void Start()
    {
        // Calculate initial distance and position offset
        if (distance == 0)
        {
            Vector3 delta = transform.position - target.transform.position;
            yOffset = delta.y;
            delta.y = 0;
            distance = delta.magnitude;

        }
        UpdatePos();
    }

    // Update is called once per frame
    void Update()
    {
        if (Input.GetMouseButton(0))
        {
            phi = phi - speedX * Time.deltaTime * Input.GetAxis("Mouse X");
            while (phi < 0) phi += 360;
            while (phi > 360) phi -= 360;

            theta = Mathf.Clamp(theta - speedY * Time.deltaTime * Input.GetAxis("Mouse Y"), Mathf.Max(minTheta, -89), Mathf.Min(maxTheta, 89));
        }

        UpdatePos();        
    }

    private void UpdatePos()
    {
        Vector3 pos = target.transform.position;

        pos.x = distance * Mathf.Cos(theta * Mathf.Deg2Rad) * Mathf.Sin(phi * Mathf.Deg2Rad);
        pos.y = yOffset + distance * Mathf.Sin(theta * Mathf.Deg2Rad);
        pos.z = -distance * Mathf.Cos(theta * Mathf.Deg2Rad) * Mathf.Cos(phi * Mathf.Deg2Rad);

        transform.position = target.transform.position + pos;
        transform.LookAt(target.transform.position + new Vector3(0, yOffset, 0));
    }
}