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

/* place on whatever object you want people to start dragging from. (so script can access "OnMouseDown()" event)
 */

public class mouseLookin : MonoBehaviour
{

    public Camera mainCamera;           //place main game camera here. it will be rotated by mouse dragging 

    public float speed = 100.0f;        //modifies how fast the view moves. exposed so you can tweak in editor
    public float clampAngle = 80.0f;    // hard limit the up/down rotation to +/- this amount
    private float rotY = 0.0f;          // horizontal rotation (around the y axis)
    private float rotX = 0.0f;          // vertical rotation (around the x axis)

    bool movingView = false;            // flag for whether we are currently dragging view around

    /* when program starts, set initial values (so the first use doesn't snap view to some weird angle) 
     */
    void Start()
    {
        Vector3 rot = mainCamera.transform.localRotation.eulerAngles; // grab the camera's starting rotation.
        rotY = rot.y;
        rotX = rot.x;
    }

    /* when you press down (*or hold) mouse button - over the object this script is on 
     */
    void OnMouseDown()
    {
        movingView = true; //enables per frame stuff in Update() (below)
    }

    /* whenever you stop dragging with your mouse
     * note that this is mouseup anywhere (even if you are way far away from object that started it) 
     */
    void OnMouseUp()
    {
        movingView = false; //stops the mouse look 
    }

    void Update()
    {
        if (movingView)
        {
            Cursor.visible = false; //hide the cursor so it's not distracting while we look around

            float mouseX = Input.GetAxis("Mouse X"); //get left/right
            float mouseY = -Input.GetAxis("Mouse Y"); //get up/down

            rotY += mouseX * speed * Time.deltaTime; //rotate around Y axis, using mouse left/right, boost by speed, boost by time between frames

            rotX += mouseY * speed * Time.deltaTime; //rotate around X axis, using mouse up/down (and boost by speed, boost by time between frames)
            rotX = Mathf.Clamp(rotX, -clampAngle, clampAngle); //restrict up/down motion between + or - the clampAngle we set above. So we can only look so far up and down.

            Quaternion localRotation = Quaternion.Euler(rotX, rotY, 0.0f); //convert rotations to something Unity natively understands

            mainCamera.transform.rotation = localRotation; //apply rotation to the camera we set in Editor
        }
        else
        {
            Cursor.visible = true; //whenever we are not looking around, show the cursor
            //!!! this might be better handled in another "master" cursor management script, if other scripts want to show and hide the cursor
        }
    }

    /* called externally: by a "turn speed" UI slider
     */
    public void setMouseLookSpeed(float s)
    {
        speed = s;
    }
}