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


public class LetterBoxer : MonoBehaviour
{    
    public enum ReferenceMode { DesignedAspectRatio, OrginalResolution };

    public Color matteColor = new Color(0, 0, 0, 1);
    public ReferenceMode referenceMode; 
    public float x=16;
    public float y=9;  
    public float width = 960;
    public float height = 540;
    public bool onAwake = true;
    public bool onUpdate = true;

    private Camera cam;
    private Camera letterBoxerCamera;

    public void Awake()
    {
        // store reference to the camera
        cam = GetComponent<Camera>();

        // add the letterboxing camera
        AddLetterBoxingCamera();

        // perform sizing if onAwake is set
        if (onAwake)
        {
            PerformSizing();
        }
    }

    public void Update()
    {
        // perform sizing if onUpdate is set
        if (onUpdate)
        {
            PerformSizing();
        }
    }

    private void OnValidate()
    {
        x = Mathf.Max(1, x);
        y = Mathf.Max(1, y);
        width = Mathf.Max(1, width);
        height = Mathf.Max(1, height);
    }

    private void AddLetterBoxingCamera()
    {
        // check that we don't have a camera already at -100 (lowest depth) which will cause issues
        Camera[] allCameras = FindObjectsOfType<Camera>();
        foreach (Camera camera in allCameras)
        {             
            if (camera.depth == -100)
            {
                Debug.LogError("Found " + camera.name + " with a depth of -100. Will cause letter boxing issues. Please increase it's depth.");
            }
        }

        // create a camera to render bcakground used for matte bars
        letterBoxerCamera = new GameObject().AddComponent<Camera>();
        letterBoxerCamera.backgroundColor = matteColor;
        letterBoxerCamera.cullingMask = 0;
        letterBoxerCamera.depth = -100;
        letterBoxerCamera.farClipPlane = 1;
        letterBoxerCamera.useOcclusionCulling = false;
        letterBoxerCamera.allowHDR = false;
        letterBoxerCamera.allowMSAA = false;
        letterBoxerCamera.clearFlags = CameraClearFlags.Color;
        letterBoxerCamera.name = "Letter Boxer Camera";        
    }

    // based on logic here from http://gamedesigntheory.blogspot.com/2010/09/controlling-aspect-ratio-in-unity.html
    private void PerformSizing()
    {
        // calc based on aspect ratio
        float targetRatio = x / y;

        // recalc if using resolution as reference
        if (referenceMode == LetterBoxer.ReferenceMode.OrginalResolution)
        {
            targetRatio = width / height;
        }

        // determine the game window's current aspect ratio
        float windowaspect = (float)Screen.width / (float)Screen.height;

        // current viewport height should be scaled by this amount
        float scaleheight = windowaspect / targetRatio;

        // if scaled height is less than current height, add letterbox
        if (scaleheight < 1.0f)
        {
            Rect rect = cam.rect;

            rect.width = 1.0f;
            rect.height = scaleheight;
            rect.x = 0;
            rect.y = (1.0f - scaleheight) / 2.0f;

            cam.rect = rect;
        }
        else // add pillarbox
        {
            float scalewidth = 1.0f / scaleheight;

            Rect rect = cam.rect;

            rect.width = scalewidth;
            rect.height = 1.0f;
            rect.x = (1.0f - scalewidth) / 2.0f;
            rect.y = 0;

            cam.rect = rect;
        }
    }
}