import type { DisplayObject } from 'pixi.js';
import { Point, Rectangle } from 'pixi.js';
import { Component } from '../core/component';
import type { IPoint } from '../data/geom';
import { EngineEvent } from '../events/engine-events';

export class Camera extends Component<DisplayObject> {

	/**
	 * Target for camera to follow.
	 */
	get target() { return this._target; }
	set target(v) {

		if (v) {
			this._target = v;

			this._viewRect.x = v.x - this._halfWidth;
			this._viewRect.y = v.y - this._halfHeight;

			this._panClip?.position.set(this._halfWidth - v.x, this._halfHeight - v.y);
		}

	}

	/**
	 * Set the clip that moves to change the camera's position.
	 * This should be a clip that contains all game objects.
	 * (As opposed to static UI elements, backgrounds, etc.)
	 */
	get panClip() { return this._panClip }
	set panClip(v: DisplayObject | null | undefined) {
		this._panClip = v;
	}

	get minScale(): number { return this._minScale || 1; }
	set minScale(v: number) { this._minScale = v; }

	get maxScale(): number { return this._maxScale || 1; }
	set maxScale(v: number) { this._maxScale = v; }


	get viewScale(): number { return this._viewScale; }
	set viewScale(v: number) {

		this._viewScale = v;
		this._panClip?.scale.set(v, v);

	}

	get x(): number { return -(this._panClip?.x ?? 0); }
	set x(v: number) {

		this._viewRect.x = v * this._viewScale;
		if (this._panClip != null) {
			this._panClip.x = -this._viewRect.x;
		}

	}

	get y(): number { return -(this._panClip?.y ?? 0); }
	set y(v: number) {


		this._viewRect.y = v * this._viewScale;
		if (this._panClip != null) {
			this._panClip.y = -this._viewRect.y;
		}


	}

	/**
	 * @property {Rectangle} Visible rectangle in the Camera's coordinate system.
	 */
	get viewRect() { return this._viewRect; }

	get centerX() { return this._viewRect.x + this._halfWidth; }
	get centerY() { return this._viewRect.y + this._halfHeight; }

	get center(): IPoint {
		return new Point(
			this._viewRect.x + this._halfWidth,
			this._viewRect.y + this._halfHeight);
	}

	get left(): number { return this._viewRect.left; }
	get right(): number { return this._viewRect.right; }
	get top(): number { return this._viewRect.top; }
	get bottom(): number { return this._viewRect.bottom; }

	/**
	 * Target camera should track.
	 */
	private _target: { position: IPoint, x: number, y: number } | null = null;
	private _minScale: number = 0;
	private _maxScale: number = 0;
	private _viewScale: number = 0;
	private readonly _viewRect: Rectangle = new Rectangle();
	private _panClip?: DisplayObject | null;

	private _halfWidth: number = 0;
	private _halfHeight: number = 0;


	constructor(rect: Rectangle) {
		super();

		this.resized(rect);

	}

	init() {

		this._target = null;
		this._panClip = this.actor!.clip;

		this._viewScale = 1;

		this._halfWidth = this._viewRect.width / 2;
		this._halfHeight = this._viewRect.height / 2;

		this.game!.on(EngineEvent.ScreenResized, this.resized, this);
	}

	/**
	 * Call when view size has changed.
	 * @param rect 
	 */
	resized(rect: { x: number, y: number, width: number, height: number }) {

		this._viewRect.width = rect.width;
		this._viewRect.height = rect.height;

		this._halfWidth = rect.width / 2;
		this._halfHeight = rect.height / 2;

	}

	/**
	 * Determines if an item is completely within the view.
	 * @param {*} it
	 * @returns true if item is completely onscreen, false otherwise.
	 */
	containsItem(it: any): boolean {
		throw Error("Not implemented.");
	}

	/**
	 *
	 * @param {*} it
	 * @returns true if item is within the camera view, false otherwise.
	 */
	itemInView(it: any): boolean {
		throw Error("Not implemented.");
	}

	/**
	 *
	 * @param p
	 */
	ptInView(p: IPoint): Boolean {
		return this._viewRect?.contains(p.x, p.y) ?? false;
	}

	/**
	 *
	 * @param {Rectangle} r
	 * @returns true if a rectangle falls within the camera view, false otherwise.
	 */
	rectInView(r: Rectangle) {

		return r.x < this._viewRect.right &&
			r.right > this._viewRect.x &&
			r.y < this._viewRect.bottom &&
			r.bottom > this._viewRect.y;

	}

	/**
	 *
	 * @param  global
	 * @param  dest=null
	 * @returns {Point}
	 */
	toCameraPoint(global: IPoint, dest?: IPoint) {

		return this._panClip?.toLocal(global, undefined, dest ?? new Point());

	}

	update() {

		if (this._target === null) return;

		const targPos = this._target.position;

		const destX = this._halfWidth - targPos.x;
		const destY = this._halfHeight - targPos.y;

		const pos = this._panClip!.position;
		pos.set(
			pos.x + (destX - pos.x) / 4,
			pos.y + (destY - pos.y) / 4
		);

		//console.log('cam pos: ' + pos.x + ', '+ pos.y );

		this._viewRect.x = -pos.x;
		this._viewRect.y = -pos.y;

	}

	onDestroy() {

		this.game?.off(EngineEvent.ScreenResized, this.resized, this);
	}

}