package kha.graphics2;

import kha.math.Vector2;
import kha.math.FastVector2;
import kha.graphics2.Graphics;
import kha.graphics2.VerTextAlignment;
import kha.graphics2.HorTextAlignment;

/**
 * Static extension functions for Graphics2.
 * Usage: "using kha.graphics2.GraphicsExtension;"
 */
class GraphicsExtension {
	/**
	 * Draws a arc.
	 * @param	ccw (optional) Specifies whether the drawing should be counterclockwise.
	 * @param	segments (optional) The amount of lines that should be used to draw the arc.
	 */
	@:deprecated("GraphicsExtension will be removed. If you want to use it, simply copy it into your own project and then remove this message.")
	public static function drawArc(g2: Graphics, cx: Float, cy: Float, radius: Float, sAngle: Float, eAngle: Float, strength: Float = 1, ccw: Bool = false,
			segments: Int = 0): Void {
		#if kha_html5
		if (kha.SystemImpl.gl == null) {
			var g: kha.js.CanvasGraphics = cast g2;
			radius -= strength / 2; // reduce radius to fit the line thickness within image width/height
			g.drawArc(cx, cy, radius, sAngle, eAngle, strength, ccw);
			return;
		}
		#end

		sAngle = sAngle % (Math.PI * 2);
		eAngle = eAngle % (Math.PI * 2);

		if (ccw) {
			if (eAngle > sAngle)
				eAngle -= Math.PI * 2;
		}
		else if (eAngle < sAngle)
			eAngle += Math.PI * 2;

		radius += strength / 2;
		if (segments <= 0)
			segments = Math.floor(10 * Math.sqrt(radius));

		var theta = (eAngle - sAngle) / segments;
		var c = Math.cos(theta);
		var s = Math.sin(theta);

		var x = Math.cos(sAngle) * radius;
		var y = Math.sin(sAngle) * radius;

		for (n in 0...segments) {
			var px = x + cx;
			var py = y + cy;

			var t = x;
			x = c * x - s * y;
			y = c * y + s * t;

			drawInnerLine(g2, x + cx, y + cy, px, py, strength);
		}
	}

	/**
	 * Draws a filled arc.
	 * @param	ccw (optional) Specifies whether the drawing should be counterclockwise.
	 * @param	segments (optional) The amount of lines that should be used to draw the arc.
	 */
	@:deprecated("GraphicsExtension will be removed. If you want to use it, simply copy it into your own project and then remove this message.")
	public static function fillArc(g2: Graphics, cx: Float, cy: Float, radius: Float, sAngle: Float, eAngle: Float, ccw: Bool = false,
			segments: Int = 0): Void {
		#if kha_html5
		if (kha.SystemImpl.gl == null) {
			var g: kha.js.CanvasGraphics = cast g2;
			g.fillArc(cx, cy, radius, sAngle, eAngle, ccw);
			return;
		}
		#end

		sAngle = sAngle % (Math.PI * 2);
		eAngle = eAngle % (Math.PI * 2);

		if (ccw) {
			if (eAngle > sAngle)
				eAngle -= Math.PI * 2;
		}
		else if (eAngle < sAngle)
			eAngle += Math.PI * 2;

		if (segments <= 0)
			segments = Math.floor(10 * Math.sqrt(radius));

		var theta = (eAngle - sAngle) / segments;
		var c = Math.cos(theta);
		var s = Math.sin(theta);

		var x = Math.cos(sAngle) * radius;
		var y = Math.sin(sAngle) * radius;
		var sx = x + cx;
		var sy = y + cy;

		for (n in 0...segments) {
			var px = x + cx;
			var py = y + cy;

			var t = x;
			x = c * x - s * y;
			y = c * y + s * t;

			g2.fillTriangle(px, py, x + cx, y + cy, sx, sy);
		}
	}

	/**
	 * Draws a circle.
	 * @param	segments (optional) The amount of lines that should be used to draw the circle.
	 */
	@:deprecated("GraphicsExtension will be removed. If you want to use it, simply copy it into your own project and then remove this message.")
	public static function drawCircle(g2: Graphics, cx: Float, cy: Float, radius: Float, strength: Float = 1, segments: Int = 0): Void {
		#if kha_html5
		if (kha.SystemImpl.gl == null) {
			var g: kha.js.CanvasGraphics = cast g2;
			radius -= strength / 2; // reduce radius to fit the line thickness within image width/height
			g.drawCircle(cx, cy, radius, strength);
			return;
		}
		#end
		radius += strength / 2;

		if (segments <= 0)
			segments = Math.floor(10 * Math.sqrt(radius));

		var theta = 2 * Math.PI / segments;
		var c = Math.cos(theta);
		var s = Math.sin(theta);

		var x = radius;
		var y = 0.0;

		for (n in 0...segments) {
			var px = x + cx;
			var py = y + cy;

			var t = x;
			x = c * x - s * y;
			y = c * y + s * t;
			drawInnerLine(g2, x + cx, y + cy, px, py, strength);
		}
	}

	@:deprecated("GraphicsExtension will be removed. If you want to use it, simply copy it into your own project and then remove this message.")
	static function drawInnerLine(g2: Graphics, x1: Float, y1: Float, x2: Float, y2: Float, strength: Float): Void {
		var side = y2 > y1 ? 1 : 0;
		if (y2 == y1)
			side = x2 - x1 > 0 ? 1 : 0;

		var vec = new FastVector2();
		if (y2 == y1)
			vec.setFrom(new FastVector2(0, -1));
		else
			vec.setFrom(new FastVector2(1, -(x2 - x1) / (y2 - y1)));
		vec.length = strength;
		var p1 = new FastVector2(x1 + side * vec.x, y1 + side * vec.y);
		var p2 = new FastVector2(x2 + side * vec.x, y2 + side * vec.y);
		var p3 = p1.sub(vec);
		var p4 = p2.sub(vec);
		g2.fillTriangle(p1.x, p1.y, p2.x, p2.y, p3.x, p3.y);
		g2.fillTriangle(p3.x, p3.y, p2.x, p2.y, p4.x, p4.y);
	}

	/**
	 * Draws a filled circle.
	 * @param	segments (optional) The amount of lines that should be used to draw the circle.
	 */
	@:deprecated("GraphicsExtension will be removed. If you want to use it, simply copy it into your own project and then remove this message.")
	public static function fillCircle(g2: Graphics, cx: Float, cy: Float, radius: Float, segments: Int = 0): Void {
		#if kha_html5
		if (kha.SystemImpl.gl == null) {
			var g: kha.js.CanvasGraphics = cast g2;
			g.fillCircle(cx, cy, radius);
			return;
		}
		#end

		if (segments <= 0) {
			segments = Math.floor(10 * Math.sqrt(radius));
		}

		var theta = 2 * Math.PI / segments;
		var c = Math.cos(theta);
		var s = Math.sin(theta);

		var x = radius;
		var y = 0.0;

		for (n in 0...segments) {
			var px = x + cx;
			var py = y + cy;

			var t = x;
			x = c * x - s * y;
			y = c * y + s * t;

			g2.fillTriangle(px, py, x + cx, y + cy, cx, cy);
		}
	}

	/**
	 * Draws a convex polygon.
	 */
	@:deprecated("GraphicsExtension will be removed. If you want to use it, simply copy it into your own project and then remove this message.")
	public static function drawPolygon(g2: Graphics, x: Float, y: Float, vertices: Array<Vector2>, strength: Float = 1) {
		var iterator = vertices.iterator();
		var v0 = iterator.next();
		var v1 = v0;

		while (iterator.hasNext()) {
			var v2 = iterator.next();
			g2.drawLine(v1.x + x, v1.y + y, v2.x + x, v2.y + y, strength);
			v1 = v2;
		}
		g2.drawLine(v1.x + x, v1.y + y, v0.x + x, v0.y + y, strength);
	}

	/**
	 * Draws a filled convex polygon.
	 */
	@:deprecated("GraphicsExtension will be removed. If you want to use it, simply copy it into your own project and then remove this message.")
	public static function fillPolygon(g2: Graphics, x: Float, y: Float, vertices: Array<Vector2>) {
		var iterator = vertices.iterator();

		if (!iterator.hasNext())
			return;
		var v0 = iterator.next();

		if (!iterator.hasNext())
			return;
		var v1 = iterator.next();

		while (iterator.hasNext()) {
			var v2 = iterator.next();
			g2.fillTriangle(v0.x + x, v0.y + y, v1.x + x, v1.y + y, v2.x + x, v2.y + y);
			v1 = v2;
		}
	}

	/**
	 * Draws a cubic bezier using 4 pairs of points. If the x and y arrays have a length bigger then 4, the additional
	 * points will be ignored. With a length smaller of 4 a error will occur, there is no check for this.
	 * You can construct the curves visually in Inkscape with a path using default nodes.
	 * Provide x and y in the following order: startPoint, controlPoint1, controlPoint2, endPoint
	 * Reference: http://devmag.org.za/2011/04/05/bzier-curves-a-tutorial/
	 */
	@:deprecated("GraphicsExtension will be removed. If you want to use it, simply copy it into your own project and then remove this message.")
	public static function drawCubicBezier(g2: Graphics, x: Array<Float>, y: Array<Float>, segments: Int = 20, strength: Float = 1.0): Void {
		var t: Float;

		var q0 = calculateCubicBezierPoint(0, x, y);
		var q1: Array<Float>;

		for (i in 1...(segments + 1)) {
			t = i / segments;
			q1 = calculateCubicBezierPoint(t, x, y);
			g2.drawLine(q0[0], q0[1], q1[0], q1[1], strength);
			q0 = q1;
		}
	}

	/**
	 * Draws multiple cubic beziers joined by the end point. The minimum size is 4 pairs of points (a single curve).
	 */
	@:deprecated("GraphicsExtension will be removed. If you want to use it, simply copy it into your own project and then remove this message.")
	public static function drawCubicBezierPath(g2: Graphics, x: Array<Float>, y: Array<Float>, segments: Int = 20, strength: Float = 1.0): Void {
		var i = 0;
		var t: Float;
		var q0: Array<Float> = null;
		var q1: Array<Float> = null;

		while (i < x.length - 3) {
			if (i == 0)
				q0 = calculateCubicBezierPoint(0, [x[i], x[i + 1], x[i + 2], x[i + 3]], [y[i], y[i + 1], y[i + 2], y[i + 3]]);

			for (j in 1...(segments + 1)) {
				t = j / segments;
				q1 = calculateCubicBezierPoint(t, [x[i], x[i + 1], x[i + 2], x[i + 3]], [y[i], y[i + 1], y[i + 2], y[i + 3]]);
				g2.drawLine(q0[0], q0[1], q1[0], q1[1], strength);
				q0 = q1;
			}

			i += 3;
		}
	}

	@:deprecated("GraphicsExtension will be removed. If you want to use it, simply copy it into your own project and then remove this message.")
	static function calculateCubicBezierPoint(t: Float, x: Array<Float>, y: Array<Float>): Array<Float> {
		var u: Float = 1 - t;
		var tt: Float = t * t;
		var uu: Float = u * u;
		var uuu: Float = uu * u;
		var ttt: Float = tt * t;

		// first term
		var p: Array<Float> = [uuu * x[0], uuu * y[0]];

		// second term
		p[0] += 3 * uu * t * x[1];
		p[1] += 3 * uu * t * y[1];

		// third term
		p[0] += 3 * u * tt * x[2];
		p[1] += 3 * u * tt * y[2];

		// fourth term
		p[0] += ttt * x[3];
		p[1] += ttt * y[3];

		return p;
	}

	@:deprecated("GraphicsExtension will be removed. If you want to use it, simply copy it into your own project and then remove this message.")
	static public function drawAlignedString(g2: Graphics, text: String, x: Float, y: Float, horAlign: HorTextAlignment, verAlign: VerTextAlignment): Void {
		var xoffset = 0.0;
		if (horAlign == TextCenter || horAlign == TextRight) {
			var width = g2.font.width(g2.fontSize, text);
			if (horAlign == TextCenter) {
				xoffset = -width * 0.5;
			}
			else {
				xoffset = -width;
			}
		}
		var yoffset = 0.0;
		if (verAlign == TextMiddle || verAlign == TextBottom) {
			var height = g2.font.height(g2.fontSize);
			if (verAlign == TextMiddle) {
				yoffset = -height * 0.5;
			}
			else {
				yoffset = -height;
			}
		}
		g2.drawString(text, x + xoffset, y + yoffset);
	}

	@:deprecated("GraphicsExtension will be removed. If you want to use it, simply copy it into your own project and then remove this message.")
	static public function drawAlignedCharacters(g2: Graphics, text: Array<Int>, start: Int, length: Int, x: Float, y: Float, horAlign: HorTextAlignment,
			verAlign: VerTextAlignment): Void {
		var xoffset = 0.0;
		if (horAlign == TextCenter || horAlign == TextRight) {
			var width = g2.font.widthOfCharacters(g2.fontSize, text, start, length);
			if (horAlign == TextCenter) {
				xoffset = -width * 0.5;
			}
			else {
				xoffset = -width;
			}
		}
		var yoffset = 0.0;
		if (verAlign == TextMiddle || verAlign == TextBottom) {
			var height = g2.font.height(g2.fontSize);
			if (verAlign == TextMiddle) {
				yoffset = -height * 0.5;
			}
			else {
				yoffset = -height;
			}
		}
		g2.drawCharacters(text, start, length, x + xoffset, y + yoffset);
	}
}