/******************************************************************************
 * Spine Runtimes License Agreement
 * Last updated January 1, 2020. Replaces all prior versions.
 *
 * Copyright (c) 2013-2020, Esoteric Software LLC
 *
 * Integration of the Spine Runtimes into software or otherwise creating
 * derivative works of the Spine Runtimes is permitted under the terms and
 * conditions of Section 2 of the Spine Editor License Agreement:
 * http://esotericsoftware.com/spine-editor-license
 *
 * Otherwise, it is permitted to integrate the Spine Runtimes into software
 * or otherwise create derivative works of the Spine Runtimes (collectively,
 * "Products"), provided that each user of the Products must obtain their own
 * Spine Editor license and redistribution of the Products in any form must
 * include this license and copyright notice.
 *
 * THE SPINE RUNTIMES ARE PROVIDED BY ESOTERIC SOFTWARE LLC "AS IS" AND ANY
 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED. IN NO EVENT SHALL ESOTERIC SOFTWARE LLC BE LIABLE FOR ANY
 * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES,
 * BUSINESS INTERRUPTION, OR LOSS OF USE, DATA, OR PROFITS) HOWEVER CAUSED AND
 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 * THE SPINE RUNTIMES, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 *****************************************************************************/

import { Disposable } from "@esotericsoftware/spine-core";
import { GLTexture } from "./GLTexture";
import { Mesh, Position2Attribute, ColorAttribute, TexCoordAttribute, Color2Attribute } from "./Mesh";
import { Shader } from "./Shader";
import { ManagedWebGLRenderingContext } from "./WebGL";

export class PolygonBatcher implements Disposable {
	private context: ManagedWebGLRenderingContext;
	private drawCalls: number;
	private isDrawing = false;
	private mesh: Mesh;
	private shader: Shader = null;
	private lastTexture: GLTexture = null;
	private verticesLength = 0;
	private indicesLength = 0;
	private srcColorBlend: number;
	private srcAlphaBlend: number;
	private dstBlend: number;

	constructor (context: ManagedWebGLRenderingContext | WebGLRenderingContext, twoColorTint: boolean = true, maxVertices: number = 10920) {
		if (maxVertices > 10920) throw new Error("Can't have more than 10920 triangles per batch: " + maxVertices);
		this.context = context instanceof ManagedWebGLRenderingContext ? context : new ManagedWebGLRenderingContext(context);
		let attributes = twoColorTint ?
			[new Position2Attribute(), new ColorAttribute(), new TexCoordAttribute(), new Color2Attribute()] :
			[new Position2Attribute(), new ColorAttribute(), new TexCoordAttribute()];
		this.mesh = new Mesh(context, attributes, maxVertices, maxVertices * 3);
		let gl = this.context.gl;
		this.srcColorBlend = gl.SRC_ALPHA;
		this.srcAlphaBlend = gl.ONE;
		this.dstBlend = gl.ONE_MINUS_SRC_ALPHA;
	}

	begin (shader: Shader) {
		if (this.isDrawing) throw new Error("PolygonBatch is already drawing. Call PolygonBatch.end() before calling PolygonBatch.begin()");
		this.drawCalls = 0;
		this.shader = shader;
		this.lastTexture = null;
		this.isDrawing = true;

		let gl = this.context.gl;
		gl.enable(gl.BLEND);
		gl.blendFuncSeparate(this.srcColorBlend, this.dstBlend, this.srcAlphaBlend, this.dstBlend);
	}

	setBlendMode (srcColorBlend: number, srcAlphaBlend: number, dstBlend: number) {
		this.srcColorBlend = srcColorBlend;
		this.srcAlphaBlend = srcAlphaBlend;
		this.dstBlend = dstBlend;
		if (this.isDrawing) {
			this.flush();
			let gl = this.context.gl;
			gl.blendFuncSeparate(srcColorBlend, dstBlend, srcAlphaBlend, dstBlend);
		}
	}

	draw (texture: GLTexture, vertices: ArrayLike<number>, indices: Array<number>) {
		if (texture != this.lastTexture) {
			this.flush();
			this.lastTexture = texture;
		} else if (this.verticesLength + vertices.length > this.mesh.getVertices().length ||
			this.indicesLength + indices.length > this.mesh.getIndices().length) {
			this.flush();
		}

		let indexStart = this.mesh.numVertices();
		this.mesh.getVertices().set(vertices, this.verticesLength);
		this.verticesLength += vertices.length;
		this.mesh.setVerticesLength(this.verticesLength)

		let indicesArray = this.mesh.getIndices();
		for (let i = this.indicesLength, j = 0; j < indices.length; i++, j++)
			indicesArray[i] = indices[j] + indexStart;
		this.indicesLength += indices.length;
		this.mesh.setIndicesLength(this.indicesLength);
	}

	flush () {
		if (this.verticesLength == 0) return;

		this.lastTexture.bind();
		this.mesh.draw(this.shader, this.context.gl.TRIANGLES);

		this.verticesLength = 0;
		this.indicesLength = 0;
		this.mesh.setVerticesLength(0);
		this.mesh.setIndicesLength(0);
		this.drawCalls++;
	}

	end () {
		if (!this.isDrawing) throw new Error("PolygonBatch is not drawing. Call PolygonBatch.begin() before calling PolygonBatch.end()");
		if (this.verticesLength > 0 || this.indicesLength > 0) this.flush();
		this.shader = null;
		this.lastTexture = null;
		this.isDrawing = false;

		let gl = this.context.gl;
		gl.disable(gl.BLEND);
	}

	getDrawCalls () {
		return this.drawCalls;
	}

	dispose () {
		this.mesh.dispose();
	}
}