import {nextPowerOf2} from '../util';

import MapState from '../model/state/MapState';
import Renderer from './renderer/Renderer';

export default class MapView {
	public static readonly tileSize: number = 32;

	private redrawPending: boolean = false;

	private readonly vertexBuffer: WebGLBuffer;
	private readonly textureBuffer: WebGLBuffer;

	constructor(
		private readonly r: Renderer,
		private readonly map: MapState,
		private readonly tileTexture: WebGLTexture,
		private readonly tileMap: Map<string, number>,
	) {
		const vertexData: number[] = [];
		const textureData: number[] = [];

		const tileCount = nextPowerOf2(tileMap.size);

		for (let x = 0; x < map.data.width; x++)
			for (let y = 0; y < map.data.height; y++)
				this.addTile(vertexData, textureData, x, y, map.data.layers[0][y][x], tileCount);

		const gl = r.getContext();

		this.vertexBuffer = r.createBuffer();
		gl.bindBuffer(gl.ARRAY_BUFFER, this.vertexBuffer);
		gl.bufferData(gl.ARRAY_BUFFER, new Float32Array(vertexData), gl.STATIC_DRAW);

		this.textureBuffer = r.createBuffer();
		gl.bindBuffer(gl.ARRAY_BUFFER, this.textureBuffer);
		gl.bufferData(gl.ARRAY_BUFFER, new Float32Array(textureData), gl.STATIC_DRAW);
	}

	public draw(): void {
		const gl = this.r.getContext();

		gl.clear(gl.COLOR_BUFFER_BIT);

		gl.activeTexture(gl.TEXTURE0);
		gl.bindTexture(gl.TEXTURE_2D, this.tileTexture);
		gl.uniform1i(this.r.getSamplerLoc(), 0);

		gl.bindBuffer(gl.ARRAY_BUFFER, this.vertexBuffer);
		gl.vertexAttribPointer(this.r.getVertexPosLoc(), 2, gl.FLOAT, false, 0, 0);

		gl.bindBuffer(gl.ARRAY_BUFFER, this.textureBuffer);
		gl.vertexAttribPointer(this.r.getTextureCoordLoc(), 2, gl.FLOAT, false, 0, 0);

		gl.drawArrays(gl.TRIANGLES, 0, 6 * this.map.data.width * this.map.data.height);
	}

	private addTile(vertexData: number[], textureData: number[], x: number, y: number, tile: string, tileCount: number) {
		const tileID = this.tileMap.get(tile);
		if (tileID === undefined)
			throw new Error('invalid tile specifier in map data');

		vertexData.push(x); vertexData.push(y);
		vertexData.push(x + 1); vertexData.push(y);
		vertexData.push(x); vertexData.push(y + 1);

		vertexData.push(x); vertexData.push(y + 1);
		vertexData.push(x + 1); vertexData.push(y);
		vertexData.push(x + 1); vertexData.push(y + 1);

		textureData.push(tileID / tileCount); textureData.push(0);
		textureData.push((tileID + 1) / tileCount); textureData.push(0);
		textureData.push(tileID / tileCount); textureData.push(1);

		textureData.push(tileID / tileCount); textureData.push(1);
		textureData.push((tileID + 1) / tileCount); textureData.push(0);
		textureData.push((tileID + 1) / tileCount); textureData.push(1);
	}
}