import { EntityView } from './entity';
import { Renderer } from './renderer/renderer';
import { SpriteCoords, SpriteView, SpriteViewBuilder } from './sprite';
import { loadImage, mkTexture } from './util/image';

import { MapData } from '../model/data/map';

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

interface StaticMapTile {
	type: 'static';
	image: HTMLImageElement;
}

interface EntityTile {
	type: 'entity';
	entity: EntityView;
}

type MapTile = StaticMapTile | EntityTile;

interface StaticTilesetTile {
	type: 'static';
	coords: SpriteCoords;
}

type TilesetTile = StaticTilesetTile | EntityTile;

interface Tileset {
	texture: WebGLTexture;
	tiles: TilesetTile[];
}

async function loadTile(r: Renderer, tile: string): Promise<MapTile> {
	const name = tile.substr(1);
	switch (tile[0]) {
		case '-':
			return {
				type: 'static',
				image: await loadImage(`resources/sprite/tile/${name}.png`),
			};

		case '@':
			return {
				type: 'entity',
				entity: await EntityView.load(r, name),
			};

		default:
			throw new Error('invalid tile specifier');
	}
}

function loadTiles(r: Renderer, tiles: string[]): Promise<MapTile[]> {
	return Promise.all(tiles.map((tile) => loadTile(r, tile)));
}

function mkTileset(r: Renderer, mapTiles: MapTile[]): Tileset {
	const tileSize = 32;

	const canvasDim = nextPowerOf2(Math.sqrt(mapTiles.length));
	const canvasSize = canvasDim * tileSize;

	const canvas = document.createElement('canvas');
	canvas.width = canvas.height = canvasSize;

	let x = 0;
	let y = 0;
	const tiles: TilesetTile[] = [];
	const ctx = canvas.getContext('2d') as CanvasRenderingContext2D;

	for (const tile of mapTiles) {
		switch (tile.type) {
			case 'static':
				ctx.drawImage(tile.image, x * tileSize, y * tileSize);
				tiles.push({
					type: 'static',
					coords: [
						x / canvasDim,
						y / canvasDim,
						(x + 1) / canvasDim,
						(y + 1) / canvasDim,
					],
				});

				x++;
				if (x === canvasDim) {
					x = 0;
					y++;
				}
				break;

			case 'entity':
				tiles.push(tile);
				break;
		}
	}

	const [texture] = mkTexture(r, canvas);

	return {
		texture,
		tiles,
	};
}

function addSprite(
	builder: SpriteViewBuilder,
	entityTiles: Array<[[number, number], EntityView]>,
	tileset: Tileset,
	x: number,
	y: number,
	tile: number,
): void {
	if (!tile) return;

	const tilesetTile = tileset.tiles[tile - 1];

	switch (tilesetTile.type) {
		case 'static':
			builder.addSprite([x, y, x + 1, y + 1], tilesetTile.coords);
			break;

		case 'entity':
			entityTiles.push([[x + 0.5, y + 0.5], tilesetTile.entity]);
			break;
	}
}

class MapLayerView {
	public constructor(
		private r: Renderer,
		private staticTiles: SpriteView,
		private entityTiles: Array<[[number, number], EntityView]>,
	) {}

	public render(time: number): void {
		this.r.setTranslation([0, 0]);
		this.staticTiles.render();

		for (const [coords, entity] of this.entityTiles) {
			this.r.setTranslation(coords);
			entity.renderByTime(time);
		}
	}
}

function buildMapLayer(r: Renderer, tileset: Tileset, layer: number[][]): MapLayerView {
	const builder = new SpriteViewBuilder(r, tileset.texture);
	const entityTiles: Array<[[number, number], EntityView]> = [];

	for (let x = 0; x < layer[0].length; x++)
		for (let y = 0; y < layer.length; y++) addSprite(builder, entityTiles, tileset, x, y, layer[y][x]);

	return new MapLayerView(r, builder.build(), entityTiles);
}

export class MapView {
	public static async load(r: Renderer, map: MapData): Promise<MapView> {
		const tiles = await loadTiles(r, map.tiles);
		const tileset = mkTileset(r, tiles);

		const layers = map.layers.map((layer) => buildMapLayer(r, tileset, layer.tiles));
		return new MapView(layers);
	}

	private constructor(private layers: MapLayerView[]) {}

	public render(time: number): void {
		for (const layer of this.layers) layer.render(time);
	}
}