'use strict';


import * as util from '../util';
import EntityPosition from '../model/EntityPosition';
import MapData from '../model/MapData';


const tileSize = 32;

const body = document.getElementsByTagName('body')[0];


function loadImage(url: string): Promise<HTMLImageElement> {
        return new Promise(function(resolve, reject) {
                var img = new Image();
                img.addEventListener('load', () => { resolve(img); });
                img.addEventListener('error', () => { reject(Error('Failed to load ' + url)); });
                img.src = url;
        });
}

function loadImages(imgs: {[key: string]: string}): Promise<{[key: string]: HTMLImageElement}> {
        return util.mapPromises(_.mapValues(imgs, loadImage));
}

function loadTiles(tiles: {[key: string]: {file: string}}): Promise<{[key: string]: HTMLImageElement}> {
        return loadImages(_.mapValues(tiles, (t) => `resources/sprite/tile/${t.file}.png`));
}

function loadEntities(entities: EntityPosition[]): Promise<{[key: string]: HTMLImageElement}> {
        var p: {[key: string]: Promise<HTMLImageElement>} = {};

        entities.forEach(e => {
                p[e.entity.name] = loadImage(`resources/sprite/entity/${e.entity.name}.png`);
        });

        return util.mapPromises(p);
}


export default class MapView {
        private redrawPending: boolean = false;

        private canvas: HTMLCanvasElement;
        private ctx: CanvasRenderingContext2D;

        private tiles: {[key: string]: HTMLImageElement};
        private entitySprites: {[key: string]: HTMLImageElement};

        constructor(private map: MapData,
                    private entities: {[key: string]: EntityPosition},
                    private updateState: (time: number) => void) {
                this.canvas = document.createElement('canvas');
                this.canvas.style.position = 'absolute';
                body.appendChild(this.canvas);

                this.ctx = this.canvas.getContext('2d');

                window.addEventListener('resize', () => this.setSize());
                this.setSize();

                var tilesReady = loadTiles(map.tiles).then((tiles) => {
                        this.tiles = tiles;
                });

                var entitiesReady = loadEntities(this.getEntities()).then((entities) => {
                        this.entitySprites = entities;
                });

                Promise.all([tilesReady, entitiesReady]).then(() => {
                        this.redraw();
                });
        }

        private getEntities(): EntityPosition[] {
                return _.values<EntityPosition>(this.entities);
        }

        private setSize() {
                var e = document.documentElement;
                this.canvas.width = window.innerWidth || e.clientWidth || body.clientWidth;
                this.canvas.height = window.innerHeight || e.clientHeight || body.clientHeight;

                this.redraw()
        }

        private drawTile(x: number, y: number, tile: HTMLImageElement) {
                if (!tile)
                        return;

                this.ctx.drawImage(tile, x, y);
        }

        private drawEntity(e: EntityPosition, time: number): boolean {
                var sprite = this.entitySprites[e.entity.name];
                if (!sprite)
                        return false;

                var x: number, y: number;

                if (e.transition) {
                        var t = e.transition;
                        var d = (time - t.start) / (t.end-t.start);

                        x = (1-d) * t.orig.x + d * t.dest.x;
                        y = (1-d) * t.orig.y + d * t.dest.y;
                }
                else {
                        x = e.position.x;
                        y = e.position.y;
                }

                this.ctx.drawImage(
                        sprite,
                        e.direction*tileSize, 0,
                        tileSize, tileSize,
                        x*tileSize, y*tileSize,
                        tileSize, tileSize
                );

                return !!e.transition;
        }

        private draw(time: number) {
                this.updateState(time);

                this.redrawPending = false;

                this.ctx.clearRect(0, 0, this.canvas.width, this.canvas.height);

                if (!this.tiles || !this.entitySprites)
                        return;

                this.map.layers.forEach((layer) => {
                        let y = 0;

                        layer.forEach((row) => {
                                let x = 0;

                                for (let tile in row) {
                                        this.drawTile(x, y, this.tiles[row[tile]]);
                                        x += tileSize;
                                }

                                y += tileSize;
                        });
                });

                var animate = false;

                this.getEntities().forEach(e => {
                        if (this.drawEntity(e, time))
                                animate = true;
                });

                if (animate)
                        this.redraw();
        }

        redraw() {
                if (this.redrawPending)
                        return;

                this.redrawPending = true;
                window.requestAnimationFrame((time: number) => this.draw(time));
        }
}