import { Pixmap } from "rkgk/haku.js";
import { OnlineUsers } from "rkgk/online-users.js";

export class Chunk {
    constructor(size) {
        this.pixmap = new Pixmap(size, size);
        this.canvas = new OffscreenCanvas(size, size);
        this.ctx = this.canvas.getContext("2d");
        this.renderDirty = false;
    }

    destroy() {
        this.pixmap.destroy();
    }

    syncFromPixmap() {
        this.ctx.putImageData(this.pixmap.getImageData(), 0, 0);
    }

    syncToPixmap() {
        let imageData = this.ctx.getImageData(0, 0, this.canvas.width, this.canvas.height);
        this.pixmap.getImageData().data.set(imageData.data, 0);
    }

    markModified() {
        this.renderDirty = true;
    }
}

let layerIdCounter = 0;

export class Layer {
    chunks = new Map();
    id = layerIdCounter++;

    constructor({ name, chunkSize, chunkLimit }) {
        this.name = name;
        this.chunkSize = chunkSize;
        this.chunkLimit = chunkLimit;

        console.info("created layer", this.id, this.name);
    }

    destroy() {
        for (let { chunk } of this.chunks.values()) {
            chunk.destroy();
        }
    }

    getChunk(x, y) {
        return this.chunks.get(chunkKey(x, y))?.chunk;
    }

    getOrCreateChunk(x, y) {
        let key = chunkKey(x, y);
        if (this.chunks.has(key)) {
            return this.chunks.get(key)?.chunk;
        } else {
            if (this.chunkLimit != null && this.chunks.size >= this.chunkLimit) return null;

            let chunk = new Chunk(this.chunkSize);
            this.chunks.set(key, { x, y, chunk });
            return chunk;
        }
    }

    compositeAlpha(src) {
        for (let { x, y, chunk: srcChunk } of src.chunks.values()) {
            srcChunk.syncFromPixmap();
            let dstChunk = this.getOrCreateChunk(x, y);
            if (dstChunk == null) continue;

            dstChunk.ctx.globalCompositeOperation = "source-over";
            dstChunk.ctx.drawImage(srcChunk.canvas, 0, 0);
            dstChunk.syncToPixmap();
            dstChunk.markModified();
        }
    }

    async toEdits() {
        let edits = [];

        let start = performance.now();

        for (let { x, y, chunk } of this.chunks.values()) {
            edits.push({
                chunk: { x, y },
                data: chunk.canvas.convertToBlob({ type: "image/png" }),
            });
        }

        for (let edit of edits) {
            edit.data = await edit.data;
        }

        let end = performance.now();
        console.debug("toEdits done", end - start);

        return edits;
    }
}

export function chunkKey(x, y) {
    return `${x},${y}`;
}

export class Wall {
    layers = []; // do not modify directly; only read
    #layersById = new Map();

    constructor(wallInfo) {
        this.chunkSize = wallInfo.chunkSize;
        this.paintArea = wallInfo.paintArea;
        this.maxEditSize = wallInfo.maxEditSize;
        this.onlineUsers = new OnlineUsers(wallInfo);

        this.mainLayer = new Layer({ name: "main", chunkSize: this.chunkSize });
        this.addLayer(this.mainLayer);
    }

    addLayer(layer) {
        if (!this.#layersById.get(layer.id)) {
            this.layers.push(layer);
            this.#layersById.set(layer.id, layer);
        } else {
            console.warn("attempt to add layer more than once", layer);
        }
        return layer;
    }

    removeLayer(layer) {
        if (this.#layersById.delete(layer.id)) {
            let index = this.layers.findIndex((x) => x == layer);
            this.layers.splice(index, 1);
        } else {
            console.warn("attempt to remove layer more than once", layer);
        }
    }

    getLayerById(id) {
        return this.#layersById.get(id);
    }
}