'use strict';

(function () {
    let ret;

    async function initialize() {
        if (ret) return ret;

        const COMPRESSION_LEVEL = 7;
        const NO_ZLIB_HEADER = -1;
        const CHUNK_SIZE = 32 * 1024;
        const map = {};
        const memory = new WebAssembly.Memory({
            initial: 1,
            maximum: 1024, // 64MB
        });
        const env = {
            memory,
            writeToJs(ptr, size) {
                const o = map[ptr];
                o.onData(new Uint8Array(memory.buffer, dstPtr, size));
            },
            _abort: errno => { console.error(`Error: ${errno}`) },
            _grow: () => { },
        };
        const ins = (await WebAssembly.instantiateStreaming(fetch('js/zlib-1.3.1.wasm'), { env })).instance;

        const srcPtr = ins.exports._malloc(CHUNK_SIZE);
        const dstPtr = ins.exports._malloc(CHUNK_SIZE);

        class RawDef {
            constructor() {
                this.zstreamPtr = ins.exports._createDeflateContext(COMPRESSION_LEVEL, NO_ZLIB_HEADER);
                map[this.zstreamPtr] = this;
                this.offset = 0;
                this.buff = new Uint8Array(CHUNK_SIZE);
            }

            deflate(chunk, flush) {
                const src = new Uint8Array(memory.buffer, srcPtr, chunk.length);
                src.set(chunk);
                ins.exports._deflate(this.zstreamPtr, srcPtr, dstPtr, chunk.length, CHUNK_SIZE, flush);
            }

            onData(chunk) {
                if (this.buff.length < this.offset + chunk.length) {
                    const buff = this.buff;
                    this.buff = new Uint8Array(this.buff.length * 2);
                    this.buff.set(buff);
                }
                this.buff.set(chunk, this.offset);
                this.offset += chunk.length;
            }

            destroy() {
                ins.exports._freeDeflateContext(this.zstreamPtr);
                delete map[this.zstreamPtr];
                this.buff = null;
            }

            getBuffer() {
                const res = new Uint8Array(this.offset);
                for (let i = 0; i < this.offset; ++i) {
                    res[i] = this.buff[i];
                }
                return res;
            }
        }

        class RawInf {
            constructor() {
                this.zstreamPtr = ins.exports._createInflateContext(NO_ZLIB_HEADER);
                map[this.zstreamPtr] = this;
                this.offset = 0;
                this.buff = new Uint8Array(CHUNK_SIZE);
            }

            inflate(chunk) {
                const src = new Uint8Array(memory.buffer, srcPtr, chunk.length);
                src.set(chunk);
                ins.exports._inflate(this.zstreamPtr, srcPtr, dstPtr, chunk.length, CHUNK_SIZE);
            }

            onData(chunk) {
                if (this.buff.length < this.offset + chunk.length) {
                    const buff = this.buff;
                    this.buff = new Uint8Array(this.buff.length * 2);
                    this.buff.set(buff);
                }
                this.buff.set(chunk, this.offset);
                this.offset += chunk.length;
            }

            destroy() {
                ins.exports._freeInflateContext(this.zstreamPtr);
                delete map[this.zstreamPtr];
                this.buff = null;
            }

            getBuffer() {
                const res = new Uint8Array(this.offset);
                for (let i = 0; i < this.offset; ++i) {
                    res[i] = this.buff[i];
                }
                return res;
            }
        }

        ret = {
            inflate(rawDeflateBuffer) {
                const rawInf = new RawInf();
                for (let offset = 0; offset < rawDeflateBuffer.length; offset += CHUNK_SIZE) {
                    const end = Math.min(offset + CHUNK_SIZE, rawDeflateBuffer.length);
                    const chunk = rawDeflateBuffer.subarray(offset, end);
                    rawInf.inflate(chunk);
                }
                const ret = rawInf.getBuffer();
                rawInf.destroy();
                return ret;
            },
            deflate(rawInflateBuffer) {
                const rawDef = new RawDef();
                for (let offset = 0; offset < rawInflateBuffer.length; offset += CHUNK_SIZE) {
                    const end = Math.min(offset + CHUNK_SIZE, rawInflateBuffer.length);
                    const chunk = rawInflateBuffer.subarray(offset, end);
                    rawDef.deflate(chunk, rawInflateBuffer.length <= offset + CHUNK_SIZE);
                }
                const ret = rawDef.getBuffer();
                rawDef.destroy();
                return ret;
            },
        }

        return ret;
    }
    this.zlib = initialize();
}).call(this);
