const CHUNK_SIZE = 1024 * 1024 * 5;
const THREAD_COUNT = navigator.hardwareConcurrency || 4;

export async function cutFile(file){
    return new Promise((resolve) => {
        const chunkCount = Math.ceil(file.size / CHUNK_SIZE);
        const threadChunkCount = Math.ceil(chunkCount / THREAD_COUNT);
        let result = [], finishCount = 0;
        for(let i = 0; i < chunkCount; i++){
            const worker = new Worker("node_modules/wxj-tools/tools/worker.js", {
                type: "module",
                name: "cutFile"
            });
            let start = i * threadChunkCount;
            let end = (i + 1 ) * threadChunkCount;
            if(end > chunkCount) end = chunkCount;
            worker.postMessage({
                file,
                chunkSize: CHUNK_SIZE,
                startChunkIndex: start,
                endChunkIndex: end
            })
            worker.onmessage = e => {
                for(let i = start; i< end; i++){
                    result[i] = e.data[i - start]
                }
                worker.terminate();
                finishCount++;
                if(finishCount === chunkCount){
                    return resolve(result)
                }
            }
        }
    })
}