const { RTCAudioSource } = require('wrtc').nonstandard;
const ffmpeg = require('fluent-ffmpeg')

class AudioSourceService extends RTCAudioSource {
    constructor() {
        super();
        this.command = null // 存储音频源
        this.cache = Buffer.alloc(0)
    }

    // 创建通道
    createTrack() {
        const track = super.createTrack()
        return track
    }


    // 获取音频源
    start() {
        if (this.command !== null) this.stop()
        this.command = ffmpeg("plughw:1,0")
            .inputFormat("alsa")
            .audioChannels(1)
            .audioFrequency(48000)
            .audioCodec("pcm_s16le")
            .outputFormat("s16le")
            .on("start", () => {
                console.log("Audio start !");
            })
            .on("error", function (err) {
                console.log('Audio processing an error occurred: ' + err.message);
                // 退出进程
                process.exit(1)
            })
        this.ffstream = this.command.pipe();
        this.ffstream.on("data", (buffer) => {
            // console.log("Audio buffer length", buffer.length);
            this.cache = Buffer.concat([this.cache, buffer]);
        });

        const processData = () => {
            while (this.cache.length > 960) {
                const buffer = this.cache.slice(0, 960);
                this.cache = this.cache.slice(960);
                const samples = new Int16Array(new Uint8Array(buffer).buffer);
                this.onData({
                    bitsPerSample: 16,
                    sampleRate: 48000,
                    channelCount: 1,
                    numberOfFrames: samples.length,
                    type: "data",
                    samples,
                });
            }
            if (this.command !== null) {
                setTimeout(() => processData(), 10);
            }
        };
        processData();
    }

    // 停止获取
    stop() {
        console.log("audio source stop");
        if (this.command != null) {
            this.command.kill("SIGHUP")
            this.command = null
        }
    }
}
module.exports = AudioSourceService