export default class PcmPlayer {
  constructor(options) {
    this._options = options;
    this.audioCtx = null;
    this.rate = this._options.rate ?? 16000;
    this.ch = this._options.ch ?? 1;
    this.fadeMs = this._options.fadeMs ?? 20;
    this.fadeSamples = (this.rate * this.fadeMs) / 1000;
    this.queue = [];
    this.isPlaying = false;
    this.startTime = 0;
    this._t = null;
    this.AllTexts = [];
    this.totalLen = 0
  }

  feed(data) {
    if (!this.audioCtx) {
      this.audioCtx = wx.createWebAudioContext();
    }

    this.queue.push(new Int16Array(data));
    if (!this.isPlaying) this._play();
  }

  loadAudio = (url) => {
    return new Promise((resolve) => {
      wx.request({
        url,
        responseType: "arraybuffer",
        success: (res) => {
          console.log("res.data", res.data);
          audioCtx.decodeAudioData(
            res.data,
            (buffer) => {
              resolve(buffer);
            },
            (err) => {
              console.error("decodeAudioData fail", err);
              reject();
            }
          );
        },
        fail: (res) => {
          console.error("request fail", res);
          reject();
        },
      });
    });
  };

  async _play() {
    this.isPlaying = true;
    if (!this.audioCtx) {
      return;
    }
    // 开始播放
    this.startTime = this.audioCtx.currentTime ?? 0;
    setTimeout(() => {
      this.syncLoop();
    });
    while (this.queue.length) {
      const pcm = this.queue.shift();
      const len = pcm.length / this.ch;
      const buf = this.audioCtx.createBuffer(this.ch, len, this.rate);

      // 1. 归一化（防溢出）
      for (let c = 0; c < this.ch; c++) {
        const data = buf.getChannelData(c);
        for (let i = 0; i < len; i++) {
          const val = pcm[i * this.ch + c];
          data[i] = val > 0 ? val / 0x7fff : val / 0x8000;
        }
      }

      // 2. 帧边界淡入淡出（防不连续滋滋）
      const fadeSamples = Math.min(this.fadeSamples, len); // 5ms@16kHz
      const data = buf.getChannelData(0);
      for (let j = 0; j < fadeSamples; j++) {
        const gain = j / fadeSamples;
        data[j] *= gain; // fade-in
        data[len - 1 - j] *= gain; // fade-out
      }

      // 3. 播放并等待结束
      await new Promise((resolve, reject) => {
        if (!this.isPlaying) {return reject()}
        const src = this.audioCtx.createBufferSource();
        src.buffer = buf;
        src.connect(this.audioCtx.destination);
        src.onended = resolve;
        src.start();
      });
    }
    this.isPlaying = false;
  }

  // 监听音频播放进度
  syncLoop() {
    const loop = () => {
      if (!this.audioCtx) {
        return;
      }
      const now = this.audioCtx.currentTime - this.startTime;
      // 找当前字幕
      const index = this.AllTexts.findIndex(
        (s) => now >= s.beginTime && now < s.endTime
      );
      if (index > -1) {
        const obj = this.AllTexts[index];
        if (this.AllTexts.length == 1) {
          // 最后一条数据
          obj.is_final = true;
        }
        const tmp = this.AllTexts.shift();
        this._options.onPlay && this._options.onPlay(tmp);
        if (!this.AllTexts.length) {
          clearTimeout(this._t);
          return;
        }
      }
      if (!this.AllTexts.length) {
        this._t = setTimeout(loop, 16);
      } else {
        if (now < this.AllTexts[this.AllTexts.length - 1].endTime) {
          this._t = setTimeout(loop, 16);
        } else {
          // 结束
          clearTimeout(this._t);
          console.log("语音播放结束");
          this.destroy();
        }
      }
    };
    loop();
  }

  // 增加文字
  addText(res) {
    if (res.result && res.result.subtitles && res.result.subtitles.length) {
      const tmpText = res.result.subtitles.map((it) => {
        return {
          ...it,
          content: it.text,
          beginTime: it.beginTime / 1000,
          endTime: it.endTime / 1000,
          request_id: res.requestId,
          sessionId: res.sessionId,
        };
      });
      this.AllTexts = [...this.AllTexts, ...tmpText];
    }
  }

  close() {
    this.isPlaying = false;
    this.audioCtx.close();
  }
  destroy() {
    this.queue = [];
    this.isPlaying = false;
    this.audioCtx && this.audioCtx.close();
    this.audioCtx = null;
    this.AllTexts = [];
    this.startTime = 0;
    this._options.onAudioEnd && this._options.onAudioEnd();
  }
}