<template>
  <div class="scaner" ref="scaner">
    <div class="banner" v-if="showBanner">
      <i class="close_icon" @click="() => showBanner = false"></i>
      <p class="text">若当前浏览器无法扫码，请切换其他浏览器尝试</p>
    </div>
    <div class="cover">
      <p class="line"></p>
      <span class="square top left"></span>
      <span class="square top right"></span>
      <span class="square bottom right"></span>
      <span class="square bottom left"></span>
      <p class="tips">将二维码放入框内，即可自动扫描</p>
    </div>
    <video
      v-show="showPlay"
      class="source"
      ref="video"
      :width="videoWH.width"
      :height="videoWH.height"
      controls
    ></video>
    <canvas v-show="!showPlay" ref="canvas" />
    <button v-show="showPlay" @click="run">开始</button>
  </div>
</template>

<script>

// eslint-disable-next-line no-unused-vars
import adapter from 'webrtc-adapter';
import jsQR from 'jsqr';

export default {
  name: 'Scaner',
  props: {
    // 使用后置相机
    useBackCamera: {
      type: Boolean,
      default: true
    },
    // 扫描识别后停止
    stopOnScaned: {
      type: Boolean,
      default: true
    },
    drawOnfound: {
      type: Boolean,
      default: true
    },
    // 线条颜色
    lineColor: {
      type: String,
      default: '#03C03C'
    },
    // 线条宽度
    lineWidth: {
      type: Number,
      default: 2
    },
    // 视频宽度
    videoWidth: {
      type: Number,
      default: document.documentElement.clientWidth || document.body.clientWidth
    },
    // 视频高度
    videoHeight: {
      type: Number,
      default: document.documentElement.clientHeight - 48 || document.body.clientHeight - 48
    },
    responsive: {
      type: Boolean,
      default: false
    }
  },
  data () {
    return {
      showPlay: false,
      showBanner: true,
      containerWidth: null,
      active: false
    }
  },
  computed: {
    videoWH () {
      if (this.containerWidth) {
        const width = this.containerWidth;
        const height = width * 0.75;
        return { width, height };
      }
      return { width: this.videoWidth, height: this.videoHeight };
    }
  },
  watch: {
    active: {
      immediate: true,
      handler(active) {
        if (!active) {
          this.fullStop();
        }
      }
    }
  },
  methods: {
    // 画线
    drawLine (begin, end) {
      this.canvas.beginPath();
      this.canvas.moveTo(begin.x, begin.y);
      this.canvas.lineTo(end.x, end.y);
      this.canvas.lineWidth = this.lineWidth;
      this.canvas.strokeStyle = this.lineColor;
      this.canvas.stroke();
    },
    // 画框
    drawBox (location) {
      if (this.drawOnfound) {
        this.drawLine(location.topLeftCorner, location.topRightCorner);
        this.drawLine(location.topRightCorner, location.bottomRightCorner);
        this.drawLine(location.bottomRightCorner, location.bottomLeftCorner);
        this.drawLine(location.bottomLeftCorner, location.topLeftCorner);
      }
    },
    tick () {
      if (this.$refs.video && this.$refs.video.readyState === this.$refs.video.HAVE_ENOUGH_DATA) {
        this.$refs.canvas.height = this.videoWH.height;
        this.$refs.canvas.width = this.videoWH.width;
        this.canvas.drawImage(this.$refs.video, 0, 0, this.$refs.canvas.width, this.$refs.canvas.height);
        const imageData = this.canvas.getImageData(0, 0, this.$refs.canvas.width, this.$refs.canvas.height);
        let code = false;
        try {
          code = jsQR(imageData.data, imageData.width, imageData.height);
        } catch (e) {
          console.error(e);
        }
        if (code) {
          this.drawBox(code.location);
          this.found(code.data);
        }
      }
      this.run();
    },
    // 初始化
    setup () {
      if (this.responsive) {
        this.$nextTick(() => {
          this.containerWidth = this.$refs.scaner.clientWidth;
        });
      }
      if (navigator.mediaDevices && navigator.mediaDevices.getUserMedia) {
        this.previousCode = null;
        this.parity = 0;
        this.active = true;
        this.canvas = this.$refs.canvas.getContext("2d");
        const facingMode = this.useBackCamera ? { exact: 'environment' } : 'user';
        const handleSuccess = stream => {
           if (this.$refs.video.srcObject !== undefined) {
            this.$refs.video.srcObject = stream;
          } else if (window.videoEl.mozSrcObject !== undefined) {
            this.$refs.video.mozSrcObject = stream;
          } else if (window.URL.createObjectURL) {
            this.$refs.video.src = window.URL.createObjectURL(stream);
          } else if (window.webkitURL) {
            this.$refs.video.src = window.webkitURL.createObjectURL(stream);
          } else {
            this.$refs.video.src = stream;
          }
          this.$refs.video.playsInline = true;
          const playPromise = this.$refs.video.play();
          playPromise.catch(() => (this.showPlay = true));
          playPromise.then(this.run);
        };
        navigator.mediaDevices
          .getUserMedia({ video: { facingMode } })
          .then(handleSuccess)
          .catch(() => {
            navigator.mediaDevices
              .getUserMedia({ video: true })
              .then(handleSuccess)
              .catch(error => {
                this.$emit("error-captured", error);
              });
          });
      }
    },
    run () {
      if (this.active) {
        requestAnimationFrame(this.tick);
      }
    },
    found (code) {
      if (this.previousCode !== code) {
        this.previousCode = code;
      } else if (this.previousCode === code) {
        this.parity += 1;
      }
      if (this.parity > 2) {
        this.active = this.stopOnScanned ? false : true;
        this.parity = 0;
        this.$emit("code-scanned", code);
      }
    },
    // 完全停止
    fullStop () {
      if (this.$refs.video && this.$refs.video.srcObject) {
        this.$refs.video.srcObject.getTracks().forEach(t => t.stop());
      }
    }
  },
  mounted () {
    this.setup();
  },
  beforeDestroy () {
    this.fullStop();
  }
}
</script>

<style lang="css" scoped>
.scaner {
  background: #000000;
  position: fixed;
  top: 48PX;
  left: 0;
  width: 100%;
  height: 100%;
  height: -webkit-calc(100% - 48PX);
  height: -moz-calc(100% - 48PX);
  height: -ms-calc(100% - 48PX);
  height: -o-calc(100% - 48PX);
  height: calc(100% - 48PX);
}
.scaner .banner {
  width: 340PX;
  position: absolute;
  top: 16PX;
  left: 50%;
  margin-left: -170PX;
  background: #FA74A2;
  border-radius: 8PX;
  box-sizing: border-box;
  padding: 12PX;
  opacity: 0.9;
  box-shadow: 1PX 1PX 10PX rgba(0, 0, 0, 0.2);
}
.scaner .banner .text {
  padding: 0;
  margin: 0;
  color: #FFFFFF;
  font-size: 12PX;
  text-align: justify;
  text-align-last: left;
}
.scaner .banner .close_icon {
  display: inline-block;
  height: 24PX;
  width: 24PX;
  /*background: url('../assets/close.png') no-repeat center;*/
  background-size: auto 100%;
  position: absolute;
  right: 8PX;
  top: 8PX;
}
.scaner .cover {
  height: 220PX;
  width: 220PX;
  position: absolute;
  top:50%;
  left:50%;
  -webkit-transform: translate(-50%,-50%);
  -moz-transform: translate(-50%,-50%);
  -ms-transform: translate(-50%,-50%);
  -o-transform: translate(-50%,-50%);
  transform: translate(-50%,-50%);
  border: .5PX solid #999999;
  z-index: 1111;
}
.scaner .cover .line {
  width: 200PX;
  height: 1PX;
  margin-left: 10PX;
  background: #5F68E8;
  background: linear-gradient(to right, transparent, #5F68E8, #0165FF, #5F68E8, transparent);
  position: absolute;
  -webkit-animation: scan 1.75s infinite linear;
  -moz-animation: scan 1.75s infinite linear;
  -ms-animation: scan 1.75s infinite linear;
  -o-animation: scan 1.75s infinite linear;
  animation: scan 1.75s infinite linear;
  -webkit-animation-fill-mode: both;
  -moz-animation-fill-mode: both;
  -ms-animation-fill-mode: both;
  -o-animation-fill-mode: both;
  animation-fill-mode: both;
  border-radius: 1PX;
}
.scaner .cover .square {
  display: inline-block;
  height: 20PX;
  width: 20PX;
  position: absolute;
}
.scaner .cover .square.top {
  top: 0;
  border-top: 1PX solid #5F68E8;
}
.scaner .cover .square.left {
  left: 0;
  border-left: 1PX solid #5F68E8;
}
.scaner .cover .square.bottom {
  bottom: 0;
  border-bottom: 1PX solid #5F68E8;
}
.scaner .cover .square.right {
 right: 0;
  border-right: 1PX solid #5F68E8;
}
.scaner .cover .tips {
  position: absolute;
  bottom: -48PX;
  width: 100%;
  font-size: 14PX;
  color: #FFFFFF;
  opacity: 0.8;
}
@-webkit-keyframes scan {
  0% {top: 0}
  25% {top: 50PX}
  50% {top: 100PX}
  75% {top: 150PX}
  100% {top: 200PX}
}
@-moz-keyframes scan {
  0% {top: 0}
  25% {top: 50PX}
  50% {top: 100PX}
  75% {top: 150PX}
  100% {top: 200PX}
}
@-o-keyframes scan {
  0% {top: 0}
  25% {top: 50PX}
  50% {top: 100PX}
  75% {top: 150PX}
  100% {top: 200PX}
}
@keyframes scan {
  0% {top: 0}
  25% {top: 50PX}
  50% {top: 100PX}
  75% {top: 150PX}
  100% {top: 200PX}
}
</style>
