// 媒体名称
export const mediaTypes = {
    "image": '图片',
    "video": "视频",
    "audio": "音频"
}

// 媒体扩展类型
export const mediaMimes = {
    "image": ["jpg", "png", "jpeg", "bmp", "gif"],
    "audio": ["mp3", "aac", "ogg", "wav" /* , "m4a" */],
    "video": ["mp4", "mov", "quicktime" /* ,"webm", "rmvb", "wmv" */] //ios:mov
}

// 媒体大小显示(MB)
export const mediaMaxSize = {
    "image": 10,
    "video": 20,
    "audio": 5
}

/**
 * 获取媒体扩展类型
 * @param {Stirng} filename 文件名称
 */
export const getMime = filename => {
    if (!filename || filename.indexOf('.') === -1) {
        return ''
    }

    return filename.split('.').pop().toLowerCase()
}

/**
 * 在路径中获取文件名
 * @param {*} path 
 */
export const getFilename = path => {
    const segment = (path || '').split('/')
    return segment[segment.length - 1]
}



/**
 * 检测媒体文件是否超过预设限制
 * @param {String} type 媒体类型
 * @param {Number} size 文件大小
 */
export const checkSizeLimit = (type, size) => {

    size = size / 1024 / 1024

    return size <= mediaMaxSize[type]
}

export const checkSizeLimitFree = (size, limit) => {

    size = size / 1024 / 1024

    return size <= limit
}

/**
 * 检测媒体类型
 * @param {String} type 媒体类型
 * @param {String} filename 文件名称
 */
export const checkMediaMime = (type, filename) => {
    const mime = getMime(filename)
    const find = mediaMimes[type]
    if (!find) {
        return false
    }

    return find.indexOf(mime) !== -1
}

export const base64ToBlob = base64 => {
    let arr = base64.split(','),
        mime = arr[0].match(/:(.*?);/)[1],
        bstr = atob(arr[1]),
        n = bstr.length,
        u8arr = new Uint8Array(n);
    while (n--) {
        u8arr[n] = bstr.charCodeAt(n);
    }
    return new Blob([u8arr], { type: mime });
}

export const base64ToDataURL = base64 => {
    return window.URL.createObjectURL(base64ToBlob(base64));
}

export const blobToBase64 = function (blob) {
    return new Promise(resolve => {
        var reader = new FileReader();
        reader.onload = function () {
            resolve(reader.result);
        };
        reader.readAsDataURL(blob);
    })
};

/**
 * 获取图片文件尺寸
 * @param {*} file 
 */
export const getImgWH = (file) => {
  return new Promise((resolve) => {
    var reader = new FileReader()
    //读取图片文件
    reader.readAsDataURL(file)
    reader.onload = function (e) {
      //初始化JavaScript图片对象
      var image = new Image()
      //FileReader获得Base64字符串
      image.src = e.target.result
      image.onload = function () {
        //获得图片高宽
        var height = this.height
        var width = this.width
        resolve({
          height,
          width
        })
      }
    }
  })
}


/**
 * 转化字节单位
 * @param {*} file 
 */
export const changeByteUnit = (x) => {
    const units = ['KB', 'MB', 'GB', 'TB', 'PB', 'EB', 'ZB', 'YB'];
    let l = 0, n = parseInt(x, 10) || 0;

    while (n >= 1024 && ++l) {
        n = n / 1024;
    }
    return (n.toFixed(n < 10 && l > 0 ? 2 : 0) + units[l]);

}