// 字体大小

var fontSize = 16

// 父容器宽度

var containerWidth = 400

// 间距

var spaceWidth = 10

/**

     * 生成随机文件名

     */

var generateFileNameas = function() {

  var randomFilename = function(randomFlag, min, max) {

    var str = "",

        range = min,

        arr = ['0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k',

               'l', 'm', 'n', 'o', 'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z', 'A', 'B', 'C', 'D', 'E', 'F', 'G',

               'H', 'I', 'J', 'K', 'L', 'M', 'N', 'O', 'P', 'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X', 'Y', 'Z'

              ];

    // 随机产生

    if (randomFlag) {

      range = Math.round(Math.random() * (max - min)) + min;

    }

    for (var i = 0; i < range; i++) {

      pos = Math.round(Math.random() * (arr.length - 1));

      str += arr[pos];

    }

    return str;

  }

  var data = []

  for (var i = 0; i < 10; i++) {

    var filename = randomFilename(true, 1, 10)

    data.push(filename)

  } 

  return data

}

/** 

     * 文件名分栏

     */

var partition = function(files, fontSize, containerWidth, spaceWidth) {

  var maxFile = files[0]

  var minFile = files[0]

  for (var i = 0; i < files.length; i++) {

    var filename = files[i]

    if (filename.length > maxFile.length) maxFile = filename

    if (filename.length < minFile.length) minFile = filename

      }

​

  var subfield = function(list, colnum, size, width, spaceWidth) {

    var result = _.chunk(list, Math.min(colnum, list.length))

    var rowWidth = 0

    for(var col=0;col<result[0].length;col++) {

      colWidth = 0

      for(var row=0; row<result.length; row++){

        var item = result[row][col] || ''

        colWidth = Math.max(colWidth, item.length * size / 2 + spaceWidth)

      }

      rowWidth += colWidth

    }

    return rowWidth < width ? result : []

  }

  // 英文数字只占半个字符宽度

  var colnum = Math.max(1, Math.floor((containerWidth - maxFile.length * fontSize / 2 - spaceWidth) / (spaceWidth + fontSize /

                                                                                                       2 * minFile.length)))

  var result = []

  while (colnum > 0 && result.length===0) {

    if (colnum === 1) {

      result = []

      for(var i=files.length;i>0;i--) {

        result.push([files.shift()])

      }

    } else {

      result = subfield(files, colnum, fontSize, containerWidth, spaceWidth)

    }

    colnum--

  }

  return result

}

/**

     * 结果渲染到页面

     */

var render = function(list) {

  var str = ''

  list.forEach(function(row) {

    str += '<tr><td>'+ row.join('</td><td>') + '</td></tr>'

  })

  document.querySelector('.ls table').innerHTML = str

}

function refresh() {

  var files = generateFileNameas()

  var groups = partition(files, fontSize, containerWidth, spaceWidth)

  render(groups)

}

refresh()