var array = require('./array.wxs');
  var object = require('./object.wxs');
  var PREFIX = 'van-';
  
  function join(name, mods) {
    name = PREFIX + name;
    mods = mods.map(function(mod) {
      return name + '--' + mod;
    });
    mods.unshift(name);
    return mods.join(' ');
  }
  
  function traversing(mods, conf) {
    if (!conf) {
      return;
    }
  
    if (typeof conf === 'string' || typeof conf === 'number') {
      mods.push(conf);
    } else if (array.isArray(conf)) {
      conf.forEach(function(item) {
        traversing(mods, item);
      });
    } else if (typeof conf === 'object') {
      object.keys(conf).forEach(function(key) {
        conf[key] && mods.push(key);
      });
    }
  }
  
  function bem(name, conf) {
    var mods = [];
    traversing(mods, conf);
    return join(name, mods);
  }
  
  module.exports.bem = bem;