var EventEmitter = require('events').EventEmitter

exports = module.exports = function (wrapper) {

  if('function' == typeof wrapper)
    return wrapper
  
  return exports[wrapper] || exports.json
}

exports.json = function (stream, _JSON) {
  _JSON = _JSON || JSON

  var write = stream.write
  var soFar = ''

  function parse (line) {
    var js
    try {
      js = _JSON.parse(line)
      //ignore lines of whitespace...
    } catch (err) { 
      err.line = line
      return stream.emit('error', err)
      //return console.error('invalid JSON', line)
    }
    if(js !== undefined)
      write.call(stream, js)
  }

  function onData (data) {
    var lines = (soFar + data).split('\n')
    soFar = lines.pop()
    while(lines.length) {
      parse(lines.shift())
    }
  }

  stream.write = onData
  
  var end = stream.end

  stream.end = function (data) {
    if(data)
      stream.write(data)
    //if there is any left over...
    if(soFar) {
      parse(soFar)
    }
    return end.call(stream)
  }

  stream.emit = function (event, data) {

    if(event == 'data') {
      data = _JSON.stringify(data) + '\n'
    }
    //since all stream events only use one argument, this is okay...
    EventEmitter.prototype.emit.call(stream, event, data)
  }

  return stream
}

exports.raw = function (stream) {
  return stream
}