class TouchDB
  @baseURL: "http://.touchdb."

  constructor: (@options={}) ->
    throw "Database name required" unless @options.name

    @replicas = {}
    @baseURL = "#{TouchDB.baseURL}/#{@options.name}"

    @eventCallbacks = {}

    @createDB {},
      onSuccess: =>
        @fireCallbacks 'ready'
      onFailure: (error) =>
        if error.status == 412
          @fireCallbacks 'ready'
        else
          console.log "unable to initialize database: " + error.error

    @startMonitoringChanges {},
      onChange: =>
        @fireCallbacks 'change'

  fireCallbacks: (name) =>
    return unless @eventCallbacks[name]

    for callback in @eventCallbacks[name]
      callback.call()

  on: (eventName, callback)->
    @eventCallbacks[eventName] ||= []
    @eventCallbacks[eventName].push callback

  startMonitoringChanges: (options={}, callbacks={}) ->
    request = new XMLHttpRequest();
    request.open("GET", "#{@baseURL}/_changes?feed=continuous")

    request.onreadystatechange = () =>
      return unless request.readyState == 3

      callbacks.onChange()

    request.send()

  createDB: (options={}, callbacks={}) ->
    request = new XMLHttpRequest();
    request.open("PUT", "#{@baseURL}/")

    request.onreadystatechange = () =>
      return unless request.readyState == 4

      if request.status == 412
        errorObj = JSON.parse(request.responseText)
        callbacks.onFailure(errorObj) if callbacks.onFailure

      if request.status == 201
        responseObj = JSON.parse(request.responseText)
        callbacks.onSuccess(responseObj) if callbacks.onSuccess

    request.send()


  addTwoWayReplica: (options={}, callbacks={}) ->

    toCloudAdded = ()=>
      @startReplication({source: options.url, target: @options.name}, {onSuccess: fromCloudAdded, onFailure: fromCloudFailed})

    toCloudFailed = ()=>
      callbacks.onFailure() if callbacks.onFailure

    fromCloudAdded = ()=>
      @replicas[options.url] = {}
      callbacks.onSuccess() if callbacks.onSuccess

    fromCloudFailed = ()=>
      callbacks.onFailure() if callbacks.onFailure


    @startReplication({source: @options.name, target: options.url}, {onSuccess: toCloudAdded, onFailure: toCloudFailed})

  replicateFrom: (options={}, callbacks={}) =>
    @startReplication {
      source: options.url
      target: @options.name
    }, {
      onSuccess: callbacks.onSuccess
      onFailure: callbacks.onFailure
    }

  startReplication: (options={}, callbacks={}) ->
    request = new XMLHttpRequest();
    request.open("POST", "#{TouchDB.baseURL}/_replicate")

    request.onreadystatechange = () =>
      return unless request.readyState == 4

      if request.status == 412
        errorObj = JSON.parse(request.responseText)
        callbacks.onFailure(errorObj)

      if request.status == 200
        responseObj = JSON.parse(request.responseText)


        callbacks.onSuccess.call(responseObj)


    request.send JSON.stringify({source: options.source, target: options.target, continuous: true})