require 'signature'

module Pusher
  class Client
    attr_accessor :scheme, :host, :port, :app_id, :key, :secret
    attr_reader :http_proxy, :proxy
    attr_writer :connect_timeout, :send_timeout, :receive_timeout,
                :keep_alive_timeout

    ## CONFIGURATION ##

    def initialize(options = {})
      options = {
        :scheme => 'http',
        :host => 'api.pusherapp.com',
        :port => 80,
      }.merge(options)
      @scheme, @host, @port, @app_id, @key, @secret = options.values_at(
        :scheme, :host, :port, :app_id, :key, :secret
      )
      @http_proxy = nil
      self.http_proxy = options[:http_proxy] if options[:http_proxy]

      # Default timeouts
      @connect_timeout = 5
      @send_timeout = 5
      @receive_timeout = 5
      @keep_alive_timeout = 30
    end

    # @private Returns the authentication token for the client
    def authentication_token
      Signature::Token.new(@key, @secret)
    end

    # @private Builds a url for this app, optionally appending a path
    def url(path = nil)
      URI::Generic.build({
        :scheme => @scheme,
        :host => @host,
        :port => @port,
        :path => "/apps/#{@app_id}#{path}"
      })
    end

    # Configure Pusher connection by providing a url rather than specifying
    # scheme, key, secret, and app_id separately.
    #
    # @example
    #   Pusher.url = http://KEY:SECRET@api.pusherapp.com/apps/APP_ID
    #
    def url=(url)
      uri = URI.parse(url)
      @scheme = uri.scheme
      @app_id = uri.path.split('/').last
      @key    = uri.user
      @secret = uri.password
      @host   = uri.host
      @port   = uri.port
    end

    def http_proxy=(http_proxy)
      @http_proxy = http_proxy
      uri = URI.parse(http_proxy)
      @proxy = {
        :scheme => uri.scheme,
        :host => uri.host,
        :port => uri.port,
        :user => uri.user,
        :password => uri.password
      }
      @http_proxy
    end

    # Configure whether Pusher API calls should be made over SSL
    # (default false)
    #
    # @example
    #   Pusher.encrypted = true
    #
    def encrypted=(boolean)
      @scheme = boolean ? 'https' : 'http'
      # Configure port if it hasn't already been configured
      @port = boolean ? 443 : 80
    end

    def encrypted?
      @scheme == 'https'
    end

    # Convenience method to set all timeouts to the same value (in seconds).
    # For more control, use the individual writers.
    def timeout=(value)
      @connect_timeout, @send_timeout, @receive_timeout = value, value, value
    end

    ## INTERACE WITH THE API ##

    def resource(path)
      Resource.new(self, path)
    end

    # GET arbitrary REST API resource using a synchronous http client.
    # All request signing is handled automatically.
    #
    # @example
    #   begin
    #     Pusher.get('/channels', filter_by_prefix: 'private-')
    #   rescue Pusher::Error => e
    #     # Handle error
    #   end
    #
    # @param path [String] Path excluding /apps/APP_ID
    # @param params [Hash] API params (see http://pusher.com/docs/rest_api)
    #
    # @return [Hash] See Pusher API docs
    #
    # @raise [Pusher::Error] Unsuccessful response - see the error message
    # @raise [Pusher::HTTPError] Error raised inside http client. The original error is wrapped in error.original_error
    #
    def get(path, params = {})
      Resource.new(self, path).get(params)
    end

    # GET arbitrary REST API resource using an asynchronous http client.
    # All request signing is handled automatically.
    #
    # When the eventmachine reactor is running, the em-http-request gem is used;
    # otherwise an async request is made using httpclient. See README for
    # details and examples.
    #
    # @param path [String] Path excluding /apps/APP_ID
    # @param params [Hash] API params (see http://pusher.com/docs/rest_api)
    #
    # @return Either an EM::DefaultDeferrable or a HTTPClient::Connection
    #
    def get_async(path, params = {})
      Resource.new(self, path).get_async(params)
    end

    # POST arbitrary REST API resource using a synchronous http client.
    # Works identially to get method, but posts params as JSON in post body.
    def post(path, params = {})
      Resource.new(self, path).post(params)
    end

    # POST arbitrary REST API resource using an asynchronous http client.
    # Works identially to get_async method, but posts params as JSON in post
    # body.
    def post_async(path, params = {})
      Resource.new(self, path).post_async(params)
    end

    ## HELPER METHODS ##

    # Convenience method for creating a new WebHook instance for validating
    # and extracting info from a received WebHook
    #
    # @param request [Rack::Request] Either a Rack::Request or a Hash containing :key, :signature, :body, and optionally :content_type.
    #
    def webhook(request)
      WebHook.new(request, self)
    end

    # Return a convenience channel object by name. No API request is made.
    #
    # @example
    #   Pusher['my-channel']
    # @return [Channel]
    # @raise [ConfigurationError] unless key, secret and app_id have been
    #   configured. Channel names should be less than 200 characters, and
    #   should not contain anything other than letters, numbers, or the
    #   characters "_\-=@,.;"
    def channel(channel_name)
      raise ConfigurationError, 'Missing client configuration: please check that key, secret and app_id are configured.' unless configured?
      Channel.new(url, channel_name, self)
    end

    alias :[] :channel

    # Request a list of occupied channels from the API
    #
    # GET /apps/[id]/channels
    #
    # @param params [Hash] Hash of parameters for the API - see REST API docs
    #
    # @return [Hash] See Pusher API docs
    #
    # @raise [Pusher::Error] Unsuccessful response - see the error message
    # @raise [Pusher::HTTPError] Error raised inside http client. The original error is wrapped in error.original_error
    #
    def channels(params = {})
      get('/channels', params)
    end

    # Request info for a specific channel
    #
    # GET /apps/[id]/channels/[channel_name]
    #
    # @param channel_name [String] Channel name (max 200 characters)
    # @param params [Hash] Hash of parameters for the API - see REST API docs
    #
    # @return [Hash] See Pusher API docs
    #
    # @raise [Pusher::Error] Unsuccessful response - see the error message
    # @raise [Pusher::HTTPError] Error raised inside http client. The original error is wrapped in error.original_error
    #
    def channel_info(channel_name, params = {})
      get("/channels/#{channel_name}", params)
    end

    # Trigger an event on one or more channels
    #
    # POST /apps/[app_id]/events
    #
    # @param channels [String or Array] 1-10 channel names
    # @param event_name [String]
    # @param data [Object] Event data to be triggered in javascript.
    #   Objects other than strings will be converted to JSON
    # @param params [Hash] Additional parameters to send to api, e.g socket_id
    #
    # @return [Hash] See Pusher API docs
    #
    # @raise [Pusher::Error] Unsuccessful response - see the error message
    # @raise [Pusher::HTTPError] Error raised inside http client. The original error is wrapped in error.original_error
    #
    def trigger(channels, event_name, data, params = {})
      post('/events', trigger_params(channels, event_name, data, params))
    end

    # Trigger an event on one or more channels asynchronously.
    # For parameters see #trigger
    #
    def trigger_async(channels, event_name, data, params = {})
      post_async('/events', trigger_params(channels, event_name, data, params))
    end

    # @private Construct a net/http http client
    def sync_http_client
      @client ||= begin
        require 'httpclient'

        HTTPClient.new(@http_proxy).tap do |c|
          c.connect_timeout = @connect_timeout
          c.send_timeout = @send_timeout
          c.receive_timeout = @receive_timeout
          c.keep_alive_timeout = @keep_alive_timeout
        end
      end
    end

    # @private Construct an em-http-request http client
    def em_http_client(uri)
      begin
        unless defined?(EventMachine) && EventMachine.reactor_running?
          raise Error, "In order to use async calling you must be running inside an eventmachine loop"
        end
        require 'em-http' unless defined?(EventMachine::HttpRequest)

        connection_opts = {
          :connect_timeout => @connect_timeout,
          :inactivity_timeout => @receive_timeout,
        }

        if defined?(@proxy)
          proxy_opts = {
            :host => @proxy[:host],
            :port => @proxy[:port]
          }
          if @proxy[:user]
            proxy_opts[:authorization] = [@proxy[:user], @proxy[:password]]
          end
          connection_opts[:proxy] = proxy_opts
        end

        EventMachine::HttpRequest.new(uri, connection_opts)
      end
    end

    private

    def trigger_params(channels, event_name, data, params)
      channels = Array(channels).map(&:to_s)
      raise Pusher::Error, "Too many channels (#{channels.length}), max 10" if channels.length > 10

      encoded_data = case data
      when String
        data
      else
        begin
          MultiJson.encode(data)
        rescue MultiJson::DecodeError => e
          Pusher.logger.error("Could not convert #{data.inspect} into JSON")
          raise e
        end
      end

      return params.merge({
        :name => event_name,
        :channels => channels,
        :data => encoded_data,
      })
    end

    def configured?
      host && scheme && key && secret && app_id
    end
  end
end