require 'faraday'
require 'koala/http_service/multipart_request'
require 'koala/http_service/uploadable_io'
require 'koala/http_service/response'

module Koala
  module HTTPService
    class << self
      # A customized stack of Faraday middleware that will be used to make each request.
      attr_accessor :faraday_middleware
      # A default set of HTTP options (see https://github.com/arsduo/koala/wiki/HTTP-Services)
      attr_accessor :http_options
    end

    @http_options ||= {}

    # Koala's default middleware stack.
    # We encode requests in a Facebook-compatible multipart request,
    # and use whichever adapter has been configured for this application.
    DEFAULT_MIDDLEWARE = Proc.new do |builder|
      builder.use Koala::HTTPService::MultipartRequest
      builder.request :url_encoded
      builder.adapter Faraday.default_adapter
    end

    # Default servers for Facebook. These are read into the config OpenStruct,
    # and can be overridden via Koala.config.
    DEFAULT_SERVERS = {
      :graph_server => 'graph.facebook.com',
      :dialog_host => 'www.facebook.com',
      :rest_server => 'api.facebook.com',
      # certain Facebook services (beta, video) require you to access different
      # servers. If you're using your own servers, for instance, for a proxy,
      # you can change both the matcher and the replacement values.
      # So for instance, if you're talking to fbproxy.mycompany.com, you could
      # set up beta.fbproxy.mycompany.com for FB's beta tier, and set the
      # matcher to /\.fbproxy/ and the beta_replace to '.beta.fbproxy'.
      :host_path_matcher => /\.facebook/,
      :video_replace => '-video.facebook',
      :beta_replace => '.beta.facebook'
    }

    # The address of the appropriate Facebook server.
    #
    # @param options various flags to indicate which server to use.
    # @option options :rest_api use the old REST API instead of the Graph API
    # @option options :video use the server designated for video uploads
    # @option options :beta use the beta tier
    # @option options :use_ssl force https, even if not needed
    # @option options :api_version a version of the Facebook API, e.g. v2.0
    #
    # @return a complete server address with protocol
    def self.server(options = {})
      server = "#{options[:rest_api] ? Koala.config.rest_server : Koala.config.graph_server}"
      server.gsub!(Koala.config.host_path_matcher, Koala.config.video_replace) if options[:video]
      server.gsub!(Koala.config.host_path_matcher, Koala.config.beta_replace) if options[:beta]
      # ...and an API version if specified
      if api_version = options[:api_version] || Koala.config.api_version
        server = "#{server}/#{api_version}"
      end
      "#{options[:use_ssl] ? "https" : "http"}://#{server}"
    end

    # Makes a request directly to Facebook.
    # @note You'll rarely need to call this method directly.
    #
    # @see Koala::Facebook::API#api
    # @see Koala::Facebook::GraphAPIMethods#graph_call
    # @see Koala::Facebook::RestAPIMethods#rest_call
    #
    # @param path the server path for this request
    # @param args (see Koala::Facebook::API#api)
    # @param verb the HTTP method to use.
    #             If not get or post, this will be turned into a POST request with the appropriate :method
    #             specified in the arguments.
    # @param options (see Koala::Facebook::API#api)
    #
    # @raise an appropriate connection error if unable to make the request to Facebook
    #
    # @return [Koala::HTTPService::Response] a response object representing the results from Facebook
    def self.make_request(path, args, verb, options = {})
      # if the verb isn't get or post, send it as a post argument
      args.merge!({:method => verb}) && verb = "post" if verb != "get" && verb != "post"

      # turn all the keys to strings (Faraday has issues with symbols under 1.8.7) and resolve UploadableIOs
      params = args.inject({}) {|hash, kv| hash[kv.first.to_s] = kv.last.is_a?(UploadableIO) ? kv.last.to_upload_io : kv.last; hash}

      # figure out our options for this request
      request_options = {:params => (verb == "get" ? params : {})}.merge(http_options || {}).merge(process_options(options))
      request_options[:use_ssl] = true if args["access_token"] # require https if there's a token
      if request_options[:use_ssl]
        ssl = (request_options[:ssl] ||= {})
        ssl[:verify] = true unless ssl.has_key?(:verify)
      end

      # set up our Faraday connection
      # we have to manually assign params to the URL or the
      conn = Faraday.new(server(request_options), faraday_options(request_options), &(faraday_middleware || DEFAULT_MIDDLEWARE))

      response = conn.send(verb, path, (verb == "post" ? params : {}))

      # Log URL information
      Koala::Utils.debug "#{verb.upcase}: #{path} params: #{params.inspect}"
      Koala::HTTPService::Response.new(response.status.to_i, response.body, response.headers)
    end

    # Encodes a given hash into a query string.
    # This is used mainly by the Batch API nowadays, since Faraday handles this for regular cases.
    #
    # @param params_hash a hash of values to CGI-encode and appropriately join
    #
    # @example
    #   Koala.http_service.encode_params({:a => 2, :b => "My String"})
    #   => "a=2&b=My+String"
    #
    # @return the appropriately-encoded string
    def self.encode_params(param_hash)
      ((param_hash || {}).sort_by{|k, v| k.to_s}.collect do |key_and_value|
        key_and_value[1] = MultiJson.dump(key_and_value[1]) unless key_and_value[1].is_a? String
        "#{key_and_value[0].to_s}=#{CGI.escape key_and_value[1]}"
      end).join("&")
    end

    # deprecations
    # not elegant or compact code, but temporary

    # @private
    def self.always_use_ssl
      Koala::Utils.deprecate("HTTPService.always_use_ssl is now HTTPService.http_options[:use_ssl]; always_use_ssl will be removed in a future version.")
      http_options[:use_ssl]
    end

    # @private
    def self.always_use_ssl=(value)
      Koala::Utils.deprecate("HTTPService.always_use_ssl is now HTTPService.http_options[:use_ssl]; always_use_ssl will be removed in a future version.")
      http_options[:use_ssl] = value
    end

    # @private
    def self.timeout
      Koala::Utils.deprecate("HTTPService.timeout is now HTTPService.http_options[:timeout]; .timeout will be removed in a future version.")
      http_options[:timeout]
    end

    # @private
    def self.timeout=(value)
      Koala::Utils.deprecate("HTTPService.timeout is now HTTPService.http_options[:timeout]; .timeout will be removed in a future version.")
      http_options[:timeout] = value
    end

    # @private
    def self.proxy
      Koala::Utils.deprecate("HTTPService.proxy is now HTTPService.http_options[:proxy]; .proxy will be removed in a future version.")
      http_options[:proxy]
    end

    # @private
    def self.proxy=(value)
      Koala::Utils.deprecate("HTTPService.proxy is now HTTPService.http_options[:proxy]; .proxy will be removed in a future version.")
      http_options[:proxy] = value
    end

    # @private
    def self.ca_path
      Koala::Utils.deprecate("HTTPService.ca_path is now (HTTPService.http_options[:ssl] ||= {})[:ca_path]; .ca_path will be removed in a future version.")
      (http_options[:ssl] || {})[:ca_path]
    end

    # @private
    def self.ca_path=(value)
      Koala::Utils.deprecate("HTTPService.ca_path is now (HTTPService.http_options[:ssl] ||= {})[:ca_path]; .ca_path will be removed in a future version.")
      (http_options[:ssl] ||= {})[:ca_path] = value
    end

    # @private
    def self.ca_file
      Koala::Utils.deprecate("HTTPService.ca_file is now (HTTPService.http_options[:ssl] ||= {})[:ca_file]; .ca_file will be removed in a future version.")
      (http_options[:ssl] || {})[:ca_file]
    end

    # @private
    def self.ca_file=(value)
      Koala::Utils.deprecate("HTTPService.ca_file is now (HTTPService.http_options[:ssl] ||= {})[:ca_file]; .ca_file will be removed in a future version.")
      (http_options[:ssl] ||= {})[:ca_file] = value
    end

    # @private
    def self.verify_mode
      Koala::Utils.deprecate("HTTPService.verify_mode is now (HTTPService.http_options[:ssl] ||= {})[:verify_mode]; .verify_mode will be removed in a future version.")
      (http_options[:ssl] || {})[:verify_mode]
    end

    # @private
    def self.verify_mode=(value)
      Koala::Utils.deprecate("HTTPService.verify_mode is now (HTTPService.http_options[:ssl] ||= {})[:verify_mode]; .verify_mode will be removed in a future version.")
      (http_options[:ssl] ||= {})[:verify_mode] = value
    end

    private

    def self.process_options(options)
      if typhoeus_options = options.delete(:typhoeus_options)
        Koala::Utils.deprecate("typhoeus_options should now be included directly in the http_options hash.  Support for this key will be removed in a future version.")
        options = options.merge(typhoeus_options)
      end

      if ca_file = options.delete(:ca_file)
        Koala::Utils.deprecate("http_options[:ca_file] should now be passed inside (http_options[:ssl] = {}) -- that is, http_options[:ssl][:ca_file].  Support for this key will be removed in a future version.")
        (options[:ssl] ||= {})[:ca_file] = ca_file
      end

      if ca_path = options.delete(:ca_path)
        Koala::Utils.deprecate("http_options[:ca_path] should now be passed inside (http_options[:ssl] = {}) -- that is, http_options[:ssl][:ca_path].  Support for this key will be removed in a future version.")
        (options[:ssl] ||= {})[:ca_path] = ca_path
      end

      if verify_mode = options.delete(:verify_mode)
        Koala::Utils.deprecate("http_options[:verify_mode] should now be passed inside (http_options[:ssl] = {}) -- that is, http_options[:ssl][:verify_mode].  Support for this key will be removed in a future version.")
        (options[:ssl] ||= {})[:verify_mode] = verify_mode
      end

      options
    end

    def self.faraday_options(options)
      valid_options = [:request, :proxy, :ssl, :builder, :url, :parallel_manager, :params, :headers, :builder_class]
      Hash[ options.select { |key,value| valid_options.include?(key) } ]
    end
  end

  # @private
  module TyphoeusService
    def self.deprecated_interface
      # support old-style interface with a warning
      Koala::Utils.deprecate("the TyphoeusService module is deprecated; to use Typhoeus, set Faraday.default_adapter = :typhoeus.  Enabling Typhoeus for all Faraday connections.")
      Faraday.default_adapter = :typhoeus
    end
  end

  # @private
  module NetHTTPService
    def self.deprecated_interface
      # support old-style interface with a warning
      Koala::Utils.deprecate("the NetHTTPService module is deprecated; to use Net::HTTP, set Faraday.default_adapter = :net_http.  Enabling Net::HTTP for all Faraday connections.")
      Faraday.default_adapter = :net_http
    end
  end
end