module Excon
  class Connection
    attr_reader :connection, :proxy

    CR_NL     = "\r\n"
    HTTP_1_1  = " HTTP/1.1\r\n"
    FORCE_ENC = CR_NL.respond_to?(:force_encoding)

    # Initializes a new Connection instance
    #   @param [String] url The destination URL
    #   @param [Hash<Symbol, >] params One or more optional params
    #     @option params [String] :body Default text to be sent over a socket. Only used if :body absent in Connection#request params
    #     @option params [Hash<Symbol, String>] :headers The default headers to supply in a request. Only used if params[:headers] is not supplied to Connection#request
    #     @option params [String] :host The destination host's reachable DNS name or IP, in the form of a String
    #     @option params [String] :path Default path; appears after 'scheme://host:port/'. Only used if params[:path] is not supplied to Connection#request
    #     @option params [Fixnum] :port The port on which to connect, to the destination host
    #     @option params [Hash]   :query Default query; appended to the 'scheme://host:port/path/' in the form of '?key=value'. Will only be used if params[:query] is not supplied to Connection#request
    #     @option params [String] :scheme The protocol; 'https' causes OpenSSL to be used
    #     @option params [String] :proxy Proxy server; e.g. 'http://myproxy.com:8888'
    def initialize(url, params = {})
      uri = URI.parse(url)
      @connection = {
        :connect_timeout  => 60,
        :headers          => {},
        :host             => uri.host,
        :mock             => Excon.mock,
        :path             => uri.path,
        :port             => uri.port.to_s,
        :query            => uri.query,
        :read_timeout     => 60,
        :scheme           => uri.scheme,
        :write_timeout    => 60
      }.merge!(params)

      # use proxy from the environment if present
      if ENV.has_key?('http_proxy')
        @proxy = setup_proxy(ENV['http_proxy'])
      elsif params.has_key?(:proxy)
        @proxy = setup_proxy(params[:proxy])
      end

      if @connection[:scheme] == 'https'
        # use https_proxy if that has been specified
        if ENV.has_key?('https_proxy')
          @proxy = setup_proxy(ENV['https_proxy'])
        end
      end

      if @proxy
        @connection[:headers]['Proxy-Connection'] ||= 'Keep-Alive'
      end

      @socket_key = '' << @connection[:host] << ':' << @connection[:port]
      reset
    end

    # Sends the supplied request to the destination host.
    #   @yield [chunk] @see Response#self.parse
    #   @param [Hash<Symbol, >] params One or more optional params, override defaults set in Connection.new
    #     @option params [String] :body text to be sent over a socket
    #     @option params [Hash<Symbol, String>] :headers The default headers to supply in a request
    #     @option params [String] :host The destination host's reachable DNS name or IP, in the form of a String
    #     @option params [String] :path appears after 'scheme://host:port/'
    #     @option params [Fixnum] :port The port on which to connect, to the destination host
    #     @option params [Hash]   :query appended to the 'scheme://host:port/path/' in the form of '?key=value'
    #     @option params [String] :scheme The protocol; 'https' causes OpenSSL to be used
    def request(params, &block)
      begin
        # connection has defaults, merge in new params to override
        params = @connection.merge(params)
        params[:headers] = @connection[:headers].merge(params[:headers] || {})
        params[:headers]['Host'] ||= '' << params[:host] << ':' << params[:port]

        # if path is empty or doesn't start with '/', insert one
        unless params[:path][0, 1] == '/'
          params[:path].insert(0, '/')
        end

        if params[:mock]
          for stub, response in Excon.stubs
            # all specified non-headers params match and no headers were specified or all specified headers match
            if (stub.keys - [:headers]).all? {|key| stub[key] == params[key] } &&
              (!stub.has_key?(:headers) || stub[:headers].keys.all? {|key| stub[:headers][key] == params[:headers][key]})
              response_attributes = case response
              when Proc
                response.call(params)
              else
                response
              end
              if block_given? && response_attributes.has_key?(:body)
                body = response_attributes.delete(:body)
                content_length = remaining = body.bytesize
                i = 0
                while i < body.length
                  yield(body[i, CHUNK_SIZE], [remaining - CHUNK_SIZE, 0].max, content_length)
                  remaining -= CHUNK_SIZE
                  i += CHUNK_SIZE
                end
              end
              return Excon::Response.new(response_attributes)
            end
          end
          # if we reach here no stubs matched
          raise(Excon::Errors::StubNotFound.new('no stubs matched ' << params.inspect))
        end

        # start with "METHOD /path"
        request = params[:method].to_s.upcase << ' '
        if @proxy
          request << params[:scheme] << '://' << params[:host] << ':' << params[:port]
        end
        request << params[:path]

        # add query to path, if there is one
        case params[:query]
        when String
          request << '?' << params[:query]
        when Hash
          request << '?'
          for key, values in params[:query]
            if values.nil?
              request << key.to_s << '&'
            else
              for value in [*values]
                request << key.to_s << '=' << CGI.escape(value.to_s) << '&'
              end
            end
          end
          request.chop! # remove trailing '&'
        end

        # finish first line with "HTTP/1.1\r\n"
        request << HTTP_1_1

        # calculate content length and set to handle non-ascii
        unless params[:headers].has_key?('Content-Length')
          params[:headers]['Content-Length'] = case params[:body]
          when File
            params[:body].binmode
            File.size(params[:body])
          when String
            if FORCE_ENC
              params[:body].force_encoding('BINARY')
            end
            params[:body].length
          else
            0
          end
        end

        # add headers to request
        for key, values in params[:headers]
          for value in [*values]
            request << key.to_s << ': ' << value.to_s << CR_NL
          end
        end

        # add additional "\r\n" to indicate end of headers
        request << CR_NL

        # write out the request, sans body
        socket.write(request)

        # write out the body
        if params[:body]
          if params[:body].is_a?(String)
            socket.write(params[:body])
          else
            while chunk = params[:body].read(CHUNK_SIZE)
              socket.write(chunk)
            end
          end
        end

        # read the response
        response = Excon::Response.parse(socket, params, &block)

        if response.headers['Connection'] == 'close'
          reset
        end

        response
      rescue Excon::Errors::StubNotFound => stub_not_found
        raise(stub_not_found)
      rescue => socket_error
        reset
        raise(Excon::Errors::SocketError.new(socket_error))
      end

      if params.has_key?(:expects) && ![*params[:expects]].include?(response.status)
        reset
        raise(Excon::Errors.status_error(params, response))
      else
        response
      end

    rescue => request_error
      if params[:idempotent] && [Excon::Errors::SocketError, Excon::Errors::HTTPStatusError].any? {|ex| request_error.kind_of? ex }
        retries_remaining ||= 4
        retries_remaining -= 1
        if retries_remaining > 0
          if params[:body].respond_to?(:pos=)
            params[:body].pos = 0
          end
          retry
        else
          raise(request_error)
        end
      else
        raise(request_error)
      end
    end

    def reset
      (old_socket = sockets.delete(@socket_key)) && old_socket.close
    end
    
    # Generate HTTP request verb methods
    Excon::HTTP_VERBS.each do |method|
      eval <<-DEF
        def #{method}(params={}, &block)
          request(params.merge!(:method => :#{method}), &block)
        end
      DEF
    end

  private

    def socket
      sockets[@socket_key] ||= Excon::Socket.new(@connection, @proxy)
    end

    def sockets
      Thread.current[:_excon_sockets] ||= {}
    end

    def setup_proxy(proxy)
      uri = URI.parse(proxy)
      unless uri.host and uri.port and uri.scheme
        raise Excon::Errors::ProxyParseError, "Proxy is invalid"
      end
      {:host => uri.host, :port => uri.port, :scheme => uri.scheme}
    end

  end
end