require 'active_support/core_ext/hash/slice'
require 'active_support/core_ext/hash/conversions'
require 'json'

module Rswag
  module Specs
    class RequestFactory

      def initialize(config = ::Rswag::Specs.config)
        @config = config
      end

      def build_request(metadata, example)
        swagger_doc = @config.get_swagger_doc(metadata[:swagger_doc])
        parameters = expand_parameters(metadata, swagger_doc, example)

        {}.tap do |request|
          add_verb(request, metadata)
          add_path(request, metadata, swagger_doc, parameters, example)
          add_headers(request, metadata, swagger_doc, parameters, example)
          add_payload(request, parameters, example)
        end
      end

      private

      def expand_parameters(metadata, swagger_doc, example)
        operation_params = metadata[:operation][:parameters] || []
        path_item_params = metadata[:path_item][:parameters] || []
        security_params = derive_security_params(metadata, swagger_doc)

        # NOTE: Use of + instead of concat to avoid mutation of the metadata object
        (operation_params + path_item_params + security_params)
          .map { |p| p['$ref'] ? resolve_parameter(p['$ref'], swagger_doc) : p }
          .uniq { |p| p[:name] }
          .reject { |p|
            p[:required] == false &&
            (!example.respond_to?(p[:name])) ||
            (example.respond_to?(p[:name]) && example.send(p[:name]).is_a?(RSpec::Matchers::BuiltIn::Include))
          }
      end

      def derive_security_params(metadata, swagger_doc)
        requirements = metadata[:operation][:security] || swagger_doc[:security] || []
        scheme_names = requirements.flat_map { |r| r.keys }
        schemes = (swagger_doc[:securityDefinitions] || {}).slice(*scheme_names).values

        schemes.map do |scheme|
          param = (scheme[:type] == :apiKey) ? scheme.slice(:name, :in) : { name: 'Authorization', in: :header }
          param.merge(type: :string, required: requirements.one?)
        end
      end

      def resolve_parameter(ref, swagger_doc)
        key = ref.sub('#/parameters/', '').to_sym
        definitions = swagger_doc[:parameters]
        raise "Referenced parameter '#{ref}' must be defined" unless definitions && definitions[key]
        definitions[key]
      end

      def add_verb(request, metadata)
        request[:verb] = metadata[:operation][:verb]
      end

      def add_path(request, metadata, swagger_doc, parameters, example)
        template = (swagger_doc[:basePath] || '') + metadata[:path_item][:template]

        request[:path] = template.tap do |template|
          parameters.select { |p| p[:in] == :path }.each do |p|
            template.gsub!("{#{p[:name]}}", example.send(p[:name]).to_s)
          end

          parameters.select { |p| p[:in] == :query }.each_with_index do |p, i|
            template.concat(i == 0 ? '?' : '&')
            template.concat(build_query_string_part(p, example.send(p[:name])))
          end
        end
      end

      def build_query_string_part(param, value)
        name = param[:name]
        return "#{name}=#{value.to_s}" unless param[:type].to_sym == :array

        case param[:collectionFormat]
        when :ssv
          "#{name}=#{value.join(' ')}"
        when :tsv
          "#{name}=#{value.join('\t')}"
        when :pipes
          "#{name}=#{value.join('|')}"
        when :multi
          value.map { |v| "#{name}=#{v}" }.join('&')
        else
          "#{name}=#{value.join(',')}" # csv is default
        end
      end

      def add_headers(request, metadata, swagger_doc, parameters, example)
        tuples = parameters
          .select { |p| p[:in] == :header }
          .map { |p| [ p[:name], example.send(p[:name]).to_s ] }

        # Accept header
        produces = metadata[:operation][:produces] || swagger_doc[:produces]
        if produces
          accept = example.respond_to?(:'Accept') ? example.send(:'Accept') : produces.first
          tuples << [ 'Accept', accept ]
        end

        # Content-Type header
        consumes = metadata[:operation][:consumes] || swagger_doc[:consumes]
        if consumes
          content_type = example.respond_to?(:'Content-Type') ? example.send(:'Content-Type') : consumes.first
          tuples << [ 'Content-Type', content_type ]
        end

        # Rails test infrastructure requires rackified headers
        rackified_tuples = tuples.map do |pair|
          [
            case pair[0]
              when 'Accept' then 'HTTP_ACCEPT'
              when 'Content-Type' then 'CONTENT_TYPE'
              when 'Authorization' then 'HTTP_AUTHORIZATION'
              else pair[0]
            end,
            pair[1]
          ]
        end

        request[:headers] = Hash[ rackified_tuples ]
      end

      def add_payload(request, parameters, example)
        content_type = request[:headers]['CONTENT_TYPE']
        return if content_type.nil?

        if [ 'application/x-www-form-urlencoded', 'multipart/form-data' ].include?(content_type)
          request[:payload] = build_form_payload(parameters, example)
        else
          request[:payload] = build_json_payload(parameters, example)
        end
      end

      def build_form_payload(parameters, example)
        # See http://seejohncode.com/2012/04/29/quick-tip-testing-multipart-uploads-with-rspec/
        # Rather that serializing with the appropriate encoding (e.g. multipart/form-data),
        # Rails test infrastructure allows us to send the values directly as a hash
        # PROS: simple to implement, CONS: serialization/deserialization is bypassed in test
        tuples = parameters
          .select { |p| p[:in] == :formData }
          .map { |p| [ p[:name], example.send(p[:name]) ] }
        Hash[ tuples ]
      end

      def build_json_payload(parameters, example)
        body_param = parameters.select { |p| p[:in] == :body }.first
        body_param ? example.send(body_param[:name]).to_json : nil
      end
    end
  end
end