module Dry
  module Swagger
    class DocumentationGenerator
      SWAGGER_FIELD_TYPE_DEFINITIONS = {
          "string" => { type: :string },
          "integer" => { type: :integer },
          "boolean" => { type: :boolean },
          "float" => { type: :float },
          "datetime" => { type: :string, format: :datetime },
          "date" => { type: :string, format: :date },
          "time" => { type: :string, format: :time },
      }.freeze

      def initialize(config)
        @config = config
      end

      def generate_documentation(fields)
        documentation = { properties: {}, required: [] }
        fields.each do |field_name, attributes_hash|
          documentation[:properties][field_name] = generate_field_properties(attributes_hash)
          if attributes_hash.is_a?(Hash)
            documentation[:required] << field_name if attributes_hash.fetch(:required, true) && @config.enable_required_validation
          else
            documentation[:required] << field_name if attributes_hash[0].fetch(:required, true) && @config.enable_required_validation
          end

        rescue Errors::MissingTypeError => e
          raise StandardError.new e.message % { field_name: field_name, valid_types: SWAGGER_FIELD_TYPE_DEFINITIONS.keys, attributes_hash: attributes_hash }
        rescue Errors::MissingHashSchemaError => e
          raise StandardError.new e.message % { field_name: field_name, valid_types: SWAGGER_FIELD_TYPE_DEFINITIONS.keys, attributes_hash: attributes_hash }
        end

        { :type => :object, :properties => documentation[:properties], :required => documentation[:required] }
      end

      def generate_field_properties(attributes_hash)
        if attributes_hash.is_a?(Array)
          properties = {}
          attributes_hash.each_with_index do |_, index|
            properties["definition_#{index + 1}"] = generate_field_properties(attributes_hash[index])
          end
          {
              oneOf: attributes_hash.map{ |it| generate_field_properties(it) },
              type: :object,
              properties: properties,
              example: 'Dynamic Field. See Model Definitions'
          }
        else
          if attributes_hash[:type] == 'array'
            items = generate_documentation(attributes_hash.fetch(:keys))
            items =  @config.enable_nullable_validation ?
                         items.merge(@config.nullable_type => attributes_hash.fetch(@config.nullable_type, false)) :
                         items.merge(@config.nullable_type => true)
            documentation = { type: :array, items: items }
          elsif attributes_hash[:array] && attributes_hash.fetch(:type) != 'array'
            items = SWAGGER_FIELD_TYPE_DEFINITIONS.fetch(attributes_hash.fetch(:type))
            items = @config.enable_nullable_validation ?
                        items.merge(@config.nullable_type => attributes_hash.fetch(@config.nullable_type, false)) :
                        items.merge(@config.nullable_type => true)
            documentation = { type: :array, items:  items }
          elsif attributes_hash[:type] == 'hash'
            raise Errors::MissingHashSchemaError.new unless attributes_hash[:keys]
            documentation = generate_documentation(attributes_hash.fetch(:keys))
          else
            documentation = SWAGGER_FIELD_TYPE_DEFINITIONS.fetch(attributes_hash.fetch(:type))
            if attributes_hash[:enum] && @config.enable_enums
              documentation = documentation.merge(enum: attributes_hash.fetch(:enum))
            end

            if attributes_hash[:description] && @config.enable_descriptions
              documentation = documentation.merge(description: attributes_hash.fetch(:description))
            end
          end

          @config.enable_nullable_validation ?
              documentation.merge(@config.nullable_type => attributes_hash.fetch(@config.nullable_type, false)) :
              documentation.merge(@config.nullable_type => true)
        end

      rescue KeyError
        raise Errors::MissingTypeError.new
      end
    end
  end
end