# frozen_string_literal: true

require 'rspec/rails/api/utils'
require 'active_support'

module RSpec
  module Rails
    module Api
      # Class to render metadata.
      # Example:
      #   ```rb
      #   renderer = RSpec::Rails::Api::OpenApiRenderer.new
      #   renderer.merge_context(example_context)
      #   renderer.write_files
      #   ```
      class OpenApiRenderer # rubocop:disable Metrics/ClassLength
        attr_writer :api_servers, :api_title, :api_version, :api_description, :api_tos
        attr_reader :redactables

        def initialize
          @metadata       = { resources: {}, entities: {} }
          @api_infos      = {}
          @api_servers    = []
          @api_paths      = {}
          @api_components = {}
          @api_tags       = []
          @api_contact    = {}
          @api_license    = {}
          @api_security   = {}
          @redactables    = {}
        end

        def redact_responses(pairs)
          @redactables = pairs
        end

        ##
        # Adds a security scheme definition to the API documentation
        #
        # @param reference  [Symbol] Reference to use in the tests
        # @param name       [String] Human friendly name
        # @param definition [Hash]   Security scheme definition as per https://swagger.io/specification/#security-scheme-object
        def add_security_scheme(reference, name, definition)
          raise "Security scheme #{reference} is already defined" if @api_security.key? reference

          definition[:name] = name unless reference == :basic
          @api_security[reference] = definition
        end

        ##
        # Merges example context definition with the renderer data
        #
        # @param context       [Hash]    Metadata hash
        # @param dump_metadata [Boolean] Saves the raw metadata in `tmp/rra_metadata.yaml` for debugging
        #
        # @return [void
        def merge_context(context, dump_metadata: false)
          @metadata[:resources].deep_merge! context.respond_to?(:resources) ? context.resources : context[:resources]

          # Save context for debug and fixtures
          File.write ::Rails.root.join('tmp', 'rra_metadata.yaml'), @metadata.to_yaml if dump_metadata
        end

        ##
        # Write OpenAPI files
        #
        # @param path [String, nil] Where to save the files. Defaults to `/tmp/rspec_api_rails.*` when unset
        # @param only [[Symbol]]    Formats to save the file to. Allowed values are `:yaml` and `:json`
        #
        # @return [void]
        def write_files(path = nil, only: %i[yaml json])
          return unless write_file? RSpec.world.filtered_examples

          path ||= ::Rails.root.join('tmp', 'rspec_api_rails')

          metadata = prepare_metadata

          file_types = %i[yaml json]
          only.each do |type|
            next unless file_types.include? type

            data = metadata.to_yaml if type == :yaml
            data = JSON.pretty_generate(metadata) if type == :json

            File.write "#{path}.#{type}", data
          end
        end

        ##
        # Extracts metadata from context to generate an OpenAPI structure
        #
        # @return [Hash] The OpenAPI structure
        def prepare_metadata
          extract_metadata
          # Example: https://github.com/OAI/OpenAPI-Specification/blob/master/examples/v3.0/petstore-expanded.yaml
          hash = {
            openapi:    '3.0.0',
            info:       @api_infos,
            servers:    @api_servers,
            paths:      @api_paths,
            components: @api_components,
            tags:       @api_tags,
          }
          JSON.parse(hash.to_json)
        end

        ##
        # Sets the contact field
        #
        # @param name  [String, nil] Contact name
        # @param email [String, nil] Contact Email
        # @param url   [String, nil] Contact URL
        #
        # @return [void]
        def api_contact=(name: nil, email: nil, url: nil)
          @api_contact[:name]  = name if name
          @api_contact[:email] = email if email
          @api_contact[:url]   = url if url
        end

        ##
        # Sets the license field
        #
        # @param name  [String, nil] License name
        # @param url   [String, nil] License URL
        #
        # @return [void]
        def api_license=(name: nil, url: nil)
          @api_license[:name] = name if name
          @api_license[:url] = url if url
        end

        private

        def write_file?(examples)
          acceptance_examples = examples.values.flatten.filter do |e|
            e.metadata[:type] == :acceptance
          end
          unless acceptance_examples.none?(&:exception)
            puts "\n\e[00;31mSome acceptance tests failed. OpenApi specification file was not updated.\n\e[00m"
            return false
          end

          true
        end

        ##
        # Extracts metadata for rendering
        #
        # @return [void]
        def extract_metadata
          extract_security
          api_infos
          api_servers
          global_entities
          extract_from_resources
        end

        ##
        # Extracts metadata from security schemes for rendering
        #
        # @return [void]
        def extract_security
          return unless @api_security.keys.count.positive?

          @api_components['securitySchemes'] = @api_security
        end

        ##
        # Extracts metadata from resources for rendering
        #
        # @return [void]
        def extract_from_resources
          @api_components[:schemas] ||= {}
          @metadata[:resources].each do |resource_key, resource|
            @api_tags.push(
              name:        resource_key.to_s,
              description: resource[:description].presence&.strip || ''
            )
            process_resource resource: resource_key, resource_config: resource
          end
        end

        ##
        # Processes a resource from metadata
        #
        # @param resource        [Symbol, nil] Resource name
        # @param resource_config [Hash, nil]   Resource declaration
        #
        #
        # @return [void]
        def process_resource(resource: nil, resource_config: nil) # rubocop:disable Metrics/MethodLength
          http_verbs = %i[get post put patch delete]
          resource_config[:paths].each do |path_key, path|
            url        = path_with_params path_key.to_s
            actions    = {}
            parameters = path.key?(:path_params) ? process_path_params(path[:path_params]) : []

            path[:actions].each_key do |action|
              next unless http_verbs.include? action

              actions[action] = process_action resource:      resource,
                                               path:          path_key,
                                               path_config:   path,
                                               action_config: action,
                                               parameters:    parameters
            end

            @api_paths[url] = actions
          end
        end

        ##
        # Processes path parameters for rendering
        #
        # @param params [Hash] Path parameters
        def process_path_params(params)
          parameters = []
          params.each do |name, param|
            parameters.push process_path_param name, param
          end

          parameters
        end

        def process_entity(entity) # rubocop:disable Metrics/AbcSize, Metrics/MethodLength, Metrics/CyclomaticComplexity, Metrics/PerceivedComplexity
          schema = {
            properties: {},
          }
          required = []
          entity.fields.each do |name, field|
            property = {
              description: field.description.presence&.strip || '',
              type:        PARAM_TYPES[field.type][:type],
            }
            property[:format] = PARAM_TYPES[field.type][:format] if PARAM_TYPES[field.type][:format]

            if PRIMITIVES.include? field.attributes
              property[:items] = { type: field.attributes }
            elsif field.type == :object && field.attributes.is_a?(Symbol)
              property = { '$ref' => "#/components/schemas/#{field.attributes}" }
            elsif field.type == :array && field.attributes.is_a?(Symbol)
              property = { type: :array, items: { '$ref' => "#/components/schemas/#{field.attributes}" } }
            elsif field.type == :array && field.attributes
              property = { type: :array, items: process_entity(field.attributes) }
            end

            required.push name unless field.required == false

            schema[:properties][name] = property
          end

          schema[:required] = required unless required.size.zero?

          schema
        end

        ##
        # Processes a path parameter from metadata
        #
        # @param name  [Symbol, nil] Parameter name
        # @param param [Hash, nil]   Parameter declaration
        #
        #
        # @return [void]
        def process_path_param(name, param) # rubocop:disable Metrics/MethodLength, Metrics/AbcSize
          parameter = {
            name:        name.to_s,
            description: param[:description].presence&.strip || '',
            required:    param[:required] || true,
            in:          param[:scope].to_s,
            schema:      {
              type: PARAM_TYPES[param[:type]][:type],
            },
          }

          parameter[:schema][:format] = PARAM_TYPES[param[:type]][:format] if PARAM_TYPES[param[:type]][:format]

          parameter
        end

        ##
        # Processes an action from metadata
        #
        # @param resource      [Symbol, nil] Target resource
        # @param path          [Symbol, nil] Target path
        # @param path_config   [Hash, nil]   Path configuraton
        # @param action_config [Symbol, nil] Target action
        # @param parameters    [Array, nil]  Path parameters
        #
        # @return [void]
        #
        # FIXME: Rename "action_config" to "action"
        # FIXME: Rename "parameters" to "path_parameters"
        # rubocop:disable Metrics/AbcSize, Metrics/MethodLength, Metrics/CyclomaticComplexity, Metrics/PerceivedComplexity
        def process_action(resource: nil, path: nil, path_config: nil, action_config: nil, parameters: nil)
          responses    = {}
          request_body = nil

          if %i[post put
                patch].include?(action_config) && path_config[:actions][action_config][:params].keys.count.positive?
            schema = path_config[:actions][action_config][:params]
            schema_ref   = escape_operation_id("#{action_config}_#{path}")
            examples     = process_examples(path_config[:actions][action_config][:statuses])
            request_body = process_request_body schema: schema, ref: schema_ref, examples: examples
          end

          path_config[:actions][action_config][:statuses].each do |status_key, status|
            content               = status[:example][:response]
            responses[status_key] = process_response status: status_key, status_config: status, content: content
          end

          action = {
            summary:     path_config[:actions][action_config][:summary]&.strip || '',
            description: path_config[:actions][action_config][:description].presence&.strip || '',
            operationId: "#{resource} #{action_config} #{path}".downcase.gsub(/[^\w]/, '_'),
            parameters:  parameters,
            responses:   responses,
            tags:        [resource.to_s],
          }

          if path_config[:actions][action_config].key? :security
            references = path_config[:actions][action_config][:security]

            action[:security] = []
            references.each do |reference|
              raise "No security scheme defined with reference #{reference}" unless @api_security.key? reference

              action[:security].push({ reference => [] })
            end
          end

          action[:requestBody] = request_body if request_body

          action
        end
        # rubocop:enable Metrics/AbcSize, Metrics/MethodLength, Metrics/CyclomaticComplexity, Metrics/PerceivedComplexity

        ##
        # Processes a request body from metadata
        #
        # @param schema   [Hash]   Schema
        # @param ref      [String] Reference
        # @param examples [Hash]   Example
        #
        # @return [void]
        def process_request_body(schema: nil, ref: nil, examples: {})
          Utils.deep_set @api_components, ['schemas', ref], schema

          {
            # description: '',
            required: true,
            content:  {
              content_type_from_schema(schema) => {
                schema:   { '$ref' => "#/components/schemas/#{ref}" },
                examples: examples,
              },
            },
          }
        end

        def content_type_from_schema(schema)
          schema_includes_file?(schema) ? 'multipart/form-data' : 'application/json'
        end

        def schema_includes_file?(schema)
          return true if schema[:type] == 'string' && schema[:format] == 'binary'
          return false unless schema[:properties].is_a?(Hash) && schema[:required].is_a?(Array)

          schema[:properties].each_value do |definition|
            next unless schema_includes_file?(definition)

            return true
          end

          false
        end

        ##
        # Process a response from metadata
        #
        # @param status        [Symbol] Status code
        # @param status_config [Hash]   Configuration for status code
        # @param content       [String] Response content
        #
        # @return [void]
        def process_response(status: nil, status_config: nil, content: nil) # rubocop:disable Metrics/MethodLength, Metrics/AbcSize, Metrics/CyclomaticComplexity, Metrics/PerceivedComplexity
          response = { description: status_config[:description].presence&.strip || '' }

          return response if status.to_s == '204' && content # No content

          data = begin
            JSON.parse(content)
          rescue JSON::ParserError, TypeError
            content
          end

          entity = status_config[:expectations][:one] || status_config[:expectations][:many]

          # TODO: handle sub-entities
          if @redactables.key?(entity) && data.is_a?(Hash)
            if status_config[:expectations][:one]
              @redactables[entity].each_pair do |attribute, replacement|
                data[attribute.to_s] = replacement
              end
            else
              data.each_index do |index|
                @redactables[entity].each_pair do |attribute, replacement|
                  data[index][attribute.to_s] = replacement
                end
              end
            end
          end

          response[:content] = {
            'application/json': {
              schema:   response_schema(status_config[:expectations]),
              examples: { default: { value: data } },
            },
          }

          response
        end

        def response_schema(expectations) # rubocop:disable Metrics/MethodLength, Metrics/PerceivedComplexity
          if expectations[:many]
            items = if PRIMITIVES.include?(expectations[:many])
                      { type: expectations[:many] }
                    else
                      { '$ref' => "#/components/schemas/#{expectations[:many]}" }
                    end
            { type: 'array', items: items }
          elsif expectations[:one]
            # Unspecified arrays
            if expectations[:one] == :array
              { type: :array, items: {} }
            # Array of specified type
            elsif PRIMITIVES.include?(expectations[:one])
              { type: expectations[:one] }
            else
              { '$ref' => "#/components/schemas/#{expectations[:one]}" }
            end
          end
        end

        ##
        # Processes examples from statuses
        #
        # @param statuses [Hash]
        #
        # @return [Hash] Request examples
        def process_examples(statuses)
          request_examples = {}

          statuses.each do |code, request|
            request_examples[code] = {
              summary: "Example for a #{code} code",
              value:   request[:example][:params],
            }
          end

          request_examples
        end

        def global_entities
          return if RSpec::Rails::Api::Metadata.entities.keys.count.zero?

          @api_components[:schemas] = {}

          RSpec::Rails::Api::Metadata.entities.each_pair do |name, entity|
            @api_components[:schemas][name] = process_entity(entity)
          end
        end

        ##
        # Converts path with params like ":id" to their OpenAPI representation
        #
        # @param string [String] The original path
        #
        # @return [String] OpenAPI path representation
        def path_with_params(string)
          string.gsub(/(?::(\w*))/) do |e|
            "{#{e.sub(':', '')}}"
          end
        end

        ##
        # Converts a string to a snake_cased string to use as operationId
        #
        # @param string [String] Original string
        #
        # @return [String] Snake_cased string
        def escape_operation_id(string)
          string.downcase.gsub(/[^\w]+/, '_')
        end

        ##
        # Fills the API general information sections
        #
        # @return [void]
        def api_infos # rubocop:disable Metrics/CyclomaticComplexity
          @api_infos = {
            title:   @api_title || 'Some sample app',
            version: @api_version || '1.0',
          }
          @api_infos[:description]    = @api_description.strip || '' if @api_description.present?
          @api_infos[:termsOfService] = @api_tos if @api_tos
          @api_infos[:contact]        = @api_contact if @api_contact[:name]
          @api_infos[:license]        = @api_license if @api_license[:name]

          @api_infos
        end

        ##
        # Fills the API servers section
        #
        # @return [void]
        def api_servers
          @api_servers || [
            { url: 'http://api.example.com' },
          ]
        end
      end
    end
  end
end