module Shutl::Resource
  module RestClassMethods
    def find(args = {}, params = {})
      params = args if @singular_resource
      auth_options = { auth: params.delete(:auth), from: params.delete(:from) }

      if @singular_resource
        url    = singular_member_url params
      elsif !args.kind_of?(Hash)
        id   = args
        args = { resource_id_name => id }
        url  = member_url args.dup, params
      else
        url = member_url args.dup, params
      end

      response     = get url, headers_with_auth(auth_options)

      check_fail response, "Failed to find #{name}! args: #{args}, params: #{params}"

      parsed = response.parsed_response

      including_parent_attributes = parsed[@resource_name].merge args
      new_object including_parent_attributes, response
    end

    def create attributes = {}, options = {}
      url = generate_collection_url attributes
      attributes.delete "response"

      response = post(
        url,
        { body: { @resource_name => attributes }.to_json }.merge(headers_with_auth(options))
      )

      check_fail response, "Create failed"

      parsed     = response.parsed_response || {}
      attributes = parsed[@resource_name] || {}

      new_object attributes, response
    end

    def destroy instance, options = {}
      message = "Failed to destroy #{name.downcase.pluralize}"

      perform_action(
        instance,
        :delete,
        headers_with_auth(options),
        message
      ).success?
    end

    def save instance, options = {}
      #TODO: this is sometimes a hash and sometimes a Rest - need to rethink this
      attributes = instance.attributes rescue instance

      payload = {
        body: { @resource_name => convert_new_id(attributes) }.to_json
      }

      payload_with_headers = payload.merge(headers_with_auth options)
      response             = perform_action(instance, :put, payload, "Save failed")

      response.success?
    end

    def update args, options = {}
      save args, options
    end


    def all(args = {})
      auth_options = { auth: args.delete(:auth), from: args.delete(:from) }
      partition    = args.partition { |key, value| !remote_collection_url.index(":#{key}").nil? }

      url_args = partition.first.inject({}) { |h, pair| h[pair.first] = pair.last; h }
      params   = partition.last.inject({}) { |h, pair| h[pair.first] = pair.last; h }

      url      = generate_collection_url url_args, params
      response = get url, headers_with_auth(auth_options)

      check_fail response, "Failed to find all #{name.downcase.pluralize}"

      response_object = response.parsed_response[@resource_name.pluralize].map do |h|
        new_object(args.merge(h), response)
      end
      if order_collection?
        response_object.sort! do |a,b|
          str_a = a.send(@order_collection_by).to_s
          str_b = b.send(@order_collection_by).to_s
          str_a.casecmp(str_b)
        end
      end

      RestCollection.new(response_object, response.parsed_response['pagination'])
    end

    class RestCollection
      include Enumerable

      attr_reader :collection

      def initialize(collection, pagination)
        @collection = collection
        @pagination = pagination
      end

      delegate :each, to: :collection

      class Pagination < Struct.new(:page,
                                    :items_on_page,
                                    :total_count,
                                    :number_of_pages)
      end

      def pagination
        return unless @pagination.present?
        Pagination.new(@pagination['page'],
                       @pagination['items_on_page'],
                       @pagination['total_count'],
                       @pagination['number_of_pages'])
      end
    end

    def singular_resource
      @singular_resource = true
    end

    def resource_name(name)
      instance_variable_set :@resource_name, name
    end

    def resource_id(variable_name)
      instance_variable_set :@resource_id, variable_name
    end

    def resource_id_name
      instance_variable_get(:@resource_id).to_sym
    end

    def remote_collection_url
      @remote_collection_url ||= "/#{@resource_name.pluralize}"
    end

    def remote_resource_url
      @remote_resource_url ||= "#{remote_collection_url}/:#{resource_id_name}"
    end

    def collection_url(url)
      @remote_collection_url = url
    end

    def resource_url(url)
      @remote_resource_url = url
    end

    def order_collection_by(field)
      @order_collection_by = field
    end

    def convert_new_id attributes
      if attributes[:new_id]
        attributes = attributes.clone.tap { |h| h[:id] = h[:new_id]; h.delete(:new_id) }
      end

      attributes
    end

    def add_resource_id_to args={}
      args = args.dup.with_indifferent_access
      unless args.has_key? "id"
        args.merge!({ "id" => args[resource_id_name] })
      end
      args
    end

    def singular_member_url params={}
      generate_url! "/#{@resource_name}", params
    end

    def member_url *args
      attributes = args.first.with_indifferent_access

      unless attributes[resource_id_name] ||= attributes[:id]
        raise ArgumentError, "Missing resource id with name: `#{resource_id_name}' for #{self}"
      end

      args[0] = attributes

      generate_url! remote_resource_url, *(args.dup)
    end

    def generate_collection_url *args
      generate_url! remote_collection_url, *args
    end


    private

    def headers_with_auth options = {}
      headers.tap do |h|
        h['Authorization'] = "Bearer #{options[:auth]}" if options[:auth]
        h['From'] = "#{options[:from]}" if options[:from]
      end
      { headers: headers }
    end

    def perform_action instance, verb, args, failure_message
      attributes = instance.is_a?(Hash) ? instance : instance.attributes
      attributes.delete "response" #used in debugging requests/responses

      url      = member_url attributes
      response = send verb, url, args

      check_fail response, failure_message

      response
    end

    def new_object(args={}, response=nil)
      instance = new add_resource_id_to(args), response

      instance.tap do |i|
        parsed_response = response.parsed_response

        if errors = (parsed_response and parsed_response["errors"])
          i.errors = errors
        end
      end
    end

    def check_fail response, message
      c             = response.code
      failure_klass = case c
                      when 299
                        if Shutl::Resource.raise_exceptions_on_no_quotes_generated
                          Shutl::NoQuotesGenerated
                        else
                          nil
                        end

                      when 400 then Shutl::BadRequest
                      when 401 then Shutl::UnauthorizedAccess
                      when 403 then Shutl::ForbiddenAccess
                      when 404 then Shutl::ResourceNotFound
                      when 409 then Shutl::ResourceConflict
                      when 410 then Shutl::ResourceGone
                      when 422
                        if Shutl::Resource.raise_exceptions_on_validation
                          Shutl::ResourceInvalid
                        else
                          nil #handled as validation failure
                        end

                      when 411..499
                        Shutl::BadRequest
                      when 500 then Shutl::ServerError
                      when 503 then Shutl::ServiceUnavailable
                      when 501..Float::INFINITY
                        Shutl::ServerError
                      end


      output = begin
                 response.parsed_response["errors"]["base"]
               rescue
                 message
               end

      raise failure_klass.new output, response if failure_klass
    end

    protected

    def generate_url!(url_pattern, args, params = {})
      url = url_pattern.dup

      url = "#{Shutl::Resource.base_uri}#{url}" unless self.base_uri

      args, url = replace_args_from_pattern! args, url

      url = URI.escape url
      unless params.empty?
        url += '?'
        params.each { |key, value| url += "#{key}=#{value}&" }
      end
      url
    end

    def order_collection?
      !!@order_collection_by
    end

    private
    def replace_args_from_pattern! args, url
      args = args.reject! do |key, value|
        if s = url[":#{key}"]
          url.gsub!(s, value.to_s)
        end
      end

      return args, url
    end
  end
end