require 'rest-client'
require 'dmao/api/base'
require 'dmao/api/errors/institution_not_found'
require 'dmao/api/errors/invalid_parent_id'
require 'dmao/api/errors/invalid_organisation_unit'
require 'dmao/api/errors/organisation_unit_not_found'
require 'dmao/api/errors/invalid_system_uuid'
require 'dmao/api/errors/invalid_response_length'

module DMAO
  module API

    class OrganisationUnit < Base

      VALID_ATTRIBUTES = [:id, :institution_id, :name, :description, :url, :system_uuid, :system_modified_at, :isni, :unit_type, :parent_id]
      attr_reader(*VALID_ATTRIBUTES)

      def initialize(attributes)

        @id = attributes[:id]
        @institution_id = attributes[:institution_id]
        @name = attributes[:name]
        @description = attributes[:description]
        @url = attributes[:url]
        @system_uuid = attributes[:system_uuid]
        @system_modified_at = attributes[:system_modified_at]
        @isni = attributes[:isni]
        @unit_type = attributes[:unit_type]

        if attributes[:parent_id]
          @parent_id = attributes[:parent_id]
        end

      end

      def self.all

        begin
          response = self.api['organisation_units'].get
        rescue RestClient::NotFound
          raise DMAO::API::Errors::InstitutionNotFound.new
        end

        org_units = []

        response_data = JSON.parse(response)["data"]

        return org_units if response_data.length == 0

        response_data.each do |data|

          org_units.push instance_from_api_data(data)

        end

        org_units

      end

      def self.get id

        validate_organisation_unit_id id

        begin
          response = self.api["organisation_units/#{id}"].get
        rescue RestClient::NotFound
          raise DMAO::API::Errors::OrganisationUnitNotFound.new
        end

        instance_from_response response

      end

      def self.find_by_system_uuid system_uuid

        validate_system_uuid system_uuid

        response = self.api["organisation_units?system_uuid=#{system_uuid}"].get

        response_data = JSON.parse(response)["data"]

        raise DMAO::API::Errors::OrganisationUnitNotFound.new if response_data.length == 0
        raise DMAO::API::Errors::InvalidResponseLength.new("Expected 1 element in response there were #{response_data.length}") if response_data.length != 1

        data = response_data[0]

        instance_from_api_data data

      end

      def self.create attributes

        validate_attributes attributes

        begin
          response = self.api['organisation_units'].post attributes.to_json
        rescue RestClient::NotFound
          raise DMAO::API::Errors::InstitutionNotFound.new
        rescue RestClient::UnprocessableEntity => e
          handle_unprocessable_entity e
        end

        instance_from_response response

      end

      def self.update id, attributes

        validate_organisation_unit_id id

        validate_attributes attributes

        begin
          response = self.api["organisation_units/#{id}"].patch attributes.to_json
        rescue RestClient::NotFound
          raise DMAO::API::Errors::OrganisationUnitNotFound.new
        rescue RestClient::UnprocessableEntity => e
          handle_unprocessable_entity e
        end

        instance_from_response response

      end

      def self.delete id

        validate_organisation_unit_id id

        begin
          self.api["organisation_units/#{id}"].delete
        rescue RestClient::NotFound
          raise DMAO::API::Errors::OrganisationUnitNotFound.new
        rescue RestClient::UnprocessableEntity => e
          handle_unprocessable_entity e
        end

        true

      end

      def self.instance_from_response response_body

        data = JSON.parse(response_body)["data"]

        instance_from_api_data data

      end

      def self.instance_from_api_data data

        parent_id = data["relationships"]["parent"]["data"].nil? ? nil : data["relationships"]["parent"]["data"]["id"]

        attributes = {
            id: data["id"],
            institution_id: data["relationships"]["institution"]["data"]["id"],
            name: data["attributes"]["name"],
            description: data["attributes"]["description"],
            url: data["attributes"]["url"],
            system_uuid: data["attributes"]["system-uuid"],
            system_modified_at: data["attributes"]["system-modified-at"],
            isni: data["attributes"]["isni"],
            unit_type: data["attributes"]["unit-type"],
            parent_id: parent_id
        }

        new(attributes)

      end

      def self.validate_attributes attributes
        attributes.keep_if { |k, _v| VALID_ATTRIBUTES.include? k }
      end

      def self.validate_organisation_unit_id id
        if id.nil? || id.to_s.empty?
          raise DMAO::API::Errors::InvalidOrganisationUnitID.new
        end
      end

      def self.validate_system_uuid system_uuid
        if system_uuid.nil? || system_uuid.to_s.empty?
          raise DMAO::API::Errors::InvalidSystemUUID.new
        end
      end

      def self.handle_unprocessable_entity error_response

        errors = JSON.parse(error_response.response.body)["errors"]

        raise DMAO::API::Errors::InvalidParentId.new if errors.keys.include? "parent"
        raise DMAO::API::Errors::InvalidOrganisationUnit.new("Invalid organisation unit details, please see errors.", errors)

      end

    end

  end
end