module Dhalang
    # Contains common logic for interacting with Puppeteer.
    class Puppeteer
        NODE_MODULES_PATH = Dir.pwd + '/node_modules/'.freeze
        private_constant :NODE_MODULES_PATH

        NAVIGATION_TIMEOUT = 10000
        private_constant :NAVIGATION_TIMEOUT

        NAVIGATION_WAIT_UNTIL = 'load'
        private_constant :NAVIGATION_WAIT_UNTIL

        USER_AGENT = ''
        private_constant :USER_AGENT

        VIEW_PORT = ''
        private_constant :VIEW_PORT

        HTTP_AUTHENTICATION_CREDENTIALS = ''
        private_constant :HTTP_AUTHENTICATION_CREDENTIALS

        DEFAULT_OPTIONS = {
            scale: 1,
            displayHeaderFooter: false,
            headerTemplate: '',
            footerTemplate: '',
            printBackground: true,
            landscape: false,
            pageRanges: '',
            format: 'A4',
            width: '',
            height: '',
            margin: { top: 36, right: 36, bottom: 20, left: 36 },
            preferCSSPageSiz: false
        }
        private_constant :DEFAULT_OPTIONS


        # Launches a new Node process, executing the (Puppeteer) script under the given script_path.
        #
        # @param [String] page_url              The url to pass to the goTo method of Puppeteer.
        # @param [String] script_path           The absolute path of the JS script to execute.
        # @param [String] temp_file_path        The absolute path of the temp file to use to write any actions from Puppeteer.
        # @param [String] temp_file_extension   The extension of the temp file.
        # @param [Object] options               Set of options to use, configurable by the user.
        def self.visit(page_url, script_path, temp_file_path, temp_file_extension, options)
            configuration = create_configuration(page_url, script_path, temp_file_path, temp_file_extension, options)
            Kernel.system("node #{script_path} #{Shellwords.escape(configuration)}")
        end


        # Returns a JSON string with the configuration to use within the Puppeteer script.
        #
        # @param [String] page_url              The url to pass to the goTo method of Puppeteer.
        # @param [String] script_path           The absolute path of the JS script to execute.
        # @param [String] temp_file_path        The absolute path of the temp file to use to write any actions from Puppeteer.
        # @param [String] temp_file_extension   The extension of the temp file.
        # @param [Hash]   options               Set of options to use, configurable by the user.
        private_class_method def self.create_configuration(page_url, script_path, temp_file_path, temp_file_extension, options)
            {
                webPageUrl: page_url,
                tempFilePath: temp_file_path,
                puppeteerPath: NODE_MODULES_PATH,
                imageType: temp_file_extension,
                userOptions: {
                    navigationParameters: {
                        timeout: options.has_key?(:navigation_timeout) ? options[:navigation_timeout] : NAVIGATION_TIMEOUT,
                        waitUntil: NAVIGATION_WAIT_UNTIL
                    },
                    userAgent: options.has_key?(:user_agent) ? options[:user_agent] : USER_AGENT,
                    viewPort: options.has_key?(:view_port) ? options[:view_port] : VIEW_PORT,
                    httpAuthenticationCredentials: options.has_key?(:http_authentication_credentials) ? options[:http_authentication_credentials] : HTTP_AUTHENTICATION_CREDENTIALS
                },
                pdfOptions: DEFAULT_OPTIONS.map { |option, value| [option, options.has_key?(option) ? options[option] : value] }.to_h
            }.to_json
        end
    end
end