require 'psych'
require_relative 'client'

module RestDSL

  ##
  # Base Class for defining a rest service DSL Object.
  # Will look in a config file contained in the same directory as the service defining its headers and/or creds
  # by environment.  This file should be named such that it matches the service file name with a .yml ending.
  class ServiceBase

    def self.inherited(clazz)
      clazz.class_eval do
        @file_name = caller_locations[2].path
        @config_file = @file_name.gsub('.rb', '.yml')
      end
    end

    class << self
      attr_reader :environment, :file_name, :client, :config_file, :last_response
      attr_writer :headers, :authentication

      # Initializes the singleton
      def environment=(environment)
        @environment = environment
        @client = Client.new(environment)
        self
      end

      def service_name=(name)
        @service_name = name
      end

      def rest_call(method, name, url_schema)
        self.class.define_method("#{method}_#{name}") do |*args, headers: nil, payload: nil, params: nil, url_args: nil, **hash_args|
          execute_request(method, url_schema.dup, *args, **hash_args, headers: headers, payload: payload, params: params, url_args: url_args)
        end
      end

      # The method wrapped by the methods generated by rest_call, these methods all follow this blueprint
      # Can by wrapped manually to create more complicated logic than what's supported by the default generators
      def execute_request(method, rest_method_call, *args, headers: nil, payload: nil, params: nil, url_args: nil, **hash_args, &block)
        headers ||= self.headers
        params ||= {}
        url_args ||= {}
        params = "?#{params.map{|key,value| "#{key}=#{value}"}.join('&')}"
        service_name = "#{@service_name}/" unless @service_name&.empty?
        hash_args.merge!(auth)
        hash_args.merge!(payload: payload) if payload
        sub_url_args!(url_args, rest_method_call)
        arg_list = [method, "#{service_name}#{rest_method_call}#{params}", headers]
        response = @client.execute(*arg_list, *args, **hash_args, &block)
        @last_response = response[:response]
        response[:parsed]
      end

      def sub_url_args!(arg_list, rest_method_call)
        # Given the protocol is handled by the client and not service_base, this should be a safe enough pattern in most cases
        arg_list.each{ |arg_name, value| rest_method_call.gsub!(":#{arg_name}", value) }
      end

      def config
        @config || reload_config
      end

      def config_file=(file_name)
        @config_file = file_name
        reload_config
      end

      def reload_config
        @config = Psych.load_file(@config_file)[@environment] if File.exist?(@config_file)
        @config = {} unless File.exist?(@config_file)
      end

      def auth
        @authentication || config&.[](:credentials) || {}
      end

      def headers
        @headers ||= config&.[](:headers) || {}
      end
    end

    def service_name
      self.class.instance_variable_get(:@service_name)
    end
  end

end