# frozen_string_literal: true

require "config_server_agent/version"
require "net/http"
require "json"

class ConfigServerAgent
	class Error < StandardError; end

	def initialize(
		auth0_client_id:        ENV['AUTH0_CLIENT_ID'],
		auth0_client_secret:    ENV['AUTH0_CLIENT_SECRET'],
		auth0_host:             ENV['AUTH0_HOST'],
		config_server_audience: ENV['CONFIG_SERVER_AUDIENCE'],
		config_server_api_key:  ENV['CONFIG_SERVER_API_KEY'],
		config_server_host:     ENV['CONFIG_SERVER_HOST'],
		user_agent:             "ConfigServerAgent/#{ConfigServerAgent::VERSION}",
		user_agent_comment:     nil
	)
		@auth0_client_id        = auth0_client_id        or raise ArgumentError, "Missing auth0_client_id parameter"
		@auth0_client_secret    = auth0_client_secret    or raise ArgumentError, "Missing auth0_client_secret parameter"
		@auth0_host             = auth0_host             or raise ArgumentError, "Missing auth0_host parameter"
		@config_server_audience = config_server_audience or raise ArgumentError, "Missing config_server_audience parameter"
		@config_server_api_key  = config_server_api_key  or raise ArgumentError, "Missing config_server_api_key parameter"
		@config_server_host     = config_server_host     or raise ArgumentError, "Missing config_server_host parameter"
		@config = nil
		@mutex = Mutex.new
		@user_agent = user_agent
		@user_agent += " (#{user_agent_comment})" if user_agent_comment
	end

	def get_config
		return @config if @config
		@mutex.synchronize do
			@config ||= _get_config
		end
	end

	def clear
		@config = nil
	end

	private

	def _get_config

		token = get_token

		url  = URI "#{@config_server_host}/api/config_pack"
		http = Net::HTTP.new url.host, url.port
		http.use_ssl = url.scheme == 'https'

		request = Net::HTTP::Post.new url
		request['user-agent']    = @user_agent
		request['content-type']  = 'application/json'
		request['authorization'] = "Bearer #{token}"
		request['accept']        = 'application/json'
		request.body = { api_key: @config_server_api_key }.to_json

		response = http.request request
		JSON.parse response.read_body
	end

	def get_token
		url  = URI "https://#{@auth0_host}/oauth/token"
		http = Net::HTTP.new url.host, url.port
		http.use_ssl = url.scheme == 'https'

		request = Net::HTTP::Post.new url
		request['user-agent'] = @user_agent
		request['content-type'] = 'application/json'
		request.body = {
			client_id:     @auth0_client_id,
			client_secret: @auth0_client_secret,
			audience:      @config_server_audience,
			grant_type:    'client_credentials',
		}.to_json

		response = http.request request
		JSON.parse(response.read_body)["access_token"] or raise Error, "No token from #{@auth0_host}"

	rescue JSON::ParserError
		raise Error, "Invalid response from #{@auth0_host}"

	end

end