# 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,
		token_ttl:              60 * 60 * 24
	)
		@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

		@token_birthday = nil
		@token          = nil
		@token_ttl      = token_ttl
	end

	def get_config
		return @config if @config
		@mutex.synchronize do
			@config ||= get_request 'config_pack'
		end
	end

	def get_selected_config(area, item=nil, **options)

		if options[:ignore_cache]
			@config = nil
		end

		data = get_config.group_by { |x| x['area'] }

		raise Error, "Area is missing: #{area}" unless data.key? area

		if item
			data.fetch(area, []).find { |row_item| break row_item["value"] if row_item["name"] == item }
		else
			data.fetch(area, [])
		end
	end

	def set_config(values)
		raise Error, 'values not found' if values.empty?
		post_request('set_values', values)
	end

	def clear
		@config = nil
	end

	def notify_missing(area, missing)
		post_request 'notify_missing', area: area, name: missing
	end

	private

	def post_request(endpoint, data={})
		url          = URI "#{@config_server_host}/api/#{endpoint}"
		http         = Net::HTTP.new url.host, url.port
		http.use_ssl = url.scheme == 'https'

		request = Net::HTTP::Post.new url
		configure_request request
		request.body = data.to_json

		JSON.parse http.request(request).read_body
	end

	def get_request(endpoint, data={})
		url          = URI "#{@config_server_host}/api/#{endpoint}"
		url.query    = URI.encode_www_form data
		http         = Net::HTTP.new url.host, url.port
		http.use_ssl = url.scheme == 'https'

		request = Net::HTTP::Get.new url
		configure_request request

		JSON.parse http.request(request).read_body
	end

	def configure_request(request)
		request['user-agent']    = @user_agent
		request['authorization'] = "Bearer #{get_token}"
		request['content-type']  = 'application/json'
		request['accept']        = 'application/json'
		request['api-key']       = @config_server_api_key
	end

	def get_token
		if @token.nil? or @token_timestamp.nil? or @token_timestamp <= Time.now.to_i
			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
			@token = JSON.parse(response.read_body)["access_token"] or raise Error, "No token from #{@auth0_host}"
			@token_timestamp = Time.now.to_i + @token_ttl
		end

		@token

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

end