# frozen_string_literal: true

require 'config_server_agent/version'
require 'net/http'
require 'json'
require 'digest/sha1'
require 'lockfile'

class ConfigServerAgent
	class Error < StandardError; end

	def initialize(
		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
	)
		@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_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={})
		dispatch_request(endpoint) do |url|
			request = Net::HTTP::Post.new url
			request.body = data.to_json
			request
		end
	end

	def get_request(endpoint, data={})
		dispatch_request(endpoint) do |url|
			url.query = URI.encode_www_form data
			Net::HTTP::Get.new url
		end
	end

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

		request = yield url
		request['user-agent']    = @user_agent
		request['content-type']  = 'application/json'
		request['accept']        = 'application/json'
		request['api-key']       = @config_server_api_key

		process_response http.request(request)
	end

	def process_response(response)
		unless response['content-type'].start_with? 'application/json'
			raise Error, "Unexpected content-type from server: #{response['content-type']}"
		end

		data = JSON.parse response.read_body

		raise Error, "Config Server error: #{data['error']}" unless response.is_a? Net::HTTPSuccess
		data

	rescue JSON::ParserError
		raise Error, "Invalid JSON received from #{@config_server_host}"
	end

end