# frozen_string_literal: true

# Released under the MIT License.
# Copyright, 2020-2023, by Samuel Williams.

require 'async/container/controller'

module Falcon
	module Controller
		# A controller which mananages several virtual hosts.
		# Spawns instances of {Proxy} and {Redirect} to handle incoming requests.
		#
		# A virtual host is an application bound to a specific authority (essentially a hostname). The virtual controller manages multiple hosts and allows a single server to host multiple applications easily.
		class Virtual < Async::Container::Controller
			# Initialize the virtual controller.
			# @parameter command [Command::Virtual] The user-specified command-line options.
			def initialize(command, **options)
				@command = command
				
				super(**options)
				
				trap(SIGHUP, &self.method(:reload))
			end
			
			# Drop privileges according to the user and group of the specified path.
			# @parameter path [String] The path to the application directory.
			def assume_privileges(path)
				stat = File.stat(path)
				
				Process::GID.change_privilege(stat.gid)
				Process::UID.change_privilege(stat.uid)
				
				home = Etc.getpwuid(stat.uid).dir
				
				return {
					'HOME' => home,
				}
			end
			
			# Spawn an application instance from the specified path.
			# @parameter path [String] The path to the application directory.
			# @parameter container [Async::Container::Generic] The container to spawn into.
			# @parameter options [Options] The options which are passed to `exec`.
			def spawn(path, container, **options)
				container.spawn(name: "Falcon Application", restart: true, key: path) do |instance|
					env = assume_privileges(path)
					
					instance.exec(env,
						"bundle", "exec", "--keep-file-descriptors",
						path, ready: false, **options)
				end
			end
			
			# The path to the falcon executable from this gem.
			# @returns [String]
			def falcon_path
				File.expand_path("../../../bin/falcon", __dir__)
			end
			
			# Setup the container with {Redirect} and {Proxy} child processes.
			# These processes are gracefully restarted if they are already running.
			# @parameter container [Async::Container::Generic]
			def setup(container)
				if proxy = container[:proxy]
					proxy.kill(:HUP)
				end
				
				if redirect = container[:redirect]
					redirect.kill(:HUP)
				end
				
				container.reload do
					@command.resolved_paths do |path|
						path = File.expand_path(path)
						root = File.dirname(path)
						
						spawn(path, container, chdir: root)
					end
					
					container.spawn(name: "Falcon Redirector", restart: true, key: :redirect) do |instance|
						instance.exec(falcon_path, "redirect",
							"--bind", @command.bind_insecure,
							"--timeout", @command.timeout.to_s,
							"--redirect", @command.bind_secure,
							*@command.paths, ready: false
						)
					end
					
					container.spawn(name: "Falcon Proxy", restart: true, key: :proxy) do |instance|
						instance.exec(falcon_path, "proxy",
							"--bind", @command.bind_secure,
							"--timeout", @command.timeout.to_s,
							*@command.paths, ready: false
						)
					end
				end
			end
		end
	end
end