#!/usr/bin/env python3


#
import datetime
import os
import re
import shlex
import subprocess
import sys


#
class MikesBackup:
	
	#
	__log_dir = None
	__log_name = None
	
	__remote_host = None
	__remote_user = None
	__destination_dir_base = None
	
	__source_dir = None
	__source_dir_includes = []
	__source_dir_excludes = []
	__source_mountpoint_demands = []
	
	__ssh_key = None
	__quiet_ssh = True
	
	__force_full = False
	__force_differential = False
	__no_incremental = False
	
	__log_file_handle = None
	
	CONST_FULL_DIRECTORY_NAME = "full"
	CONST_DIFFERENTIAL_DIRECTORY_NAME = "differential"
	CONST_DIFFERENTIAL_IN_PROGRESS_DIRECTORY_NAME = "IN-PROGRESS"
	
	#
	def __init__(self):
		
		self.parse_args()
	
	#
	def __del__(self):
		
		self.close_log_file()
	
	#
	def __str__(self):
		
		s = ""
		
		s += "MikesBackup Class Instance"
		s += "\nLog Dir: " + str(self.__log_dir)
		s += "\nLog Name: " + str(self.__log_name)
		s += "\nRemote Host: " + str(self.__remote_host)
		s += "\nRemote User: " + str(self.__remote_user)
		s += "\nDestination Dir Base: " + str(self.__destination_dir_base)
		s += "\nSource Dir (Main): " + str(self.__source_dir)
		s += "\nSource Dirs (Includes): " + str(self.__source_dir_includes)
		s += "\nSource Dirs (Excludes): " + str(self.__source_dir_excludes)
		s += "\nSource Mountpoint Demands: " + str(self.__source_mountpoint_demands)
		s += "\nSSH Key: " + str(self.__ssh_key)
		s += "\nQuiet SSH: " + str(self.__quiet_ssh)
		s += "\nForce Full Backup: " + str(self.__force_full)
		s += "\nForce Differential: " + str(self.__force_differential)
		s += "\nDisallow Incremental: " + str(self.__no_incremental)
		
		return s
	
	#
	def log(self, s, o=None):
	
		the_date = self.get_datetime_for_logging()
		
		to_log = "[MikesBackup][" + the_date + "] " + s
		
		# Print the log line
		print(to_log)
		
		# Append the log line to the log file
		f = self.open_log_file()
		if f:
			f.write(to_log + "\n")
		
		# Recurse in order to print whatever o is outputting, if anything
		if o is not None:
			o_lines = str(o).split("\n")
			for line in o_lines:
				self.log(line)
	
	#
	def open_log_file(self):
		
		if self.__log_file_handle:
			return self.__log_file_handle
		
		log_file_path = self.make_log_path()
		if log_file_path:
			self.__log_file_handle = open(log_file_path, "w")
		
		return self.__log_file_handle
	
	#
	def close_log_file(self):
		
		if self.__log_file_handle:
			self.__log_file_handle.close()
			self.__log_file_handle = None
	
	#
	def eprint(*args, **kwargs):
		
		print(*args, file=sys.stderr, **kwargs)
	
	#
	def parse_args(self):
		
		#
		print()
		self.log("Parsing arguments")
		a = 0
		while a + 1 < len(sys.argv):
			
			a += 1
			
			#
			arg = sys.argv[a]
			
			#
			valid_arg = False
			if arg == "":
				valid_arg = True
			elif arg == "--full":
				valid_arg = True
				self.__force_full = True
				self.log("Forcing a full backup")
			elif arg == "--diff" or arg == "--differential":
				valid_arg = True
				self.__force_differential = True
				self.log("Forcing a differential backup")
			elif arg == "--no-incremental":
				valid_arg = True
				self.__no_incremental = True
				self.log("Disallowing incremental backups (differentials will only link back to full)")
			elif arg == "--log-dir":
				valid_arg = True
				self.__log_dir = sys.argv[a + 1]
				self.log("Found log dir: " + self.__log_dir)
				a = a + 1
			elif arg == "--log-name":
				valid_arg = True
				self.__log_name = sys.argv[a + 1]
				self.log("Found log name: " + self.__log_name)
				self.close_log_file()
				a = a + 1
			elif arg == "--source-dir":
				valid_arg = True
				if self.__source_dir:
					raise Exception("--source-dir can only be used once")
				self.__source_dir = sys.argv[a + 1]
				self.log("Found source dir: " + sys.argv[a + 1])
				a = a + 1
			elif arg == "--include":
				valid_arg = True
				self.__source_dir_includes.append(sys.argv[a + 1])
				self.log("Found additional source dir include: " + sys.argv[a + 1])
				a = a + 1
			elif arg == "--source-mountpoint":
				valid_arg = True
				self.__source_mountpoint_demands.append(sys.argv[a + 1])
				self.log("Found required source mountpoint: " + sys.argv[a + 1])
				a += 1
			elif arg == "--destination-dir":
				valid_arg = True
				self.__destination_dir_base = sys.argv[a + 1]
				self.log("Found destination dir: " + self.__destination_dir_base)
				a = a + 1
			elif arg == "--exclude":
				valid_arg = True
				self.__source_dir_excludes.append(sys.argv[a + 1])
				self.log("Found exclude dir: " + sys.argv[a + 1])
				a = a + 1
			elif arg == "--remote-host":
				valid_arg = True
				self.__remote_host = sys.argv[a + 1]
				self.log("Found remote host: " + self.__remote_host)
				a = a + 1
			elif arg == "--remote-user":
				valid_arg = True
				self.__remote_user = sys.argv[a + 1]
				self.log("Found remote user: " + self.__remote_user)
				a = a + 1
			elif arg == "--ssh-key":
				valid_arg = True
				self.__ssh_key = sys.argv[a + 1]
				self.log("Found ssh key: " + self.__ssh_key)
				a = a + 1
			
			#
			if not valid_arg:
				raise Exception("Invalid argument:", arg)
	
	@staticmethod
	def get_datetime_for_logging():
		
		#
		return datetime.datetime.now().strftime("%b %d %Y; %I%M%p")
	
	@staticmethod
	def get_datetime_for_filename():
		
		#
		return datetime.datetime.now().strftime('%Y-%b-%d_%I%M%p')
	
	#
	def is_using_source_mountpoints(self):
	
		return len(self.__source_mountpoint_demands) > 0
	
	#
	def demand_source_mountpoints(self):
		
		for mountpoint_path in self.__source_mountpoint_demands:
			if not os.path.ismount(mountpoint_path):
				raise Exception("Required mountpoint is not mounted: " + str(mountpoint_path))
			self.log("Verified mountpoint: " + mountpoint_path)
	
	#
	def is_using_ssh(self):
		
		#
		if (
			self.__remote_host is not None
			or self.__remote_user is not None
			or self.__ssh_key is not None
		):
			return True
		
		return False
	
	#
	def demand_ssh_config(self):
		
		#
		if self.is_using_ssh():
			if self.__remote_host is None:
				raise Exception("Please provide remote host")
			if self.__remote_user is None:
				raise Exception("Please provide remote user")
	
	#
	def demand_source_directory_config(self):
		
		#
		if self.__source_dir is None:
			raise Exception("Please provide a source directory")
	
	#
	def demand_destination_directory_config(self):
		
		#
		if self.__destination_dir_base is None:
			raise Exception("Please provide backup destination directory")
	
	#
	def does_destination_directory_exist(self, destination_path):
		
		#
		self.log("Trying to determine if destination path exists:" + destination_path)
		
		# Local?
		if not self.is_using_ssh():
			self.log("Checking for local destination path")
			if os.path.isdir(destination_path):
				self.log("Local destination path exists")
				return True
			else:
				self.log("Local destination path does not exist")
				return False
		
		#
		self.log("Checking for remote destination path: " + destination_path)
		command = [
			"[ -d " + destination_path + " ]"
		]
		
		#
		code, stdout, stderr = self.execute_remote_ssh_command(command)
		if code == 0:
			self.log("Remote destination dir was found: " + destination_path)
			return True
		
		#
		self.log("Remote dir didn't seem to exist: " + destination_path)
		return False
	
	#
	def demand_destination_base_backup_directory(self):
		
		#
		self.demand_destination_directory_config()
		
		#
		destination_path = self.__destination_dir_base
		
		#
		if self.does_destination_directory_exist(destination_path) is False:
			raise Exception("Backup destination directory doesn't exist: " + destination_path)
		
	#
	def does_full_backup_destination_directory_exist(self):
		
		#
		dir_path = self.make_full_backup_destination_path()
		
		#
		self.log("Trying to determine if Full backup destination directory exists:", dir_path)
		return self.does_destination_directory_exist(dir_path)
	
	#
	def do_backup(self):
		
		#
		print()
		self.log("Enter: do_backup")
		
		# Source mountpoints must be mounted
		self.demand_source_mountpoints()
		
		# Remote base dir must exist
		self.demand_destination_base_backup_directory()
		
		# Forced full or differential by args?
		if self.__force_full is True or self.__force_differential is True:
			if self.__force_full is True:
				self.log("Forcing full backup")
				self.do_full_backup()
			else:
				self.log("Forcing differential backup")
				self.do_differential_backup()
			return
		
		# Automatically choose full or differential
		if self.does_full_backup_destination_directory_exist():
			self.log("Automatically choosing differential backup, because full backup destination directory already exists")
			self.do_differential_backup()
		else:
			self.log("Automatically choosing full backup, because full backup destination directory wasn't found")
			self.do_full_backup()
	
	#
	def do_full_backup(self):
		
		# Start args
		args = []
		
		# Get destination directory
		destination_dir = self.make_full_backup_destination_path()
		
		# Append source directory
		args.append(self.make_rsync_source_directory_part())
		
		# Append remote destination directory
		# args.append( self.__remote_user + "@" + self.__remote_host + ":" + remote_dir)
		args.append(self.make_rsync_remote_destination_part(destination_dir))
		
		# print("Args", str(args))
		self.log("Destination dir:" + destination_dir)
		
		self.execute_rsync(args)
		
		self.log("Rsync seems to have finished successfully")
		self.log("Because a full backup has succeeded, will now delete any differential backups")
		args_remove_differentials = [
			"rm",
			"-rfv",
			self.make_remote_differential_backup_path_base()
		]
		if self.is_using_ssh():
			self.execute_remote_ssh_command(args_remove_differentials)
		else:
			self.execute_command(args_remove_differentials)
		self.log("Finished deleting old differentials")
	
	#
	def do_differential_backup(self):
		
		# Start args
		args = []
		
		# Get directories
		link_dest_dir = self.determine_rsync_backup_link_destination_path()
		destination_dir_in_progress = self.make_remote_differential_in_progress_backup_path()
		destination_dir_final = self.make_remote_differential_backup_path()
		self.ensure_destination_directory(destination_dir_in_progress)
		
		# Add link dest arg?
		if link_dest_dir:
			args.append("--link-dest")
			args.append(link_dest_dir)
		
		# Append source directory
		args.append(self.make_rsync_source_directory_part())
		
		# Append remote destination directory
		args.append(self.make_rsync_remote_destination_part(destination_dir_in_progress))
		
		self.log("Link destination dir: " + link_dest_dir)
		self.log("Destination dir: " + destination_dir_in_progress)
		
		self.execute_rsync(args)
		
		self.log("Rsync seems to have finished successfully")
		self.log("Renaming temporary directory")
		self.log("Old: " + destination_dir_in_progress)
		self.log("New: " + destination_dir_final)
		if self.is_using_ssh():
			return_code, stdout, stderr = self.execute_remote_ssh_command([
				"mv",
				destination_dir_in_progress,
				destination_dir_final
			])
			if return_code != 0:
				raise Exception("Failed to move temporary diff directory to its final home")
		else:
			os.rename(destination_dir_in_progress, destination_dir_final)
		self.log("Rename was successful")
	
	#
	def make_log_directory_path(self):
		
		#
		log_dir = self.__log_dir
		if log_dir is None:
			print("No log directory specified; Won't log")
			return None
		
		return log_dir
		
	#
	def make_log_path(self):
		
		# Log dir
		log_dir = self.make_log_directory_path()
		if not log_dir:
			return None
		
		# Filename
		file_name = self.get_datetime_for_filename()
		if self.__log_name:
			file_name += "-" + self.__log_name
		file_name += ".log"
		
		# Path
		log_path = os.path.join(log_dir, file_name)
		
		return log_path
	
	#
	def make_full_backup_destination_path(self):
		
		#
		if self.__destination_dir_base is None:
			raise Exception("No remote directory was specified")
		
		#
		return os.path.join(self.__destination_dir_base, self.CONST_FULL_DIRECTORY_NAME)
	
	#
	def make_remote_differential_backup_path_base(self):
		
		#
		if self.__destination_dir_base is None:
			raise Exception("No remote directory was specified")
		
		return os.path.join(self.__destination_dir_base, self.CONST_DIFFERENTIAL_DIRECTORY_NAME)
		
	#
	def make_remote_differential_in_progress_backup_path(self):
		
		diff_path_base = self.make_remote_differential_backup_path_base()
		
		return os.path.join(diff_path_base, self.CONST_DIFFERENTIAL_IN_PROGRESS_DIRECTORY_NAME)
	
	#
	def make_remote_differential_backup_path(self):
		
		diff_path_base = self.make_remote_differential_backup_path_base()
		
		#
		return os.path.join(diff_path_base, self.get_datetime_for_filename())
	
	#
	def make_rsync_source_includes_part(self):
		
		args = []
		
		for d in self.__source_dir_includes:
			args.append("--include")
			args.append(d)
		
		return args
	
	#
	def make_rsync_source_directory_part(self):
		
		self.demand_source_directory_config()
		
		#
		return self.__source_dir
	
	#
	def make_rsync_remote_destination_part(self, destination_dir):
		
		#
		part = ""
		
		#
		if self.__remote_host is not None:
			if self.__remote_user is not None:
				part += self.__remote_user + "@"
			part += self.__remote_host + ":"
			
		#
		part += destination_dir
		
		return part
	
	#
	def determine_rsync_backup_link_destination_path(self):
		
		self.demand_destination_directory_config()
		
		self.log("Begin trying to determine which previous backup path to use as link")
		
		#
		newest_path = None
		newest_path_date = None
		
		# Pattern to parse the 'ls' command
		pattern = re.compile(
			""".*(?P<date>[0-9]{4}-[0-9]{2}-[0-9]{2} [0-9]{2}:[0-9]{2}:[0-9]{2}\.[0-9]{9} .{5}) (?P<name>.+)$""",
			re.MULTILINE
		)
		
		# Get listing info for the full path
		destination_path_full = self.make_full_backup_destination_path()
		args_full_destination_path_ls = [
			"ls",
			"-l",
			"-c",
			"--all",
			"--full-time",
			destination_path_full
		]
		if self.is_using_ssh():
			return_code, stdout, stderr = self.execute_remote_ssh_command(args_full_destination_path_ls)
		else:
			return_code, stdout, stderr = self.execute_command(args_full_destination_path_ls)
		if return_code != 0:
			raise Exception("Failed to get listing info for base destination directory")
		for match in pattern.finditer(stdout):
			name = match.group("name")
			date = match.group("date")
			if name == ".":
				self.log("Start by assuming \"Full\" is the most recent backup: " + destination_path_full)
				self.log("; With a date of " + date)
				newest_path = destination_path_full
				newest_path_date = date
				break
		if not newest_path:
			self.log("Didn't find a \"Full\" backup on remote")
		
		if self.__no_incremental:
			self.log("Incremental backups are disabled; Won't consider any differential directories for the link target")
			return newest_path
		
		# Get listing info for all differential directories
		differential_path_base = self.make_remote_differential_backup_path_base()
		self.ensure_destination_directory(differential_path_base)
		args_differential_destination_path_ls = [
			"ls",
			"-l",
			"-c",
			"--all",
			"--full-time",
			differential_path_base
		]
		if self.is_using_ssh():
			return_code, stdout, stderr = self.execute_remote_ssh_command(args_differential_destination_path_ls)
		else:
			return_code, stdout, stderr = self.execute_command(args_differential_destination_path_ls)
		if return_code != 0:
			raise Exception("Failed to get listing info for destination differential base directory")
		
		# Look for the most recent differential directory
		# (must be newer than the Full directory too)
		for match in pattern.finditer(stdout):
			
			name = match.group("name")
			date = match.group("date")
			
			if name == "." or name == ".." or name == self.CONST_DIFFERENTIAL_IN_PROGRESS_DIRECTORY_NAME:
				continue
			
			if newest_path is None or date > newest_path_date:
				self.log("Found a newer differential backup: " + name + "; " + date)
				newest_path = os.path.join(differential_path_base, name)
				newest_path_date = date
			else:
				self.log("Not newer: " + name + "; " + date)
		
		#
		self.log("Newest backup path is: " + newest_path)
		self.log("; With a date of: " + newest_path_date)
		
		return newest_path
	
	@staticmethod
	def ensure_local_directory(d):
		
		#
		if not os.path.exists(d):
			os.makedirs(d)
	
	#
	def ensure_destination_directory(self, d):
		
		#
		if not self.does_destination_directory_exist(d):
			
			#
			self.log("Destination directory doesn't exist; Will create:" + d)
			
			#
			if self.is_using_ssh():
				command = [
					"mkdir",
					"--parents",
					d
				]
				self.execute_remote_ssh_command(command)
			else:
				os.makedirs(d)
	
	#
	def start_rsync_args(self):
		
		#
		args = [
			"rsync",
			"--archive",
			"--compress",
			"--progress",
			"--stats",
			"--verbose",
			"--human-readable",
			"--itemize-changes",
			"--no-links",
			"--one-file-system",
			"--delete",
			"--delete-excluded"
		]
		
		log_dir = self.make_log_directory_path()
		log_path = self.make_log_path()
		if log_dir and log_path:
			self.ensure_local_directory(log_dir)
			args.append("--log-file")
			args.append(log_path)
		
		# Only allow recursion into multiple file systems
		# if any mountpoints were specified
		if not self.is_using_source_mountpoints():
			args.append("--one-file-system")
		
		#
		for i in self.__source_dir_includes:
			args.append("--include")
			args.append(i)
		
		#
		for e in self.__source_dir_excludes:
			args.append("--exclude")
			args.append(e)
		
		#
		# args.append("--dry-run") # DEBUG !!!
		
		return args
	
	#
	def start_rsync_environment_variables(self):
		
		#
		env = {}
		
		#
		if self.__ssh_key is not None or self.__quiet_ssh is True:
			env["RSYNC_RSH"] = "ssh"
			if self.__ssh_key is not None:
				env["RSYNC_RSH"] += " -i " + shlex.quote(self.__ssh_key)
			if self.__quiet_ssh is True:
				env["RSYNC_RSH"] += " -q"
		
		return env
	
	@staticmethod
	def execute_command(command):
		
		#
		args = list()
		
		# Append the command
		if isinstance(command, str):
			args.append(command)
		elif isinstance(command, list):
			args.extend(command)
		else:
			raise Exception("Unsupported command datatype")
		
		# Spawn
		process = subprocess.Popen(args, stdout=subprocess.PIPE, stderr=subprocess.PIPE)
		stdout, stderr = process.communicate()
		
		stdout = stdout.decode()
		stderr = stderr.decode()
		
		return process.returncode, stdout, stderr
	
	#
	def execute_remote_ssh_command(self, command):
		
		#
		self.demand_ssh_config()
		
		#
		args = list()
		
		# ssh command
		args.append("ssh")
		
		# Quiet?
		if self.__quiet_ssh is True:
			args.append("-q")
		
		# ssh key
		if self.__ssh_key is not None:
			args.append("-i")
			args.append(self.__ssh_key)
		
		# ssh user@host
		args.append(self.__remote_user + "@" + self.__remote_host)
		
		# Append the command
		args.append("--")
		if isinstance(command, str):
			args.append(command)
		elif isinstance(command, list):
			args.extend(command)
		else:
			raise Exception("Unsupported command datatype")
		
		# Spawn
		# print(args)
		process = subprocess.Popen(args, stdout=subprocess.PIPE, stderr=subprocess.PIPE)
		# process = subprocess.Popen(args)
		stdout, stderr = process.communicate()
		
		stdout = stdout.decode()
		stderr = stderr.decode()
		
		# process.communicate()
		# stdout = ""
		# stderr = ""
		# print(stderr.decode())
		
		return process.returncode, stdout, stderr
	
	#
	def execute_rsync(self, _args):
		
		# Demand stuff
		self.demand_source_directory_config()
		self.demand_destination_directory_config()
		if self.is_using_ssh():
			self.demand_ssh_config()
		
		#
		args = self.start_rsync_args()
		args.extend(_args)
		# print(str(args))
		
		#
		env = self.start_rsync_environment_variables()
		
		#
		self.log("Executing rsync with the following arguments:", args)
		self.log("; And the following environment:", env)
		
		#
		# print("Debug -> Want to execute Rsync")
		# print("Args:", str(args))
		# print("Env:", str(env))
		# return (0, "", "")
		
		# Spawn Rsync in shell
		# process = subprocess.Popen(args, stdout=subprocess.PIPE, stderr=subprocess.PIPE, env=env)
		process = subprocess.Popen(args, env=env)
		# stdout, stderr = process.communicate()
		process.communicate()
		# self.eprint(stderr.decode())
		
		stdout = ""
		stderr = ""
		
		# Check return code
		# 0 = Success
		# 24 = Source files vanished
		return_code = process.returncode
		if return_code != 0 and return_code != 24:
			raise Exception("Rsync seems to have failed somehow! Got return code: " + str(return_code))
		
		return return_code, stdout, stderr


def main():
	
	b = MikesBackup()
	b.do_backup()


#
if __name__ == "__main__":
	
	#
	main()