#!/usr/bin/env python3

#
import datetime
import os
import shlex
import subprocess
import sys

#
class MikesBackup:
	
	#
	_log_dir = None
	_remote_host = None
	_remote_user = None
	_remote_dir_base = None
	#
	_ssh_key = None
	_quiet_ssh = True
	#
	_source_dir = None
	_source_dir_excludes = []
	#
	_force_full = False
	_force_differential = False
	
	
	#
	def __init__(self):
		self.ParseArgs()
	
	#
	def eprint(*args, **kwargs):
		print(*args, file=sys.stderr, **kwargs)
	
	#
	def log():
		pass
		
	#
	def ParseArgs(self):
		
		#	Simple mapped args
		args_map = {
			"--log-dir" : "_log_dir",
			"--source-dir" : "_source_dir",
			"--remote-host" : "_remote_host",
			"--remote-user" : "_remote_user",
			"--remote-dir" : "_remote_dir_base",
			"--ssh-key" : "_ssh_key"
		}
		
		#
		print()
		print ("Parsing arguments")
		a = 1
		while a < len(sys.argv):
			
			#
			arg = sys.argv[a]
			
			#
			valid_arg = False
			for arg_name in args_map:
				if arg == arg_name:
					valid_arg = True
					self_var_name = args_map[arg_name]
					self_var_value = sys.argv[ a + 1 ]
					self.__dict__[self_var_name] = self_var_value
					print("Found argument \"", arg_name, "\" ==>", self_var_value)
					a = a + 1
					break
			if arg == "":
				valid_arg = True
			elif arg == "--full":
				valid_arg = True
				self._force_full = True
			elif arg == "--diff" or arg == "--differential":
				valid_arg = True
				self._force_differential = True
			elif arg == "--exclude":
				valid_arg = True
				self._source_dir_excludes.append( sys.argv[ a + 1 ] )
				print("Found exclude dir:", sys.argv[ a + 1 ])
				a = a + 1
			
			a = a + 1
			
			#
			if not valid_arg:
				raise Exception("Invalid argument:", arg);
	
	#
	def GetDatetimeForFilename(self):
		
		#
		return datetime.datetime.now().strftime('%Y-%b-%d_%I%M%p')
	
	#
	def DemandSSHStuff(self):
		
		#
		if self._remote_host == None:
			raise Exception("Please provide remote host")
		if self._remote_user == None:
			raise Exception("Please provide remote user")
		if self._remote_dir_base == None:
			raise Exception("Please provide remote backup destination directory")
	
	#
	def DoesRemoteDirectoryExist(self, remote_path):
		
		#
		command = [
			"[ -d " + remote_path + " ]"
		]
		
		#
		print("Trying to determine if remote path exists:", remote_path)
		code, stdout, stderr = self.ExecuteRemoteSSHCommand(command)
		if code == 0:
			print("Remote dir was found: " + remote_path)
			return True
		
		#
		print("Remote dir didn't seem to exist: " + remote_path)
		return False
	
	#
	def DemandRemoteBaseBackupDirectory(self):
		
		#
		remote_path = self._remote_dir_base
		
		#
		if self.DoesRemoteDirectoryExist(remote_path) == False:
			raise Exception("Remote backup directory doesn't exist: " + remote_path)
		
	#
	def DoesRemoteFullBackupDirectoryExist(self):
		
		#
		remote_path = self.MakeRemoteFullBackupPath()
		
		#
		print("Trying to determine if remote Full backup path exists:", remote_path)
		return self.DoesRemoteDirectoryExist(remote_path)
	
	#
	def GetSourceDirectory(self):
		
		#
		if self._source_dir == None:
			raise Exception("No source directory specified")
		
		return self._source_dir
	
	#
	def DoBackup(self):
		
		#
		print()
		print("Enter: DoBackup")
		
		#	Remote base dir must exist
		self.DemandRemoteBaseBackupDirectory()
		
		#	Forced full or differential by args?
		if self._force_full == True or self._force_differential == True:
			if self._force_full == True:
				print("Forcing full backup")
				self.DoFullBackup()
			else:
				print("Forcing differential backup")
				self.DoDifferentialBackup()
			return
		
		#	Automatically choose full or differential 
		if self.DoesRemoteFullBackupDirectoryExist():
			print("Automatically choosing differential backup, because full backup remote dir already exists")
			self.DoDifferentialBackup()
		else:
			print("Automatically choosing full backup, because full backup remote dir wasn't found")
			self.DoFullBackup()
	
	#
	def DoFullBackup(self):
		
		#	Start args
		args = []
		
		#	Get directory
		remote_dir = self.MakeRemoteFullBackupPath()
		
		#	Append source directory
		args.append(self.GetSourceDirectory())
		
		#	Append remote destination directory
		args.append( self._remote_user + "@" + self._remote_host + ":" + remote_dir)
		
		#print("Args", str(args))
		print("Remote dir:", remote_dir)
		
		self.ExecuteRsync(args)
	
	#
	def DoDifferentialBackup(self):
		
		#	Start args
		args = []
		
		#	Get directories
		remote_link_dest_dir = self.MakeRemoteFullBackupPath()
		remote_dir = self.MakeRemoteDifferentialBackupPath()
		self.EnsureRemoteDirectory(remote_dir)
		
		#	Add link dest arg
		args.append("--link-dest")
		args.append(remote_link_dest_dir)
		
		#	Append source directory
		args.append(self.GetSourceDirectory())
		
		#	Append remote destination directory
		args.append( self._remote_user + "@" + self._remote_host + ":" + remote_dir)
		
		#print("Args", str(args))
		print("Remote link dest dir:", remote_link_dest_dir)
		print("Remote dir:", remote_dir)
		
		self.ExecuteRsync(args)
	
	#
	def MakeLogDirectoryPath(self):
		
		#
		log_dir = self._log_dir
		if log_dir == None:
			print("No log directory specified; Defaulting to current working directory")
			log_dir = "."
		
		return log_dir
		
	#
	def MakeLogPath(self):
		
		#	Log dir
		log_dir = self.MakeLogDirectoryPath()
		
		#	Path
		log_path = os.path.join(log_dir, self.GetDatetimeForFilename() + ".log")
		
		return log_path
	
	#
	def MakeRemoteFullBackupPath(self):
		
		#
		if self._remote_dir_base == None:
			raise Exception("No remote directory was specified")
		
		#
		return os.path.join(self._remote_dir_base, "Full")
	
	#
	def MakeRemoteDifferentialBackupPath(self):
		
		#
		if self._remote_dir_base == None:
			raise Exception("No remote directory was specified")
		
		#
		return os.path.join(self._remote_dir_base, "Differential", self.GetDatetimeForFilename())
	
	#
	def EnsureLocalDirectory(self, d):
		
		#
		if not os.path.exists(d):
			os.makedirs(d)
	
	#
	def EnsureRemoteDirectory(self, d):
		
		#
		if not self.DoesRemoteDirectoryExist(d):
			
			#
			command = [
				"mkdir",
				"--parents",
				d
			]
			self.ExecuteRemoteSSHCommand(command)
	
	#
	def StartRsyncArgs(self):
		
		#
		self.EnsureLocalDirectory(self.MakeLogDirectoryPath())
		args = [
			"rsync",
			"--log-file", self.MakeLogPath(),
			"--archive",
			"--compress",
			"--progress",
			"--stats",
			"--human-readable",
			"--itemize-changes",
			"--one-file-system",
			"--delete",
			"--delete-excluded"
		]
		
		#
		for e in self._source_dir_excludes:
			args.append("--exclude")
			args.append(e)
		
		#
		#args.append("--dry-run") # DEBUG !!!
		
		return args
	
	#
	def StartRsyncEnvironmentalVariables(self):
		
		#
		env = {}
		
		#
		if self._ssh_key != None or self._quiet_ssh == True:
			env["RSYNC_RSH"] = "ssh"
			if self._ssh_key != None:
				env["RSYNC_RSH"] += " -i " + shlex.quote(self._ssh_key)
			if self._quiet_ssh == True:
				env["RSYNC_RSH"] += " -q"
		
		return env
	
	#
	def ExecuteRemoteSSHCommand(self, command):
		
		#
		self.DemandSSHStuff()
		
		#
		args = []
		
		#	ssh command
		args.append("ssh")
		
		#	Quiet?
		if self._quiet_ssh == True:
			args.append("-q")
		
		#	ssh key
		if self._ssh_key != 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 SSH in shell
		#process = subprocess.Popen(args, stdout=subprocess.PIPE, stderr=subprocess.PIPE)
		process = subprocess.Popen(args)
		#stdout, stderr = process.communicate()
		process.communicate()
		stdout = ""
		stderr = ""
		#print (stderr.decode())
		
		return (process.returncode, stdout, stderr)
	
	#
	def ExecuteRsync(self, _args):
		
		#
		self.DemandSSHStuff()
		
		#
		args = self.StartRsyncArgs()
		args.extend(_args)
		#print(str(args))
		
		#
		env = self.StartRsyncEnvironmentalVariables()
		
		#	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 = ""
		
		return (process.returncode, stdout, stderr)

#
if __name__ == "__main__":
	
	#
	b = MikesBackup()
	b.DoBackup()