#!/usr/bin/python3

# Import libraries
from sys import exit, argv

import os
from os.path import expanduser, isfile, isdir, islink, exists
from shutil import move, rmtree

import subprocess

from datetime import datetime
from tempfile import mkstemp

class Backup():

    def __init__(self, *args, **kwargs):
        super(Backup, self).__init__(*args, **kwargs)
        
        self.log_path = ''
        self.logfile = None
        self.err_path = ''
        self.errfile = None
        self.warn_path = ''
        self.warnfile = None
        self.homedir = ''
        self.backup_dev = ''
        self.backup_dir = ''
        self.last_backup = ''
        self.inputs = ''
        self.inputs_path = ''
        self.exclude_path = ''
        self.exclude = ''
        self.options = ''
        self.user = ''
        self.keep = -1
        self.n_in = 0

    # Help function
    def help_function(self):
        print('simple_backup, version 2.0.0')
        print('')
        print('Usage: {} [OPTIONS]'.format(argv[0]))
        print('')
        print('Options:')
        print('-h, --help                             Print this help and exit.')
        print('-c, --config      CONFIG_FILE          Use the specified configuration file')
        print('                                       instead of the default one.')
        print('                                       All other options are ignored.')
        print('-i, --input       INPUT [INPUT...]     Specify a file/dir to include in the backup.')
        print('-d, --directory   DIR                  Specify the output directory for the backup.')
        print('-e, --exclude     PATTERN [PATTERN...] Specify a file/dir/pattern to exclude from')
        print('                                       the backup.')
        print('-k, --keep        NUMBER               Specify the number of old backups to keep.')
        print('                                       Default: keep all.')
        print('-u, --user        USER                 User performing the backup.')
        print('                                       Useful when running with "sudo"')
        print('-s, --checksum                         Use the checksum rsync option to compare files')
        print('                                       (MUCH slower).')
        print('')
        print('If no option is given, the program uses the default')
        print('configuration file: $HOMEDIR/.simple_backup/config.')
        print('')
        print('Report bugs to dfucini@gmail.com')

        exit(0)

    # Function to read configuration file
    def read_conf(self, config=None):
        if config is None:
            config = self.homedir + '/.simple_backup/config'

            if not isfile(config):
            # If default config file doesn't exist, exit
                log_message = str(datetime.now()) + ': Backup failed (see errors.log)'
                self.logfile.write(log_message)
                self.logfile.write('\n')
                print('Backup failed')
                err_message = 'Error: Configuration file not found'
                print(err_message)
                self.errfile.write(err_message)
                self.errfile.write('\n')

                self.logfile.close()
                self.errfile.close()
                self.warnfile.close()

                move(self.log_path, self.homedir + '/.simple_backup/simple_backup.log')
                move(self.err_path, self.homedir + '/.simple_backup/errors.log')
                move(self.warn_path, self.homedir + '/.simple_backup/warnings.log')

                exit(1)
        else:
            if not isfile(config):
                # If the provided configuration file doesn't exist, exit
                log_message = str(datetime.now()) + ': Backup failed (see errors.log)'
                self.logfile.write(log_message)
                self.logfile.write('\n')
                print('Backup failed')
                err_message = 'Error: Configuration file not found'
                print(err_message)
                self.errfile.write(err_message)
                self.errfile.write('\n')

                self.logfile.close()
                self.errfile.close()
                self.warnfile.close()

                move(self.log_path, self.homedir + '/.simple_backup/simple_backup.log')
                move(self.err_path, self.homedir + '/.simple_backup/errors.log')
                move(self.warn_path, self.homedir + '/.simple_backup/warnings.log')

                exit(1)

        # Create temporary files
        inputs_handle, self.inputs_path = mkstemp(prefix='tmp_inputs', text=True)
        exclude_handle, self.exclude_path = mkstemp(prefix='tmp_exclude', text=True)

        # Open temporary files
        self.inputs = open(self.inputs_path, 'w')
        self.exclude = open(self.exclude_path, 'w')

        # Parse the configuration file
        with open(config, 'r') as fp:
            line = fp.readline()

            while line:
                if line[:7] == 'inputs=':
                    line = line[7:].rstrip()
                    input_values = line.split(',')
                    n_in = 0
                    for i in input_values:
                        if not exists(i):
                            warn_message = 'Warning: input "' + i + '" not found. Skipping'
                            print(warn_message)
                            self.warnfile.write(warn_message)
                            self.warnfile.write('\n')
                        else:
                            self.inputs.write(i)
                            self.inputs.write('\n')
                            self.n_in = self.n_in + 1
                elif line[:11] == 'backup_dir=':
                    line = line[11:].rstrip()
                    self.backup_dev = line
                elif line[:8] == 'exclude=':
                    line = line[8:].rstrip()
                    exclude_values = line.split(',')
                    for i in exclude_values:
                        self.exclude.write(i)
                        self.exclude.write('\n')
                elif line[:5] == 'keep=':
                    line = line[5:].rstrip()
                    self.keep = int(line)

                line = fp.readline()

            fp.close()
            self.inputs.close()
            self.exclude.close()

        # If the backup directory is not set or doesn't exist, exit
        if self.backup_dev == '' or not isdir(self.backup_dev):
            log_message = str(datetime.now()) + ': Backup failed (see errors.log)'
            self.logfile.write(log_message)
            self.logfile.write('\n')
            print('Backup failed')
            err_message = 'Error: Output folder "' + self.backup_dev + '" not found'
            print(err_message)
            self.errfile.write(err_message)
            self.errfile.write('\n')

            self.logfile.close()
            self.errfile.close()
            self.warnfile.close()

            move(self.log_path, self.homedir + '/.simple_backup/simple_backup.log')
            move(self.err_path, self.homedir + '/.simple_backup/errors.log')
            move(self.warn_path, self.homedir + '/.simple_backup/warnings.log')

            exit(1)

        self.backup_dir = self.backup_dev + '/simple_backup'
        date = str(datetime.now())

        # Create the backup subdirectory using date
        if isdir(self.backup_dir):
            # If previous backups exist, save link to the last backup
            self.last_backup = self.backup_dir + '/last_backup'
            if islink(self.last_backup):
                try:
                    self.last_backup = os.readlink(self.last_backup)
                except:
                    print('An error occurred when reading the last_backup link')
                    exit(1)
            else:
                self.last_backup = ''

        self.backup_dir = self.backup_dir + '/' + date

        try:
            os.makedirs(self.backup_dir)
        except PermissionError as e:
            print(str(e))
            exit(1)
        except:
            print('Failed to create backup directory')
            exit(1)

        return

    # Function to parse options
    def parse_options(self):
        # Create temporary files
        inputs_handle, self.inputs_path = mkstemp(prefix='tmp_inputs', text=True)
        exclude_handle, self.exclude_path = mkstemp(prefix='tmp_exclude', text=True)

        # Open temporary files
        self.inputs = open(self.inputs_path, 'w')
        self.exclude = open(self.exclude_path, 'w')

        i = 1
        while i < len(argv):
            var = argv[i]

            if var == '-h' or var == '--help':
                self.help_function()
            elif var == '-i' or var == '--input':
                val = argv[i+1]
                while i < len(argv) - 1 and val[0] != '-':
                    inp = val

                    if not exists(inp):
                        warn_message = 'Warning: input "' + inp + '" not found. Skipping'
                        print(warn_message)
                        self.warnfile.write(warn_message)
                        self.warnfile.write('\n')
                    else:
                        self.n_in = self.n_in + 1
                        self.inputs.write(inp)
                        self.inputs.write('\n')

                    i = i + 1
                    val = argv[i+1]
            elif var == '-d' or var == '--directory':
                self.backup_dev = argv[i+1]

                if not exists(self.backup_dev) or not isdir(self.backup_dev):
                    log_message = str(datetime.now()) + ': Backup failed (see errors.log)'
                    self.logfile.write(log_message)
                    self.logfile.write('\n')
                    print('Backup failed')
                    err_message = 'Error: output folder "' + self.backup_dev + '" not found'
                    print(err_message)
                    self.errfile.write(err_message)
                    self.errfile.write('\n')

                    self.logfile.close()
                    self.errfile.close()
                    self.warnfile.close()

                    move(self.log_path, self.homedir + '/.simple_backup/simple_backup.log')
                    move(self.err_path, self.homedir + '/.simple_backup/errors.log')
                    move(self.warn_path, self.homedir + '/.simple_backup/warnings.log')

                    exit(1)

                self.backup_dir = self.backup_dev + '/simple_backup'
                date = str(datetime.now())

                # Create the backup subdirectory using date
                if isdir(self.backup_dir):
                    #If previous backups exist, save link to the last backup
                    self.last_backup = self.backup_dir + '/last_backup'
                    if islink(self.last_backup):
                        try:
                            self.last_backup = os.readlink(self.last_backup)
                        except:
                            print('An error occurred when reading the last_backup link')
                            exit(1)
                    else:
                        self.last_backup = ''

                self.backup_dir = self.backup_dir + '/' + date

                try:
                    os.makedirs(self.backup_dir)
                except PermissionError as e:
                    print(str(e))
                    exit(1)
                except:
                    print('Failed to create backup directory')
                    exit(1)

                i = i + 1
            elif var == '-e' or var == '--exclude':
                val = argv[i+1]
                while i < len(argv) - 1 and val[0] != '-':
                    exc = val
                    self.exclude.write(exc)
                    self.exclude.write('\n')

                    i = i + 1
                    val = argv[i+1]
            elif var == '-k' or var == '--keep':
                self.keep = int(argv[i+1])

                i = i + 1
            elif var == '-c' or var == '--config':
                self.read_conf(argv[i+1])

                i = i + 1
            elif var == '-u' or var == '--user':
                self.homedir = '/home/' + argv[i+1]
                if not isdir(self.homedir):
                    log_message = str(datetime.now()) + ': Backup failed (see errors.log)'
                    self.logfile.write(log_message)
                    self.logfile.write('\n')
                    print('Backup failed')
                    err_message = 'Error: user "' + argv[i+1] + '"doesn\'t exist'
                    self.errfile.write(err_message)
                    self.errfile.write('\n')

                    self.logfile.close()
                    self.errfile.close()
                    self.warnfile.close()

                    move(self.log_path, self.homedir + '/.simple_backup/simple_backup.log')
                    move(self.err_path, self.homedir + '/.simple_backup/errors.log')
                    move(self.warn_path, self.homedir + '/.simple_backup/warnings.log')

                    exit(1)

                if not isdir(self.homedir + '/.simple_backup'):
                    try:
                        os.makedir(self.homedir + '/.simple_backup')
                        print('Created directory "' + self.homedir + '/.simple_backup".')
                    except:
                        print('Failed to create .simple_backup directory in HOME')
                        exit(1)

                self.user = argv[i+1]

                i = i + 1
            elif var == '-s' or var == '--checksum':
                self.options = '-arcvh -H -X'
            else:
                log_message = str(datetime.now()) + ': Backup failed (see errors.log)'
                self.logfile.write(log_message)
                self.logfile.write('\n')
                print('Backup failed')
                err_message = 'Error: Option "' + var + '" not recognised. Use "simple-backup -h" to see available options'
                self.errfile.write(err_message)
                self.errfile.write('\n')

                self.logfile.close()
                self.errfile.close()
                self.warnfile.close()

                move(self.log_path, self.homedir + '/.simple_backup/simple_backup.log')
                move(self.err_path, self.homedir + '/.simple_backup/errors.log')
                move(self.warn_path, self.homedir + '/.simple_backup/warnings.log')

                exit(1)

            i = i + 1

        self.inputs.close()
        self.exclude.close()

        return

    def exec_(self):
        print('Copying files. This may take a long time...')

        if self.last_backup == '':
            rsync = 'rsync ' + self.options + ' --exclude-from=' + self.exclude_path +\
                    ' --files-from=' + self.inputs_path + ' / "' + self.backup_dir +\
                    '" --ignore-missing-args >> ' + self.log_path + ' 2>> ' + self.err_path
        else:
            rsync = 'rsync ' + self.options + ' --link-dest="' + self.last_backup + '" --exclude-from=' +\
                    self.exclude_path + ' --files-from=' + self.inputs_path + ' / "' + self.backup_dir +\
                    '" --ignore-missing-args >> ' + self.log_path + ' 2>> ' + self.err_path

        subprocess.run(rsync, shell=True)

        return

def main():

    backup = Backup()

    # Create temporary log files
    log_handle, backup.log_path = mkstemp(prefix='tmp_log', text=True)
    err_handle, backup.err_path = mkstemp(prefix='tmp_err', text=True)
    warn_handle, backup.warn_path = mkstemp(prefix='tmp_warn', text=True)

    # Open log files
    backup.logfile = open(backup.log_path, 'w')
    backup.errfile = open(backup.err_path, 'w')
    backup.warnfile = open(backup.warn_path, 'w')

    # Set homedir and default options
    backup.homedir = expanduser('~')
    backup.options = '-arvh -H -X'

    # Check number of parameters
    if len(argv) == 1:
        # If simple backup directory doesn't exist, create it and exit
        if not isdir(backup.homedir + '/.simple_backup'):
            try:
                os.makedir(backup.homedir + '/.simple_backup')
                print('Created directory "' + backup.homedir + '/.simple_backup".')
                print('Copy there the sample configuration and edit it')
                print('to your needs before running the backup,')
                print('or pass options on the command line.')
            except:
                print('Failed to create .simple_backup directory in HOME')

            exit(1)

        # Read configuration file
        backup.read_conf()
    else:
        backup.parse_options()

    if backup.n_in > 0 and (backup.backup_dir == '' or 
            not isdir(backup.backup_dir)):
        #If the backup directory is not set or doesn't exist, exit
        log_message = str(datetime.now()) + ': Backup failed (see errors.log)'
        backup.logfile.write(log_message)
        backup.logfile.write('\n')
        err_message = 'Error: Output folder "' + backup.backup_dev.getBackupDev + '" not found'
        backup.errfile.write(err_message)
        backup.errfile.write('\n')

        backup.logfile.close()
        backup.errfile.close()
        backup.warnfile.close()

        move(backup.log_path, backup.homedir + '/.simple_backup/simple_backup.log')
        move(backup.err_path, backup.homedir + '/.simple_backup/errors.log')
        move(backup.warn_path, backup.homedir + '/.simple_backup/warnings.log')

        exit(1)
    elif backup.n_in == 0 and backup.backup_dir == '':
        if not isdir(backup.homedir + '/.simple_backup'):
            try:
                os.makedir(backup.homedir + '/.simple_backup')
                print('Created directory "' + backup.homedir + '/.simple_backup".')
                print('Copy there the sample configuration and edit it')
                print('to your needs before running the backup')
                print('or pass options on the command line.')
            except:
                print('Failed to create .simple_backup directory in HOME')

            exit(1)

        backup.read_conf(backup.homedir + '/.simple_backup/config')

    if backup.n_in == 0:
        log_message = str(datetime.now()) + ': Backup finished (no files copied)'
        backup.logfile.write(log_message)
        backup.logfile.write('\n')
        print('Backup finished (no files copied')
        warn_message = 'Warning: no valid input selected. Nothing to do'
        backup.warnfile.write(warn_message)
        backup.warnfile.write('\n')
        print(warn_message)
               
        backup.logfile.close()
        backup.errfile.close()
        backup.warnfile.close()

        move(backup.log_path, backup.homedir + '/.simple_backup/simple_backup.log')
        move(backup.err_path, backup.homedir + '/.simple_backup/errors.log')
        move(backup.warn_path, backup.homedir + '/.simple_backup/warnings.log')

        exit(0)

    log_message = str(datetime.now()) + ': Starting backup'
    backup.logfile.write(log_message)
    backup.logfile.write('\n')
    print('Starting backup...')

    #If specified, keep the last n backups and remove the others. Default: keep all
    if backup.keep > -1:
        try:
            dirs = os.listdir(backup.backup_dev + '/simple_backup')
        except:
            print('Failed to list backup directory')
            exit(1)
        if dirs.count('last_backup') > 0:
            dirs.remove('last_backup')
        n_backup = len(dirs) - 1

        if n_backup > backup.keep:
            log_message = str(datetime.now()) + ': Removing old backups'
            backup.logfile.write(log_message)
            backup.logfile.write('\n')
            print('Removing old backups...')
            dirs.sort()

            err_flag = 0

            for i in range(n_backup-backup.keep):
                try:
                    rmtree(backup.backup_dev + '/simple_backup/' + dirs[i])
                    log_message = 'Removed backup: ' + dirs[i]
                    backup.logfile.write(log_message)
                    backup.logfile.write('\n')
                except:
                    err_message = 'Error while removing backup ' + dirs[i]
                    backup.errfile.write(err_message)
                    backup.errfile.write('\n')
                    err_flag = 1

            if err_flag:
                print(err_message)

    backup.logfile.close()
    backup.errfile.close()
    backup.warnfile.close()

    backup.exec_()

    # Update the logs
    backup.logfile = open(backup.log_path, 'a')

    if os.stat(backup.err_path).st_size > 0:
        log_message = str(datetime.now()) + ': Backup finished with errors'
        backup.logfile.write(log_message)
        backup.logfile.write('\n')
        print('Backup finished with errors')
    elif os.stat(backup.warn_path).st_size > 0:
        log_message = str(datetime.now()) + ': Backup finished with warnings'
        backup.logfile.write(log_message)
        backup.logfile.write('\n')
        print('Backup finished (warnings)')
    else: 
        log_message = str(datetime.now()) + ': Backup finished'
        backup.logfile.write(log_message)
        backup.logfile.write('\n')
        print('Backup finished')

    backup.logfile.close()

    # Copy log files in home directory
    move(backup.log_path, backup.homedir + '/.simple_backup/simple_backup.log')
    move(backup.err_path, backup.homedir + '/.simple_backup/errors.log')
    move(backup.warn_path, backup.homedir + '/.simple_backup/warnings.log')

    if islink(backup.backup_dev + '/simple_backup/last_backup'):
        try:
            os.remove(backup.backup_dev + '/simple_backup/last_backup')
        except:
            print('Failed to remove last_backup link')

    try:
        os.symlink(backup.backup_dir, backup.backup_dev + '/simple_backup/last_backup')
    except:
        print('Failed to create last_backup link')

    # Delete temporary files
    try:
        os.remove(backup.inputs_path)
        os.remove(backup.exclude_path)
    except:
        print('Failed to remove temporary files')

    exit(0)

if __name__ == '__main__':
    main()