Merge pull request #47 from mruwek/undo

Introduce backup feature and `revert` command

topydo.conf

@@ -6,6 +6,7 @@ default_command             = ls
 ; archive_filename          = done.txt
 colors                      = 1
 identifiers                 = linenumber ; or: text
+backup_count                = 5
 
 [add]
 auto_creation_date          = 1

topydo/Commands.py

@@ -47,6 +47,7 @@ _SUBCOMMAND_MAP = {
     'postpone': 'PostponeCommand',
     'pri': 'PriorityCommand',
     'quit': 'ExitCommand',
+    'revert': 'RevertCommand',
     'rm': 'DeleteCommand',
     'sort': 'SortCommand',
     'tag': 'TagCommand',

topydo/cli/CLIApplicationBase.py

@@ -25,6 +25,7 @@ from six import PY2
 from six.moves import input
 
 MAIN_OPTS = "ac:d:ht:v"
+READ_ONLY_COMMANDS = ('List', 'ListContext', 'ListProject')
 
 
 def usage():
@@ -56,6 +57,7 @@ Available commands:
 * listprojects (lsprj)
 * postpone
 * pri
+* revert
 * sort
 * tag
 
@@ -104,6 +106,7 @@ from topydo.commands.SortCommand import SortCommand
 from topydo.lib import TodoFile
 from topydo.lib import TodoList
 from topydo.lib import TodoListBase
+from topydo.lib.ChangeSet import ChangeSet
 from topydo.lib.Utils import escape_ansi
 
 
@@ -119,6 +122,7 @@ class CLIApplicationBase(object):
         self.todolist = TodoList.TodoList([])
         self.todofile = None
         self.do_archive = True
+        self.backup = None
 
     def _usage(self):
         usage()
@@ -170,6 +174,9 @@ class CLIApplicationBase(object):
         archive_file = TodoFile.TodoFile(config().archive())
         archive = TodoListBase.TodoListBase(archive_file.read())
 
+        if self.backup:
+            self.backup.add_archive(archive)
+
         if archive:
             command = ArchiveCommand(self.todolist, archive)
             command.execute()
@@ -194,6 +201,11 @@ class CLIApplicationBase(object):
         Execute a subcommand with arguments. p_command is a class (not an
         object).
         """
+        cmds_wo_backup = tuple(cmd + 'Command' for cmd in ('Revert', ) + READ_ONLY_COMMANDS)
+        if config().backup_count() > 0 and p_command and not p_command.__module__.endswith(cmds_wo_backup):
+            call = [p_command.__module__.lower()[16:-7]] + p_args # strip "topydo.commands" and "Command"
+            self.backup = ChangeSet(self.todolist, p_call=call)
+
         command = p_command(
             p_args,
             self.todolist,
@@ -222,7 +234,12 @@ class CLIApplicationBase(object):
             if config().keep_sorted():
                 self._execute(SortCommand, [])
 
+            if self.backup:
+                self.backup.save(self.todolist)
+
             self.todofile.write(self.todolist.print_todos())
 
+        self.backup = None
+
     def run(self):
         raise NotImplementedError

topydo/commands/RevertCommand.py

+# Topydo - A todo.txt client written in Python.
+# Copyright (C) 2014 - 2015 Bram Schoenmakers <me@bramschoenmakers.nl>
+#
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+from topydo.lib.Command import Command
+from topydo.lib.ChangeSet import ChangeSet
+from topydo.lib import TodoFile
+from topydo.lib import TodoList
+from topydo.lib.Config import config
+
+class RevertCommand(Command):
+    def __init__(self, p_args, p_todolist,
+                 p_out=lambda a: None,
+                 p_err=lambda a: None,
+                 p_prompt=lambda a: None):
+        super(RevertCommand, self).__init__(
+            p_args, p_todolist, p_out, p_err, p_prompt=lambda a: None)
+
+    def execute(self):
+        if not super(RevertCommand, self).execute():
+            return False
+
+        archive_file = TodoFile.TodoFile(config().archive())
+        archive = TodoList.TodoList(archive_file.read())
+
+        last_change = ChangeSet()
+
+        try:
+            last_change.get_backup(self.todolist)
+            last_change.apply(self.todolist, archive)
+            archive_file.write(archive.print_todos())
+            last_change.delete()
+
+            self.out("Successfully reverted: " + last_change.call)
+        except (ValueError, KeyError):
+            self.error('No backup was found for the current state of ' + config().todotxt())
+
+        last_change.close()
+
+
+    def usage(self):
+        return """Synopsis: revert"""
+
+    def help(self):
+        return """\
+Reverts the last command.
+"""

topydo/lib/ChangeSet.py

+# Topydo - A todo.txt client written in Python.
+# Copyright (C) 2014 - 2015 Bram Schoenmakers <me@bramschoenmakers.nl>
+#
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+""" This module serves for managing todo and archive changesets. """
+
+import json
+import time
+import zlib
+
+from copy import deepcopy
+from hashlib import sha1
+from os import path
+
+from topydo.lib.Config import config
+from topydo.lib.TodoList import TodoList
+
+def hash_todolist(p_todolist):
+    """ Calculates hash for TodoList.TodoList object. """
+    todolist_hash = sha1(p_todolist.print_todos().encode('utf-8')).hexdigest()
+
+    return todolist_hash
+
+def get_backup_path():
+    """ Returns full path and filename of backup file """
+    dirname, filename = path.split(path.splitext(config().todotxt())[0])
+    filename = '.' + filename + '.bak'
+
+    return path.join(dirname, filename)
+
+class ChangeSet(object):
+    """ Class for operations related with backup management. """
+
+    def __init__(self, p_todolist=None, p_archive=None, p_call=[]):
+        self.todolist = deepcopy(p_todolist)
+        self.archive = deepcopy(p_archive)
+        self.timestamp = str(int(time.time()))
+        self.call = ' '.join(p_call)
+
+        try:
+            self.json_file = open(get_backup_path(), 'r+b')
+        except IOError:
+            self.json_file = open(get_backup_path(), 'w+b')
+
+        self._read()
+
+    def _read(self):
+        """
+        Reads backup file from json_file property and sets backup_dict property
+        with data decompressed and deserialized from that file. If no usable
+        data is found backup_dict is set to the empty dict.
+        """
+        self.json_file.seek(0)
+        try:
+            data = zlib.decompress(self.json_file.read())
+            self.backup_dict = json.loads(data.decode('utf-8'))
+        except (EOFError, zlib.error):
+            self.backup_dict = {}
+
+    def _write(self):
+        """
+        Writes data from backup_dict property in serialized and compressed form
+        to backup file pointed in json_file property.
+        """
+        self.json_file.seek(0)
+        self.json_file.truncate()
+        dump = json.dumps(self.backup_dict)
+        dump_c = zlib.compress(dump.encode('utf-8'))
+        self.json_file.write(dump_c)
+
+    def add_archive(self, p_archive):
+        """ Sets deep copy of p_archive as archive attribute. """
+        self.archive = deepcopy(p_archive)
+
+    def add_todolist(self, p_todolist):
+        """ Sets deep copy of p_todolist as todolist attribute. """
+        self.todolist = deepcopy(p_todolist)
+
+    def save(self, p_todolist):
+        """
+        Saves a tuple with archive, todolist and command with its arguments
+        into the backup file with unix timestamp as the key. Tuple is then
+        indexed in backup file with combination of hash calculated from
+        p_todolist and unix timestamp. Backup file is closed afterwards.
+        """
+        self._trim()
+
+        current_hash = hash_todolist(p_todolist)
+        list_todo = (self.todolist.print_todos()+'\n').splitlines(True)
+        list_archive = (self.archive.print_todos()+'\n').splitlines(True)
+
+        self.backup_dict[self.timestamp] = (list_todo, list_archive,  self.call)
+
+        index = self._get_index()
+        index.insert(0, (self.timestamp, current_hash))
+        self._save_index(index)
+
+        self._write()
+        self.close()
+
+    def delete(self, p_timestamp=None):
+        """ Removes backup from the backup file. """
+        timestamp = p_timestamp or self.timestamp
+        index = self._get_index()
+
+        try:
+            del self.backup_dict[timestamp]
+            index.remove(index[[change[0] for change in index].index(timestamp)])
+            self._save_index(index)
+            self._write()
+        except KeyError:
+            pass
+
+    def _get_index(self):
+        try:
+            index = self.backup_dict['index']
+        except KeyError:
+            self.backup_dict['index'] = []
+            index = self.backup_dict['index']
+
+        return index
+
+    def _save_index(self, p_index):
+        """
+        Saves index of backups supplied in p_index into the backup_file
+        property with 'index' as the key.
+        """
+        self.backup_dict['index'] = p_index
+
+    def _trim(self):
+        """
+        Removes oldest backups that exceed the limit configured in backup_count
+        option.
+        """
+        index = self._get_index()
+        backup_limit = config().backup_count() - 1
+
+        for changeset in index[backup_limit:]:
+            self.delete(changeset[0])
+
+    def get_backup(self, p_todolist):
+        """
+        Retrieves a backup for p_todolist from backup file and sets todolist,
+        archive and call attributes to appropriate data from it.
+        """
+        change_hash = hash_todolist(p_todolist)
+
+        index = self._get_index()
+        self.timestamp = index[[change[1] for change in index].index(change_hash)][0]
+
+        d = self.backup_dict[self.timestamp]
+
+        self.todolist = TodoList(d[0])
+        self.archive = TodoList(d[1])
+        self.call = d[2]
+
+    def apply(self, p_todolist, p_archive):
+        """ Applies backup on supplied p_todolist. """
+        if self.todolist:
+            p_todolist.replace(self.todolist.todos())
+
+        if self.archive:
+            p_archive.replace(self.archive.todos())
+
+    def close(self):
+        """ Closes backup file. """
+        self.json_file.close()

topydo/lib/Config.py

@@ -57,6 +57,7 @@ class _Config:
             'filename': 'todo.txt',
             'archive_filename': 'done.txt',
             'identifiers': 'linenumber',
+            'backup_count': '5',
 
             # add
             'auto_creation_date': '1',
@@ -139,6 +140,15 @@ class _Config:
     def identifiers(self):
         return self.cp.get('topydo', 'identifiers')
 
+    def backup_count(self):
+        try:
+            value = self.cp.getint('topydo', 'backup_count')
+            if value < 0:
+                value = 0
+            return value
+        except ValueError:
+            return int(self.defaults['backup_count'])
+
     def list_limit(self):
         try:
             return self.cp.getint('ls', 'list_limit')
@@ -256,7 +266,6 @@ class _Config:
         except ValueError:
             return self.defaults['auto_creation_date'] == '1'
 
-
 def config(p_path=None, p_overrides=None):
     """
     Retrieve the config instance.

topydo/lib/TodoListBase.py

@@ -173,6 +173,12 @@ class TodoListBase(object):
         self._todos = []
         self.dirty = True
 
+    def replace(self, p_todos):
+        """ Replaces whole todolist with todo objects supplied as p_todos. """
+        self.erase()
+        self.add_todos(p_todos)
+        self.dirty = True
+
     def count(self):
         """ Returns the number of todos on this list. """
         return len(self._todos)