Add plugin loader

9 files changed, 60 insertions, 260 deletions

diff --git a/dotbot/__init__.py b/dotbot/__init__.py
index 401da57..1d03464 100644
--- a/dotbot/__init__.py
+++ b/dotbot/__init__.py
@@ -1 +1,2 @@
 from .cli import main
+from .plugin import Plugin
diff --git a/dotbot/cli.py b/dotbot/cli.py
index dc90909..d77ab42 100644
--- a/dotbot/cli.py
+++ b/dotbot/cli.py
@@ -1,8 +1,11 @@
+import os, glob
+
 from argparse import ArgumentParser
 from .config import ConfigReader, ReadingError
 from .dispatcher import Dispatcher, DispatchError
 from .messenger import Messenger
 from .messenger import Level
+from .util import module
 
 def add_options(parser):
     parser.add_argument('-Q', '--super-quiet', dest='super_quiet', action='store_true',
@@ -17,6 +20,12 @@ def add_options(parser):
     parser.add_argument('-c', '--config-file', nargs=1, dest='config_file',
         help='run commands given in CONFIGFILE', metavar='CONFIGFILE',
         required=True)
+    parser.add_argument('-p', '--plugin', action='append', dest='plugins', default=[],
+        help='load PLUGIN as a plugin', metavar='PLUGIN')
+    parser.add_argument('--disable-built-in-plugins', dest='disable_built_in_plugins',
+        action='store_true', help='disable built-in plugins')
+    parser.add_argument('--plugin-dir', action='append', dest='plugin_dirs', default=[],
+        metavar='PLUGIN_DIR', help='load all plugins in PLUGIN_DIR')
 
 def read_config(config_file):
     reader = ConfigReader(config_file)
@@ -28,12 +37,24 @@ def main():
         parser = ArgumentParser()
         add_options(parser)
         options = parser.parse_args()
-        if (options.super_quiet):
+        if options.super_quiet:
             log.set_level(Level.WARNING)
-        if (options.quiet):
+        if options.quiet:
             log.set_level(Level.INFO)
-        if (options.verbose):
+        if options.verbose:
             log.set_level(Level.DEBUG)
+        plugin_directories = list(options.plugin_dirs)
+        if not options.disable_built_in_plugins:
+          plugin_directories.append(os.path.join(os.path.dirname(__file__), '..', 'plugins'))
+        plugin_paths = []
+        for directory in plugin_directories:
+          for plugin_path in glob.glob(os.path.join(directory, '*.py')):
+            plugin_paths.append(plugin_path)
+        for plugin_path in options.plugins:
+            plugin_paths.append(plugin_path)
+        for plugin_path in plugin_paths:
+            abspath = os.path.abspath(plugin_path)
+            module.load(abspath)
         tasks = read_config(options.config_file[0])
         if not isinstance(tasks, list):
             raise ReadingError('Configuration file must be a list of tasks')
diff --git a/dotbot/dispatcher.py b/dotbot/dispatcher.py
index c3c7fe8..79231a0 100644
--- a/dotbot/dispatcher.py
+++ b/dotbot/dispatcher.py
@@ -1,5 +1,5 @@
 import os
-from .executor import Executor
+from .plugin import Plugin
 from .messenger import Messenger
 
 class Dispatcher(object):
@@ -37,7 +37,7 @@ class Dispatcher(object):
 
     def _load_plugins(self):
         self._plugins = [plugin(self._base_directory)
-            for plugin in Executor.__subclasses__()]
+            for plugin in Plugin.__subclasses__()]
 
 class DispatchError(Exception):
     pass
diff --git a/dotbot/executor/__init__.py b/dotbot/executor/__init__.py
deleted file mode 100644
index d87ca4b..0000000
--- a/dotbot/executor/__init__.py
+++ /dev/null
@@ -1,4 +0,0 @@
-from .executor import Executor
-from .linker import Linker
-from .cleaner import Cleaner
-from .commandrunner import CommandRunner
diff --git a/dotbot/executor/cleaner.py b/dotbot/executor/cleaner.py
deleted file mode 100644
index 504c0de..0000000
--- a/dotbot/executor/cleaner.py
+++ /dev/null
@@ -1,52 +0,0 @@
-import os
-from . import Executor
-
-class Cleaner(Executor):
-    '''
-    Cleans broken symbolic links.
-    '''
-
-    _directive = 'clean'
-
-    def can_handle(self, directive):
-        return directive == self._directive
-
-    def handle(self, directive, data):
-        if directive != self._directive:
-            raise ValueError('Cleaner cannot handle directive %s' % directive)
-        return self._process_clean(data)
-
-    def _process_clean(self, targets):
-        success = True
-        for target in targets:
-            success &= self._clean(target)
-        if success:
-            self._log.info('All targets have been cleaned')
-        else:
-            self._log.error('Some targets were not successfully cleaned')
-        return success
-
-    def _clean(self, target):
-        '''
-        Cleans all the broken symbolic links in target that point to
-        a subdirectory of the base directory.
-        '''
-        if not os.path.isdir(os.path.expanduser(target)):
-            self._log.debug('Ignoring nonexistent directory %s' % target)
-            return True
-        for item in os.listdir(os.path.expanduser(target)):
-            path = os.path.join(os.path.expanduser(target), item)
-            if not os.path.exists(path) and os.path.islink(path):
-                if self._in_directory(path, self._base_directory):
-                    self._log.lowinfo('Removing invalid link %s -> %s' %
-                        (path, os.path.join(os.path.dirname(path), os.readlink(path))))
-                    os.remove(path)
-        return True
-
-    def _in_directory(self, path, directory):
-        '''
-        Returns true if the path is in the directory.
-        '''
-        directory = os.path.join(os.path.realpath(directory), '')
-        path = os.path.realpath(path)
-        return os.path.commonprefix([path, directory]) == directory
diff --git a/dotbot/executor/commandrunner.py b/dotbot/executor/commandrunner.py
deleted file mode 100644
index 45d40f5..0000000
--- a/dotbot/executor/commandrunner.py
+++ /dev/null
@@ -1,53 +0,0 @@
-import os, subprocess
-from . import Executor
-
-class CommandRunner(Executor):
-    '''
-    Run arbitrary shell commands.
-    '''
-
-    _directive = 'shell'
-
-    def can_handle(self, directive):
-        return directive == self._directive
-
-    def handle(self, directive, data):
-        if directive != self._directive:
-            raise ValueError('CommandRunner cannot handle directive %s' %
-                directive)
-        return self._process_commands(data)
-
-    def _process_commands(self, data):
-        success = True
-        with open(os.devnull, 'w') as devnull:
-            for item in data:
-                stdin = stdout = stderr = devnull
-                if isinstance(item, dict):
-                    cmd = item['command']
-                    msg = item.get('description', None)
-                    if item.get('stdin', False) is True:
-                        stdin = None
-                    if item.get('stdout', False) is True:
-                        stdout = None
-                    if item.get('stderr', False) is True:
-                        stderr = None
-                elif isinstance(item, list):
-                    cmd = item[0]
-                    msg = item[1] if len(item) > 1 else None
-                else:
-                    cmd = item
-                    msg = None
-                if msg is None:
-                    self._log.lowinfo(cmd)
-                else:
-                    self._log.lowinfo('%s [%s]' % (msg, cmd))
-                ret = subprocess.call(cmd, shell=True, stdin=stdin, stdout=stdout,
-                    stderr=stderr, cwd=self._base_directory)
-                if ret != 0:
-                    success = False
-                    self._log.warning('Command [%s] failed' % cmd)
-        if success:
-            self._log.info('All commands have been executed')
-        else:
-            self._log.error('Some commands were not successfully executed')
-        return success
diff --git a/dotbot/executor/linker.py b/dotbot/executor/linker.py
deleted file mode 100644
index 5c12ea0..0000000
--- a/dotbot/executor/linker.py
+++ /dev/null
@@ -1,142 +0,0 @@
-import os, shutil
-from . import Executor
-
-class Linker(Executor):
-    '''
-    Symbolically links dotfiles.
-    '''
-
-    _directive = 'link'
-
-    def can_handle(self, directive):
-        return directive == self._directive
-
-    def handle(self, directive, data):
-        if directive != self._directive:
-            raise ValueError('Linker cannot handle directive %s' % directive)
-        return self._process_links(data)
-
-    def _process_links(self, links):
-        success = True
-        for destination, source in links.items():
-            source = os.path.expandvars(source)
-            destination = os.path.expandvars(destination)
-            if isinstance(source, dict):
-                # extended config
-                path = source['path']
-                force = source.get('force', False)
-                relink = source.get('relink', False)
-                create = source.get('create', False)
-                if create:
-                    success &= self._create(destination)
-                if force:
-                    success &= self._delete(path, destination, force=True)
-                elif relink:
-                    success &= self._delete(path, destination, force=False)
-            else:
-                path = source
-            success &= self._link(path, destination)
-        if success:
-            self._log.info('All links have been set up')
-        else:
-            self._log.error('Some links were not successfully set up')
-        return success
-
-    def _is_link(self, path):
-        '''
-        Returns true if the path is a symbolic link.
-        '''
-        return os.path.islink(os.path.expanduser(path))
-
-    def _link_destination(self, path):
-        '''
-        Returns the absolute path to the destination of the symbolic link.
-        '''
-        path = os.path.expanduser(path)
-        rel_dest = os.readlink(path)
-        return os.path.join(os.path.dirname(path), rel_dest)
-
-    def _exists(self, path):
-        '''
-        Returns true if the path exists.
-        '''
-        path = os.path.expanduser(path)
-        return os.path.exists(path)
-
-    def _create(self, path):
-        success = True
-        parent = os.path.abspath(os.path.join(os.path.expanduser(path), os.pardir))
-        if not self._exists(parent):
-            try:
-                os.makedirs(parent)
-            except OSError:
-                self._log.warning('Failed to create directory %s' % parent)
-                success = False
-            else:
-                self._log.lowinfo('Creating directory %s' % parent)
-        return success
-
-    def _delete(self, source, path, force):
-        success = True
-        source = os.path.join(self._base_directory, source)
-        if ((self._is_link(path) and self._link_destination(path) != source) or
-                (self._exists(path) and not self._is_link(path))):
-            fullpath = os.path.expanduser(path)
-            removed = False
-            try:
-                if os.path.islink(fullpath):
-                    os.unlink(fullpath)
-                    removed = True
-                elif force:
-                    if os.path.isdir(fullpath):
-                        shutil.rmtree(fullpath)
-                        removed = True
-                    else:
-                        os.remove(fullpath)
-                        removed = True
-            except OSError:
-                self._log.warning('Failed to remove %s' % path)
-                success = False
-            else:
-                if removed:
-                    self._log.lowinfo('Removing %s' % path)
-        return success
-
-    def _link(self, source, link_name):
-        '''
-        Links link_name to source.
-
-        Returns true if successfully linked files.
-        '''
-        success = False
-        source = os.path.join(self._base_directory, source)
-        if (not self._exists(link_name) and self._is_link(link_name) and
-                self._link_destination(link_name) != source):
-            self._log.warning('Invalid link %s -> %s' %
-                (link_name, self._link_destination(link_name)))
-        elif not self._exists(link_name) and self._exists(source):
-            try:
-                os.symlink(source, os.path.expanduser(link_name))
-            except OSError:
-                self._log.warning('Linking failed %s -> %s' % (link_name, source))
-            else:
-                self._log.lowinfo('Creating link %s -> %s' % (link_name, source))
-                success = True
-        elif self._exists(link_name) and not self._is_link(link_name):
-            self._log.warning(
-                '%s already exists but is a regular file or directory' %
-                link_name)
-        elif self._is_link(link_name) and self._link_destination(link_name) != source:
-            self._log.warning('Incorrect link %s -> %s' %
-                (link_name, self._link_destination(link_name)))
-        elif not self._exists(source):
-            if self._is_link(link_name):
-                self._log.warning('Nonexistent target %s -> %s' %
-                    (link_name, source))
-            else:
-                self._log.warning('Nonexistent target for %s : %s' %
-                    (link_name, source))
-        else:
-            self._log.lowinfo('Link exists %s -> %s' % (link_name, source))
-            success = True
-        return success
diff --git a/dotbot/executor/executor.py b/dotbot/plugin.py
index e6862c0..a79639e 100644
--- a/dotbot/executor/executor.py
+++ b/dotbot/plugin.py
@@ -1,6 +1,6 @@
-from ..messenger import Messenger
+from .messenger import Messenger
 
-class Executor(object):
+class Plugin(object):
     '''
     Abstract base class for commands that process directives.
     '''
@@ -11,7 +11,7 @@ class Executor(object):
 
     def can_handle(self, directive):
         '''
-        Returns true if the Executor can handle the directive.
+        Returns true if the Plugin can handle the directive.
         '''
         raise NotImplementedError
 
@@ -19,6 +19,6 @@ class Executor(object):
         '''
         Executes the directive.
 
-        Returns true if the Executor successfully handled the directive.
+        Returns true if the Plugin successfully handled the directive.
         '''
         raise NotImplementedError
diff --git a/dotbot/util/module.py b/dotbot/util/module.py
new file mode 100644
index 0000000..af6b0ed
--- /dev/null
+++ b/dotbot/util/module.py
@@ -0,0 +1,29 @@
+import sys, os.path
+
+# We keep references to loaded modules so they don't get garbage collected.
+loaded_modules = []
+
+def load(path):
+  basename = os.path.basename(path)
+  module_name, extension = os.path.splitext(basename)
+  plugin = load_module(module_name, path)
+  loaded_modules.append(plugin)
+
+if sys.version_info >= (3, 5):
+  import importlib.util
+
+  def load_module(module_name, path):
+    spec = importlib.util.spec_from_file_location(module_name, path)
+    module = importlib.util.module_from_spec(spec)
+    spec.loader.exec_module(module)
+    return module
+elif sys.version_info >= (3, 3):
+  from importlib.machinery import SourceFileLoader
+
+  def load_module(module_name, path):
+    return SourceFileLoader(module_name, path).load_module()
+else:
+  import imp
+
+  def load_module(module_name, path):
+    return imp.load_source(module_name, path)