Improve the filter configuration

Move enabled filter list to the config file, add support
for custom filter types, updated the configuration.

README

@@ -43,7 +43,7 @@ And I'd like to suggest to install afew as your unprivileged user.
 If you do, make sure ~/.local/bin is in your path.
 
 $ python setup.py install --prefix=~/.local
-$ mkdir -p ~/.local/share/afew/categories
+$ mkdir -p ~/.config/afew ~/.local/share/afew/categories
 
 
 Configuration
@@ -56,6 +56,18 @@ Make sure that ~/.notmuch-config reads:
 tags=new
 ~~~ snip ~~~
 
+Put a list of filters into ~/.config/afew/config:
+~~~ snip ~~~
+# This is the default filter chain
+[SpamFilter]
+[ClassifyingFilter]
+[KillThreadsFilter]
+[ListMailsFilter]
+[ArchiveSentMailsFilter]
+[InboxFilter]
+~~~ snip ~~~
+
+
 
 Commandline help
 ================
@@ -94,7 +106,8 @@ Options:
                         path to the notmuch configuration file [default:
                         $NOTMUCH_CONFIG or ~/.notmuch-config]
     -e ENABLE_FILTERS, --enable-filters=ENABLE_FILTERS
-                        filter classes to use, separated by ',' [default: all]
+                        filter classes to use, separated by ',' [default:
+                        filters specified in afew's config]
     -d, --dry-run       don't change the db [default: False]
     -R REFERENCE_SET_SIZE, --reference-set-size=REFERENCE_SET_SIZE
                         size of the reference set [default: 1000]
@@ -127,11 +140,17 @@ postsynchook = ionice -c 3 chrt --idle 0 /bin/sh -c "notmuch new && afew --tag -
 
 Tag filters
 -----------
-Tag filters are plugin-like modules that encapsulate tagging functionality. There is a filter that handles the archiving of mails you sent, one that handles spam, one for killed threads, one for mailing list magic... 
+Tag filters are plugin-like modules that encapsulate tagging
+functionality. There is a filter that handles the archiving of mails
+you sent, one that handles spam, one for killed threads, one for
+mailing list magic...
 
-By default, all filters are enabled and when you run afew with the --tag option, you get all of the goodness afew has to offer. If you want to change that behaviour, you can override the default by specifying what filters should be run with the --enable-filters option.
+The tag filter concept allows you to easily extend afew's tagging
+abilities by writing your own filters. Take a look at the default
+configuration file (afew/defaults/afew.config) for a list of
+available filters and how to enable filters and create customize
+filter types.
 
-The tag filter concept allows you to easily extend afew's tagging abilities by writing your own filters.
 
 
 The real deal

afew/Settings.py

@@ -17,8 +17,12 @@
 #
 
 import os
+import re
+import functools
 import ConfigParser
 
+from .Filter import all_filters, register_filter
+
 notmuch_config = ConfigParser.RawConfigParser()
 
 def read_notmuch_config(path = None):
@@ -32,3 +36,39 @@ def read_notmuch_config(path = None):
 settings.read(os.path.join(os.environ.get('XDG_CONFIG_HOME',
                                           os.path.expanduser('~/.config')),
                            'afew', 'config'))
+
+def make_factory(klass, kwargs):
+    @functools.wraps(klass)
+    def factory(db_path):
+        return klass(db_path, **kwargs)
+    return factory
+
+section_re = re.compile(r'''^(?P<name>[a-z_][a-z0-9_]*)(\((?P<parent_class>[a-z_][a-z0-9_]*)\)|\.(?P<index>\d+))?$''', re.I)
+def get_filter_chain():
+    filter_chain = []
+
+    for section in settings.sections():
+        if section == 'global':
+            continue
+
+        match = section_re.match(section)
+        if not match:
+            raise SyntaxError('Malformed section title %r.' % section)
+
+        if match.group('parent_class'):
+            try:
+                parent_class = all_filters[match.group('parent_class')]
+            except KeyError as e:
+                raise NameError('Parent class %r not found in filter type definition %r.' % (match.group('parent_class'), section))
+
+            new_type = type(match.group('name'), (parent_class, ), dict(settings.items(section)))
+            register_filter(new_type)
+        else:
+            try:
+                klass = all_filters[match.group('name')]
+            except KeyError as e:
+                raise NameError('Filter type %r not found.' % match.group('name'))
+
+            filter_chain.append(make_factory(klass, dict(settings.items(section))))
+
+    return filter_chain

afew/defaults/afew.config

@@ -1 +1,29 @@
+# global configuration
+[global]
 
+# This is the default filter chain
+#[SpamFilter]
+#[ClassifyingFilter]
+#[KillThreadsFilter]
+#[ListMailsFilter]
+#[ArchiveSentMailsFilter]
+#[InboxFilter]
+
+# Let's say you like the SpamFilter, but it is way too polite
+
+# 1. create an filter object and customize it
+#[SpamFilter.0] # note the index
+#message = meh
+
+# 2. create a new type and...
+#[ShitFilter(SpamFilter)]
+#message = I hatez teh spam!
+
+#    create an object or two...
+#[ShitFilter.0]
+#[ShitFilter.1]
+#message = Me hatez it too.
+
+# 3. drop a custom filter type in ~/.config/afew/
+# TODO: implement this
+# and create objects of this kind

bin/afew

@@ -25,7 +25,7 @@ import optparse
 
 from afew.main import main
 from afew.Filter import all_filters
-from afew.Settings import read_notmuch_config
+from afew.Settings import read_notmuch_config, get_filter_chain
 
 option_parser = optparse.OptionParser(
     usage = '%prog [options] [--] [query]'
@@ -89,8 +89,7 @@ options_group.add_option(
 )
 options_group.add_option(
     '-e', '--enable-filters',
-    default = 'SpamFilter,ClassifyingFilter,KillThreadsFilter,ListMailsFilter,ArchiveSentMailsFilter,InboxFilter',
-    help = "filter classes to use, separated by ',' [default: all]"
+    help = "filter classes to use, separated by ',' [default: filters specified in afew's config]"
 )
 options_group.add_option(
     '-d', '--dry-run', default = False, action = 'store_true',
@@ -142,14 +141,18 @@ elif options.update or options.update_reference:
 else:
     sys.exit('Weird... please file a bug containing your command line.')
 
-options.enable_filters = options.enable_filters.split(',')
+configured_filter_chain = get_filter_chain()
+if options.enable_filters:
+    options.enable_filters = options.enable_filters.split(',')
 
-all_filters_set = set(all_filters.keys())
-enabled_filters_set = set(options.enable_filters)
-if not all_filters_set.issuperset(enabled_filters_set):
-    sys.exit('Unknown filter(s) selected: %s' % (' '.join(enabled_filters_set.difference(all_filters_set))))
+    all_filters_set = set(all_filters.keys())
+    enabled_filters_set = set(options.enable_filters)
+    if not all_filters_set.issuperset(enabled_filters_set):
+        sys.exit('Unknown filter(s) selected: %s' % (' '.join(enabled_filters_set.difference(all_filters_set))))
 
-options.enable_filters = [all_filters[filter_name] for filter_name in options.enable_filters]
+    options.enable_filters = [all_filters[filter_name] for filter_name in options.enable_filters]
+else:
+    options.enable_filters = configured_filter_chain
 
 loglevel = {
     0: logging.WARNING,