[core] Refactor engine

This is going to be a bit more comprehensive than anticipated. In order
to cleanly refactor the core and the engine, basically start from
scratch with the implementation.

Goals:

* Test coverage
* Maintain backwards compatibility with module interface as much as
  possible (but still make modules easier to code)
* Simplicity

see #23

bumblebee/theme.py

@@ -1,129 +0,0 @@
-import os
-import copy
-import json
-import yaml
-import glob
-
-def getpath():
-    return os.path.dirname("{}/../themes/".format(os.path.dirname(os.path.realpath(__file__))))
-
-def themes():
-    d = getpath()
-    return [ os.path.basename(f).replace(".json", "") for f in glob.iglob("{}/*.json".format(d)) ]
-
-class Theme:
-    def __init__(self, config):
-        self._config = config
-
-        self._data = self.get_theme(config.theme())
-
-        for iconset in self._data.get("icons", []):
-            self.merge(self._data, self.get_theme(iconset))
-
-        self._defaults = self._data.get("defaults", {})
-        self._cycles = self._defaults.get("cycle", [])
-        self.begin()
-
-    def get_theme(self, name):
-        for path in [ getpath(), "{}/icons/".format(getpath()) ]:
-            if os.path.isfile("{}/{}.yaml".format(path, name)):
-                with open("{}/{}.yaml".format(path, name)) as f:
-                    return yaml.load(f)
-            if os.path.isfile("{}/{}.json".format(path, name)):
-                with open("{}/{}.json".format(path, name)) as f:
-                    return json.load(f)
-        return None
-
-    # algorithm copied from
-    # http://blog.impressiver.com/post/31434674390/deep-merge-multiple-python-dicts
-    # nicely done :)
-    def merge(self, target, *args):
-        if len(args) > 1:
-            for item in args:
-                self.merge(item)
-            return target
-
-        item = args[0]
-        if not isinstance(item, dict):
-            return item
-        for key, value in item.items():
-            if key in target and isinstance(target[key], dict):
-                self.merge(target[key], value)
-            else:
-                target[key] = copy.deepcopy(value)
-        return target
-
-    def begin(self):
-        self._config.set("theme.cycleidx", 0)
-        self._cycle = self._cycles[0] if len(self._cycles) > 0 else {}
-        self._background = [ None, None ]
-
-    def next_widget(self):
-        self._background[1] = self._background[0]
-        idx = self._config.increase("theme.cycleidx", len(self._cycles), 0)
-        self._cycle = self._cycles[idx] if len(self._cycles) > idx else {}
-
-    def prefix(self, widget):
-        return self._get(widget, "prefix", "")
-
-    def suffix(self, widget):
-        return self._get(widget, "suffix", "")
-
-    def color(self, widget):
-        result = self._get(widget, "fg")
-        if widget.warning():
-            result = self._get(widget, "fg-warning")
-        if widget.critical():
-            result = self._get(widget, "fg-critical")
-        return result
-
-    def background(self, widget):
-        result = self._get(widget, "bg")
-        if widget.warning():
-            result = self._get(widget, "bg-warning")
-        if widget.critical():
-            result = self._get(widget, "bg-critical")
-        self._background[0] = result
-        return result
-
-    def separator(self, widget):
-        return self._get(widget, "separator")
-
-    def default_separators(self, widget, default):
-        return self._get(widget, "default-separators", default)
-
-    def separator_color(self, widget):
-        return self.background(widget)
-
-    def separator_background(self, widget):
-        return self._background[1]
-
-    def separator_block_width(self, widget, default):
-        return self._get(widget, "separator-block-width", default)
-
-    def _get(self, widget, name, default = None):
-        module = widget.module()
-        state = widget.state()
-        inst = widget.instance()
-        inst = inst.replace("{}.".format(module), "")
-        module_theme = self._data.get(module, {})
-        state_theme = module_theme.get("states", {}).get(state, {})
-        instance_theme = module_theme.get(inst, {})
-        instance_state_theme = instance_theme.get("states", {}).get(state, {})
-
-        value = None
-        value = self._defaults.get(name, value)
-        value = self._cycle.get(name, value)
-        value = module_theme.get(name, value)
-        value = state_theme.get(name, value)
-        value = instance_theme.get(name, value)
-        value = instance_state_theme.get(name, value)
-
-        if type(value) is list:
-            key = "{}{}".format(widget.instance(), value)
-            idx = self._config.increase(key, len(value), 0)
-            value = value[idx]
-
-        return value if value else default
-
-# vim: tabstop=8 expandtab shiftwidth=4 softtabstop=4