rework custom stylesheet loading

Previously, the stylesheet was copied to the user's .config dir, and
this was then loaded as a style (with priority "application").
The user could alter this stylesheet directly.
This stylesheet was called "safeeyes_styles.css".

Now, we split the stylesheets into two:
- The system stylesheet, which is directly loaded with priority
  "application".
- The user's stylesheet, if it exists, which is loaded from the .config
  dir with priority "user", overriding both the system stylesheet and
  any themes the user might have.
  This is now called "safeeyes_custom_styles.css".

This means in the future, we can simply add new default styles to the
system stylesheet without breaking the user. Additionally, any styles
loaded with a higher priority than "application" (eg. certain GTK
themes, see slgobinath#687), can now
be overridden by the user's stylesheet.

We also check if the old path ("safeeyes_styles.css") contains an old
default stylesheet. If it does, we delete it.
If it (likely) contains a customized stylesheet, don't delete it, but
warn the user that they should use "safeeyes_custom_styles.css" instead
now.

Author: deltragon

safeeyes/__main__.py

@@ -130,7 +130,7 @@ def main():
     utility.initialize_logging(args.debug)
     utility.initialize_platform()
     config = Config()
-    utility.create_user_stylesheet_if_missing()
+    utility.cleanup_old_user_stylesheet()
 
     if __running():
         logging.info("Safe Eyes is already running")

safeeyes/model.py

@@ -327,8 +327,6 @@ def __init__(self, init=True):
                             self.__user_config, self.__system_config
                         )
                         self.__user_config = self.__system_config
-                        # Update the style sheet
-                        utility.replace_style_sheet()
 
             utility.merge_plugins(self.__user_config)
             self.save()

safeeyes/safeeyes.py

@@ -167,7 +167,10 @@ def do_activate(self):
 
     def _initialize_styles(self):
         utility.load_css_file(
-            utility.STYLE_SHEET_PATH, Gtk.STYLE_PROVIDER_PRIORITY_APPLICATION
+            utility.SYSTEM_STYLE_SHEET_PATH, Gtk.STYLE_PROVIDER_PRIORITY_APPLICATION
+        )
+        utility.load_css_file(
+            utility.CUSTOM_STYLE_SHEET_PATH, Gtk.STYLE_PROVIDER_PRIORITY_USER
         )
 
     def _retry_errored_plugins(self):

safeeyes/utility.py

@@ -19,6 +19,7 @@
 """This module contains utility functions for Safe Eyes and its plugins."""
 
 import errno
+import hashlib
 import inspect
 import importlib
 import json
@@ -56,7 +57,10 @@
 CONFIG_FILE_PATH = os.path.join(CONFIG_DIRECTORY, "safeeyes.json")
 CONFIG_RESOURCE = os.path.join(CONFIG_DIRECTORY, "resource")
 SESSION_FILE_PATH = os.path.join(CONFIG_DIRECTORY, "session.json")
-STYLE_SHEET_PATH = os.path.join(STYLE_SHEET_DIRECTORY, "safeeyes_style.css")
+OLD_STYLE_SHEET_PATH = os.path.join(STYLE_SHEET_DIRECTORY, "safeeyes_style.css")
+CUSTOM_STYLE_SHEET_PATH = os.path.join(
+    STYLE_SHEET_DIRECTORY, "safeeyes_custom_style.css"
+)
 SYSTEM_CONFIG_FILE_PATH = os.path.join(BIN_DIRECTORY, "config/safeeyes.json")
 SYSTEM_STYLE_SHEET_PATH = os.path.join(BIN_DIRECTORY, "config/style/safeeyes_style.css")
 LOG_FILE_PATH = os.path.join(HOME_DIRECTORY, "safeeyes.log")
@@ -373,6 +377,17 @@ def merge_configs(new_config, old_config):
     return new_config
 
 
+def sha256sum(filename):
+    """Get the sha256 hash of the given file."""
+    h = hashlib.sha256()
+    b = bytearray(128 * 1024)
+    mv = memoryview(b)
+    with open(filename, "rb", buffering=0) as f:
+        for n in iter(lambda: f.readinto(mv), 0):
+            h.update(mv[:n])
+    return h.hexdigest()
+
+
 def load_css_file(style_sheet_path, priority):
     css_provider = Gtk.CssProvider()
     css_provider.load_from_path(style_sheet_path)
@@ -382,7 +397,7 @@ def load_css_file(style_sheet_path, priority):
 
 
 def initialize_safeeyes():
-    """Create the config file and style sheet in XDG_CONFIG_HOME(or
+    """Create the config file in XDG_CONFIG_HOME(or
     ~/.config)/safeeyes directory.
     """
     logging.info("Copy the config files to XDG_CONFIG_HOME(or ~/.config)/safeeyes")
@@ -397,24 +412,45 @@ def initialize_safeeyes():
     shutil.copy2(SYSTEM_CONFIG_FILE_PATH, CONFIG_FILE_PATH)
     os.chmod(CONFIG_FILE_PATH, 0o666)
 
-    create_user_stylesheet_if_missing()
-
     # initialize_safeeyes gets called when the configuration file is not present, which
     # happens just after installation or manual deletion of
     # .config/safeeyes/safeeyes.json file. In these cases, we want to force the creation
     # of a startup entry
     create_startup_entry(force=True)
 
 
-def create_user_stylesheet_if_missing():
+def cleanup_old_user_stylesheet():
     # Create the XDG_CONFIG_HOME(or ~/.config)/safeeyes/style directory
     if not os.path.isdir(STYLE_SHEET_DIRECTORY):
         mkdir(STYLE_SHEET_DIRECTORY)
 
-    # Copy the new style sheet
-    if not os.path.isfile(STYLE_SHEET_PATH):
-        shutil.copy2(SYSTEM_STYLE_SHEET_PATH, STYLE_SHEET_PATH)
-        os.chmod(STYLE_SHEET_PATH, 0o666)
+    # Delete the old stylesheet, unless it has customizations
+    if os.path.isfile(OLD_STYLE_SHEET_PATH):
+        hash = sha256sum(OLD_STYLE_SHEET_PATH)
+        old_default_versions = [
+            # 2.2.3
+            "fdc2a305613ae4eeb269650452789d35df3df5bdf1c56eb576cd5ebac70a6f09",
+            # 2.1.0 - 2.2.2
+            "fbde048fc234db757461971a7542df43a467869035ca3d05ff9b236ca250e4c5",
+            # 2.0.9
+            "70ca55c12d83ad7a6a4e1c5e7758a38617a43f5d32f28709ede75426d3186713",
+            # 2.0.7 - 2.0.8
+            "7a15f985e0da6d92c8a62d49ce151781e6d423f87e66d205cc1dc4536e369e19",
+            # 2.0.6 and earlier
+            "f26621a883e323ca7685a4adba25027e70daa471e0db4a21c261e6c15caaa5ee",
+        ]
+        if hash in old_default_versions:
+            logging.info("Deleting old stylesheet containing default content")
+            delete(OLD_STYLE_SHEET_PATH)
+        else:
+            # Stylesheet was likely customized, don't delete but warn
+            logging.warning(
+                _(
+                    "Old stylesheet found at '%(old)s', ignoring. For custom styles, "
+                    "create a new stylesheet in '%(new)s' instead.",
+                )
+                % {"old": OLD_STYLE_SHEET_PATH, "new": CUSTOM_STYLE_SHEET_PATH}
+            )
 
 
 def create_startup_entry(force=False):
@@ -526,26 +562,16 @@ def initialize_platform():
 def reset_config():
     # Remove the ~/.config/safeeyes/safeeyes.json and safeeyes_style.css
     delete(CONFIG_FILE_PATH)
-    delete(STYLE_SHEET_PATH)
 
     # Copy the safeeyes.json and safeeyes_style.css
     shutil.copy2(SYSTEM_CONFIG_FILE_PATH, CONFIG_FILE_PATH)
-    shutil.copy2(SYSTEM_STYLE_SHEET_PATH, STYLE_SHEET_PATH)
 
     # Add write permission (e.g. if original file was stored in /nix/store)
     os.chmod(CONFIG_FILE_PATH, 0o666)
-    os.chmod(STYLE_SHEET_PATH, 0o666)
 
     create_startup_entry()
 
 
-def replace_style_sheet():
-    """Replace the user style sheet by system style sheet."""
-    delete(STYLE_SHEET_PATH)
-    shutil.copy2(SYSTEM_STYLE_SHEET_PATH, STYLE_SHEET_PATH)
-    os.chmod(STYLE_SHEET_PATH, 0o666)
-
-
 def initialize_logging(debug):
     """Initialize the logging framework using the Safe Eyes specific
     configurations.