custom manifest static files storage that also minify scss and js files

sith/settings.py

@@ -273,6 +273,15 @@ STATICFILES_FINDERS = [
     "sith.finders.ScssFinder",
 ]
 
+STORAGES = {
+    "default": {
+        "BACKEND": "django.core.files.storage.FileSystemStorage",
+    },
+    "staticfiles": {
+        "BACKEND": "sith.storage.SithStorage",
+    },
+}
+
 # Auth configuration
 AUTH_USER_MODEL = "core.User"
 AUTH_ANONYMOUS_MODEL = "core.models.AnonymousUser"
@@ -716,7 +725,7 @@ if TESTING:
             "BACKEND": "django.core.files.storage.InMemoryStorage",
         },
         "staticfiles": {
-            "BACKEND": "django.contrib.staticfiles.storage.StaticFilesStorage",
+            "BACKEND": "sith.storage.SithStorage",
         },
     }
 

sith/storage.py

@@ -0,0 +1,73 @@
+import logging
+import subprocess
+import warnings
+
+import sass
+from django.conf import settings
+from django.contrib.staticfiles.storage import (
+    ManifestStaticFilesStorage,
+)
+from django.core.files.storage import Storage
+
+
+class SithStorage(ManifestStaticFilesStorage):
+    def _compile_scss(self):
+        to_exec = list(settings.STATIC_ROOT.rglob("*.scss"))
+        if len(to_exec) == 0:
+            return
+        for file in to_exec:
+            # remove existing css files that will be replaced
+            # keeping them while compiling the scss would break
+            # import statements resolution
+            css_file = file.with_suffix(".css")
+            if css_file.exists():
+                css_file.unlink()
+        scss_paths = [p.resolve() for p in to_exec if p.suffix == ".scss"]
+        base_args = {"output_style": "compressed", "precision": settings.SASS_PRECISION}
+        compiled_files = {
+            p: sass.compile(filename=str(p), **base_args) for p in scss_paths
+        }
+        for file, scss in compiled_files.items():
+            file.replace(file.with_suffix(".css")).write_text(scss)
+
+        # once the files are compiled, the manifest must be updated
+        # to have the right suffix
+        new_entries = {
+            k.replace(".scss", ".css"): self.hashed_files.pop(k).replace(
+                ".scss", ".css"
+            )
+            for k in list(self.hashed_files.keys())
+            if k.endswith(".scss")
+        }
+        self.hashed_files.update(new_entries)
+        self.save_manifest()
+
+    @staticmethod
+    def _minify_js():
+        try:
+            subprocess.run(["uglifyjs", "-v"])
+        except FileNotFoundError:
+            warnings.warn(
+                "Couldn't minify JS files. Make sure UglifyJs is installed.",
+                stacklevel=1,
+            )
+            return
+        to_exec = [
+            p for p in settings.STATIC_ROOT.rglob("*.js") if ".min" not in p.suffixes
+        ]
+        for path in to_exec:
+            p = path.resolve()
+            subprocess.run(["uglifyjs", p, "-o", p])
+            logging.getLogger("main").info(f"Minified {path}")
+
+    def post_process(
+        self, paths: dict[str, tuple[Storage, str]], *, dry_run: bool = False
+    ):
+        # Whether we get the files that were processed by ManifestFilesMixin
+        # by calling super() or whether we get them from the manifest file
+        # makes no difference - we have to open the manifest file anyway
+        # because we need to update the paths stored inside it.
+        yield from super().post_process(paths, dry_run)
+
+        self._compile_scss()
+        self._minify_js()