Feature: Add customisable icons in topology (#193)

* [up] add config for custom images, better js

* [up] use bundler to bundle js

* [fix] remove domcontentloaded since defer is used

* [fix] formatting with black

* [fix] images drf api

* [up] add support for custom icons on additional roles: power panel, power feed, circuit

* [up] optimize topology generation by using `_id` when trying to access pk of related object

* [fix] kebab case instead of slugification

* [fix] use empty queryset in api views & change coord save logic

netbox_topology_views/utils.py

@@ -0,0 +1,86 @@
+from dataclasses import dataclass
+from functools import lru_cache
+from pathlib import Path
+from typing import Type
+
+from django.conf import settings
+from django.db.models import Model
+from django.templatetags.static import static
+from django.utils.text import camel_case_to_spaces, re_camel_case
+
+IMAGE_DIR = Path(settings.STATIC_ROOT) / "netbox_topology_views/img"
+CONF_IMAGE_DIR: Path = Path(settings.STATIC_ROOT) / settings.PLUGINS_CONFIG[
+    "netbox_topology_views"
+]["static_image_directory"].removeprefix("/")
+
+
+def image_static_url(path: Path) -> str:
+    return settings.BASE_PATH + static(
+        f"/{path.relative_to(Path(settings.STATIC_ROOT))}"
+    )
+
+
+def get_image_from_url(url: str) -> str:
+    return url.removeprefix(settings.BASE_PATH + settings.STATIC_URL)
+
+
+IMAGE_FILETYPES = (
+    "apng",
+    "avif",
+    "bmp",
+    "cur",
+    "gif",
+    "ico",
+    "jfif",
+    "jpeg",
+    "jpg",
+    "pjp",
+    "pjpeg",
+    "png",
+    "svg",
+    "webp",
+)
+
+
+def find_image_in_dir(glob: str, dir: Path):
+    return next(
+        (f for f in dir.glob(f"{glob}.*") if f.suffix.lstrip(".") in IMAGE_FILETYPES),
+        None,
+    )
+
+
+@lru_cache(maxsize=50)
+def find_image_url(glob: str, dir: Path = CONF_IMAGE_DIR):
+    """
+    will attempt to find a file that matches glob in given directory with any file extension,
+    otherwise will try to find a `role-unknown` image
+
+    returns static file url
+    """
+    if file := find_image_in_dir(glob, dir):
+        return image_static_url(file)
+
+    if glob != "role-unknown" and (file := find_image_in_dir("role-unknown", dir)):
+        return image_static_url(file)
+
+    if dir != IMAGE_DIR and (file := find_image_in_dir("role-unknown", IMAGE_DIR)):
+        return image_static_url(file)
+
+    return ""
+
+
+@dataclass
+class Role:
+    slug: str
+    name: str
+
+
+def get_model_slug(model: Type[Model]):
+    return camel_case_to_spaces(model.__name__).replace(" ", "-")
+
+
+def get_model_role(model: Type[Model]) -> Role:
+    return Role(
+        slug=get_model_slug(model),
+        name=re_camel_case.sub(r" \1", model.__name__),
+    )