Feat: Add a utility function to compare builds between errata (#305)

- Introduced `ErratumBuilds` model to parse and store build data
  from ET API.
- Added `get_erratum_builds()` to fetch builds for a given erratum ID.
- Implemented `errata_have_same_file_lists()` to check if two errata
  ship the same subpackages.

Author: Jazzcort

supervisor/errata_utils.py

@@ -10,7 +10,7 @@
 from typing_extensions import Literal
 
 from bs4 import BeautifulSoup, Tag  # type: ignore
-from pydantic import BaseModel
+from pydantic import BaseModel, RootModel
 from requests_gssapi import HTTPSPNEGOAuth
 
 from .constants import DATETIME_MIN_UTC
@@ -157,6 +157,55 @@ def get_erratum_for_link(link: str, full: bool = False) -> Erratum | FullErratum
     return get_erratum(erratum_id, full=full)
 
 
+class ErratumBuilds(RootModel):
+    # Map variant and architecture to a set of subpackage names
+    # we ship for that architecture
+    # {
+    #     "AppStream": {
+    #           "SRPMS": {"libtiff"}
+    #           "aarch64": {"libtiff", "libtiff-devel", ...}
+    #     }
+    # }
+    root: dict[str, dict[str, set[str]]]
+
+
+def variant_to_base_variant(variant: str) -> str:
+    return variant.split("-")[0]
+
+
+def nvr_to_package_name(nvr: str) -> str:
+    return nvr.rsplit("-", 2)[0]
+
+
+def get_erratum_builds(id: int | str) -> ErratumBuilds:
+    data = ET_api_get(f"erratum/{id}/builds_list")
+
+    if len(data) != 1:
+        raise ValueError("Expected JSON object to have a single product version key.")
+    detail = next(iter(data.values()))
+
+    builds = detail.get("builds", [])
+    if len(builds) != 1:
+        raise ValueError("Expected a single build in the 'builds' list.")
+
+    build = builds[0]
+    if len(build) != 1:
+        raise ValueError("Expected build to have a single NVR key.")
+    build_detail = next(iter(build.values()))
+
+    variant_arch = build_detail["variant_arch"]
+
+    file_list_map = {
+        variant_to_base_variant(variant): {
+            arch: set([nvr_to_package_name(rpm["filename"]) for rpm in rmps])
+            for arch, rmps in arches.items()
+        }
+        for variant, arches in variant_arch.items()
+    }
+
+    return ErratumBuilds(root=file_list_map)
+
+
 class RHELVersion(BaseModel):
     major: int
     minor: int
@@ -381,6 +430,19 @@ def get_erratum_build_nvr(erratum_id: str | int, package_name: str) -> str | Non
     return None
 
 
+def errata_have_same_file_lists(errata_id1: int | str, errata_id2: int | str):
+    """Check if the given errata have the same file lists
+
+    After stripping package versions and RHEL release versions,
+    do the two errata ship the same subpackages for each
+    variant and architecture?
+
+    Throws an exception if either errata has more than one build
+    attached to it.
+    """
+    return get_erratum_builds(errata_id1) == get_erratum_builds(errata_id2)
+
+
 class RuleParseError(Exception):
     pass