feat(sorting): SortSpec/SortTerm types + parse_sort_terms (#68)

games/sorting.py

@@ -0,0 +1,55 @@
+"""Structured sorting for list views (Stash-inspired, paired with games/filters.py).
+
+A list view maps a public sort key to a SortSpec; the URL ?sort= param is a
+signed comma-list of those keys (e.g. "-playtime,name"). See
+docs/superpowers/specs/2026-06-21-list-view-sort-param-design.md.
+"""
+
+from dataclasses import dataclass
+from typing import NamedTuple
+
+from django.db.models import Aggregate
+
+type SortKey = str         # public column key in a *_SORTS map and in a URL term ("playtime", "name")
+type SortString = str      # comma-list of signed SortKeys: the URL ?sort= value and *_DEFAULT_SORT ("-date,created")
+type AnnotationName = str  # an alias added via .annotate(), then referenced by SortSpec.expression
+type OrderField = str      # SortSpec.expression: a real model field path OR an AnnotationName
+
+# alias name -> the ORM aggregate that computes it, applied via queryset.annotate()
+# e.g. {"total_playtime": Sum("sessions__duration_total")}
+type Annotations = dict[AnnotationName, Aggregate]
+
+
+@dataclass(frozen=True)
+class SortSpec:
+    expression: OrderField           # unsigned; a real column path or an AnnotationName
+    annotate: Annotations | None = None
+
+
+class SortTerm(NamedTuple):
+    key: SortKey
+    descending: bool      # True = "-key" (desc), False = bare key (asc)
+
+
+type SortMap = dict[SortKey, SortSpec]
+
+
+class ParsedSort(NamedTuple):
+    terms: list[SortTerm]
+    unknown: list[SortKey]   # keys not in the map — the view turns these into warnings
+
+
+def parse_sort_terms(raw: SortString, sort_map: SortMap) -> ParsedSort:
+    terms: list[SortTerm] = []
+    unknown: list[SortKey] = []
+    for token in raw.split(","):
+        token = token.strip()
+        if not token:
+            continue
+        descending = token.startswith("-")
+        key = token.lstrip("-")
+        if key in sort_map:
+            terms.append(SortTerm(key, descending))
+        else:
+            unknown.append(key)
+    return ParsedSort(terms, unknown)

tests/test_sorting.py

@@ -0,0 +1,40 @@
+"""Tests for the list-view sorting system (games/sorting.py)."""
+
+from games.sorting import SortSpec, SortTerm, parse_sort_terms
+
+# A minimal map; parse_sort_terms only checks key membership, not spec internals.
+SAMPLE_MAP = {"name": SortSpec("name"), "date": SortSpec("created_at")}
+
+
+class TestParseSortTerms:
+    def test_bare_key_is_ascending(self):
+        parsed = parse_sort_terms("name", SAMPLE_MAP)
+        assert parsed.terms == [SortTerm("name", False)]
+        assert parsed.unknown == []
+
+    def test_dash_prefix_is_descending(self):
+        parsed = parse_sort_terms("-date", SAMPLE_MAP)
+        assert parsed.terms == [SortTerm("date", True)]
+
+    def test_multi_column_preserves_order(self):
+        parsed = parse_sort_terms("date,-name", SAMPLE_MAP)
+        assert parsed.terms == [SortTerm("date", False), SortTerm("name", True)]
+
+    def test_unknown_key_is_reported_not_raised(self):
+        parsed = parse_sort_terms("bogus", SAMPLE_MAP)
+        assert parsed.terms == []
+        assert parsed.unknown == ["bogus"]
+
+    def test_mixed_valid_and_unknown(self):
+        parsed = parse_sort_terms("-name,bogus", SAMPLE_MAP)
+        assert parsed.terms == [SortTerm("name", True)]
+        assert parsed.unknown == ["bogus"]
+
+    def test_whitespace_and_empty_tokens_ignored(self):
+        parsed = parse_sort_terms(" name , , -date ", SAMPLE_MAP)
+        assert parsed.terms == [SortTerm("name", False), SortTerm("date", True)]
+
+    def test_empty_string_yields_nothing(self):
+        parsed = parse_sort_terms("", SAMPLE_MAP)
+        assert parsed.terms == []
+        assert parsed.unknown == []