Add Weekend Outlook generation

internal/changes/weekend.go

@@ -0,0 +1,26 @@
+package changes
+
+import (
+	"fmt"
+
+	"gitea.maximumdirect.net/eric/weatherreporter/internal/briefing"
+)
+
+func CompareWeekend(previous briefing.Package, current briefing.Package, thresholds Thresholds) ([]Change, error) {
+	if previous.Weekend == nil {
+		return nil, fmt.Errorf("previous weekend briefing is required")
+	}
+	if current.Weekend == nil {
+		return nil, fmt.Errorf("current weekend briefing is required")
+	}
+	previousOutlook := briefing.Package{ThreeDay: &briefing.ThreeDay{Days: previous.Weekend.Days}}
+	currentOutlook := briefing.Package{ThreeDay: &briefing.ThreeDay{Days: current.Weekend.Days}}
+	changes, err := CompareThreeDay(previousOutlook, currentOutlook, thresholds)
+	if err != nil {
+		return nil, err
+	}
+	for i := range changes {
+		changes[i].Type = "weekend_" + changes[i].Type
+	}
+	return changes, nil
+}

internal/changes/weekend_test.go

@@ -0,0 +1,43 @@
+package changes
+
+import (
+	"testing"
+
+	"gitea.maximumdirect.net/eric/weatherreporter/internal/briefing"
+	"gitea.maximumdirect.net/eric/weatherreporter/internal/forecast"
+	"gitea.maximumdirect.net/eric/weatherreporter/internal/report"
+)
+
+func TestCompareWeekendDetectsOutlookChanges(t *testing.T) {
+	previousTemp := 70.0
+	currentTemp := 78.0
+	previous := briefing.Package{
+		Metadata: briefing.Metadata{ReportID: report.Weekend},
+		Weekend: &briefing.Weekend{Days: []briefing.OutlookDay{{
+			Date:        "2026-05-30",
+			Temperature: forecast.Range{Max: &previousTemp},
+		}}},
+	}
+	current := briefing.Package{
+		Metadata: briefing.Metadata{ReportID: report.Weekend},
+		Weekend: &briefing.Weekend{Days: []briefing.OutlookDay{{
+			Date:        "2026-05-30",
+			Temperature: forecast.Range{Max: &currentTemp},
+			Dayparts:    []forecast.DaypartSummary{{Indicators: forecast.Indicators{Thunder: true}}},
+		}}},
+	}
+
+	changes, err := CompareWeekend(previous, current, Thresholds{TemperatureDegrees: 5})
+	if err != nil {
+		t.Fatalf("CompareWeekend() error = %v", err)
+	}
+	if len(changes) == 0 {
+		t.Fatal("changes length = 0, want weekend changes")
+	}
+	for _, change := range changes {
+		if change.Type == "weekend_outlook_thunder_risk_change" {
+			return
+		}
+	}
+	t.Fatalf("changes = %#v, want thunder risk change", changes)
+}