Add 3-Day Outlook generation

internal/changes/three_day.go

@@ -0,0 +1,78 @@
+package changes
+
+import (
+	"fmt"
+	"time"
+
+	"gitea.maximumdirect.net/eric/weatherreporter/internal/briefing"
+)
+
+func CompareThreeDay(previous briefing.Package, current briefing.Package, thresholds Thresholds) ([]Change, error) {
+	if previous.ThreeDay == nil {
+		return nil, fmt.Errorf("previous 3-day briefing is required")
+	}
+	if current.ThreeDay == nil {
+		return nil, fmt.Errorf("current 3-day briefing is required")
+	}
+	previousDays := outlookDaysByDate(previous.ThreeDay.Days)
+	currentDays := outlookDaysByDate(current.ThreeDay.Days)
+	var changes []Change
+	for date, currentDay := range currentDays {
+		previousDay, ok := previousDays[date]
+		if !ok {
+			changes = append(changes, Change{Type: "outlook_day_added", Message: fmt.Sprintf("Outlook day added: %s.", date), Current: date})
+			continue
+		}
+		changes = append(changes, compareOutlookDay(date, previousDay, currentDay, thresholds)...)
+	}
+	for date := range previousDays {
+		if _, ok := currentDays[date]; !ok {
+			changes = append(changes, Change{Type: "outlook_day_removed", Message: fmt.Sprintf("Outlook day removed: %s.", date), Previous: date})
+		}
+	}
+	sortChanges(changes)
+	return changes, nil
+}
+
+func compareOutlookDay(date string, previous briefing.OutlookDay, current briefing.OutlookDay, thresholds Thresholds) []Change {
+	var changes []Change
+	for _, change := range compareTemperature(previous.Temperature, current.Temperature, thresholds.TemperatureDegrees) {
+		change.Message = date + ": " + change.Message
+		changes = append(changes, change)
+	}
+	for _, change := range comparePrecipitation(previous.MaxPrecipitationProbability, current.MaxPrecipitationProbability, thresholds) {
+		change.Message = date + ": " + change.Message
+		changes = append(changes, change)
+		changes[len(changes)-1].Type = "outlook_" + change.Type
+	}
+	for _, change := range compareWind(previous.PeakWindGust, current.PeakWindGust, float64(thresholds.WindGustMilesPerHour)) {
+		change.Message = date + ": " + change.Message
+		change.Type = "outlook_" + change.Type
+		changes = append(changes, change)
+	}
+	for _, change := range compareAlerts(previous.RelevantAlerts, current.RelevantAlerts) {
+		change.Message = date + ": " + change.Message
+		change.Type = "outlook_" + change.Type
+		changes = append(changes, change)
+	}
+	for _, change := range compareIndicators(aggregateIndicators(previous.Dayparts), aggregateIndicators(current.Dayparts)) {
+		change.Message = date + ": " + change.Message
+		change.Type = "outlook_" + change.Type
+		changes = append(changes, change)
+	}
+	return changes
+}
+
+func outlookDaysByDate(days []briefing.OutlookDay) map[string]briefing.OutlookDay {
+	out := map[string]briefing.OutlookDay{}
+	for _, day := range days {
+		date := day.Date
+		if date == "" && !day.Period.Start.IsZero() {
+			date = day.Period.Start.Format(time.DateOnly)
+		}
+		if date != "" {
+			out[date] = day
+		}
+	}
+	return out
+}

internal/changes/three_day_test.go

@@ -0,0 +1,66 @@
+package changes
+
+import (
+	"testing"
+	"time"
+
+	"gitea.maximumdirect.net/eric/weatherreporter/internal/briefing"
+	"gitea.maximumdirect.net/eric/weatherreporter/internal/forecast"
+	"gitea.maximumdirect.net/eric/weatherreporter/internal/report"
+)
+
+func TestCompareThreeDayDetectsDayChanges(t *testing.T) {
+	previousTemp := 70.0
+	currentTemp := 78.0
+	previousPrecip := 20.0
+	currentPrecip := 70.0
+	previous := briefing.Package{
+		Metadata: briefing.Metadata{ReportID: report.ThreeDay},
+		ThreeDay: &briefing.ThreeDay{Days: []briefing.OutlookDay{{
+			Date:        "2026-05-29",
+			Temperature: forecast.Range{Max: &previousTemp},
+			MaxPrecipitationProbability: &forecast.TimedValue{
+				Value: previousPrecip,
+				Time:  time.Date(2026, 5, 29, 9, 0, 0, 0, time.UTC),
+			},
+		}}},
+	}
+	current := briefing.Package{
+		Metadata: briefing.Metadata{ReportID: report.ThreeDay},
+		ThreeDay: &briefing.ThreeDay{Days: []briefing.OutlookDay{{
+			Date:        "2026-05-29",
+			Temperature: forecast.Range{Max: &currentTemp},
+			MaxPrecipitationProbability: &forecast.TimedValue{
+				Value: currentPrecip,
+				Time:  time.Date(2026, 5, 29, 12, 0, 0, 0, time.UTC),
+			},
+			Dayparts: []forecast.DaypartSummary{{Indicators: forecast.Indicators{Thunder: true}}},
+		}}},
+	}
+
+	changes, err := CompareThreeDay(previous, current, Thresholds{
+		TemperatureDegrees:       5,
+		PrecipProbabilityPoints:  20,
+		PrecipTimingShiftMinutes: 120,
+	})
+	if err != nil {
+		t.Fatalf("CompareThreeDay() error = %v", err)
+	}
+
+	if len(changes) == 0 {
+		t.Fatal("changes length = 0, want detected 3-day changes")
+	}
+	var foundPrecip bool
+	var foundThunder bool
+	for _, change := range changes {
+		if change.Type == "outlook_precip_probability_change" {
+			foundPrecip = true
+		}
+		if change.Type == "outlook_thunder_risk_change" {
+			foundThunder = true
+		}
+	}
+	if !foundPrecip || !foundThunder {
+		t.Fatalf("changes = %#v, want precipitation and thunder changes", changes)
+	}
+}