Add Daily recent changes comparison

This commit is contained in:
2026-05-29 17:53:03 +00:00
parent b17a3591e0
commit 53a4abd508
12 changed files with 602 additions and 12 deletions

201
internal/changes/daily.go Normal file
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// Package changes compares structured briefing snapshots.
package changes
import (
"fmt"
"math"
"sort"
"time"
"gitea.maximumdirect.net/eric/weatherreporter/internal/briefing"
"gitea.maximumdirect.net/eric/weatherreporter/internal/forecast"
)
type Thresholds struct {
TemperatureDegrees float64
PrecipProbabilityPoints int
WindGustMilesPerHour int
PrecipTimingShiftMinutes int
}
type Change struct {
Type string `json:"type"`
Message string `json:"message"`
Previous string `json:"previous,omitempty"`
Current string `json:"current,omitempty"`
}
func CompareDaily(previous briefing.Package, current briefing.Package, thresholds Thresholds) ([]Change, error) {
if previous.Daily == nil {
return nil, fmt.Errorf("previous daily briefing is required")
}
if current.Daily == nil {
return nil, fmt.Errorf("current daily briefing is required")
}
var changes []Change
changes = append(changes, compareTemperature(previous.Daily.BottomLine.Temperature, current.Daily.BottomLine.Temperature, thresholds.TemperatureDegrees)...)
changes = append(changes, comparePrecipitation(previous.Daily.BottomLine.MaxPrecipProbability, current.Daily.BottomLine.MaxPrecipProbability, thresholds)...)
changes = append(changes, compareWind(previous.Daily.BottomLine.PeakWindGust, current.Daily.BottomLine.PeakWindGust, float64(thresholds.WindGustMilesPerHour))...)
changes = append(changes, compareAlerts(previous.Daily.RelevantAlerts, current.Daily.RelevantAlerts)...)
changes = append(changes, compareIndicators(aggregateIndicators(previous.Daily.Dayparts), aggregateIndicators(current.Daily.Dayparts))...)
return changes, nil
}
func compareTemperature(previous forecast.Range, current forecast.Range, threshold float64) []Change {
var changes []Change
if previous.Min != nil && current.Min != nil && differenceAtLeast(*previous.Min, *current.Min, threshold) {
changes = append(changes, Change{
Type: "temperature_shift",
Message: fmt.Sprintf("Low temperature changed from %.0f to %.0f.", *previous.Min, *current.Min),
Previous: fmt.Sprintf("%.0f", *previous.Min),
Current: fmt.Sprintf("%.0f", *current.Min),
})
}
if previous.Max != nil && current.Max != nil && differenceAtLeast(*previous.Max, *current.Max, threshold) {
changes = append(changes, Change{
Type: "temperature_shift",
Message: fmt.Sprintf("High temperature changed from %.0f to %.0f.", *previous.Max, *current.Max),
Previous: fmt.Sprintf("%.0f", *previous.Max),
Current: fmt.Sprintf("%.0f", *current.Max),
})
}
return changes
}
func comparePrecipitation(previous *forecast.TimedValue, current *forecast.TimedValue, thresholds Thresholds) []Change {
if previous == nil || current == nil {
return nil
}
var changes []Change
previousCategory := precipitationCategory(previous.Value)
currentCategory := precipitationCategory(current.Value)
if previousCategory != currentCategory || differenceAtLeast(previous.Value, current.Value, float64(thresholds.PrecipProbabilityPoints)) {
changes = append(changes, Change{
Type: "precip_probability_change",
Message: fmt.Sprintf("Peak precipitation chance changed from %.0f%% (%s) to %.0f%% (%s).", previous.Value, previousCategory, current.Value, currentCategory),
Previous: fmt.Sprintf("%.0f%% %s", previous.Value, previousCategory),
Current: fmt.Sprintf("%.0f%% %s", current.Value, currentCategory),
})
}
shiftMinutes := int(math.Abs(current.Time.Sub(previous.Time).Minutes()))
if thresholds.PrecipTimingShiftMinutes > 0 && shiftMinutes >= thresholds.PrecipTimingShiftMinutes {
changes = append(changes, Change{
Type: "precip_timing_shift",
Message: fmt.Sprintf("Peak precipitation timing shifted from %s to %s.", clock(previous.Time), clock(current.Time)),
Previous: clock(previous.Time),
Current: clock(current.Time),
})
}
return changes
}
func compareWind(previous *forecast.TimedValue, current *forecast.TimedValue, threshold float64) []Change {
if previous == nil || current == nil || !differenceAtLeast(previous.Value, current.Value, threshold) {
return nil
}
return []Change{{
Type: "wind_gust_change",
Message: fmt.Sprintf("Peak wind gust changed from %.0f mph to %.0f mph.", previous.Value, current.Value),
Previous: fmt.Sprintf("%.0f mph", previous.Value),
Current: fmt.Sprintf("%.0f mph", current.Value),
}}
}
func compareAlerts(previous []forecast.AlertOverlap, current []forecast.AlertOverlap) []Change {
previousSet := alertSet(previous)
currentSet := alertSet(current)
var changes []Change
for event := range currentSet {
if _, ok := previousSet[event]; !ok {
changes = append(changes, Change{Type: "alert_added", Message: fmt.Sprintf("Alert added: %s.", event), Current: event})
}
}
for event := range previousSet {
if _, ok := currentSet[event]; !ok {
changes = append(changes, Change{Type: "alert_removed", Message: fmt.Sprintf("Alert removed: %s.", event), Previous: event})
}
}
sortChanges(changes)
return changes
}
func compareIndicators(previous forecast.Indicators, current forecast.Indicators) []Change {
var changes []Change
for _, item := range []struct {
name string
previous bool
current bool
}{
{name: "thunder", previous: previous.Thunder, current: current.Thunder},
{name: "snow", previous: previous.Snow, current: current.Snow},
{name: "ice", previous: previous.Ice, current: current.Ice},
} {
if item.previous == item.current {
continue
}
changeType := item.name + "_risk_change"
if item.current {
changes = append(changes, Change{Type: changeType, Message: fmt.Sprintf("%s risk is now present.", item.name), Current: "present"})
} else {
changes = append(changes, Change{Type: changeType, Message: fmt.Sprintf("%s risk is no longer present.", item.name), Previous: "present"})
}
}
return changes
}
func aggregateIndicators(dayparts []forecast.DaypartSummary) forecast.Indicators {
out := forecast.Indicators{}
for _, daypart := range dayparts {
out.Thunder = out.Thunder || daypart.Indicators.Thunder
out.Snow = out.Snow || daypart.Indicators.Snow
out.Ice = out.Ice || daypart.Indicators.Ice
}
return out
}
func alertSet(alerts []forecast.AlertOverlap) map[string]struct{} {
out := map[string]struct{}{}
for _, alert := range alerts {
event := alert.Event
if event == "" {
event = alert.Headline
}
if event != "" {
out[event] = struct{}{}
}
}
return out
}
func precipitationCategory(value float64) string {
switch {
case value >= 70:
return "high"
case value >= 50:
return "likely"
case value >= 20:
return "possible"
default:
return "low"
}
}
func differenceAtLeast(previous float64, current float64, threshold float64) bool {
if threshold <= 0 {
return previous != current
}
return math.Abs(current-previous) >= threshold
}
func clock(t time.Time) string {
return t.Format("15:04")
}
func sortChanges(items []Change) {
sort.SliceStable(items, func(i, j int) bool {
if items[i].Type == items[j].Type {
return items[i].Message < items[j].Message
}
return items[i].Type < items[j].Type
})
}

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package changes
import (
"testing"
"time"
"gitea.maximumdirect.net/eric/weatherreporter/internal/briefing"
"gitea.maximumdirect.net/eric/weatherreporter/internal/forecast"
)
func TestCompareDailyNoMeaningfulChanges(t *testing.T) {
previous := dailyBriefing(60, 70, 30, at("2026-05-29T08:00:00Z"), nil, forecast.Indicators{})
current := dailyBriefing(61, 71, 35, at("2026-05-29T08:30:00Z"), nil, forecast.Indicators{})
changes, err := CompareDaily(previous, current, testThresholds())
if err != nil {
t.Fatalf("CompareDaily() error = %v", err)
}
if len(changes) != 0 {
t.Fatalf("changes = %#v, want none", changes)
}
}
func TestCompareDailyTemperatureThreshold(t *testing.T) {
previous := dailyBriefing(50, 70, 10, at("2026-05-29T08:00:00Z"), nil, forecast.Indicators{})
current := dailyBriefing(58, 79, 10, at("2026-05-29T08:00:00Z"), nil, forecast.Indicators{})
changes, err := CompareDaily(previous, current, testThresholds())
if err != nil {
t.Fatalf("CompareDaily() error = %v", err)
}
if countType(changes, "temperature_shift") != 2 {
t.Fatalf("changes = %#v, want low and high temperature changes", changes)
}
}
func TestCompareDailyPrecipTimingShift(t *testing.T) {
previous := dailyBriefing(60, 70, 60, at("2026-05-29T08:00:00Z"), nil, forecast.Indicators{})
current := dailyBriefing(60, 70, 60, at("2026-05-29T11:00:00Z"), nil, forecast.Indicators{})
changes, err := CompareDaily(previous, current, testThresholds())
if err != nil {
t.Fatalf("CompareDaily() error = %v", err)
}
if countType(changes, "precip_timing_shift") != 1 {
t.Fatalf("changes = %#v, want timing shift", changes)
}
}
func TestCompareDailyAlertAddedAndRemoved(t *testing.T) {
previous := dailyBriefing(60, 70, 10, at("2026-05-29T08:00:00Z"), []string{"Wind Advisory"}, forecast.Indicators{})
current := dailyBriefing(60, 70, 10, at("2026-05-29T08:00:00Z"), []string{"Flood Watch"}, forecast.Indicators{})
changes, err := CompareDaily(previous, current, testThresholds())
if err != nil {
t.Fatalf("CompareDaily() error = %v", err)
}
if countType(changes, "alert_added") != 1 || countType(changes, "alert_removed") != 1 {
t.Fatalf("changes = %#v, want one alert added and one removed", changes)
}
}
func TestCompareDailyIndicatorChange(t *testing.T) {
previous := dailyBriefing(60, 70, 10, at("2026-05-29T08:00:00Z"), nil, forecast.Indicators{})
current := dailyBriefing(60, 70, 10, at("2026-05-29T08:00:00Z"), nil, forecast.Indicators{Thunder: true})
changes, err := CompareDaily(previous, current, testThresholds())
if err != nil {
t.Fatalf("CompareDaily() error = %v", err)
}
if countType(changes, "thunder_risk_change") != 1 {
t.Fatalf("changes = %#v, want thunder risk change", changes)
}
}
func dailyBriefing(low float64, high float64, precip float64, precipTime time.Time, alerts []string, indicators forecast.Indicators) briefing.Package {
alertOverlaps := make([]forecast.AlertOverlap, 0, len(alerts))
for _, alert := range alerts {
alertOverlaps = append(alertOverlaps, forecast.AlertOverlap{Event: alert})
}
return briefing.Package{
Daily: &briefing.Daily{
BottomLine: briefing.BottomLine{
Temperature: forecast.Range{Min: &low, Max: &high},
MaxPrecipProbability: &forecast.TimedValue{
Value: precip,
Time: precipTime,
},
},
RelevantAlerts: alertOverlaps,
Dayparts: []forecast.DaypartSummary{
{Name: "morning", Indicators: indicators},
},
},
}
}
func testThresholds() Thresholds {
return Thresholds{
TemperatureDegrees: 5,
PrecipProbabilityPoints: 20,
WindGustMilesPerHour: 10,
PrecipTimingShiftMinutes: 120,
}
}
func countType(changes []Change, changeType string) int {
var count int
for _, change := range changes {
if change.Type == changeType {
count++
}
}
return count
}
func at(value string) time.Time {
parsed, err := time.Parse(time.RFC3339, value)
if err != nil {
panic(err)
}
return parsed
}