Files
weatherreporter/internal/changes/daily.go

314 lines
10 KiB
Go

// Package changes compares structured module snapshots.
package changes
import (
"fmt"
"math"
"sort"
"strconv"
"strings"
"time"
"gitea.maximumdirect.net/eric/weatherreporter/internal/module"
)
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 module.Snapshot, current module.Snapshot, thresholds Thresholds) ([]Change, error) {
previousSummary, err := requiredStanza[dailySummaryStanza](previous, "derived_daily_summary")
if err != nil {
return nil, fmt.Errorf("previous daily summary: %w", err)
}
currentSummary, err := requiredStanza[dailySummaryStanza](current, "derived_daily_summary")
if err != nil {
return nil, fmt.Errorf("current daily summary: %w", err)
}
previousDayparts, err := requiredStanza[map[string]daypartSummaryStanza](previous, "derived_daypart_summaries")
if err != nil {
return nil, fmt.Errorf("previous daypart summaries: %w", err)
}
currentDayparts, err := requiredStanza[map[string]daypartSummaryStanza](current, "derived_daypart_summaries")
if err != nil {
return nil, fmt.Errorf("current daypart summaries: %w", err)
}
previousAlerts, _, err := module.StanzaValue[alertDigestStanza](previous, "alert_digest")
if err != nil {
return nil, err
}
currentAlerts, _, err := module.StanzaValue[alertDigestStanza](current, "alert_digest")
if err != nil {
return nil, err
}
previousTiming, previousHasTiming, err := module.StanzaValue[precipTimingStanza](previous, "precip_timing")
if err != nil {
return nil, err
}
currentTiming, currentHasTiming, err := module.StanzaValue[precipTimingStanza](current, "precip_timing")
if err != nil {
return nil, err
}
var changes []Change
changes = append(changes, compareTemperatureValues("Low", previousSummary.LowTempF, currentSummary.LowTempF, thresholds.TemperatureDegrees)...)
changes = append(changes, compareTemperatureValues("High", previousSummary.HighTempF, currentSummary.HighTempF, thresholds.TemperatureDegrees)...)
changes = append(changes, comparePrecipitationValues(previousSummary.DailyPrecipitationProbability, currentSummary.DailyPrecipitationProbability, thresholds.PrecipProbabilityPoints, "")...)
if previousHasTiming && currentHasTiming {
changes = append(changes, comparePrecipTiming(previousTiming.MaxPopTime, currentTiming.MaxPopTime, thresholds.PrecipTimingShiftMinutes, "")...)
}
changes = append(changes, compareWindValues(previousSummary.MaxWindGustMph, currentSummary.MaxWindGustMph, thresholds.WindGustMilesPerHour, "")...)
changes = append(changes, compareAlerts(previousAlerts.Relevant, currentAlerts.Relevant)...)
changes = append(changes, compareIndicators(aggregateIndicators(previousDayparts), aggregateIndicators(currentDayparts), "")...)
sortChanges(changes)
return changes, nil
}
type dailySummaryStanza struct {
Date string `json:"date,omitempty"`
HighTempF *int `json:"high_temp_f,omitempty"`
LowTempF *int `json:"low_temp_f,omitempty"`
DailyPrecipitationProbability *int `json:"daily_precipitation_probability,omitempty"`
MaxWindGustMph *int `json:"max_wind_gust_mph,omitempty"`
}
type daypartSummaryStanza struct {
Date string `json:"date,omitempty"`
PeriodBegins string `json:"period_begins,omitempty"`
PeriodEnds string `json:"period_ends,omitempty"`
TempRangeF string `json:"temp_range_f,omitempty"`
MaxPopPercent *int `json:"max_pop_percent,omitempty"`
MaxPopTime string `json:"max_pop_time,omitempty"`
MaxWindGustMph *int `json:"max_wind_gust_mph,omitempty"`
Snow bool `json:"snow,omitempty"`
Ice bool `json:"ice,omitempty"`
}
type precipTimingStanza struct {
MaxPopPercent *int `json:"max_pop_percent,omitempty"`
MaxPopTime string `json:"max_pop_time,omitempty"`
}
type alertDigestStanza struct {
Relevant []alertSummaryStanza `json:"relevant,omitempty"`
}
type alertSummaryStanza struct {
Event string `json:"event,omitempty"`
Headline string `json:"headline,omitempty"`
}
type indicators struct {
Snow bool
Ice bool
}
func requiredStanza[T any](snapshot module.Snapshot, name string) (T, error) {
value, ok, err := module.StanzaValue[T](snapshot, name)
if err != nil {
return value, err
}
if !ok {
return value, fmt.Errorf("stanza %q is required", name)
}
return value, nil
}
func compareTemperatureValues(label string, previous *int, current *int, threshold float64) []Change {
if previous == nil || current == nil {
return nil
}
if !differenceAtLeast(float64(*previous), float64(*current), threshold) {
return nil
}
return []Change{{
Type: "temperature_shift",
Message: fmt.Sprintf("%s temperature changed from %d to %d.", label, *previous, *current),
Previous: fmt.Sprintf("%d", *previous),
Current: fmt.Sprintf("%d", *current),
}}
}
func comparePrecipitationValues(previous *int, current *int, threshold int, prefix string) []Change {
if previous == nil || current == nil {
return nil
}
previousCategory := precipitationCategory(float64(*previous))
currentCategory := precipitationCategory(float64(*current))
if previousCategory == currentCategory && !differenceAtLeast(float64(*previous), float64(*current), float64(threshold)) {
return nil
}
changeType := prefix + "precip_probability_change"
return []Change{{
Type: changeType,
Message: fmt.Sprintf("Peak precipitation chance changed from %d%% (%s) to %d%% (%s).", *previous, previousCategory, *current, currentCategory),
Previous: fmt.Sprintf("%d%% %s", *previous, previousCategory),
Current: fmt.Sprintf("%d%% %s", *current, currentCategory),
}}
}
func comparePrecipTiming(previous string, current string, thresholdMinutes int, prefix string) []Change {
if thresholdMinutes <= 0 || previous == "" || current == "" || previous == current {
return nil
}
previousTime, previousOK := parseClock(previous)
currentTime, currentOK := parseClock(current)
if !previousOK || !currentOK {
return nil
}
if int(math.Abs(currentTime.Sub(previousTime).Minutes())) < thresholdMinutes {
return nil
}
return []Change{{
Type: prefix + "precip_timing_shift",
Message: fmt.Sprintf("Peak precipitation timing shifted from %s to %s.", previous, current),
Previous: previous,
Current: current,
}}
}
func compareWindValues(previous *int, current *int, threshold int, prefix string) []Change {
if previous == nil || current == nil || !differenceAtLeast(float64(*previous), float64(*current), float64(threshold)) {
return nil
}
return []Change{{
Type: prefix + "wind_gust_change",
Message: fmt.Sprintf("Peak wind gust changed from %d mph to %d mph.", *previous, *current),
Previous: fmt.Sprintf("%d mph", *previous),
Current: fmt.Sprintf("%d mph", *current),
}}
}
func compareAlerts(previous []alertSummaryStanza, current []alertSummaryStanza) []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 indicators, current indicators, prefix string) []Change {
var changes []Change
for _, item := range []struct {
name string
previous bool
current bool
}{
{name: "snow", previous: previous.Snow, current: current.Snow},
{name: "ice", previous: previous.Ice, current: current.Ice},
} {
if item.previous == item.current {
continue
}
changeType := prefix + 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 map[string]daypartSummaryStanza) indicators {
out := indicators{}
for _, daypart := range dayparts {
out.Snow = out.Snow || daypart.Snow
out.Ice = out.Ice || daypart.Ice
}
return out
}
func alertSet(alerts []alertSummaryStanza) 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 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
})
}
func parseClock(value string) (time.Time, bool) {
value = strings.TrimSpace(value)
for _, layout := range []string{"3 PM", "3:04 PM", "15:04"} {
if parsed, err := time.Parse(layout, value); err == nil {
return parsed, true
}
}
return time.Time{}, false
}
func parseTempRange(value string) (*int, *int) {
value = strings.TrimSpace(value)
if value == "" {
return nil, nil
}
parts := strings.Split(value, "-")
if len(parts) == 1 {
if parsed, err := strconv.Atoi(strings.TrimSpace(parts[0])); err == nil {
return &parsed, &parsed
}
return nil, nil
}
minValue, minErr := strconv.Atoi(strings.TrimSpace(parts[0]))
maxValue, maxErr := strconv.Atoi(strings.TrimSpace(parts[len(parts)-1]))
if minErr != nil || maxErr != nil {
return nil, nil
}
return &minValue, &maxValue
}