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
}