package briefing

import (
	"fmt"

	"gitea.maximumdirect.net/eric/weatherreporter/internal/forecast"
	"gitea.maximumdirect.net/eric/weatherreporter/internal/module"
	"gitea.maximumdirect.net/eric/weatherreporter/internal/weatherdata"
)

type DerivedDailySummaryModule 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"`
	MostLikelyPrecipitationHour   string   `json:"most_likely_precipitation_hour,omitempty"`
	ThunderMentioned              bool     `json:"thunder_mentioned"`
	MaxWindGustMph                *int     `json:"max_wind_gust_mph,omitempty"`
	HeatIndexMaxF                 *int     `json:"heat_index_max_f,omitempty"`
	DominantConditions            []string `json:"dominant_conditions,omitempty"`
	Hazards                       []string `json:"hazards,omitempty"`
}

func buildDerivedDailySummaryModule(ctx ModuleContext, _ any) (*module.Output, error) {
	summary := ctx.Derived.FirstDailySummary()
	if summary == nil {
		return nil, fmt.Errorf("daily summary facts are required")
	}
	value, err := derivedDailySummaryValue(*summary, ctx.Derived.PrecipTiming, ctx.Timezone)
	if err != nil {
		return nil, err
	}
	return &module.Output{ID: module.DerivedDailySummary, StanzaName: "derived_daily_summary", Value: value}, nil
}

func derivedDailySummaryValue(summary forecast.DailySummary, timing forecast.PrecipTiming, timezone string) (DerivedDailySummaryModule, error) {
	value := DerivedDailySummaryModule{
		Date:             friendlyDateLabel(summary.Date, timezone),
		ThunderMentioned: timing.ThunderMentioned,
	}
	conditions := map[string]struct{}{}
	hazards := map[string]struct{}{}
	var temperature forecast.Range
	var apparent forecast.Range
	var maxPop *forecast.TimedValue
	var maxGust *forecast.TimedValue
	for _, daypart := range summary.Dayparts {
		addRange(&temperature, daypart.Temperature)
		addRange(&apparent, daypart.ApparentTemperature)
		maxTimedValue(&maxPop, daypart.MaxPrecipitationProbability)
		maxTimedValue(&maxGust, daypart.PeakWindGust)
		if daypart.DominantCondition != "" {
			conditions[daypart.DominantCondition] = struct{}{}
		}
		for _, hazard := range hazardsForIndicators(daypart.Indicators) {
			hazards[hazard] = struct{}{}
		}
	}
	for _, alert := range summary.AlertOverlaps {
		if alert.Event != "" {
			hazards[alert.Event] = struct{}{}
		}
	}
	narrativeTemperature := narrativeTemperatureRange(summary.NarrativePeriods)
	if narrativeTemperature.Max != nil {
		value.HighTempF = roundedInt(narrativeTemperature.Max)
	} else {
		value.HighTempF = roundedInt(temperature.Max)
	}
	if narrativeTemperature.Min != nil {
		value.LowTempF = roundedInt(narrativeTemperature.Min)
	} else {
		value.LowTempF = roundedInt(temperature.Min)
	}
	value.HeatIndexMaxF = roundedInt(apparent.Max)
	narrativePrecipitation := narrativeMaxPrecipitation(summary.NarrativePeriods)
	if narrativePrecipitation != nil {
		value.DailyPrecipitationProbability = roundedInt(&narrativePrecipitation.Value)
	} else if maxPop != nil {
		value.DailyPrecipitationProbability = roundedInt(&maxPop.Value)
	}
	if maxPop != nil {
		value.MostLikelyPrecipitationHour = mostLikelyPrecipitationHour(maxPop, timezone)
	}
	if maxGust != nil {
		value.MaxWindGustMph = roundedInt(&maxGust.Value)
	}
	value.DominantConditions = sortedSet(conditions)
	value.Hazards = sortedSet(hazards)
	return value, nil
}

func narrativeTemperatureRange(periods []weatherdata.ForecastPeriod) forecast.Range {
	var out forecast.Range
	for _, period := range periods {
		addNarrativeHigh(&out, period.TemperatureFMax)
		addNarrativeLow(&out, period.TemperatureFMin)
		if period.TemperatureF != nil && period.IsDay != nil {
			if *period.IsDay {
				addNarrativeHigh(&out, period.TemperatureF)
			} else {
				addNarrativeLow(&out, period.TemperatureF)
			}
		}
	}
	return out
}

func addNarrativeHigh(target *forecast.Range, value *float64) {
	if value == nil {
		return
	}
	if target.Max == nil || *value > *target.Max {
		copied := *value
		target.Max = &copied
	}
}

func addNarrativeLow(target *forecast.Range, value *float64) {
	if value == nil {
		return
	}
	if target.Min == nil || *value < *target.Min {
		copied := *value
		target.Min = &copied
	}
}

func narrativeMaxPrecipitation(periods []weatherdata.ForecastPeriod) *forecast.TimedValue {
	var maxPop *forecast.TimedValue
	for _, period := range periods {
		if period.ProbabilityOfPrecipitationPercent == nil {
			continue
		}
		value := forecast.TimedValue{
			Value: *period.ProbabilityOfPrecipitationPercent,
			Time:  period.StartTime,
		}
		maxTimedValue(&maxPop, &value)
	}
	return maxPop
}

func mostLikelyPrecipitationHour(maxPop *forecast.TimedValue, timezone string) string {
	if maxPop == nil || maxPop.Value <= 0 {
		return ""
	}
	percent := roundedInt(&maxPop.Value)
	if percent == nil {
		return ""
	}
	return fmt.Sprintf("%d%% at %s", *percent, clockLabel(maxPop.Time, timezone))
}