package briefing

import (
	"fmt"
	"strings"
	"unicode"

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

type DerivedDaypartSummaryModule 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"`
	ApparentTempRangeF string   `json:"apparent_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"`
	MaxWindGustTime    string   `json:"max_wind_gust_time,omitempty"`
	DominantCondition  string   `json:"dominant_condition,omitempty"`
	NotableConditions  []string `json:"notable_conditions,omitempty"`
	Snow               bool     `json:"snow,omitempty"`
	Ice                bool     `json:"ice,omitempty"`
	Fog                bool     `json:"fog,omitempty"`
	Heat               bool     `json:"heat,omitempty"`
	Cold               bool     `json:"cold,omitempty"`
	Wind               bool     `json:"wind,omitempty"`
	RelevantAlertCount int      `json:"relevant_alert_count,omitempty"`
}

func buildDerivedDaypartSummariesModule(ctx ModuleContext, _ any) (*module.Output, error) {
	if len(ctx.Derived.DaypartSummaries) == 0 {
		return nil, fmt.Errorf("daypart summary facts are required")
	}
	value := map[string]DerivedDaypartSummaryModule{}
	prefixDates := multipleSummaryDates(ctx.Derived.DailySummaries)
	for _, daypart := range ctx.Derived.DaypartSummaries {
		key := daypartKey(daypart, prefixDates)
		value[key] = derivedDaypartSummaryValue(daypart, ctx.Timezone)
	}
	return &module.Output{ID: module.DerivedDaypartSummaries, StanzaName: "derived_daypart_summaries", Value: value}, nil
}

func derivedDaypartSummaryValue(daypart forecast.DaypartSummary, timezone string) DerivedDaypartSummaryModule {
	value := DerivedDaypartSummaryModule{
		Date:               localDateLabel(daypart.Period.Start, timezone),
		PeriodBegins:       friendlyPeriodBeginsLabel(daypart.Period, timezone),
		PeriodEnds:         friendlyPeriodEndsLabel(daypart.Period, timezone),
		TempRangeF:         rangeLabel(daypart.Temperature),
		ApparentTempRangeF: daypartApparentRangeLabel(daypart.ApparentTemperature),
		DominantCondition:  daypart.DominantCondition,
		NotableConditions:  append([]string(nil), daypart.NotableConditions...),
		Snow:               daypart.Indicators.Snow,
		Ice:                daypart.Indicators.Ice,
		Fog:                daypart.Indicators.Fog,
		Heat:               daypart.Indicators.Heat,
		Cold:               daypart.Indicators.Cold,
		Wind:               daypart.Indicators.Wind,
		RelevantAlertCount: len(daypart.AlertOverlaps),
	}
	if daypart.MaxPrecipitationProbability != nil {
		value.MaxPopPercent = roundedInt(&daypart.MaxPrecipitationProbability.Value)
		value.MaxPopTime = clockLabel(daypart.MaxPrecipitationProbability.Time, timezone)
	}
	if daypart.PeakWindGust != nil {
		value.MaxWindGustMph = roundedInt(&daypart.PeakWindGust.Value)
		value.MaxWindGustTime = clockLabel(daypart.PeakWindGust.Time, timezone)
	}
	return value
}

func multipleSummaryDates(summaries []forecast.DailySummary) bool {
	seen := map[string]struct{}{}
	for _, summary := range summaries {
		seen[summary.Date] = struct{}{}
	}
	return len(seen) > 1
}

func daypartKey(daypart forecast.DaypartSummary, prefixDate bool) string {
	key := normalizedKey(daypart.Name)
	if key == "" {
		key = "unnamed"
	}
	if !prefixDate {
		return key
	}
	return daypart.Period.Start.Format(timeutil.DateLayout) + "_" + key
}

func normalizedKey(value string) string {
	lower := strings.ToLower(strings.TrimSpace(value))
	var out strings.Builder
	lastUnderscore := false
	for _, r := range lower {
		if unicode.IsLetter(r) || unicode.IsDigit(r) {
			out.WriteRune(r)
			lastUnderscore = false
			continue
		}
		if !lastUnderscore {
			out.WriteByte('_')
			lastUnderscore = true
		}
	}
	return strings.Trim(out.String(), "_")
}