package generatedtext

import (
	"fmt"
	"time"

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

type HourlyRenderContext struct {
	Report        HourlyReportContext
	GeneratedText Hourly
	Modules       HourlyTemplateModules
	Collected     facts.CollectedFacts
	Derived       facts.DerivedFacts
}

type HourlyReportContext struct {
	Title            string
	LocationName     string
	GeneratedAt      time.Time
	GeneratedAtLabel string
	ValidPeriod      timeutil.Period
	ValidPeriodLabel string
	Timezone         string
}

type HourlyTemplateModules struct {
	Metadata                *briefing.MetadataModule
	CurrentConditions       *briefing.CurrentConditionsModule
	HourlyForecast          *briefing.HourlyForecastModule
	PrecipTiming            *briefing.PrecipTimingModule
	AlertDigest             *briefing.AlertDigestModule
	SPCConvectiveOutlooks   *briefing.SPCConvectiveOutlooksModule
	AreaForecastDiscussion  *briefing.AreaForecastDiscussionModule
	SPCConvectiveDiscussion *briefing.SPCConvectiveDiscussionModule
	WeatherStory            *briefing.WeatherStoryModule
}

func BuildHourlyRenderContext(metadata briefing.Metadata, snapshot module.Snapshot, generated Hourly, collected facts.CollectedFacts, derived facts.DerivedFacts) (HourlyRenderContext, error) {
	location, err := timeutil.LoadLocation(metadata.Timezone)
	if err != nil {
		return HourlyRenderContext{}, fmt.Errorf("build hourly render context: %w", err)
	}
	if metadata.GeneratedAt.IsZero() {
		return HourlyRenderContext{}, fmt.Errorf("build hourly render context: generatedAt is required")
	}
	if !metadata.ValidPeriod.IsValid() {
		return HourlyRenderContext{}, fmt.Errorf("build hourly render context: valid period is required")
	}
	modules, err := hourlyTemplateModules(snapshot)
	if err != nil {
		return HourlyRenderContext{}, err
	}
	return HourlyRenderContext{
		Report: HourlyReportContext{
			Title:            "Hourly Report",
			LocationName:     locationName(metadata),
			GeneratedAt:      metadata.GeneratedAt,
			GeneratedAtLabel: timeLabel(metadata.GeneratedAt, location),
			ValidPeriod:      metadata.ValidPeriod,
			ValidPeriodLabel: periodLabel(metadata.ValidPeriod, location),
			Timezone:         metadata.Timezone,
		},
		GeneratedText: generated,
		Modules:       modules,
		Collected:     collected,
		Derived:       derived,
	}, nil
}

func hourlyTemplateModules(snapshot module.Snapshot) (HourlyTemplateModules, error) {
	metadata, err := optionalStanza[briefing.MetadataModule](snapshot, string(module.Metadata))
	if err != nil {
		return HourlyTemplateModules{}, err
	}
	current, err := optionalStanza[briefing.CurrentConditionsModule](snapshot, string(module.CurrentConditions))
	if err != nil {
		return HourlyTemplateModules{}, err
	}
	hourly, err := optionalStanza[briefing.HourlyForecastModule](snapshot, string(module.HourlyForecast))
	if err != nil {
		return HourlyTemplateModules{}, err
	}
	precip, err := optionalStanza[briefing.PrecipTimingModule](snapshot, string(module.PrecipTiming))
	if err != nil {
		return HourlyTemplateModules{}, err
	}
	alerts, err := optionalStanza[briefing.AlertDigestModule](snapshot, string(module.AlertDigest))
	if err != nil {
		return HourlyTemplateModules{}, err
	}
	outlooks, err := optionalStanza[briefing.SPCConvectiveOutlooksModule](snapshot, string(module.SPCConvectiveOutlooks))
	if err != nil {
		return HourlyTemplateModules{}, err
	}
	discussion, err := optionalStanza[briefing.AreaForecastDiscussionModule](snapshot, string(module.AreaForecastDiscussion))
	if err != nil {
		return HourlyTemplateModules{}, err
	}
	spcDiscussion, err := optionalStanza[briefing.SPCConvectiveDiscussionModule](snapshot, string(module.SPCConvectiveDiscussion))
	if err != nil {
		return HourlyTemplateModules{}, err
	}
	story, err := optionalStanza[briefing.WeatherStoryModule](snapshot, string(module.WeatherStory))
	if err != nil {
		return HourlyTemplateModules{}, err
	}
	return HourlyTemplateModules{
		Metadata:                metadata,
		CurrentConditions:       current,
		HourlyForecast:          hourly,
		PrecipTiming:            precip,
		AlertDigest:             alerts,
		SPCConvectiveOutlooks:   outlooks,
		AreaForecastDiscussion:  discussion,
		SPCConvectiveDiscussion: spcDiscussion,
		WeatherStory:            story,
	}, nil
}

func optionalStanza[T any](snapshot module.Snapshot, name string) (*T, error) {
	output, ok := snapshot.LookupStanza(name)
	if !ok || output.Value == nil {
		return nil, nil
	}
	value, _, err := module.StanzaValue[T](snapshot, name)
	if err != nil {
		return nil, fmt.Errorf("build hourly render context: %w", err)
	}
	return &value, nil
}

func locationName(metadata briefing.Metadata) string {
	if metadata.Location != nil {
		if metadata.Location.Name != "" && metadata.Location.Region != "" {
			return metadata.Location.Name + ", " + metadata.Location.Region
		}
		if metadata.Location.Name != "" {
			return metadata.Location.Name
		}
	}
	if metadata.SourceLocation != "" {
		return metadata.SourceLocation
	}
	if metadata.SourceLocationID != "" {
		return metadata.SourceLocationID
	}
	return "Unknown location"
}

func periodLabel(period timeutil.Period, location *time.Location) string {
	return fmt.Sprintf("%s to %s", timeLabel(period.Start, location), timeLabel(period.End, location))
}

func timeLabel(value time.Time, location *time.Location) string {
	return value.In(location).Format("2006-01-02 at 3:04 PM")
}