package postgres

import (
	"context"
	"encoding/json"
	"fmt"
	"strings"
	"time"

	fkevent "gitea.maximumdirect.net/ejr/feedkit/event"
	fksinks "gitea.maximumdirect.net/ejr/feedkit/sinks"
	"gitea.maximumdirect.net/ejr/weatherfeeder/model"
	"gitea.maximumdirect.net/ejr/weatherfeeder/standards"
)

func mapPostgresEvent(_ context.Context, e fkevent.Event) ([]fksinks.PostgresWrite, error) {
	schema := strings.TrimSpace(e.Schema)
	switch schema {
	case standards.SchemaWeatherObservationV1:
		return mapObservationEvent(e)
	case standards.SchemaWeatherForecastV1:
		return mapForecastEvent(e)
	case standards.SchemaWeatherForecastDiscussionV1:
		return mapForecastDiscussionEvent(e)
	case standards.SchemaWeatherAlertV1:
		return mapAlertEvent(e)
	default:
		return nil, nil
	}
}

func mapObservationEvent(e fkevent.Event) ([]fksinks.PostgresWrite, error) {
	obs, err := decodePayload[model.WeatherObservation](e.Payload)
	if err != nil {
		return nil, fmt.Errorf("decode observation payload: %w", err)
	}
	if obs.Timestamp.IsZero() {
		return nil, fmt.Errorf("decode observation payload: timestamp is required")
	}

	observedAt := obs.Timestamp.UTC()
	writes := make([]fksinks.PostgresWrite, 0, 1+len(obs.PresentWeather))

	writes = append(writes, fksinks.PostgresWrite{
		Table: tableObservations,
		Values: map[string]any{
			"event_id":                  e.ID,
			"event_kind":                string(e.Kind),
			"event_source":              e.Source,
			"event_schema":              e.Schema,
			"event_emitted_at":          e.EmittedAt.UTC(),
			"event_effective_at":        nullableTime(e.EffectiveAt),
			"station_id":                nullableString(obs.StationID),
			"station_name":              nullableString(obs.StationName),
			"observed_at":               observedAt,
			"condition_code":            int(obs.ConditionCode),
			"is_day":                    nullableBool(obs.IsDay),
			"text_description":          nullableString(obs.TextDescription),
			"temperature_c":             nullableFloat64(obs.TemperatureC),
			"dewpoint_c":                nullableFloat64(obs.DewpointC),
			"wind_direction_degrees":    nullableFloat64(obs.WindDirectionDegrees),
			"wind_speed_kmh":            nullableFloat64(obs.WindSpeedKmh),
			"wind_gust_kmh":             nullableFloat64(obs.WindGustKmh),
			"barometric_pressure_pa":    nullableFloat64(obs.BarometricPressurePa),
			"visibility_meters":         nullableFloat64(obs.VisibilityMeters),
			"relative_humidity_percent": nullableFloat64(obs.RelativeHumidityPercent),
			"apparent_temperature_c":    nullableFloat64(obs.ApparentTemperatureC),
		},
	})

	for i, pw := range obs.PresentWeather {
		rawText, err := compactJSONText(pw.Raw)
		if err != nil {
			return nil, fmt.Errorf("observation presentWeather[%d].raw: %w", i, err)
		}
		writes = append(writes, fksinks.PostgresWrite{
			Table: tableObservationPresentWeather,
			Values: map[string]any{
				"event_id":      e.ID,
				"weather_index": i,
				"observed_at":   observedAt,
				"raw_text":      rawText,
			},
		})
	}

	return writes, nil
}

func mapForecastEvent(e fkevent.Event) ([]fksinks.PostgresWrite, error) {
	run, err := decodePayload[model.WeatherForecastRun](e.Payload)
	if err != nil {
		return nil, fmt.Errorf("decode forecast payload: %w", err)
	}
	if run.IssuedAt.IsZero() {
		return nil, fmt.Errorf("decode forecast payload: issuedAt is required")
	}
	if strings.TrimSpace(string(run.Product)) == "" {
		return nil, fmt.Errorf("decode forecast payload: product is required")
	}

	issuedAt := run.IssuedAt.UTC()
	writes := make([]fksinks.PostgresWrite, 0, 1+len(run.Periods))

	writes = append(writes, fksinks.PostgresWrite{
		Table: tableForecasts,
		Values: map[string]any{
			"event_id":           e.ID,
			"event_kind":         string(e.Kind),
			"event_source":       e.Source,
			"event_schema":       e.Schema,
			"event_emitted_at":   e.EmittedAt.UTC(),
			"event_effective_at": nullableTime(e.EffectiveAt),
			"location_id":        nullableString(run.LocationID),
			"location_name":      nullableString(run.LocationName),
			"issued_at":          issuedAt,
			"updated_at":         nullableTime(run.UpdatedAt),
			"product":            string(run.Product),
			"latitude":           nullableFloat64(run.Latitude),
			"longitude":          nullableFloat64(run.Longitude),
			"elevation_meters":   nullableFloat64(run.ElevationMeters),
			"period_count":       len(run.Periods),
		},
	})

	for i, p := range run.Periods {
		if p.StartTime.IsZero() || p.EndTime.IsZero() {
			return nil, fmt.Errorf("decode forecast payload: periods[%d] startTime/endTime are required", i)
		}
		writes = append(writes, fksinks.PostgresWrite{
			Table: tableForecastPeriods,
			Values: map[string]any{
				"run_event_id":                         e.ID,
				"period_index":                         i,
				"issued_at":                            issuedAt,
				"start_time":                           p.StartTime.UTC(),
				"end_time":                             p.EndTime.UTC(),
				"name":                                 nullableString(p.Name),
				"is_day":                               nullableBool(p.IsDay),
				"condition_code":                       int(p.ConditionCode),
				"text_description":                     nullableString(p.TextDescription),
				"temperature_c":                        nullableFloat64(p.TemperatureC),
				"temperature_c_min":                    nullableFloat64(p.TemperatureCMin),
				"temperature_c_max":                    nullableFloat64(p.TemperatureCMax),
				"dewpoint_c":                           nullableFloat64(p.DewpointC),
				"relative_humidity_percent":            nullableFloat64(p.RelativeHumidityPercent),
				"wind_direction_degrees":               nullableFloat64(p.WindDirectionDegrees),
				"wind_speed_kmh":                       nullableFloat64(p.WindSpeedKmh),
				"wind_gust_kmh":                        nullableFloat64(p.WindGustKmh),
				"barometric_pressure_pa":               nullableFloat64(p.BarometricPressurePa),
				"visibility_meters":                    nullableFloat64(p.VisibilityMeters),
				"apparent_temperature_c":               nullableFloat64(p.ApparentTemperatureC),
				"cloud_cover_percent":                  nullableFloat64(p.CloudCoverPercent),
				"probability_of_precipitation_percent": nullableFloat64(p.ProbabilityOfPrecipitationPercent),
				"precipitation_amount_mm":              nullableFloat64(p.PrecipitationAmountMm),
				"snowfall_depth_mm":                    nullableFloat64(p.SnowfallDepthMM),
				"uv_index":                             nullableFloat64(p.UVIndex),
			},
		})
	}

	return writes, nil
}

func mapForecastDiscussionEvent(e fkevent.Event) ([]fksinks.PostgresWrite, error) {
	run, err := decodePayload[model.WeatherForecastDiscussion](e.Payload)
	if err != nil {
		return nil, fmt.Errorf("decode forecast discussion payload: %w", err)
	}
	if run.IssuedAt.IsZero() {
		return nil, fmt.Errorf("decode forecast discussion payload: issuedAt is required")
	}
	if strings.TrimSpace(string(run.Product)) == "" {
		return nil, fmt.Errorf("decode forecast discussion payload: product is required")
	}

	issuedAt := run.IssuedAt.UTC()
	shortTermQualifier, shortTermIssuedAt, shortTermText := nullableDiscussionSection(run.ShortTerm)
	longTermQualifier, longTermIssuedAt, longTermText := nullableDiscussionSection(run.LongTerm)

	writes := make([]fksinks.PostgresWrite, 0, 1+len(run.KeyMessages))
	writes = append(writes, fksinks.PostgresWrite{
		Table: tableForecastDiscussions,
		Values: map[string]any{
			"event_id":             e.ID,
			"event_kind":           string(e.Kind),
			"event_source":         e.Source,
			"event_schema":         e.Schema,
			"event_emitted_at":     e.EmittedAt.UTC(),
			"event_effective_at":   nullableTime(e.EffectiveAt),
			"office_id":            nullableString(run.OfficeID),
			"office_name":          nullableString(run.OfficeName),
			"issued_at":            issuedAt,
			"updated_at":           nullableTime(run.UpdatedAt),
			"product":              string(run.Product),
			"short_term_qualifier": shortTermQualifier,
			"short_term_issued_at": shortTermIssuedAt,
			"short_term_text":      shortTermText,
			"long_term_qualifier":  longTermQualifier,
			"long_term_issued_at":  longTermIssuedAt,
			"long_term_text":       longTermText,
			"key_message_count":    len(run.KeyMessages),
		},
	})

	for i, msg := range run.KeyMessages {
		writes = append(writes, fksinks.PostgresWrite{
			Table: tableForecastDiscussionKeyMessages,
			Values: map[string]any{
				"run_event_id":  e.ID,
				"message_index": i,
				"issued_at":     issuedAt,
				"message_text":  nullableString(msg),
			},
		})
	}

	return writes, nil
}

func mapAlertEvent(e fkevent.Event) ([]fksinks.PostgresWrite, error) {
	run, err := decodePayload[model.WeatherAlertRun](e.Payload)
	if err != nil {
		return nil, fmt.Errorf("decode alert payload: %w", err)
	}
	if run.AsOf.IsZero() {
		return nil, fmt.Errorf("decode alert payload: asOf is required")
	}

	asOf := run.AsOf.UTC()
	writes := make([]fksinks.PostgresWrite, 0, 1+len(run.Alerts)+countAlertReferences(run.Alerts))

	writes = append(writes, fksinks.PostgresWrite{
		Table: tableAlertRuns,
		Values: map[string]any{
			"event_id":           e.ID,
			"event_kind":         string(e.Kind),
			"event_source":       e.Source,
			"event_schema":       e.Schema,
			"event_emitted_at":   e.EmittedAt.UTC(),
			"event_effective_at": nullableTime(e.EffectiveAt),
			"location_id":        nullableString(run.LocationID),
			"location_name":      nullableString(run.LocationName),
			"as_of":              asOf,
			"latitude":           nullableFloat64(run.Latitude),
			"longitude":          nullableFloat64(run.Longitude),
			"alert_count":        len(run.Alerts),
		},
	})

	for i, a := range run.Alerts {
		if strings.TrimSpace(a.ID) == "" {
			return nil, fmt.Errorf("decode alert payload: alerts[%d].id is required", i)
		}

		writes = append(writes, fksinks.PostgresWrite{
			Table: tableAlerts,
			Values: map[string]any{
				"run_event_id":     e.ID,
				"alert_index":      i,
				"as_of":            asOf,
				"alert_id":         a.ID,
				"event":            nullableString(a.Event),
				"headline":         nullableString(a.Headline),
				"severity":         nullableString(a.Severity),
				"urgency":          nullableString(a.Urgency),
				"certainty":        nullableString(a.Certainty),
				"status":           nullableString(a.Status),
				"message_type":     nullableString(a.MessageType),
				"category":         nullableString(a.Category),
				"response":         nullableString(a.Response),
				"description":      nullableString(a.Description),
				"instruction":      nullableString(a.Instruction),
				"sent":             nullableTime(a.Sent),
				"effective":        nullableTime(a.Effective),
				"onset":            nullableTime(a.Onset),
				"expires":          nullableTime(a.Expires),
				"area_description": nullableString(a.AreaDescription),
				"sender_name":      nullableString(a.SenderName),
				"reference_count":  len(a.References),
			},
		})

		for j, ref := range a.References {
			writes = append(writes, fksinks.PostgresWrite{
				Table: tableAlertReferences,
				Values: map[string]any{
					"run_event_id":    e.ID,
					"alert_index":     i,
					"reference_index": j,
					"as_of":           asOf,
					"id":              nullableString(ref.ID),
					"identifier":      nullableString(ref.Identifier),
					"sender":          nullableString(ref.Sender),
					"sent":            nullableTime(ref.Sent),
				},
			})
		}
	}

	return writes, nil
}

func decodePayload[T any](payload any) (T, error) {
	var out T
	if payload == nil {
		return out, fmt.Errorf("payload is nil")
	}

	if typed, ok := payload.(T); ok {
		return typed, nil
	}
	if ptr, ok := payload.(*T); ok {
		if ptr == nil {
			return out, fmt.Errorf("payload pointer is nil")
		}
		return *ptr, nil
	}

	b, err := json.Marshal(payload)
	if err != nil {
		return out, fmt.Errorf("marshal payload: %w", err)
	}
	if err := json.Unmarshal(b, &out); err != nil {
		return out, fmt.Errorf("unmarshal payload: %w", err)
	}
	return out, nil
}

func nullableDiscussionSection(section *model.WeatherForecastDiscussionSection) (any, any, any) {
	if section == nil {
		return nil, nil, nil
	}
	return nullableString(section.Qualifier), nullableTime(section.IssuedAt), nullableString(section.Text)
}

func countAlertReferences(alerts []model.WeatherAlert) int {
	total := 0
	for _, a := range alerts {
		total += len(a.References)
	}
	return total
}

func nullableString(s string) any {
	if strings.TrimSpace(s) == "" {
		return nil
	}
	return s
}

func nullableFloat64(v *float64) any {
	if v == nil {
		return nil
	}
	return *v
}

func nullableBool(v *bool) any {
	if v == nil {
		return nil
	}
	return *v
}

func nullableTime(v *time.Time) any {
	if v == nil || v.IsZero() {
		return nil
	}
	return v.UTC()
}

func compactJSONText(v any) (any, error) {
	if v == nil {
		return nil, nil
	}
	b, err := json.Marshal(v)
	if err != nil {
		return nil, err
	}
	if string(b) == "null" {
		return nil, nil
	}
	return string(b), nil
}