package postgres

import (
	"context"
	"database/sql"
	"encoding/json"
	"errors"
	"fmt"
	"strings"
	"time"

	"gitea.maximumdirect.net/ejr/weatherapi/internal/core"
	"gitea.maximumdirect.net/ejr/weatherfeeder/model"
)

const (
	queryLatestObservation = `
SELECT
  event_id,
  station_id,
  station_name,
  observed_at,
  condition_code,
  is_day,
  text_description,
  temperature_c,
  dewpoint_c,
  wind_direction_degrees,
  wind_speed_kmh,
  wind_gust_kmh,
  barometric_pressure_pa,
  visibility_meters,
  relative_humidity_percent,
  apparent_temperature_c
FROM observations
ORDER BY observed_at DESC, event_emitted_at DESC
LIMIT 1`

	queryObservationPresentWeather = `
SELECT weather_index, raw_text
FROM observation_present_weather
WHERE event_id = $1
ORDER BY weather_index ASC`

	queryLatestHourlyForecast = `
SELECT
  event_id,
  location_id,
  location_name,
  issued_at,
  updated_at,
  product,
  latitude,
  longitude,
  elevation_meters
FROM forecasts
WHERE product = 'hourly'
ORDER BY issued_at DESC, event_emitted_at DESC
LIMIT 1`

	queryForecastPeriods = `
SELECT
  period_index,
  start_time,
  end_time,
  name,
  is_day,
  condition_code,
  condition_text,
  provider_raw_description,
  text_description,
  detailed_text,
  icon_url,
  temperature_c,
  temperature_c_min,
  temperature_c_max,
  dewpoint_c,
  relative_humidity_percent,
  wind_direction_degrees,
  wind_speed_kmh,
  wind_gust_kmh,
  barometric_pressure_pa,
  visibility_meters,
  apparent_temperature_c,
  cloud_cover_percent,
  probability_of_precipitation_percent,
  precipitation_amount_mm,
  snowfall_depth_mm,
  uv_index
FROM forecast_periods
WHERE run_event_id = $1
ORDER BY period_index ASC`

	queryLatestAlertRun = `
SELECT
  event_id,
  location_id,
  location_name,
  as_of,
  latitude,
  longitude
FROM alert_runs
ORDER BY as_of DESC, event_emitted_at DESC
LIMIT 1`

	queryAlerts = `
SELECT
  alert_index,
  alert_id,
  event,
  headline,
  severity,
  urgency,
  certainty,
  status,
  message_type,
  category,
  response,
  description,
  instruction,
  sent,
  effective,
  onset,
  expires,
  area_description,
  sender_name
FROM alerts
WHERE run_event_id = $1
ORDER BY alert_index ASC`

	queryAlertReferences = `
SELECT
  alert_index,
  id,
  identifier,
  sender,
  sent
FROM alert_references
WHERE run_event_id = $1
ORDER BY alert_index ASC, reference_index ASC`
)

// Repository is a Postgres-backed implementation of weatherapi read ports.
type Repository struct {
	db *sql.DB
}

var _ core.Repository = (*Repository)(nil)

func NewRepository(db *sql.DB) *Repository {
	return &Repository{db: db}
}

func (r *Repository) LatestObservation(ctx context.Context) (*model.WeatherObservation, error) {
	if r == nil || r.db == nil {
		return nil, fmt.Errorf("postgres repository is not configured")
	}

	var row observationParentRow
	err := r.db.QueryRowContext(ctx, queryLatestObservation).Scan(
		&row.EventID,
		&row.StationID,
		&row.StationName,
		&row.ObservedAt,
		&row.ConditionCode,
		&row.IsDay,
		&row.TextDescription,
		&row.TemperatureC,
		&row.DewpointC,
		&row.WindDirectionDegrees,
		&row.WindSpeedKmh,
		&row.WindGustKmh,
		&row.BarometricPressurePa,
		&row.VisibilityMeters,
		&row.RelativeHumidityPercent,
		&row.ApparentTemperatureC,
	)
	if errors.Is(err, sql.ErrNoRows) {
		return nil, nil
	}
	if err != nil {
		return nil, fmt.Errorf("query latest observation: %w", err)
	}

	obs := mapObservationParentRow(row)

	presentWeather, err := r.loadObservationPresentWeather(ctx, row.EventID)
	if err != nil {
		return nil, err
	}
	obs.PresentWeather = presentWeather

	return &obs, nil
}

func (r *Repository) LatestHourlyForecast(ctx context.Context) (*model.WeatherForecastRun, error) {
	if r == nil || r.db == nil {
		return nil, fmt.Errorf("postgres repository is not configured")
	}

	var row forecastParentRow
	err := r.db.QueryRowContext(ctx, queryLatestHourlyForecast).Scan(
		&row.EventID,
		&row.LocationID,
		&row.LocationName,
		&row.IssuedAt,
		&row.UpdatedAt,
		&row.Product,
		&row.Latitude,
		&row.Longitude,
		&row.ElevationMeters,
	)
	if errors.Is(err, sql.ErrNoRows) {
		return nil, nil
	}
	if err != nil {
		return nil, fmt.Errorf("query latest hourly forecast: %w", err)
	}

	run := mapForecastParentRow(row)

	periods, err := r.loadForecastPeriods(ctx, row.EventID)
	if err != nil {
		return nil, err
	}
	run.Periods = periods

	return &run, nil
}

func (r *Repository) LatestActiveAlerts(ctx context.Context) (*model.WeatherAlertRun, error) {
	if r == nil || r.db == nil {
		return nil, fmt.Errorf("postgres repository is not configured")
	}

	var row alertRunParentRow
	err := r.db.QueryRowContext(ctx, queryLatestAlertRun).Scan(
		&row.EventID,
		&row.LocationID,
		&row.LocationName,
		&row.AsOf,
		&row.Latitude,
		&row.Longitude,
	)
	if errors.Is(err, sql.ErrNoRows) {
		return nil, nil
	}
	if err != nil {
		return nil, fmt.Errorf("query latest alert run: %w", err)
	}

	run := mapAlertRunParentRow(row)

	alerts, err := r.loadAlerts(ctx, row.EventID)
	if err != nil {
		return nil, err
	}
	run.Alerts = alerts

	return &run, nil
}

func (r *Repository) loadObservationPresentWeather(ctx context.Context, eventID string) ([]model.PresentWeather, error) {
	rows, err := r.db.QueryContext(ctx, queryObservationPresentWeather, eventID)
	if err != nil {
		return nil, fmt.Errorf("query observation present weather: %w", err)
	}
	defer rows.Close()

	out := make([]model.PresentWeather, 0)
	for rows.Next() {
		var row observationPresentWeatherRow
		if err := rows.Scan(&row.WeatherIndex, &row.RawText); err != nil {
			return nil, fmt.Errorf("scan observation present weather row: %w", err)
		}
		pw, err := mapObservationPresentWeatherRow(row)
		if err != nil {
			return nil, fmt.Errorf("decode observation present weather row (index=%d): %w", row.WeatherIndex, err)
		}
		out = append(out, pw)
	}
	if err := rows.Err(); err != nil {
		return nil, fmt.Errorf("iterate observation present weather rows: %w", err)
	}
	return out, nil
}

func (r *Repository) loadForecastPeriods(ctx context.Context, eventID string) ([]model.WeatherForecastPeriod, error) {
	rows, err := r.db.QueryContext(ctx, queryForecastPeriods, eventID)
	if err != nil {
		return nil, fmt.Errorf("query forecast periods: %w", err)
	}
	defer rows.Close()

	out := make([]model.WeatherForecastPeriod, 0)
	for rows.Next() {
		var row forecastPeriodRow
		if err := rows.Scan(
			&row.PeriodIndex,
			&row.StartTime,
			&row.EndTime,
			&row.Name,
			&row.IsDay,
			&row.ConditionCode,
			&row.ConditionText,
			&row.ProviderRawDescription,
			&row.TextDescription,
			&row.DetailedText,
			&row.IconURL,
			&row.TemperatureC,
			&row.TemperatureCMin,
			&row.TemperatureCMax,
			&row.DewpointC,
			&row.RelativeHumidityPercent,
			&row.WindDirectionDegrees,
			&row.WindSpeedKmh,
			&row.WindGustKmh,
			&row.BarometricPressurePa,
			&row.VisibilityMeters,
			&row.ApparentTemperatureC,
			&row.CloudCoverPercent,
			&row.ProbabilityOfPrecipitationPercent,
			&row.PrecipitationAmountMM,
			&row.SnowfallDepthMM,
			&row.UVIndex,
		); err != nil {
			return nil, fmt.Errorf("scan forecast period row: %w", err)
		}
		out = append(out, mapForecastPeriodRow(row))
	}
	if err := rows.Err(); err != nil {
		return nil, fmt.Errorf("iterate forecast period rows: %w", err)
	}
	return out, nil
}

func (r *Repository) loadAlerts(ctx context.Context, eventID string) ([]model.WeatherAlert, error) {
	alertsRows, err := r.db.QueryContext(ctx, queryAlerts, eventID)
	if err != nil {
		return nil, fmt.Errorf("query alerts: %w", err)
	}
	defer alertsRows.Close()

	indexedAlerts := make([]indexedAlert, 0)
	for alertsRows.Next() {
		var row alertRow
		if err := alertsRows.Scan(
			&row.AlertIndex,
			&row.AlertID,
			&row.Event,
			&row.Headline,
			&row.Severity,
			&row.Urgency,
			&row.Certainty,
			&row.Status,
			&row.MessageType,
			&row.Category,
			&row.Response,
			&row.Description,
			&row.Instruction,
			&row.Sent,
			&row.Effective,
			&row.Onset,
			&row.Expires,
			&row.AreaDescription,
			&row.SenderName,
		); err != nil {
			return nil, fmt.Errorf("scan alerts row: %w", err)
		}
		indexedAlerts = append(indexedAlerts, mapAlertRow(row))
	}
	if err := alertsRows.Err(); err != nil {
		return nil, fmt.Errorf("iterate alerts rows: %w", err)
	}

	referenceRows, err := r.db.QueryContext(ctx, queryAlertReferences, eventID)
	if err != nil {
		return nil, fmt.Errorf("query alert references: %w", err)
	}
	defer referenceRows.Close()

	indexedReferences := make([]indexedAlertReference, 0)
	for referenceRows.Next() {
		var row alertReferenceRow
		if err := referenceRows.Scan(
			&row.AlertIndex,
			&row.ID,
			&row.Identifier,
			&row.Sender,
			&row.Sent,
		); err != nil {
			return nil, fmt.Errorf("scan alert reference row: %w", err)
		}
		indexedReferences = append(indexedReferences, mapAlertReferenceRow(row))
	}
	if err := referenceRows.Err(); err != nil {
		return nil, fmt.Errorf("iterate alert reference rows: %w", err)
	}

	return attachAlertReferences(indexedAlerts, indexedReferences), nil
}

type observationParentRow struct {
	EventID                 string
	StationID               sql.NullString
	StationName             sql.NullString
	ObservedAt              time.Time
	ConditionCode           int
	IsDay                   sql.NullBool
	TextDescription         sql.NullString
	TemperatureC            sql.NullFloat64
	DewpointC               sql.NullFloat64
	WindDirectionDegrees    sql.NullFloat64
	WindSpeedKmh            sql.NullFloat64
	WindGustKmh             sql.NullFloat64
	BarometricPressurePa    sql.NullFloat64
	VisibilityMeters        sql.NullFloat64
	RelativeHumidityPercent sql.NullFloat64
	ApparentTemperatureC    sql.NullFloat64
}

func mapObservationParentRow(row observationParentRow) model.WeatherObservation {
	return model.WeatherObservation{
		StationID:               stringValue(row.StationID),
		StationName:             stringValue(row.StationName),
		Timestamp:               row.ObservedAt.UTC(),
		ConditionCode:           model.WMOCode(row.ConditionCode),
		IsDay:                   boolPtr(row.IsDay),
		TextDescription:         stringValue(row.TextDescription),
		TemperatureC:            float64Ptr(row.TemperatureC),
		DewpointC:               float64Ptr(row.DewpointC),
		WindDirectionDegrees:    float64Ptr(row.WindDirectionDegrees),
		WindSpeedKmh:            float64Ptr(row.WindSpeedKmh),
		WindGustKmh:             float64Ptr(row.WindGustKmh),
		BarometricPressurePa:    float64Ptr(row.BarometricPressurePa),
		VisibilityMeters:        float64Ptr(row.VisibilityMeters),
		RelativeHumidityPercent: float64Ptr(row.RelativeHumidityPercent),
		ApparentTemperatureC:    float64Ptr(row.ApparentTemperatureC),
	}
}

type observationPresentWeatherRow struct {
	WeatherIndex int
	RawText      sql.NullString
}

func mapObservationPresentWeatherRow(row observationPresentWeatherRow) (model.PresentWeather, error) {
	if !row.RawText.Valid || strings.TrimSpace(row.RawText.String) == "" {
		return model.PresentWeather{}, nil
	}

	var raw map[string]any
	if err := json.Unmarshal([]byte(row.RawText.String), &raw); err != nil {
		return model.PresentWeather{}, err
	}
	return model.PresentWeather{Raw: raw}, nil
}

type forecastParentRow struct {
	EventID         string
	LocationID      sql.NullString
	LocationName    sql.NullString
	IssuedAt        time.Time
	UpdatedAt       sql.NullTime
	Product         string
	Latitude        sql.NullFloat64
	Longitude       sql.NullFloat64
	ElevationMeters sql.NullFloat64
}

func mapForecastParentRow(row forecastParentRow) model.WeatherForecastRun {
	return model.WeatherForecastRun{
		LocationID:      stringValue(row.LocationID),
		LocationName:    stringValue(row.LocationName),
		IssuedAt:        row.IssuedAt.UTC(),
		UpdatedAt:       timePtr(row.UpdatedAt),
		Product:         model.ForecastProduct(row.Product),
		Latitude:        float64Ptr(row.Latitude),
		Longitude:       float64Ptr(row.Longitude),
		ElevationMeters: float64Ptr(row.ElevationMeters),
	}
}

type forecastPeriodRow struct {
	PeriodIndex                       int
	StartTime                         time.Time
	EndTime                           time.Time
	Name                              sql.NullString
	IsDay                             sql.NullBool
	ConditionCode                     int
	ConditionText                     sql.NullString
	ProviderRawDescription            sql.NullString
	TextDescription                   sql.NullString
	DetailedText                      sql.NullString
	IconURL                           sql.NullString
	TemperatureC                      sql.NullFloat64
	TemperatureCMin                   sql.NullFloat64
	TemperatureCMax                   sql.NullFloat64
	DewpointC                         sql.NullFloat64
	RelativeHumidityPercent           sql.NullFloat64
	WindDirectionDegrees              sql.NullFloat64
	WindSpeedKmh                      sql.NullFloat64
	WindGustKmh                       sql.NullFloat64
	BarometricPressurePa              sql.NullFloat64
	VisibilityMeters                  sql.NullFloat64
	ApparentTemperatureC              sql.NullFloat64
	CloudCoverPercent                 sql.NullFloat64
	ProbabilityOfPrecipitationPercent sql.NullFloat64
	PrecipitationAmountMM             sql.NullFloat64
	SnowfallDepthMM                   sql.NullFloat64
	UVIndex                           sql.NullFloat64
}

func mapForecastPeriodRow(row forecastPeriodRow) model.WeatherForecastPeriod {
	return model.WeatherForecastPeriod{
		StartTime:                         row.StartTime.UTC(),
		EndTime:                           row.EndTime.UTC(),
		Name:                              stringValue(row.Name),
		IsDay:                             boolPtr(row.IsDay),
		ConditionCode:                     model.WMOCode(row.ConditionCode),
		ConditionText:                     stringValue(row.ConditionText),
		ProviderRawDescription:            stringValue(row.ProviderRawDescription),
		TextDescription:                   stringValue(row.TextDescription),
		DetailedText:                      stringValue(row.DetailedText),
		IconURL:                           stringValue(row.IconURL),
		TemperatureC:                      float64Ptr(row.TemperatureC),
		TemperatureCMin:                   float64Ptr(row.TemperatureCMin),
		TemperatureCMax:                   float64Ptr(row.TemperatureCMax),
		DewpointC:                         float64Ptr(row.DewpointC),
		RelativeHumidityPercent:           float64Ptr(row.RelativeHumidityPercent),
		WindDirectionDegrees:              float64Ptr(row.WindDirectionDegrees),
		WindSpeedKmh:                      float64Ptr(row.WindSpeedKmh),
		WindGustKmh:                       float64Ptr(row.WindGustKmh),
		BarometricPressurePa:              float64Ptr(row.BarometricPressurePa),
		VisibilityMeters:                  float64Ptr(row.VisibilityMeters),
		ApparentTemperatureC:              float64Ptr(row.ApparentTemperatureC),
		CloudCoverPercent:                 float64Ptr(row.CloudCoverPercent),
		ProbabilityOfPrecipitationPercent: float64Ptr(row.ProbabilityOfPrecipitationPercent),
		PrecipitationAmountMm:             float64Ptr(row.PrecipitationAmountMM),
		SnowfallDepthMM:                   float64Ptr(row.SnowfallDepthMM),
		UVIndex:                           float64Ptr(row.UVIndex),
	}
}

type alertRunParentRow struct {
	EventID      string
	LocationID   sql.NullString
	LocationName sql.NullString
	AsOf         time.Time
	Latitude     sql.NullFloat64
	Longitude    sql.NullFloat64
}

func mapAlertRunParentRow(row alertRunParentRow) model.WeatherAlertRun {
	return model.WeatherAlertRun{
		LocationID:   stringValue(row.LocationID),
		LocationName: stringValue(row.LocationName),
		AsOf:         row.AsOf.UTC(),
		Latitude:     float64Ptr(row.Latitude),
		Longitude:    float64Ptr(row.Longitude),
	}
}

type alertRow struct {
	AlertIndex      int
	AlertID         string
	Event           sql.NullString
	Headline        sql.NullString
	Severity        sql.NullString
	Urgency         sql.NullString
	Certainty       sql.NullString
	Status          sql.NullString
	MessageType     sql.NullString
	Category        sql.NullString
	Response        sql.NullString
	Description     sql.NullString
	Instruction     sql.NullString
	Sent            sql.NullTime
	Effective       sql.NullTime
	Onset           sql.NullTime
	Expires         sql.NullTime
	AreaDescription sql.NullString
	SenderName      sql.NullString
}

type indexedAlert struct {
	Index int
	Alert model.WeatherAlert
}

func mapAlertRow(row alertRow) indexedAlert {
	return indexedAlert{
		Index: row.AlertIndex,
		Alert: model.WeatherAlert{
			ID:              row.AlertID,
			Event:           stringValue(row.Event),
			Headline:        stringValue(row.Headline),
			Severity:        stringValue(row.Severity),
			Urgency:         stringValue(row.Urgency),
			Certainty:       stringValue(row.Certainty),
			Status:          stringValue(row.Status),
			MessageType:     stringValue(row.MessageType),
			Category:        stringValue(row.Category),
			Response:        stringValue(row.Response),
			Description:     stringValue(row.Description),
			Instruction:     stringValue(row.Instruction),
			Sent:            timePtr(row.Sent),
			Effective:       timePtr(row.Effective),
			Onset:           timePtr(row.Onset),
			Expires:         timePtr(row.Expires),
			AreaDescription: stringValue(row.AreaDescription),
			SenderName:      stringValue(row.SenderName),
		},
	}
}

type alertReferenceRow struct {
	AlertIndex int
	ID         sql.NullString
	Identifier sql.NullString
	Sender     sql.NullString
	Sent       sql.NullTime
}

type indexedAlertReference struct {
	AlertIndex int
	Reference  model.AlertReference
}

func mapAlertReferenceRow(row alertReferenceRow) indexedAlertReference {
	return indexedAlertReference{
		AlertIndex: row.AlertIndex,
		Reference: model.AlertReference{
			ID:         stringValue(row.ID),
			Identifier: stringValue(row.Identifier),
			Sender:     stringValue(row.Sender),
			Sent:       timePtr(row.Sent),
		},
	}
}

func attachAlertReferences(alerts []indexedAlert, references []indexedAlertReference) []model.WeatherAlert {
	refsByAlertIndex := make(map[int][]model.AlertReference, len(alerts))
	for _, ref := range references {
		refsByAlertIndex[ref.AlertIndex] = append(refsByAlertIndex[ref.AlertIndex], ref.Reference)
	}

	out := make([]model.WeatherAlert, 0, len(alerts))
	for _, alert := range alerts {
		mapped := alert.Alert
		if refs := refsByAlertIndex[alert.Index]; len(refs) > 0 {
			mapped.References = refs
		}
		out = append(out, mapped)
	}
	return out
}

func stringValue(v sql.NullString) string {
	if !v.Valid {
		return ""
	}
	return v.String
}

func boolPtr(v sql.NullBool) *bool {
	if !v.Valid {
		return nil
	}
	b := v.Bool
	return &b
}

func float64Ptr(v sql.NullFloat64) *float64 {
	if !v.Valid {
		return nil
	}
	f := v.Float64
	return &f
}

func timePtr(v sql.NullTime) *time.Time {
	if !v.Valid {
		return nil
	}
	t := v.Time.UTC()
	return &t
}