package data

import (
	"context"
	"database/sql"
	"fmt"
	"strings"
)

// GetStationName returns stations.name by station_id; empty string if not found/null.
func GetStationName(ctx context.Context, stationID string) (string, error) {
	const q = `SELECT COALESCE(name, '') FROM stations WHERE station_id = $1`
	var name sql.NullString
	err := DB().QueryRowContext(ctx, q, stationID).Scan(&name)
	if err != nil {
		if err == sql.ErrNoRows {
			return "", nil
		}
		return "", err
	}
	if name.Valid {
		return name.String, nil
	}
	return "", nil
}

// StationInfo contains minimal fields for alert checks.
type StationInfo struct {
	ID        string
	Name      string
	Location  string
	Latitude  float64
	Longitude float64
	Altitude  float64
}

// ListEligibleStations returns WH65LP stations with required non-empty fields.
func ListEligibleStations(ctx context.Context) ([]StationInfo, error) {
	const q = `
SELECT
  station_id,
  COALESCE(NULLIF(BTRIM(name), ''), station_id) AS name,
  location,
  latitude::float8,
  longitude::float8,
  altitude::float8
FROM stations
WHERE
  device_type = 'WH65LP' AND
  name IS NOT NULL AND BTRIM(name) <> '' AND
  location IS NOT NULL AND BTRIM(location) <> '' AND
  latitude IS NOT NULL AND latitude <> 0 AND
  longitude IS NOT NULL AND longitude <> 0 AND
  altitude IS NOT NULL AND altitude <> 0`

	rows, err := DB().QueryContext(ctx, q)
	if err != nil {
		return nil, err
	}
	defer rows.Close()

	var out []StationInfo
	for rows.Next() {
		var st StationInfo
		if err := rows.Scan(&st.ID, &st.Name, &st.Location, &st.Latitude, &st.Longitude, &st.Altitude); err != nil {
			continue
		}
		out = append(out, st)
	}
	return out, nil
}

// ListStationsByIDs returns stations by a given id list (ignores missing ones).
func ListStationsByIDs(ctx context.Context, ids []string) ([]StationInfo, error) {
	if len(ids) == 0 {
		return nil, nil
	}
	var placeholders []string
	args := make([]interface{}, 0, len(ids))
	for i, id := range ids {
		placeholders = append(placeholders, fmt.Sprintf("$%d", i+1))
		args = append(args, id)
	}
	q := fmt.Sprintf(`
SELECT
  station_id,
  COALESCE(NULLIF(BTRIM(name), ''), station_id) AS name,
  location,
  latitude::float8,
  longitude::float8,
  altitude::float8
FROM stations
WHERE station_id IN (%s)`, strings.Join(placeholders, ","))

	rows, err := DB().QueryContext(ctx, q, args...)
	if err != nil {
		return nil, err
	}
	defer rows.Close()

	var out []StationInfo
	for rows.Next() {
		var st StationInfo
		if err := rows.Scan(&st.ID, &st.Name, &st.Location, &st.Latitude, &st.Longitude, &st.Altitude); err != nil {
			continue
		}
		out = append(out, st)
	}
	return out, nil
}