/**
 * Migration: Add location coordinates to weather_stations table
 *
 * Fixes: WeatherStation has no location/coordinates - how do you know where the station is?
 *
 * @type {import('node-pg-migrate').ColumnDefinitions | undefined}
 */
export const shorthands = undefined;

/**
 * @param pgm {import('node-pg-migrate').MigrationBuilder}
 * @param run {() => void | undefined}
 * @returns {Promise<void> | void}
 */
export const up = (pgm) => {
  console.log('Adding location coordinates to weather_stations...');

  // Add location coordinate columns
  pgm.addColumns('weather_stations', {
    latitude: {
      type: 'decimal(10,7)',
      notNull: false,
      comment: 'Latitude coordinate of the weather station (-90 to 90)',
    },
    longitude: {
      type: 'decimal(10,7)',
      notNull: false,
      comment: 'Longitude coordinate of the weather station (-180 to 180)',
    },
    elevation: {
      type: 'decimal(6,1)',
      notNull: false,
      comment: 'Elevation above sea level in meters',
    },
    timezone: {
      type: 'varchar(50)',
      notNull: false,
      comment: 'Timezone identifier (e.g., Asia/Shanghai)',
    },
  });

  // Add CHECK constraints for coordinate validation
  pgm.addConstraint('weather_stations', 'chk_weather_stations_latitude', {
    check: 'latitude IS NULL OR (latitude >= -90 AND latitude <= 90)',
  });

  pgm.addConstraint('weather_stations', 'chk_weather_stations_longitude', {
    check: 'longitude IS NULL OR (longitude >= -180 AND longitude <= 180)',
  });

  // Add index for geospatial queries (basic, for more advanced use PostGIS)
  pgm.createIndex('weather_stations', ['latitude', 'longitude'], {
    name: 'idx_weather_stations_coordinates',
    where: 'latitude IS NOT NULL AND longitude IS NOT NULL',
  });

  console.log('Weather station location columns added successfully.');
};

/**
 * @param pgm {import('node-pg-migrate').MigrationBuilder}
 * @param run {() => void | undefined}
 * @returns {Promise<void> | void}
 */
export const down = (pgm) => {
  console.log('Removing location coordinates from weather_stations...');

  // Drop index first
  pgm.dropIndex('weather_stations', ['latitude', 'longitude'], {
    name: 'idx_weather_stations_coordinates',
    ifExists: true,
  });

  // Drop constraints
  pgm.dropConstraint('weather_stations', 'chk_weather_stations_longitude', {
    ifExists: true,
  });
  pgm.dropConstraint('weather_stations', 'chk_weather_stations_latitude', {
    ifExists: true,
  });

  // Drop columns
  pgm.dropColumns('weather_stations', ['latitude', 'longitude', 'elevation', 'timezone']);

  console.log('Weather station location columns removed.');
};