<?php
/**
 * Open-Meteo API handler. No API key required; used as universal fallback
 * and as the only source for historical (ERA5) data.
 *
 * @package FontdelboscEltemps
 */

defined( 'ABSPATH' ) || exit;

/**
 * Handles Open-Meteo forecast and ERA5 archive requests.
 */
final class Fontdelbosc_Api_OpenMeteo {

	/**
	 * Forecast endpoint.
	 */
	private const FORECAST_URL = 'https://api.open-meteo.com/v1/forecast';

	/**
	 * ERA5 archive endpoint.
	 */
	private const ARCHIVE_URL = 'https://archive-api.open-meteo.com/v1/archive';

	/**
	 * WMO weather interpretation code to condition key.
	 *
	 * @var array<int,string>
	 */
	private const WMO_MAP = array(
		0  => 'clear',
		1  => 'mainly_clear',
		2  => 'partly_cloudy',
		3  => 'overcast',
		45 => 'fog',
		48 => 'fog',
		51 => 'drizzle_light',
		53 => 'drizzle',
		55 => 'drizzle_heavy',
		61 => 'rain_light',
		63 => 'rain',
		65 => 'rain_heavy',
		71 => 'snow_light',
		73 => 'snow',
		75 => 'snow_heavy',
		80 => 'rain_showers_light',
		81 => 'rain_showers',
		82 => 'rain_showers_heavy',
		95 => 'thunderstorm',
		96 => 'thunderstorm_hail',
		99 => 'thunderstorm_hail',
	);

	/**
	 * Returns normalized current conditions.
	 *
	 * @return array<string,mixed>|null
	 */
	public static function get_current(): ?array {
		$url  = add_query_arg(
			array(
				'latitude'      => FONTDELBOSC_ELTEMPS_LAT,
				'longitude'     => FONTDELBOSC_ELTEMPS_LON,
				'current'       => 'temperature_2m,relative_humidity_2m,apparent_temperature,precipitation,weather_code,wind_speed_10m,wind_direction_10m',
				'timezone'      => FONTDELBOSC_ELTEMPS_TIMEZONE,
				'forecast_days' => 1,
			),
			self::FORECAST_URL
		);
		$data = self::request( $url );
		$time = Fontdelbosc_Payload::str( Fontdelbosc_Payload::path( $data, 'current', 'time' ) );

		if ( null === $time ) {
			return null;
		}

		return array(
			'temperature'    => Fontdelbosc_Payload::float( Fontdelbosc_Payload::path( $data, 'current', 'temperature_2m' ) ),
			'apparent'       => Fontdelbosc_Payload::float( Fontdelbosc_Payload::path( $data, 'current', 'apparent_temperature' ) ),
			'humidity'       => Fontdelbosc_Payload::int( Fontdelbosc_Payload::path( $data, 'current', 'relative_humidity_2m' ) ),
			'precipitation'  => Fontdelbosc_Payload::float( Fontdelbosc_Payload::path( $data, 'current', 'precipitation' ) ),
			'wind_speed'     => Fontdelbosc_Payload::float( Fontdelbosc_Payload::path( $data, 'current', 'wind_speed_10m' ) ),
			'wind_direction' => Fontdelbosc_Payload::int( Fontdelbosc_Payload::path( $data, 'current', 'wind_direction_10m' ) ),
			'condition'      => self::condition( Fontdelbosc_Payload::path( $data, 'current', 'weather_code' ) ),
			'source'         => 'open-meteo',
			'time'           => self::timestamp( $time ),
		);
	}

	/**
	 * Returns the normalized hourly forecast, from the current hour onwards.
	 *
	 * @return array<string,mixed>|null
	 */
	public static function get_hourly(): ?array {
		$url   = add_query_arg(
			array(
				'latitude'      => FONTDELBOSC_ELTEMPS_LAT,
				'longitude'     => FONTDELBOSC_ELTEMPS_LON,
				'hourly'        => 'temperature_2m,precipitation_probability,weather_code,wind_speed_10m',
				'timezone'      => FONTDELBOSC_ELTEMPS_TIMEZONE,
				'forecast_days' => 3,
			),
			self::FORECAST_URL
		);
		$data  = self::request( $url );
		$times = Fontdelbosc_Payload::arr( Fontdelbosc_Payload::path( $data, 'hourly', 'time' ) );
		$now   = self::now_key();
		$hours = array();

		foreach ( $times as $index => $iso_time ) {
			$raw = Fontdelbosc_Payload::str( $iso_time );

			if ( null === $raw ) {
				continue;
			}

			$time = str_replace( 'T', ' ', $raw );

			if ( $time < $now ) {
				continue;
			}

			$hours[] = array(
				'time'        => self::timestamp( $time ),
				'hour'        => (int) substr( $time, 11, 2 ),
				'temperature' => Fontdelbosc_Payload::float( Fontdelbosc_Payload::path( $data, 'hourly', 'temperature_2m', $index ) ),
				'pop'         => Fontdelbosc_Payload::int( Fontdelbosc_Payload::path( $data, 'hourly', 'precipitation_probability', $index ) ),
				'condition'   => self::condition( Fontdelbosc_Payload::path( $data, 'hourly', 'weather_code', $index ) ),
				'wind'        => Fontdelbosc_Payload::float( Fontdelbosc_Payload::path( $data, 'hourly', 'wind_speed_10m', $index ) ),
			);
		}

		if ( array() === $hours ) {
			return null;
		}

		return array(
			'source' => 'open-meteo',
			'hours'  => $hours,
		);
	}

	/**
	 * Returns the normalized daily forecast.
	 *
	 * @return array<string,mixed>|null
	 */
	public static function get_daily(): ?array {
		$url   = add_query_arg(
			array(
				'latitude'      => FONTDELBOSC_ELTEMPS_LAT,
				'longitude'     => FONTDELBOSC_ELTEMPS_LON,
				'daily'         => 'weather_code,temperature_2m_max,temperature_2m_min,precipitation_sum,precipitation_probability_max,wind_speed_10m_max',
				'timezone'      => FONTDELBOSC_ELTEMPS_TIMEZONE,
				'forecast_days' => 7,
			),
			self::FORECAST_URL
		);
		$data  = self::request( $url );
		$times = Fontdelbosc_Payload::arr( Fontdelbosc_Payload::path( $data, 'daily', 'time' ) );
		$days  = array();

		foreach ( $times as $index => $date ) {
			$date = Fontdelbosc_Payload::str( $date );

			if ( null === $date ) {
				continue;
			}

			$days[] = array(
				'date'          => $date,
				'condition'     => self::condition( Fontdelbosc_Payload::path( $data, 'daily', 'weather_code', $index ) ),
				'temp_max'      => Fontdelbosc_Payload::float( Fontdelbosc_Payload::path( $data, 'daily', 'temperature_2m_max', $index ) ),
				'temp_min'      => Fontdelbosc_Payload::float( Fontdelbosc_Payload::path( $data, 'daily', 'temperature_2m_min', $index ) ),
				'precipitation' => Fontdelbosc_Payload::float( Fontdelbosc_Payload::path( $data, 'daily', 'precipitation_sum', $index ) ),
				'pop'           => Fontdelbosc_Payload::int( Fontdelbosc_Payload::path( $data, 'daily', 'precipitation_probability_max', $index ) ),
				'wind_max'      => Fontdelbosc_Payload::float( Fontdelbosc_Payload::path( $data, 'daily', 'wind_speed_10m_max', $index ) ),
			);
		}

		if ( array() === $days ) {
			return null;
		}

		return array(
			'source' => 'open-meteo',
			'days'   => $days,
		);
	}

	/**
	 * Returns the normalized daily history for a given month (ERA5).
	 *
	 * @param int $year  Year (1940 or later).
	 * @param int $month Month (1-12).
	 * @return array<string,mixed>|null
	 */
	public static function get_historical( int $year, int $month ): ?array {
		try {
			$start = new DateTimeImmutable( sprintf( '%04d-%02d-01', $year, $month ), new DateTimeZone( FONTDELBOSC_ELTEMPS_TIMEZONE ) );
		} catch ( Exception ) {
			return null;
		}

		$url  = add_query_arg(
			array(
				'latitude'   => FONTDELBOSC_ELTEMPS_LAT,
				'longitude'  => FONTDELBOSC_ELTEMPS_LON,
				'start_date' => $start->format( 'Y-m-d' ),
				'end_date'   => $start->modify( 'last day of this month' )->format( 'Y-m-d' ),
				'daily'      => 'temperature_2m_max,temperature_2m_min,precipitation_sum,wind_speed_10m_max',
				'timezone'   => FONTDELBOSC_ELTEMPS_TIMEZONE,
			),
			self::ARCHIVE_URL
		);
		$data = self::request( $url );

		$times = Fontdelbosc_Payload::arr( Fontdelbosc_Payload::path( $data, 'daily', 'time' ) );
		$days  = array();

		foreach ( $times as $index => $date ) {
			$date = Fontdelbosc_Payload::str( $date );
			$max  = Fontdelbosc_Payload::float( Fontdelbosc_Payload::path( $data, 'daily', 'temperature_2m_max', $index ) );
			$min  = Fontdelbosc_Payload::float( Fontdelbosc_Payload::path( $data, 'daily', 'temperature_2m_min', $index ) );

			if ( null === $date || ( null === $max && null === $min ) ) {
				continue;
			}

			$days[] = array(
				'date'          => $date,
				'temp_max'      => $max,
				'temp_min'      => $min,
				'precipitation' => Fontdelbosc_Payload::float( Fontdelbosc_Payload::path( $data, 'daily', 'precipitation_sum', $index ) ),
				'wind_max'      => Fontdelbosc_Payload::float( Fontdelbosc_Payload::path( $data, 'daily', 'wind_speed_10m_max', $index ) ),
			);
		}

		if ( array() === $days ) {
			return null;
		}

		return array(
			'source' => 'open-meteo',
			'year'   => $year,
			'month'  => $month,
			'days'   => $days,
			'stats'  => self::stats( $days ),
		);
	}

	/**
	 * Computes monthly statistics for a set of normalized history days.
	 *
	 * @param array<int,array<string,mixed>> $days Normalized days.
	 * @return array<string,float|null>
	 */
	private static function stats( array $days ): array {
		$maxes      = array();
		$mins       = array();
		$precip_sum = 0.0;
		$wind_max   = null;

		foreach ( $days as $day ) {
			$max = Fontdelbosc_Payload::float( Fontdelbosc_Payload::get( $day, 'temp_max' ) );
			$min = Fontdelbosc_Payload::float( Fontdelbosc_Payload::get( $day, 'temp_min' ) );
			$pre = Fontdelbosc_Payload::float( Fontdelbosc_Payload::get( $day, 'precipitation' ) );
			$win = Fontdelbosc_Payload::float( Fontdelbosc_Payload::get( $day, 'wind_max' ) );

			if ( null !== $max ) {
				$maxes[] = $max;
			}

			if ( null !== $min ) {
				$mins[] = $min;
			}

			if ( null !== $pre ) {
				$precip_sum += $pre;
			}

			if ( null !== $win ) {
				$wind_max = max( (float) $wind_max, $win );
			}
		}

		return array(
			'avg_max'      => array() === $maxes ? null : round( array_sum( $maxes ) / count( $maxes ), 1 ),
			'avg_min'      => array() === $mins ? null : round( array_sum( $mins ) / count( $mins ), 1 ),
			'total_precip' => round( $precip_sum, 1 ),
			'max_wind'     => $wind_max,
		);
	}

	/**
	 * Maps a WMO code to a condition key.
	 *
	 * @param mixed $code WMO weather code.
	 * @return string|null
	 */
	private static function condition( mixed $code ): ?string {
		if ( ! is_numeric( $code ) ) {
			return null;
		}

		return self::WMO_MAP[ (int) $code ] ?? 'cloudy';
	}

	/**
	 * Converts a local (Europe/Madrid) ISO string to a Unix timestamp.
	 *
	 * @param string $iso ISO date-time string.
	 * @return int
	 */
	private static function timestamp( string $iso ): int {
		try {
			return ( new DateTimeImmutable( $iso, new DateTimeZone( FONTDELBOSC_ELTEMPS_TIMEZONE ) ) )->getTimestamp();
		} catch ( Exception ) {
			return time();
		}
	}

	/**
	 * Returns the current hour key used to filter hourly series.
	 *
	 * @return string Format: Y-m-d H:00.
	 */
	private static function now_key(): string {
		return ( new DateTimeImmutable( 'now', new DateTimeZone( FONTDELBOSC_ELTEMPS_TIMEZONE ) ) )->format( 'Y-m-d H:00' );
	}

	/**
	 * Performs a GET request and decodes the JSON response.
	 *
	 * @param string $url Request URL.
	 * @return array<mixed>|null
	 */
	private static function request( string $url ): ?array {
		$response = wp_remote_get(
			$url,
			array(
				'timeout' => 5,
				'headers' => array(
					'Accept' => 'application/json',
				),
			)
		);

		if ( is_wp_error( $response ) ) {
			self::log( 'Open-Meteo request failed: ' . $response->get_error_message() );

			return null;
		}

		$code = wp_remote_retrieve_response_code( $response );

		if ( 200 !== $code ) {
			self::log( 'Open-Meteo returned HTTP ' . $code );

			return null;
		}

		$data = json_decode( (string) wp_remote_retrieve_body( $response ), true );

		return is_array( $data ) ? $data : null;
	}

	/**
	 * Writes a message to the error log with the plugin prefix.
	 *
	 * @param string $message Message.
	 * @return void
	 */
	private static function log( string $message ): void {
		error_log( '[fontdelbosc-eltemps] ' . $message );
	}
}