<?php
/**
 * Number formatting for emails.
 *
 * @package TurtleReport
 */

namespace TurtleReport\Policy;

defined( 'ABSPATH' ) || exit;

/**
 * Formats numbers and changes the same way the report screen does.
 */
final class Format {

	const GOOD = '#127a4f';
	const BAD  = '#c03a2b';
	const FLAT = '#66736d';

	/**
	 * Whole number with thousands separators.
	 *
	 * @param float $v Value.
	 * @return string
	 */
	public static function number( $v ) {
		return number_format_i18n( round( (float) $v ) );
	}

	/**
	 * A traffic metric value.
	 *
	 * @param string $format int, pct, duration or money.
	 * @param float  $v      Value.
	 * @return string
	 */
	public static function metric( $format, $v ) {
		switch ( $format ) {
			case 'pct':
				return number_format_i18n( (float) $v * 100, 1 ) . '%';
			case 'duration':
				$s = (int) round( $v );
				return sprintf( '%d:%02d', intdiv( $s, 60 ), $s % 60 );
			case 'money':
				return number_format_i18n( (float) $v, 2 );
			default:
				return self::number( $v );
		}
	}

	/**
	 * Change between two values, with a colour.
	 *
	 * @param float  $cur   Current value.
	 * @param float  $prev  Previous value.
	 * @param string $kind  'rel' (percent), 'abs' (difference), 'pts' (percentage points) or 'pos' (position).
	 * @param bool   $lower Whether a decrease is good.
	 * @return array{text:string,color:string}
	 */
	public static function delta( $cur, $prev, $kind = 'rel', $lower = false ) {
		$cur  = (float) $cur;
		$prev = (float) $prev;
		$diff = $cur - $prev;
		switch ( $kind ) {
			case 'abs':
				$text = self::sign( $diff ) . self::number( abs( $diff ) );
				break;
			case 'pts':
				$diff = $diff * 100;
				/* translators: %s: change in percentage points. */
				$text = sprintf( __( '%s pts', 'turtlereport' ), self::sign( $diff ) . number_format_i18n( abs( $diff ), 1 ) );
				break;
			case 'pos':
				$lower = true;
				$text  = ( $diff < 0 ? '▲ ' : ( $diff > 0 ? '▼ ' : '' ) ) . number_format_i18n( abs( $diff ), 1 );
				break;
			default:
				if ( 0.0 === $prev ) {
					$text = $cur > 0 ? __( 'new', 'turtlereport' ) : '±0%';
				} else {
					$pct  = $diff / $prev * 100;
					$text = self::sign( $pct ) . number_format_i18n( abs( $pct ), abs( $pct ) < 10 ? 1 : 0 ) . '%';
				}
		}
		if ( abs( $diff ) < 0.0001 ) {
			$color = self::FLAT;
			$text  = __( 'No change', 'turtlereport' );
		} else {
			$good  = $lower ? $diff < 0 : $diff > 0;
			$color = $good ? self::GOOD : self::BAD;
		}
		return array(
			'text'  => $text,
			'color' => $color,
		);
	}

	/**
	 * Sign character for a number.
	 *
	 * @param float $n Number.
	 * @return string
	 */
	private static function sign( $n ) {
		if ( $n > 0 ) {
			return '+';
		}
		return $n < 0 ? '−' : '±';
	}

	/**
	 * A date range in the site's language, e.g. "1 Sept 2026 – 30 Sept 2026".
	 *
	 * @param string $s Start date.
	 * @param string $e End date.
	 * @return string
	 */
	public static function range( $s, $e ) {
		$fmt = (string) get_option( 'date_format', 'j M Y' );
		return wp_date( $fmt, strtotime( $s . ' 12:00:00 UTC' ), new \DateTimeZone( 'UTC' ) ) . ' – ' . wp_date( $fmt, strtotime( $e . ' 12:00:00 UTC' ), new \DateTimeZone( 'UTC' ) );
	}
}