<?php
/**
 * Order total search term parser.
 *
 * @package AdminPowerups
 */

namespace SmartWP\AdminPowerups\Modules\AdvancedOrderSearch;

/**
 * Turns a search term into an inclusive [min, max] total range.
 *
 * Supported: `49.99`, `$1,299.00`, `10-20`, `10..20`, `10 to 20`, `>100`, `>=100`, `<50`, `<=50`.
 * Pure PHP (no WordPress calls) so it can be unit-tested in isolation.
 *
 * @since 1.0.0
 */
final class TotalQuery {

	/**
	 * Smallest step used to make `>` / `<` exclusive.
	 */
	const EPSILON = 0.0001;

	/**
	 * Largest total we will ever search for.
	 */
	const MAX = 999999999999.0;

	/**
	 * Parse a term.
	 *
	 * @since 1.0.0
	 * @param string $term      Raw search term.
	 * @param float  $tolerance ± tolerance applied to exact searches.
	 * @param string $decimal   Store decimal separator.
	 * @return array{0: float, 1: float}|null Null when the term is not a total. Both ends are finite
	 *                                        and within [0, MAX].
	 */
	public static function parse( $term, $tolerance = 0.0, $decimal = '.' ) {
		$range = self::parse_raw( $term, $tolerance, $decimal );
		if ( null === $range ) {
			return null;
		}
		return array( self::clamp( $range[0] ), self::clamp( $range[1] ) );
	}

	/**
	 * A value inside [0, MAX] (a total column can't hold more, and %f of a huge float is a
	 * 300-digit literal).
	 *
	 * @since 1.0.0
	 * @param float $value Value (finite).
	 * @return float
	 */
	private static function clamp( $value ) {
		return min( self::MAX, max( 0.0, (float) $value ) );
	}

	/**
	 * Parse a term without clamping.
	 *
	 * @param string $term      Raw search term.
	 * @param float  $tolerance ± tolerance applied to exact searches.
	 * @param string $decimal   Store decimal separator.
	 * @return array{0: float, 1: float}|null
	 */
	private static function parse_raw( $term, $tolerance, $decimal ) {
		$term = trim( strtolower( (string) $term ) );
		if ( '' === $term ) {
			return null;
		}

		// Comparisons.
		if ( preg_match( '/^(>=|<=|>|<)\s*(.+)$/', $term, $m ) ) {
			$value = self::number( $m[2], $decimal );
			if ( null === $value ) {
				return null;
			}
			switch ( $m[1] ) {
				case '>':
					return array( $value + self::EPSILON, self::MAX );
				case '>=':
					return array( $value, self::MAX );
				case '<':
					return array( 0.0, max( 0.0, $value - self::EPSILON ) );
				default:
					return array( 0.0, $value );
			}
		}

		// Ranges such as 10-20, 10 - 20, 10..20 or 10 to 20.
		if ( preg_match( '/^(.+?)\s*(?:\.\.|\bto\b|\s-\s|-)\s*(.+)$/', $term, $m ) ) {
			$a = self::number( $m[1], $decimal );
			$b = self::number( $m[2], $decimal );
			if ( null !== $a && null !== $b ) {
				return array( min( $a, $b ), max( $a, $b ) );
			}
			return null;
		}

		$value = self::number( $term, $decimal );
		if ( null === $value ) {
			return null;
		}
		$tolerance = is_finite( (float) $tolerance ) ? max( 0.0, (float) $tolerance ) : 0.0;
		return array( max( 0.0, $value - $tolerance ), $value + $tolerance );
	}

	/**
	 * Parse a single amount, ignoring currency symbols and thousand separators.
	 *
	 * @since 1.0.0
	 * @param string $raw     Raw amount.
	 * @param string $decimal Decimal separator.
	 * @return float|null Null when not an amount, or too large to be a number (INF).
	 */
	public static function number( $raw, $decimal = '.' ) {
		$raw = trim( (string) $raw );
		// Reject anything containing letters (other than currency codes stripped below) to avoid matching IDs like "wc_123".
		$raw = preg_replace( '/^[a-z]{3}\s*|\s*[a-z]{3}$/i', '', $raw );
		if ( preg_match( '/[a-z]/i', $raw ) ) {
			return null;
		}

		$raw = preg_replace( '/[^0-9.,]/', '', $raw );
		if ( '' === $raw || ! preg_match( '/[0-9]/', $raw ) ) {
			return null;
		}

		if ( ',' === $decimal ) {
			$raw = str_replace( array( '.', ',' ), array( '', '.' ), $raw );
		} else {
			$raw = str_replace( ',', '', $raw );
		}

		if ( ! is_numeric( $raw ) ) {
			return null;
		}
		$value = (float) $raw;
		// 309+ digits overflow to INF, which prepare()'s %f prints as the bare word "INF".
		return is_finite( $value ) ? $value : null;
	}
}