<?php
/**
 * Money for agents: a decimal string plus an ISO 4217 code, never a float and
 * never a "smallest unit" integer an agent would have to know to divide.
 *
 * @package AgentAdapt
 */

defined( 'ABSPATH' ) || exit;

/**
 * Money formatting.
 */
final class AgentAdapt_Money {

	/**
	 * From the Store API's minor-unit string ("1999", minor unit 2) to
	 * {"amount": "19.99", "currency": "GBP"}.
	 *
	 * @param string|int|null $minor      Amount in the smallest unit.
	 * @param int             $minor_unit Decimal places.
	 * @param string          $currency   ISO 4217 code.
	 * @return array{amount: string, currency: string}|null
	 */
	public static function from_minor( $minor, int $minor_unit, string $currency ): ?array {
		if ( null === $minor || '' === $minor || ! preg_match( '/^-?\d+$/', (string) $minor ) ) {
			return null;
		}
		$s   = ltrim( (string) $minor, '-' );
		$neg = str_starts_with( (string) $minor, '-' );
		if ( $minor_unit > 0 ) {
			$s = str_pad( $s, $minor_unit + 1, '0', STR_PAD_LEFT );
			$s = substr( $s, 0, -$minor_unit ) . '.' . substr( $s, -$minor_unit );
		}
		return array( 'amount' => ( $neg ? '-' : '' ) . $s, 'currency' => $currency );
	}

	/**
	 * From a WooCommerce decimal price string to the same shape.
	 *
	 * @param string|float|null $amount   Price as WooCommerce stores it.
	 * @param string            $currency ISO 4217 code.
	 * @return array{amount: string, currency: string}|null
	 */
	public static function from_decimal( $amount, string $currency ): ?array {
		if ( null === $amount || '' === $amount ) {
			return null;
		}
		return array( 'amount' => wc_format_decimal( $amount, wc_get_price_decimals() ), 'currency' => $currency );
	}

	/**
	 * JSON Schema for a money object.
	 *
	 * @return array<string,mixed>
	 */
	public static function schema(): array {
		return array(
			'type'       => array( 'object', 'null' ),
			'properties' => array(
				'amount'   => array( 'type' => 'string', 'description' => 'Decimal amount, e.g. "19.99".' ),
				'currency' => array( 'type' => 'string', 'description' => 'ISO 4217 code.' ),
			),
		);
	}
}