<?php
/**
 * Free shipping goal.
 *
 * @package Extrova
 */

declare( strict_types=1 );

namespace Extrova\Goals;

use Extrova\Core\Context;
use Extrova\Core\Money;
use Extrova\Core\SettingsRepository;

defined( 'ABSPATH' ) || exit;

/**
 * Reads the minimum amount of the active "Free shipping" method of the customer's zone and
 * computes progress with the same formula as WC_Shipping_Free_Shipping::is_available().
 *
 * @since 1.0.0
 */
final class FreeShippingGoal implements GoalInterface {

	/**
	 * Constructor.
	 *
	 * @param SettingsRepository $settings Settings.
	 */
	public function __construct( private SettingsRepository $settings ) {}

	/**
	 * {@inheritDoc}
	 */
	public function id(): string {
		return 'free_shipping';
	}

	/**
	 * {@inheritDoc}
	 *
	 * @param Context $context Context.
	 */
	public function evaluate( Context $context ): ?array {
		$cart = $context->cart;
		if ( ! $cart || ! $cart->needs_shipping() ) {
			return null;
		}

		$target = $this->threshold( $cart );
		if ( null === $target ) {
			return null;
		}
		list( $threshold, $ignore_discounts ) = $target;

		$current   = $this->current_amount( $cart, $ignore_discounts );
		$remaining = max( 0.0, $threshold - $current );
		$reached   = $remaining <= 0;

		if ( $reached && empty( $this->settings->get()['free_shipping_bar']['show_when_reached'] ) ) {
			return null;
		}

		$message = $reached
			? __( 'You have unlocked free shipping!', 'extrova' )
			: sprintf(
				/* translators: %s: amount left to reach free shipping. */
				__( 'Add %s more to get free shipping.', 'extrova' ),
				Money::plain( $remaining )
			);

		return array(
			'threshold' => Money::decimal( $threshold ),
			'current'   => Money::decimal( min( $current, $threshold ) ),
			'remaining' => Money::decimal( $remaining ),
			'reached'   => $reached,
			'message'   => $message,
		);
	}

	/**
	 * Lowest free shipping minimum in the first package's zone.
	 *
	 * @param \WC_Cart $cart Cart.
	 * @return array{0: float, 1: bool}|null [ threshold, ignore_discounts ].
	 */
	private function threshold( \WC_Cart $cart ): ?array {
		$packages = $cart->get_shipping_packages();
		$package  = is_array( $packages ) ? reset( $packages ) : false;
		if ( ! is_array( $package ) ) {
			return null;
		}

		$zone   = \WC_Shipping_Zones::get_zone_matching_package( $package );
		$result = null;

		foreach ( $zone->get_shipping_methods( true ) as $method ) {
			if ( ! $method instanceof \WC_Shipping_Free_Shipping ) {
				continue;
			}
			$requires = (string) $method->get_option( 'requires', '' );
			if ( ! in_array( $requires, array( 'min_amount', 'either', 'both' ), true ) ) {
				continue;
			}
			$min = (float) wc_format_decimal( (string) $method->get_option( 'min_amount', '0' ) );
			if ( $min <= 0 ) {
				continue;
			}
			if ( null === $result || $min < $result[0] ) {
				$result = array( $min, 'yes' === $method->get_option( 'ignore_discounts', 'no' ) );
			}
		}

		return $result;
	}

	/**
	 * Amount counted towards the threshold (mirrors WC_Shipping_Free_Shipping).
	 *
	 * @param \WC_Cart $cart             Cart.
	 * @param bool     $ignore_discounts Whether coupons are ignored.
	 */
	private function current_amount( \WC_Cart $cart, bool $ignore_discounts ): float {
		$total = (float) $cart->get_displayed_subtotal();
		if ( $cart->display_prices_including_tax() ) {
			$total -= (float) $cart->get_discount_tax();
		}
		if ( ! $ignore_discounts ) {
			$total -= (float) $cart->get_discount_total();
		}
		return round( $total, wc_get_price_decimals() );
	}
}