<?php
/**
 * Frontend / checkout integration.
 *
 * @package WC_Email_Discount_Manager
 */

if ( ! defined( 'ABSPATH' ) ) {
	exit;
}

/**
 * Applies discounts, auto-applies coupons and filters shipping methods on checkout.
 */
class WC_EDM_Frontend {

	/**
	 * Session key holding the tracked guest email.
	 */
	const SESSION_EMAIL_KEY = 'wc_edm_email';

	/**
	 * Guard so the coupon is only auto-applied once per request.
	 *
	 * @var bool
	 */
	private $coupon_applied = false;

	/**
	 * Hook everything up.
	 */
	public function __construct() {
		add_action( 'wp_enqueue_scripts', array( $this, 'enqueue_scripts' ) );

		add_action( 'wp_ajax_wc_edm_track_email', array( $this, 'ajax_track_email' ) );
		add_action( 'wp_ajax_nopriv_wc_edm_track_email', array( $this, 'ajax_track_email' ) );

		add_action( 'woocommerce_cart_calculate_fees', array( $this, 'apply_discount_fees' ), 20 );
		add_action( 'woocommerce_before_calculate_totals', array( $this, 'maybe_apply_coupon' ), 20 );
		add_filter( 'woocommerce_package_rates', array( $this, 'filter_shipping_rates' ), 20, 2 );
	}

	/**
	 * Enqueue the checkout email tracking script.
	 */
	public function enqueue_scripts() {
		if ( ! function_exists( 'is_checkout' ) || ( ! is_checkout() && ! is_cart() ) ) {
			return;
		}

		$params = array(
			'ajax_url' => admin_url( 'admin-ajax.php' ),
			'nonce'    => wp_create_nonce( 'wc-edm-track-email' ),
		);

		$script = '
		jQuery( function( $ ) {
			var wcEdm = ' . wp_json_encode( $params ) . ';
			var timer = null;
			var lastTracked = "";

			function trackEmail( email ) {
				if ( ! email || email.indexOf( "@" ) < 1 || email === lastTracked ) {
					return;
				}
				lastTracked = email;
				$.post( wcEdm.ajax_url, {
					action: "wc_edm_track_email",
					nonce: wcEdm.nonce,
					email: email
				}, function() {
					$( document.body ).trigger( "update_checkout" );
				} );
			}

			$( document.body ).on( "keyup change blur", "#billing_email", function() {
				var email = $( this ).val();
				clearTimeout( timer );
				timer = setTimeout( function() {
					trackEmail( email );
				}, 600 );
			} );

			// Track a prefilled email on page load.
			var initial = $( "#billing_email" ).val();
			if ( initial ) {
				trackEmail( initial );
			}
		} );';

		wp_add_inline_script( 'jquery', $script );
	}

	/**
	 * AJAX: store the checkout email in the WooCommerce session so
	 * discounts apply when totals are recalculated.
	 */
	public function ajax_track_email() {
		check_ajax_referer( 'wc-edm-track-email', 'nonce' );

		$email = isset( $_POST['email'] ) ? sanitize_email( wp_unslash( $_POST['email'] ) ) : '';

		if ( ! WC()->session ) {
			wp_send_json_error( array( 'message' => 'No session.' ) );
		}

		if ( $email && is_email( $email ) ) {
			WC()->session->set( self::SESSION_EMAIL_KEY, $email );
		} else {
			WC()->session->set( self::SESSION_EMAIL_KEY, null );
		}

		$this->clear_shipping_cache();

		$match = $email ? WC_EDM_Helpers::find_email_match( $email ) : null;

		wp_send_json_success(
			array(
				'matched' => (bool) $match,
			)
		);
	}

	/**
	 * Clear cached shipping rates so shipping rules re-evaluate.
	 */
	private function clear_shipping_cache() {
		if ( ! WC()->cart || ! WC()->session ) {
			return;
		}

		$packages = WC()->cart->get_shipping_packages();

		foreach ( array_keys( $packages ) as $index ) {
			WC()->session->set( 'shipping_for_package_' . $index, null );
		}
	}

	/**
	 * Resolve the email address of the current customer.
	 *
	 * Logged-in users use their account email; guests use the tracked
	 * session email or the billing email WooCommerce already knows.
	 *
	 * @return string
	 */
	public function get_customer_email() {
		if ( is_user_logged_in() ) {
			$user = wp_get_current_user();
			if ( $user && $user->user_email ) {
				return $user->user_email;
			}
		}

		if ( WC()->session ) {
			$session_email = WC()->session->get( self::SESSION_EMAIL_KEY );
			if ( $session_email ) {
				return $session_email;
			}
		}

		if ( WC()->customer ) {
			$billing_email = WC()->customer->get_billing_email();
			if ( $billing_email ) {
				return $billing_email;
			}
		}

		return '';
	}

	/**
	 * Get the current customer's email assignment match, if any.
	 *
	 * @return object|null
	 */
	private function get_current_match() {
		$email = $this->get_customer_email();

		if ( ! $email ) {
			return null;
		}

		return WC_EDM_Helpers::find_email_match( $email );
	}

	/**
	 * Apply group/custom discounts as negative fees.
	 *
	 * @param WC_Cart $cart Cart object.
	 */
	public function apply_discount_fees( $cart ) {
		if ( is_admin() && ! defined( 'DOING_AJAX' ) ) {
			return;
		}

		$match = $this->get_current_match();

		if ( ! $match ) {
			return;
		}

		if ( 'group' === $match->assignment_type ) {
			$this->apply_group_fee( $cart, $match );
		} elseif ( 'custom' === $match->assignment_type ) {
			$this->apply_custom_fee( $cart, $match );
		}
	}

	/**
	 * Group discount: percentage off cart items in the group's categories.
	 *
	 * @param WC_Cart $cart  Cart object.
	 * @param object  $match Email assignment row.
	 */
	private function apply_group_fee( $cart, $match ) {
		if ( ! $match->group_id ) {
			return;
		}

		$group = WC_EDM_DB::get_group( (int) $match->group_id );

		if ( ! $group || (float) $group->discount_percent <= 0 ) {
			return;
		}

		$category_ids = WC_EDM_DB::get_group_category_ids( (int) $group->id );

		if ( empty( $category_ids ) ) {
			return;
		}

		$eligible_total = 0;

		foreach ( $cart->get_cart() as $cart_item ) {
			$product_id = (int) $cart_item['product_id']; // Parent ID for variations.

			if ( has_term( $category_ids, 'product_cat', $product_id ) ) {
				$eligible_total += (float) $cart_item['line_total'];
			}
		}

		if ( $eligible_total <= 0 ) {
			return;
		}

		$discount = $eligible_total * ( (float) $group->discount_percent / 100 );

		$cart->add_fee(
			/* translators: %s: discount group name */
			sprintf( __( 'Email discount: %s', 'wc-email-discount' ), $group->name ),
			-$discount,
			false
		);
	}

	/**
	 * Custom discount: percentage off the entire cart contents.
	 *
	 * @param WC_Cart $cart  Cart object.
	 * @param object  $match Email assignment row.
	 */
	private function apply_custom_fee( $cart, $match ) {
		$percent = (float) $match->custom_discount;

		if ( $percent <= 0 ) {
			return;
		}

		$cart_total = 0;

		foreach ( $cart->get_cart() as $cart_item ) {
			$cart_total += (float) $cart_item['line_total'];
		}

		if ( $cart_total <= 0 ) {
			return;
		}

		$discount = $cart_total * ( $percent / 100 );

		$cart->add_fee(
			/* translators: %s: discount percent */
			sprintf( __( 'Email discount (%s%%)', 'wc-email-discount' ), wc_format_localized_decimal( $percent ) ),
			-$discount,
			false
		);
	}

	/**
	 * Auto-apply a coupon for coupon-type assignments.
	 *
	 * @param WC_Cart $cart Cart object.
	 */
	public function maybe_apply_coupon( $cart ) {
		if ( $this->coupon_applied || ( is_admin() && ! defined( 'DOING_AJAX' ) ) ) {
			return;
		}

		$match = $this->get_current_match();

		if ( ! $match || 'coupon' !== $match->assignment_type || empty( $match->coupon_code ) ) {
			return;
		}

		$code = wc_format_coupon_code( $match->coupon_code );

		if ( ! wc_get_coupon_id_by_code( $code ) ) {
			return;
		}

		if ( $cart->has_discount( $code ) ) {
			return;
		}

		$this->coupon_applied = true;
		$cart->apply_coupon( $code );
	}

	/**
	 * Filter shipping rates for the matched email assignment.
	 *
	 * Group assignments get their show/hide rules applied; any assignment
	 * with the free shipping flag gets all remaining rates at zero cost.
	 *
	 * @param array $rates   Available shipping rates (rate_id => WC_Shipping_Rate).
	 * @param array $package Shipping package.
	 * @return array
	 */
	public function filter_shipping_rates( $rates, $package ) {
		$match = $this->get_current_match();

		// $match is null for a customer who matches nothing — the common case,
		// and the one this whole method exists to constrain now.
		if ( $match && 'group' === $match->assignment_type && $match->group_id ) {
			$rates = $this->apply_group_shipping_rules( $rates, (int) $match->group_id );
		} else {
			// 🔴 Everyone else — including a matched customer whose assignment
			// is not a group — must not see a method some group reserved.
			//
			// This used to return $rates untouched, and a test asserted that
			// as intended: "an unmatched customer sees every method". It made
			// a "show" rule a whitelist FOR THE GROUP and nothing more, so
			// reserving free delivery for approved addresses left it on the
			// checkout for every other customer. Reported from a live shop,
			// where a gmail address could pick a free-delivery method meant
			// for one company.
			$rates = $this->remove_restricted_rates( $rates );
		}

		if ( $match && ! empty( $match->free_shipping ) ) {
			foreach ( $rates as $rate ) {
				$rate->set_cost( 0 );
				$rate->set_taxes( array() );
			}
		}

		return $rates;
	}

	/**
	 * Remove every method some group reserved for itself.
	 *
	 * @param array $rates Available shipping rates.
	 * @return array
	 */
	private function remove_restricted_rates( $rates ) {
		$restricted = WC_EDM_DB::restricted_shipping_methods();

		if ( empty( $restricted ) ) {
			return $rates;
		}

		$filtered = array();

		foreach ( $rates as $rate_id => $rate ) {
			if ( ! in_array( $rate_id, $restricted, true ) ) {
				$filtered[ $rate_id ] = $rate;
			}
		}

		// The same guard the group rules carry: a shop that reserved every
		// method it offers would otherwise leave an ordinary customer unable
		// to check out at all, which is worse than the leak being fixed.
		return empty( $filtered ) ? $rates : $filtered;
	}

	/**
	 * Apply a group's show/hide shipping rules.
	 *
	 * If the group has no rules, all rates pass through untouched.
	 * "show" rules act as a whitelist; "hide" rules remove rates.
	 * Rates are reordered to follow the rules' sort order.
	 *
	 * @param array $rates    Available shipping rates (rate_id => WC_Shipping_Rate).
	 * @param int   $group_id Discount group ID.
	 * @return array
	 */
	private function apply_group_shipping_rules( $rates, $group_id ) {
		$rules = WC_EDM_DB::get_shipping_rules( $group_id );

		// 🔴 Not `return $rates` — a group with no rules of its own must still
		// not see what ANOTHER group reserved. Same for a group carrying only
		// "hide" rules: its own shown-set is empty, so the whitelist below
		// never engages and every other group's reserved method would survive.
		// The leak this fixes was reported for customers matching nothing; it
		// existed for these two shapes as well.
		if ( empty( $rules ) ) {
			return $this->remove_restricted_rates( $rates );
		}

		$show = array();
		$hide = array();

		foreach ( $rules as $rule ) {
			if ( 'show' === $rule->action ) {
				$show[] = $rule->shipping_method_id;
			} else {
				$hide[] = $rule->shipping_method_id;
			}
		}

		$filtered = array();

		// Reserved by some group, but not by THIS one.
		$others = array_diff( WC_EDM_DB::restricted_shipping_methods(), $show );

		foreach ( $rates as $rate_id => $rate ) {
			// Whitelist mode: only explicitly shown methods survive.
			if ( ! empty( $show ) && ! in_array( $rate_id, $show, true ) ) {
				continue;
			}

			if ( in_array( $rate_id, $hide, true ) ) {
				continue;
			}

			if ( in_array( $rate_id, $others, true ) ) {
				continue;
			}

			$filtered[ $rate_id ] = $rate;
		}

		// Never leave the customer without shipping because of misconfigured rules.
		if ( empty( $filtered ) ) {
			return $rates;
		}

		// Reorder rates to follow the rules' sort order; unmatched rates keep their position at the end.
		$rule_order = wp_list_pluck( $rules, 'shipping_method_id' );
		$ordered    = array();

		foreach ( $rule_order as $method_id ) {
			if ( isset( $filtered[ $method_id ] ) ) {
				$ordered[ $method_id ] = $filtered[ $method_id ];
				unset( $filtered[ $method_id ] );
			}
		}

		return $ordered + $filtered;
	}
}