<?php
/**
 * First-purchase referrals using the shared transactional ledger.
 *
 * @package DevoynxRewards
 */

namespace Devoynx\Rewards\Programs;

use Devoynx\Rewards\Database\ProgramStore;
use Devoynx\Rewards\Database\Transaction;
use Devoynx\Rewards\Domain\LedgerService;

defined( 'ABSPATH' ) || exit;

/** One explicit attribution per account and billing mailbox, never a cookie award. */
final class Referrals {

	const OPTION      = 'devoynx_rewards_basic_referrals';
	const HOOK        = 'devoynx_rewards_referral_retry';
	const RETRY_GROUP = 'devoynx-rewards-referral-';

	/** Shared points ledger.
	 *
	 * @var LedgerService
	 */
	private $ledger;
	/** Durable attribution and reversal checkpoints.
	 *
	 * @var ProgramStore
	 */
	private $store;

	/**
	 * Inject the ledger.
	 *
	 * @param LedgerService $ledger Ledger.
	 */
	public function __construct( LedgerService $ledger ) {
		$this->ledger = $ledger;
		$this->store  = new ProgramStore();
	}

	/** Register status-independent paid-order reconciliation for classic and Blocks. */
	public function register() {
		add_action( 'woocommerce_order_status_changed', array( $this, 'observe' ), 35 );
		add_action( 'woocommerce_payment_complete', array( $this, 'observe' ), 35 );
		add_action( 'woocommerce_order_refunded', array( $this, 'observe' ), 35 );
		add_action( self::HOOK, array( $this, 'observe' ), 10, 2 );
	}

	/**
	 * Bounded opt-in economics. Accepted invitations retain their original terms.
	 *
	 * @return array
	 */
	public function settings() {
		$value = get_option( self::OPTION, array() );
		$value = is_array( $value ) ? $value : array();
		return array(
			'enabled'         => ! empty( $value['enabled'] ),
			'referrer_points' => min( 100000, absint( $value['referrer_points'] ?? 100 ) ),
			'friend_points'   => min( 100000, absint( $value['friend_points'] ?? 50 ) ),
			'minimum_order'   => min( 1000000, max( 0, (float) ( $value['minimum_order'] ?? 10 ) ) ),
		);
	}

	/**
	 * Read an owner's signed share code without writing user metadata on GET.
	 *
	 * @param int $user_id Owner.
	 * @return string
	 */
	public function code( $user_id ) {
		return $user_id && get_current_user_id() === (int) $user_id ? $this->signed_code( $user_id ) : '';
	}

	/**
	 * Sign a public identifier, not an authentication credential.
	 *
	 * @param int $user_id Inviter.
	 * @return string
	 */
	private function signed_code( $user_id ) {
		$id = (string) absint( $user_id );
		return 'D' . $id . '-' . substr( hash_hmac( 'sha256', 'basic-referral:' . $id, wp_salt( 'auth' ) ), 0, 24 );
	}

	/**
	 * Whether Free already owns this customer's explicit attribution (including tombstones).
	 *
	 * @param int $user_id Friend.
	 * @return bool
	 */
	public function owns_customer( $user_id ) {
		return $user_id && (bool) $this->store->find( 'referral:friend:' . absint( $user_id ) );
	}

	/**
	 * Preserve ownership after a merchant reassigns an already-qualified order.
	 *
	 * @param int $order_id Order.
	 * @return bool
	 */
	public function owns_order( $order_id ) {
		return (bool) $this->order_key( $order_id );
	}

	/**
	 * Find the immutable referral receipt for an order.
	 *
	 * @param int $order_id Order.
	 * @return string|null
	 */
	private function order_key( $order_id ) {
		if ( ! absint( $order_id ) ) {
			return null;
		}
		global $wpdb;
		// phpcs:ignore WordPress.DB.DirectDatabaseQuery -- Indexed uncached receipt lookup survives Woo order reassignment.
		return $wpdb->get_var( $wpdb->prepare( "SELECT event_key FROM %i WHERE order_id = %d AND kind = 'basic_referral' LIMIT 1", $wpdb->prefix . 'devoynx_rewards_program_records', absint( $order_id ) ) );
	}

	/**
	 * Consent is a nonce-protected POST at the UI; identity always comes from the session.
	 *
	 * @param string $code Signed invitation.
	 * @return array|\WP_Error
	 */
	public function accept( $code ) {
		$user   = wp_get_current_user();
		$config = $this->settings();
		if ( ! $user->ID || get_user_meta( $user->ID, '_devoynx_rewards_referral_optout', true ) || ! $config['enabled'] || ! is_string( $code ) || ! preg_match( '/^D([1-9][0-9]{0,18})-[a-f0-9]{24}$/D', $code, $match ) ) {
			return $this->error();
		}
		$inviter = get_userdata( (int) $match[1] );
		if ( ! $inviter || get_user_meta( $inviter->ID, '_devoynx_rewards_referral_optout', true ) || $user->ID === $inviter->ID || ! hash_equals( $this->signed_code( $inviter->ID ), $code ) || ! is_email( $user->user_email ) || strcasecmp( $user->user_email, $inviter->user_email ) === 0 ) {
			return $this->error();
		}
		$hash = GuestClaims::email_hash( $user->user_email );
		try {
			// One mailbox cannot be recycled through another account for a second invitation.
			return $this->store->locked(
				'referral:mail:' . $hash,
				'referral_mail',
				function ( $mail ) use ( $user, $inviter, $config, $hash ) {
					if ( 'new' !== $mail['status'] && (int) $mail['user_id'] !== $user->ID ) {
						return $this->error();
					}
					return $this->store->locked(
						'referral:friend:' . $user->ID,
						'basic_referral',
						function ( $row ) use ( $mail, $user, $inviter, $config, $hash ) {
							$data = json_decode( $row['payload'], true );
							if ( 'new' !== $row['status'] ) {
								return (int) ( $data['inviter'] ?? 0 ) === $inviter->ID && 'erased' !== $row['status'] ? $row : $this->error();
							}
							foreach ( array( array( 'customer_id' => $user->ID ), array( 'billing_email' => $user->user_email ) ) as $identity ) {
								if ( wc_get_orders(
									array_merge(
										$identity,
										array(
											'type'      => 'shop_order',
											'date_paid' => '>0',
											'limit'     => 1,
											'return'    => 'ids',
										)
									)
								) ) {
									return $this->error();
								}
							}
							$data = array_merge(
								$config,
								array(
									'inviter'           => $inviter->ID,
									'email_hash'        => $hash,
									'accepted_at'       => time(),
									'currency'          => get_woocommerce_currency(),
									'referrer_reversed' => 0,
									'friend_reversed'   => 0,
								)
							);
							unset( $data['enabled'] );
							$this->store->save( $mail, array(), 'claimed', array( 'user_id' => $user->ID ) );
							return $this->store->save(
								$row,
								$data,
								'pending',
								array(
									'user_id'   => $user->ID,
									'group_key' => 'inviter:' . $inviter->ID,
								)
							);
						}
					);
				}
			);
		} catch ( \Throwable $error ) {
			return $this->error();
		}
	}

	/**
	 * Observe committed WooCommerce events; retry at most three times after a safe rollback.
	 *
	 * @param int $order_id Order.
	 * @param int $attempt Retry count (only supplied by the private scheduled hook).
	 */
	public function observe( $order_id, $attempt = 0 ) {
		$result = $this->process( $order_id );
		if ( ! is_wp_error( $result ) ) {
			return;
		}
		$this->record_failure( $order_id, $attempt );
		if ( $attempt >= 3 ) {
			return;
		}
		$next = absint( $attempt ) + 1;
		$args = array( absint( $order_id ), $next );
		if ( function_exists( 'as_schedule_single_action' ) ) {
			as_schedule_single_action( time() + 300, self::HOOK, $args, self::RETRY_GROUP . absint( $order_id ) . '-' . $next, true );
		} elseif ( ! wp_next_scheduled( self::HOOK, $args ) ) {
			wp_schedule_single_event( time() + 300, self::HOOK, $args );
		}
	}

	/**
	 * Surface failed reconciliation without retaining an exception or sensitive payment data.
	 *
	 * @param int $order_id Order.
	 * @param int $attempt Retry count.
	 */
	private function record_failure( $order_id, $attempt ) {
		try {
			$order = $this->fresh_order( $order_id );
			$key   = $this->order_key( $order_id );
			$key   = $key ? $key : ( $order ? 'referral:friend:' . $order->get_customer_id() : '' );
			if ( ! $key || ! $this->store->find( $key ) ) {
				return;
			}
			$this->store->locked(
				$key,
				'basic_referral',
				function ( $row ) use ( $order_id, $attempt ) {
					$data                  = json_decode( $row['payload'], true );
					$data['needs_review']  = true;
					$data['retry_attempt'] = min( 3, absint( $attempt ) );
					return $this->store->save( $row, $data, $row['status'], array( 'order_id' => $order_id ) );
				}
			);
		} catch ( \Throwable $error ) {
			// A database outage may prevent the diagnostic checkpoint too; do not break a payment.
			return;
		}
	}

	/**
	 * Reconcile one order. Ledger observers and both wallets commit with the same receipt.
	 *
	 * @param int $order_id Paid or refunded order.
	 * @return array|\WP_Error|null
	 */
	public function process( $order_id ) {
		$order = $this->fresh_order( $order_id );
		if ( ! $order ) {
			return null;
		}
		$owned = $this->order_key( $order_id );
		$key   = $owned ? $owned : 'referral:friend:' . $order->get_customer_id();
		if ( ! $this->store->find( $key ) ) {
			return null;
		}
		try {
			return $this->store->locked(
				$key,
				'basic_referral',
				function ( $row ) use ( $order_id ) {
					$data = json_decode( $row['payload'], true );
					if ( ! in_array( $row['status'], array( 'pending', 'awarded', 'reversed' ), true ) || empty( $data['inviter'] ) || ( $row['order_id'] && (int) $row['order_id'] !== (int) $order_id ) ) {
						return $row;
					}
					$owners = array( (int) $row['user_id'], (int) $data['inviter'] );
					sort( $owners, SORT_NUMERIC );
					return Transaction::wallet(
						$owners[0],
						function () use ( $owners, $row, $data, $order_id ) {
							return Transaction::wallet(
								$owners[1],
								function () use ( $row, $data, $order_id ) {
									$order = $this->fresh_order( $order_id );
									if ( ! $order ) {
										return $this->error();
									}
									if ( 'pending' === $row['status'] ) {
										if ( ! $this->settings()['enabled'] || ! $this->qualifies( $order, $row, $data ) ) {
											return $row;
										}
										$data['order_total'] = (float) $order->get_total();
										foreach ( array(
											'referrer' => $data['inviter'],
											'friend'   => $row['user_id'],
										) as $role => $owner ) {
											$points = (int) $data[ $role . '_points' ];
											if ( $points ) {
												$result = $this->ledger->award(
													$owner,
													$points,
													false,
													array(
														'idempotency_key' => $row['event_key'] . ':' . $role,
														'event_type' => 'friend' === $role ? 'referral_friend_award' : 'referral_award',
														'source_type' => 'basic_referral',
														'source_id' => (string) $row['id'],
														'trace' => array(
															'order_id' => $order_id,
															'role' => $role,
														),
													)
												);
												if ( is_wp_error( $result ) ) {
														return $result;
												}
												$data[ $role . '_entry' ] = $result;
											}
										}
									}
									$ratio = min( 1, max( 0, (float) $order->get_total_refunded() / max( 0.01, $data['order_total'] ) ) );
									foreach ( array(
										'referrer' => $data['inviter'],
										'friend'   => $row['user_id'],
									) as $role => $owner ) {
										$target = (int) round( $data[ $role . '_points' ] * $ratio, 0, PHP_ROUND_HALF_UP );
										$needed = max( 0, $target - $data[ $role . '_reversed' ] );
										if ( ! $needed ) {
											continue;
										}
										$now = min( $needed, $this->ledger->balance( $owner )['available'] );
										if ( $now ) {
											$result = $this->ledger->reverse(
												$owner,
												$now,
												'available',
												array(
													'idempotency_key' => $row['event_key'] . ':' . $role . ':reverse:' . $target,
													'event_type' => 'referral_reversal',
													'source_type' => 'basic_referral',
													'source_id' => (string) $row['id'],
													'trace' => array(
														'order_id' => $order_id,
														'target_reversal' => $target,
													),
												)
											);
											if ( is_wp_error( $result ) ) {
												return $result;
											}
										}
										$debt = absint( get_user_meta( $owner, '_devoynx_rewards_reversal_due', true ) );
										if ( $needed > $now && false === update_user_meta( $owner, '_devoynx_rewards_reversal_due', $debt + $needed - $now ) ) {
											return $this->error();
										}
										$data[ $role . '_reversed' ] = $target;
									}
									unset( $data['needs_review'], $data['retry_attempt'] );
									return $this->store->save( $row, $data, $ratio >= 1 ? 'reversed' : 'awarded', array( 'order_id' => $order_id ) );
								}
							);
						}
					);
				}
			);
		} catch ( \Throwable $error ) {
			return $this->error();
		}
	}

	/**
	 * Verify current billing identity, first qualifying payment and immutable invitation terms.
	 *
	 * @param \WC_Order $order Candidate.
	 * @param array     $row Attribution.
	 * @param array     $data Frozen terms.
	 * @return bool
	 */
	private function qualifies( $order, $row, $data ) {
		$friend  = get_userdata( $row['user_id'] );
		$inviter = get_userdata( $data['inviter'] );
		if ( get_user_meta( $row['user_id'], '_devoynx_rewards_referral_optout', true ) || get_user_meta( $data['inviter'], '_devoynx_rewards_referral_optout', true ) ) {
			return false;
		}
		if ( ! $friend || ! $inviter || (int) $order->get_customer_id() !== $friend->ID || ! $order->is_paid() || ! $order->get_date_paid() || $order->get_date_paid()->getTimestamp() < $data['accepted_at'] || $data['currency'] !== $order->get_currency() || (float) $order->get_total() < max( 0.01, $data['minimum_order'] ) || ! hash_equals( $data['email_hash'], GuestClaims::email_hash( $friend->user_email ) ) || strcasecmp( $order->get_billing_email(), $friend->user_email ) || ! strcasecmp( $order->get_billing_email(), $inviter->user_email ) ) {
			return false;
		}
		// Native Woo queries work with HPOS and posts storage. Bounded history fails closed.
		foreach ( array( array( 'customer_id' => $friend->ID ), array( 'billing_email' => $friend->user_email ) ) as $identity ) {
			$history = wc_get_orders(
				array_merge(
					$identity,
					array(
						'type'      => 'shop_order',
						'date_paid' => '>0',
						'limit'     => 101,
						'orderby'   => 'ID',
						'order'     => 'ASC',
					)
				)
			);
			if ( count( $history ) > 100 ) {
				return false;
			}
			foreach ( $history as $prior ) {
				$paid = $prior->get_date_paid();
				if ( ! $paid ) {
					continue;
				}
				if ( $paid->getTimestamp() < $data['accepted_at'] ) {
					return false;
				}
				$earlier = $paid->getTimestamp() < $order->get_date_paid()->getTimestamp() || ( $paid->getTimestamp() === $order->get_date_paid()->getTimestamp() && $prior->get_id() < $order->get_id() );
				if ( $earlier && $prior->get_currency() === $data['currency'] && (float) $prior->get_total() >= max( 0.01, $data['minimum_order'] ) ) {
					return false;
				}
			}
		}
		return true;
	}

	/**
	 * Drop potentially stale Woo caches after waiting for a workflow/wallet lock.
	 *
	 * @param int $order_id Order.
	 * @return \WC_Order|false
	 */
	private function fresh_order( $order_id ) {
		clean_post_cache( $order_id );
		if ( class_exists( '\Automattic\WooCommerce\Caches\OrderCache' ) ) {
			wc_get_container()->get( \Automattic\WooCommerce\Caches\OrderCache::class )->remove( $order_id );
		}
		$store = '\Automattic\WooCommerce\Internal\DataStores\Orders\OrdersTableDataStore';
		if ( class_exists( $store ) && method_exists( $store, 'clear_cached_data' ) ) {
			wc_get_container()->get( $store )->clear_cached_data( array( $order_id ) );
		}
		return wc_get_order( $order_id );
	}

	/**
	 * Non-disclosing error for invalid invitations or transactional failures.
	 *
	 * @return \WP_Error
	 */
	public function error() {
		return new \WP_Error( 'referral_unavailable', __( 'This referral could not be completed. Check eligibility or contact the store for help.', 'devoynx-rewards' ) );
	}
}