<?php

namespace AIbender\ArticleVault\Payments;

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

use AIbender\ArticleVault\Access\SecureToken;
use AIbender\ArticleVault\Core\Constants;
use AIbender\ArticleVault\Databases\PurchaseRepository;

class StripeWebhook {

	private StripeManager $stripe_manager;

	private PurchaseRepository $purchase_repository;

	private SecureToken $secure_token;

	public function __construct(
		StripeManager $stripe_manager,
		PurchaseRepository $purchase_repository,
		SecureToken $secure_token
	) {

		$this->stripe_manager      = $stripe_manager;
		$this->purchase_repository = $purchase_repository;
		$this->secure_token        = $secure_token;

	}

	public function register(): void {

		add_action(
			'init',
			array( $this, 'maybe_handle_webhook' )
		);

	}

	public function maybe_handle_webhook(): void {

		if ( ! isset( $_GET[ Constants::STRIPE_WEBHOOK_QUERY_VAR ] ) ) {
			return;
		}

		$payload   = file_get_contents( 'php://input' );
		$signature = isset( $_SERVER['HTTP_STRIPE_SIGNATURE'] )
			? sanitize_text_field( wp_unslash( $_SERVER['HTTP_STRIPE_SIGNATURE'] ) )
			: '';

		if ( ! $this->verify_signature( $payload, $signature ) ) {
			status_header( 400 );
			exit;
		}

		$event = json_decode( $payload, true );

		if ( ! is_array( $event ) || empty( $event['type'] ) ) {
			status_header( 400 );
			exit;
		}

		if ( 'checkout.session.completed' === $event['type'] ) {
			$this->handle_checkout_completed( $event );
		}

		status_header( 200 );
		exit;

	}

	private function handle_checkout_completed( array $event ): void {

		$session = $event['data']['object'] ?? array();

		if (
	empty( $session['payment_status'] ) ||
	'paid' !== $session['payment_status']
) {
	return;
}

		if ( empty( $session['id'] ) ) {
			return;
		}

		$article_id = ! empty( $session['metadata']['article_id'] )
			? absint( $session['metadata']['article_id'] )
			: absint( $session['client_reference_id'] ?? 0 );

		if ( ! $article_id ) {
			return;
		}

		$purchase = $this->purchase_repository->find_by_session_id(
	sanitize_text_field( $session['id'] )
);

if ( ! $purchase ) {
	return;
}

if (
	(int) $purchase['article_id'] !== $article_id
	|| (int) $purchase['amount'] !== (int) $session['amount_total']
	|| strtolower( $purchase['currency'] ) !== strtolower( $session['currency'] )
) {
	return;
}

if ( 'paid' === $purchase['status'] ) {
	return;
}

		$email = '';

		if ( ! empty( $session['customer_details']['email'] ) ) {
			$email = sanitize_email( $session['customer_details']['email'] );
		} elseif ( ! empty( $session['customer_email'] ) ) {
			$email = sanitize_email( $session['customer_email'] );
		}

		$raw_token  = $this->secure_token->generate();
		$token_hash = $this->secure_token->hash( $raw_token );

		$this->purchase_repository->mark_paid(
			sanitize_text_field( $session['id'] ),
			sanitize_text_field( $session['payment_intent'] ?? '' ),
			$article_id,
			$email,
			absint( $session['amount_total'] ?? 0 ),
			sanitize_text_field( $session['currency'] ?? 'usd' ),
			$token_hash
		);

	}

	private function verify_signature(
		string $payload,
		string $signature_header
	): bool {

		$secret = $this->stripe_manager->get_webhook_secret();

		if ( '' === $secret || '' === $signature_header ) {
			return false;
		}

		$timestamp = '';
		$signature = '';

		foreach ( explode( ',', $signature_header ) as $part ) {
			$pieces = explode( '=', $part, 2 );

			if ( 2 !== count( $pieces ) ) {
				continue;
			}

			if ( 't' === $pieces[0] ) {
				$timestamp = $pieces[1];
			}

			if ( 'v1' === $pieces[0] ) {
				$signature = $pieces[1];
			}
		}

		if ( '' === $timestamp || '' === $signature ) {
			return false;
		}

		if ( abs( time() - (int) $timestamp ) > 300 ) {
	return false;
}

		$expected = hash_hmac(
			'sha256',
			$timestamp . '.' . $payload,
			$secret
		);

		return hash_equals(
			$expected,
			$signature
		);

	}

}