<?php

namespace WooOrderCart\Front\AddToCart;

class AddToCartRequestFingerprint {
    private const SESSION_KEY = 'ips_add_to_cart_recent_fingerprints';
    private const TTL_SECONDS = 3;

    /**
     * @param array<string,mixed> $attributes
     */
    public static function build(
        int $product_id,
        int $quantity = 1,
        int $variation_id = 0,
        array $attributes = [],
        int $order_bump_id = 0
    ): string {
        if ( $product_id <= 0 ) {
            return '';
        }

        ksort( $attributes );

        return hash(
            'sha256',
            wp_json_encode(
                [
                    'product_id' => $product_id,
                    'quantity' => max( 1, $quantity ),
                    'variation_id' => max( 0, $variation_id ),
                    'attributes' => $attributes,
                    'order_bump_id' => max( 0, $order_bump_id ),
                ]
            )
        );
    }

    public static function build_from_request(): string {
        $product_id = AddToCartContext::get_requested_product_id();
        if ( $product_id <= 0 ) {
            return '';
        }

        if ( ! is_scalar( $_REQUEST['quantity'] ?? 1 ) ) {
            return '';
        }
        $quantity = wc_stock_amount( wp_unslash( $_REQUEST['quantity'] ?? 1 ) );
        $variation_id = is_scalar( $_REQUEST['variation_id'] ?? null ) ? absint( wp_unslash( $_REQUEST['variation_id'] ) ) : 0;
        $order_bump_id = is_scalar( $_REQUEST['ips_order_bump_id'] ?? null ) ? absint( wp_unslash( $_REQUEST['ips_order_bump_id'] ) ) : 0;

        return self::build(
            $product_id,
            (int) $quantity,
            $variation_id,
            self::extract_attributes_from_request(),
            $order_bump_id
        );
    }

    /**
     * @param array<string,mixed> $variation_attributes
     */
    public static function has_recent_match(
        int $product_id,
        int $quantity = 1,
        int $variation_id = 0,
        array $variation_attributes = [],
        int $order_bump_id = 0
    ): bool {
        $fingerprint = self::build( $product_id, $quantity, $variation_id, $variation_attributes, $order_bump_id );

        if ( '' === $fingerprint ) {
            return false;
        }

        $fingerprints = self::get_recent_fingerprints();

        return isset( $fingerprints[ $fingerprint ] )
            && ( time() - (int) $fingerprints[ $fingerprint ] ) <= self::TTL_SECONDS;
    }

    public static function remember_request( string $fingerprint ): void {
        if ( '' === $fingerprint ) {
            return;
        }

        $fingerprints = self::get_recent_fingerprints();
        $fingerprints[ $fingerprint ] = time();

        self::set_recent_fingerprints( $fingerprints );
    }

    public static function has_recent_fingerprint( string $fingerprint ): bool {
        if ( '' === $fingerprint ) {
            return false;
        }

        $fingerprints = self::get_recent_fingerprints();

        return isset( $fingerprints[ $fingerprint ] )
            && ( time() - (int) $fingerprints[ $fingerprint ] ) <= self::TTL_SECONDS;
    }

    /**
     * @return array<string,int>
     */
    private static function get_recent_fingerprints(): array {
        if ( ! function_exists( 'WC' ) || ! WC()->session ) {
            return [];
        }

        $stored = WC()->session->get( self::SESSION_KEY, [] );
        if ( ! is_array( $stored ) ) {
            $stored = [];
        }

        $cutoff = time() - self::TTL_SECONDS;

        return array_filter(
            $stored,
            static function ( $timestamp ) use ( $cutoff ) {
                return is_numeric( $timestamp ) && (int) $timestamp >= $cutoff;
            }
        );
    }

    /**
     * @param array<string,int> $fingerprints
     */
    private static function set_recent_fingerprints( array $fingerprints ): void {
        if ( ! function_exists( 'WC' ) || ! WC()->session ) {
            return;
        }

        WC()->session->set( self::SESSION_KEY, $fingerprints );
    }

    /**
     * @return array<string,string>
     */
    private static function extract_attributes_from_request(): array {
        $attributes = [];

        foreach ( $_REQUEST as $key => $value ) {
            $attribute_key = sanitize_text_field( (string) $key );
            if ( 0 !== strpos( $attribute_key, 'attribute_' ) || ! is_scalar( $value ) ) {
                continue;
            }

            $attributes[ $attribute_key ] = sanitize_title( (string) wp_unslash( $value ) );
        }

        return $attributes;
    }
}