<?php
declare(strict_types=1);

namespace wpengine\cache_plugin;

require_once __DIR__ . '/security/security-checks.php';
require_once __DIR__ . '/cache-db-settings.php';
require_once __DIR__ . '/cache-setting-values.php';
require_once __DIR__ . '/logging-trait.php';
\wpengine\cache_plugin\check_security();

class CacheControl {
	use CachePluginLoggingTrait;

	private $db_settings;

	public function __construct( CacheDbSettings $db_settings ) {
		$this->db_settings = $db_settings;
	}

	public function send_header_cache_control_length( $last_modified, $post_id, $post_type ): void {
		$last_mod_seconds = time() - $last_modified;

		$builtin_post_types = $this->db_settings->get( 'sanitized_builtin_post_types' );
		if ( ! is_array( $builtin_post_types ) ) {
			return;
		}
		if ( $this->db_settings->get( 'smarter_cache_enabled' ) &&
			in_array( $post_type, $builtin_post_types, true ) && $last_mod_seconds > CacheSettingValues::FOUR_WEEKS_IN_SECONDS ) {
			$cache_length = CacheSettingValues::SIX_MONTHS_IN_SECONDS;
			$cache_length = apply_filters( 'wpe_smarter_cache_length', $cache_length );
		} else {
			$cache_length = $this->db_settings->get( $post_type . '_cache_expires_value' );
		}

		if ( ! $this->is_int_or_numeric_string( $cache_length ) ) {
			return;
		}

		if ( ! $this->headers_sent() ) {
			$this->header( $cache_length );
		}
	}

	public function send_header_last_modified( $last_modified, $post_id, $post_type ) {
		$last_modified_toggle = $this->db_settings->get( 'last_modified_enabled' );
		$sanitized_post_types = $this->db_settings->get( 'sanitized_post_types' );
		if ( ! is_array( $sanitized_post_types ) ) {
			return;
		}
		if ( '1' === $last_modified_toggle && in_array( $post_type, $sanitized_post_types, true ) ) {
			$last_modified = apply_filters( 'wpe_last_modified_header', $last_modified, $post_id );
			if ( ! $this->is_pure_int( $last_modified ) ) {
				return;
			}
			$last_modified_header = gmdate( 'D, d M Y H:i:s T', $last_modified );
			$this->send_last_modified_header( $last_modified_header );
		}
	}

	public function headers_sent(): bool {
		return headers_sent();
	}

	public function is_pure_int( $value ): bool {
		return is_int( $value );
	}

	public function send_last_modified_header( $last_modified ) {
		header( "Last-Modified: $last_modified" );
	}

	public function header( $cache_length ): void {
		if ( $this->is_setting_default_value( $cache_length ) ) {
			return;
		}
		header( "Cache-Control: max-age=$cache_length, must-revalidate" );
	}

	public function is_on_active_woocommerce_page(): bool {
		if ( $this->is_woocommerce_plugin_active() ) {
			return is_cart() || is_checkout();
		} else {
			return false;
		}
	}

	private function is_woocommerce_plugin_active(): bool {
		return class_exists( 'WooCommerce' ) && function_exists( 'is_cart' ) && function_exists( 'is_checkout' );
	}

	public function wpe_add_cache_header(): void {
		try {
			if ( ! $this->is_singular() ) {
				return;
			}
			// Displaying headers when users were logged in lead to some weird stuff with browser cache.
			// Better to just avoid it when we're passing through varnish anyway.
			if ( $this->is_user_logged_in() ) {
				return;
			}
			$post_id       = $this->get_the_id();
			$post_type     = get_post_type( $post_id );
			$last_modified = get_the_modified_date( 'U' );
			if ( $this->is_on_active_woocommerce_page() ) {
				return;
			}
			if ( ! $this->is_int_or_numeric_string( $last_modified ) ) {
				return;
			}
			$this->send_header_cache_control_length( $last_modified, $post_id, $post_type );
			$this->send_header_last_modified( $last_modified, $post_id, $post_type );
		} catch ( \Exception $e ) {
			$this->log_error( "Caught exception while sending headers: {$e->getMessage()} {$e->getTraceAsString()}" );
		}
	}

	public function get_the_id() {
		return get_the_ID();
	}

	public function is_singular(): bool {
		return is_singular();
	}

	public function is_user_logged_in(): bool {
		return is_user_logged_in();
	}

	public function get_namespace( $route ) {
		try {
			$namespaces = $this->db_settings->get( 'namespaces' );
			if ( ! is_array( $namespaces ) ) {
				return;
			}
			foreach ( $namespaces as $namespace ) {
				if ( ! is_string( $namespace ) ) {
					continue;
				}

				if ( $this->is_empty_string( $namespace ) ) {
					return;
				}

				if ( false !== strpos( $route, $namespace ) ) {
					return $namespace;
				}
			}
		} catch ( \Exception $e ) {
			$this->log_error( "Caught exception while getting namespace: {$e->getMessage()} {$e->getTraceAsString()}" );
		}
	}

	public function send_header_cache_control_api( $route ) {
		try {
			if ( $this->is_user_logged_in() ) {
				return;
			}
			$namespace              = $this->get_namespace( $route );
			$namespace_cache_length = $this->db_settings->get( $namespace . '_cache_expires_value' );
			$namespace_cache_length = apply_filters( 'wpe_cache_namespace_cache_length', $namespace_cache_length, $namespace, $route );
			if ( ! $this->is_int_or_numeric_string( $namespace_cache_length ) ) {
				return;
			}
			if ( ! $this->headers_sent() ) {
				$this->header( $namespace_cache_length );
			}
		} catch ( \Exception $e ) {
			$this->log_error( "Caught exception while sending REST API headers: {$e->getMessage()} {$e->getTraceAsString()}" );
		}
	}

	public function is_int_or_numeric_string( $value ) {
		return is_int( $value ) || $this->is_string_of_all_digits( $value );
	}

	public function is_empty_string( $value ) {
		return empty( $value );
	}

	private function is_setting_default_value( $value ): bool {
		return CacheSettingValues::SETTING_DEFAULT_VALUE === $value;
	}

	private function is_string_of_all_digits( $value ): bool {
		if ( ! is_string( $value ) ) {
			return false;
		}
		return (bool) preg_match( '/^[0-9]+$/', $value );
	}
}