<?php
/**
 * Finds configuration mistakes before visitors do.
 *
 * @package TFlexForms
 */

declare( strict_types = 1 );

namespace TFlexForms;

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

/**
 * Checks a form's template, mail and settings for common problems.
 */
final class Config_Validator {

	/**
	 * Constructor.
	 *
	 * @param Form $form Form to check.
	 */
	public function __construct( private readonly Form $form ) {}

	/**
	 * Returns problems found, each as [ 'tab' => form|mail|settings, 'level' => error|warning, 'message' => string ].
	 *
	 * @return array<int,array{tab:string,level:string,message:string}>
	 */
	public function issues(): array {
		$issues = array();
		$add    = static function ( string $tab, string $level, string $message ) use ( &$issues ): void {
			$issues[] = array(
				'tab'     => $tab,
				'level'   => $level,
				'message' => $message,
			);
		};

		// Template.
		$fields = $this->form->fields();
		foreach ( $this->form->problems() as $error ) {
			$add( 'form', 'error', $error );
		}
		$inputs = $this->form->input_fields();
		if ( array() === $inputs ) {
			$add( 'form', 'error', __( 'The form has no input fields.', 'flexsolutions-form-builder' ) );
		}
		if ( ! array_filter( $fields, static fn( Field $f ) => 'submit' === $f->type ) ) {
			$add( 'form', 'error', __( 'The form has no [submit] button.', 'flexsolutions-form-builder' ) );
		}

		foreach ( $this->form->conditions() as $field_name => $conditions ) {
			foreach ( $conditions as $condition ) {
				if ( ! isset( $inputs[ $condition->field ] ) ) {
					$add(
						'form',
						'error',
						sprintf(
							/* translators: 1: field name in the condition, 2: field inside the group. */
							__( 'The [if] group around [%2$s] refers to an unknown field "%1$s", so the group is always hidden.', 'flexsolutions-form-builder' ),
							$condition->field,
							$field_name
						)
					);
				}
			}
		}

		$has_files = array() !== array_filter( $inputs, static fn( Field $f ): bool => 'file' === $f->type );
		if ( $has_files && empty( $this->form->mail['attach_files'] ) && empty( $this->form->settings['store_entries'] ) ) {
			$add( 'mail', 'warning', __( 'This form accepts files, but they are neither attached to the email nor stored as entries, so uploaded files are discarded.', 'flexsolutions-form-builder' ) );
		}

		// Mail.
		$mail = $this->form->mail;
		if ( '' === $mail['recipient'] ) {
			$add(
				'mail',
				'warning',
				sprintf(
					/* translators: %s: email address. */
					__( 'No recipient set. Messages will go to the site admin email (%s).', 'flexsolutions-form-builder' ),
					(string) get_option( 'admin_email' )
				)
			);
		}

		$known = array_merge(
			array_keys( $inputs ),
			array_map( static fn( string $n ): string => '_raw_' . $n, array_keys( $inputs ) ),
			Mailer::SPECIAL_TAGS
		);

		// Address lists may only use placeholders of piped choice fields (routing).
		foreach ( array(
			'recipient' => __( 'To', 'flexsolutions-form-builder' ),
			'cc'        => __( 'CC', 'flexsolutions-form-builder' ),
			'bcc'       => __( 'BCC', 'flexsolutions-form-builder' ),
		) as $key => $label ) {
			foreach ( self::placeholders( (string) ( $mail[ $key ] ?? '' ) ) as $name ) {
				if ( ! isset( $inputs[ $name ] ) || ! $inputs[ $name ]->has_pipes() ) {
					$add(
						'mail',
						'error',
						sprintf(
							/* translators: 1: placeholder, 2: setting label. */
							__( '[%1$s] in %2$s must be a drop-down, radio or checkbox field whose choices use pipes, e.g. "Sales|sales@example.com". It will be ignored.', 'flexsolutions-form-builder' ),
							$name,
							$label
						)
					);
				}
			}
		}
		$check = array(
			'subject'           => __( 'Subject', 'flexsolutions-form-builder' ),
			'body'              => __( 'Message body', 'flexsolutions-form-builder' ),
			'reply_to'          => __( 'Reply-To', 'flexsolutions-form-builder' ),
			'from_name'         => __( 'From name', 'flexsolutions-form-builder' ),
			'autoreply_subject' => __( 'Auto-reply subject', 'flexsolutions-form-builder' ),
			'autoreply_body'    => __( 'Auto-reply body', 'flexsolutions-form-builder' ),
		);
		foreach ( $check as $key => $label ) {
			foreach ( self::placeholders( (string) $mail[ $key ] ) as $name ) {
				if ( ! in_array( $name, $known, true ) ) {
					$add(
						'mail',
						'warning',
						sprintf(
							/* translators: 1: placeholder, 2: setting label. */
							__( 'Unknown placeholder [%1$s] in %2$s. It will be sent as plain text.', 'flexsolutions-form-builder' ),
							$name,
							$label
						)
					);
				}
			}
		}

		if ( Form::is_placeholder( (string) $mail['reply_to'] ) && ! $this->is_email_field( trim( (string) $mail['reply_to'], '[]' ) ) ) {
			$add( 'mail', 'error', __( 'Reply-To must be an email field placeholder, such as [your-email].', 'flexsolutions-form-builder' ) );
		}

		if ( ! empty( $mail['autoreply_enabled'] ) ) {
			if ( ! $this->is_email_field( trim( (string) $mail['autoreply_to'], '[]' ) ) ) {
				$add( 'mail', 'error', __( 'Auto-reply is on, but "Auto-reply to" is not an email field placeholder, so no auto-reply will be sent.', 'flexsolutions-form-builder' ) );
			}
			// Content the visitor controls, mailed to an address the visitor controls, is a spam relay.
			$used   = array_map(
				static fn( string $n ): string => str_starts_with( $n, '_raw_' ) ? substr( $n, 5 ) : $n,
				array_merge( self::placeholders( (string) $mail['autoreply_subject'] ), self::placeholders( (string) $mail['autoreply_body'] ) )
			);
			$echoed = array_values( array_intersect( array_keys( $inputs ), $used ) );
			if ( array() !== $echoed ) {
				$add(
					'mail',
					'warning',
					sprintf(
						/* translators: %s: list of placeholders. */
						__( 'The auto-reply repeats visitor input (%s). Spammers can abuse this to send their text through your site. Consider removing it.', 'flexsolutions-form-builder' ),
						'[' . implode( '], [', $echoed ) . ']'
					)
				);
			}
		}

		$from_domain = $this->from_domain();
		$site_domain = preg_replace( '/^www\./i', '', (string) wp_parse_url( home_url(), PHP_URL_HOST ) );
		if ( '' !== $from_domain && '' !== $site_domain && strtolower( $from_domain ) !== strtolower( $site_domain ) && ! str_ends_with( strtolower( $from_domain ), '.' . strtolower( $site_domain ) ) ) {
			$add(
				'mail',
				'warning',
				sprintf(
					/* translators: 1: sender domain, 2: site domain. */
					__( 'Mail is sent from @%1$s, which differs from this site (%2$s). Make sure that domain authorises your server (SPF/DKIM), or messages may land in spam.', 'flexsolutions-form-builder' ),
					$from_domain,
					$site_domain
				)
			);
		}

		// Settings.
		if ( Captcha::requested_by( $this->form ) && null === Captcha::active() ) {
			$add( 'settings', 'error', __( 'CAPTCHA is switched on, but no provider is configured in Flexsolutions Form Builder → Settings, so the form is not protected by CAPTCHA.', 'flexsolutions-form-builder' ) );
		}
		if ( ! empty( $this->form->settings['akismet'] ) && ! Content_Filter::akismet_available() ) {
			$add( 'settings', 'warning', __( 'Akismet checking is on, but Akismet is not active with an API key.', 'flexsolutions-form-builder' ) );
		}
		if ( ! empty( $this->form->settings['demo_mode'] ) ) {
			$add( 'settings', 'warning', __( 'Demo mode is on: submissions are validated but no email is sent.', 'flexsolutions-form-builder' ) );
		}

		/**
		 * Filters configuration issues for a form.
		 *
		 * @param array $issues Issues found.
		 * @param Form  $form   Form.
		 */
		return (array) apply_filters( 'tflexforms_config_issues', $issues, $this->form );
	}

	/**
	 * Placeholder names used in a text, e.g. "[a] [_date]" => [ 'a', '_date' ].
	 *
	 * @param string $text Text.
	 * @return string[]
	 */
	public static function placeholders( string $text ): array {
		preg_match_all( '/\[(_?[A-Za-z][A-Za-z0-9_-]*)\]/', $text, $m );
		return array_values( array_unique( $m[1] ) );
	}

	/**
	 * Whether a field name refers to an email field in this form.
	 *
	 * @param string $name Field name.
	 */
	private function is_email_field( string $name ): bool {
		$fields = $this->form->input_fields();
		return isset( $fields[ $name ] ) && 'email' === $fields[ $name ]->type;
	}

	/**
	 * Domain of the address WordPress will send from (after other plugins' filters).
	 */
	private function from_domain(): string {
		$host = (string) wp_parse_url( network_home_url(), PHP_URL_HOST );
		$host = preg_replace( '/^www\./i', '', $host );
		$from = (string) ( $this->form->mail['from_email'] ?? '' );
		if ( '' === $from ) {
			$from = (string) apply_filters( 'wp_mail_from', 'wordpress@' . $host ); // phpcs:ignore WordPress.NamingConventions.PrefixAllGlobals.NonPrefixedHooknameFound -- Reading core's filter.
		}
		$at = strrpos( $from, '@' );
		return false === $at ? '' : substr( $from, $at + 1 );
	}
}