<?php
/**
 * Form templates: ready-made forms to start from.
 *
 * @package TFlexForms
 */

declare( strict_types = 1 );

namespace TFlexForms;

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

/**
 * Reads the templates in templates/*.json (one file per template; the file
 * name is its id) and creates forms from them.
 *
 * A template file holds a title, a description, a category, a sort order,
 * the form's fields (and optional layout) in the form schema format (see
 * docs/form-schema.md), and optional mail settings and messages in the Mail
 * and Messages tab format, which are merged over the defaults. The text is
 * English; its translations come from Template_Strings, which bin/template-strings.php
 * regenerates from the files whenever they change.
 *
 * Add-ons add or change templates with the tflexforms_templates filter and
 * categories with tflexforms_template_categories.
 */
final class Templates {

	/** Folder of the template files, in the plugin. */
	public const DIR = 'templates';

	/** A section heading element's content (its text is translated). */
	public const HEADING = '#^<h([2-4]) class="tflexforms-heading">([^<]*)</h\\1>$#';

	/**
	 * Valid templates, keyed by id (cached per request).
	 *
	 * @var array<string,array<string,mixed>>|null
	 */
	private static ?array $all = null;

	/**
	 * Template categories, in display order: key => label.
	 *
	 * @return array<string,string>
	 */
	public static function categories(): array {
		$categories = array(
			'basic'      => __( 'Basic', 'flexsolutions-form-builder' ),
			'marketing'  => __( 'Marketing', 'flexsolutions-form-builder' ),
			'events'     => __( 'Events', 'flexsolutions-form-builder' ),
			'feedback'   => __( 'Feedback', 'flexsolutions-form-builder' ),
			'recruiting' => __( 'Recruiting', 'flexsolutions-form-builder' ),
			'support'    => __( 'Support', 'flexsolutions-form-builder' ),
		);
		/**
		 * Filters the template categories shown in the template picker.
		 *
		 * @param array<string,string> $categories Category key => label.
		 */
		$categories = apply_filters( 'tflexforms_template_categories', $categories );
		return is_array( $categories ) ? array_map( 'strval', $categories ) : array();
	}

	/**
	 * Every valid template, sorted by order then title, keyed by id. Each has
	 * id, title, description, category, order, schema (Form_Schema), mail and
	 * messages. A template whose fields are not a valid schema is left out.
	 *
	 * @return array<string,array<string,mixed>>
	 */
	public static function all(): array {
		if ( null !== self::$all ) {
			return self::$all;
		}
		$raw = self::files();
		/**
		 * Filters the form templates before they are checked: add, change or
		 * remove templates. Each is an array in the format of the plugin's
		 * templates/*.json files (title, description, category, order, fields,
		 * layout, mail, messages), keyed by a unique id.
		 *
		 * @param array<string,array<string,mixed>> $raw Templates by id.
		 */
		$raw        = apply_filters( 'tflexforms_templates', $raw );
		$categories = self::categories();
		$all        = array();
		foreach ( is_array( $raw ) ? $raw : array() as $id => $data ) {
			$id       = sanitize_key( (string) $id );
			$template = '' !== $id && is_array( $data ) ? self::normalize( $id, self::translate( $data ), $categories ) : null;
			if ( null !== $template ) {
				$all[ $id ] = $template;
			}
		}
		uasort(
			$all,
			static fn( array $a, array $b ): int => array( $a['order'], $a['title'] ) <=> array( $b['order'], $b['title'] )
		);
		self::$all = $all;
		return $all;
	}

	/**
	 * One template, or null when there is no valid template with that id.
	 *
	 * @param string $id Template id.
	 * @return array<string,mixed>|null
	 */
	public static function get( string $id ): ?array {
		return self::all()[ $id ] ?? null;
	}

	/**
	 * Forgets the cached templates (after filters change, in tests).
	 */
	public static function reset(): void {
		self::$all = null;
	}

	/**
	 * Gives a form a template's fields, mail settings and messages.
	 *
	 * @param int    $form_id Form post ID.
	 * @param string $id      Template id.
	 */
	public static function apply( int $form_id, string $id ): bool {
		$template = self::get( $id );
		if ( null === $template ) {
			return false;
		}
		$meta = Schema_Migration::store_meta( $template['schema'] );

		$meta[ Form_Post_Type::META_MAIL ] = $template['mail'];
		if ( array() !== $template['messages'] ) {
			$meta[ Form_Post_Type::META_MESSAGES ] = $template['messages'];
		}
		Schema_Migration::write_meta( $form_id, $meta );
		return true;
	}

	/**
	 * The text of a template that is translated: title, description, the
	 * fields' labels, help, placeholders, button and choice text, headings,
	 * mail subjects and bodies, and messages.
	 *
	 * @param array<string,mixed> $data Template file data.
	 * @return string[]
	 */
	public static function strings( array $data ): array {
		$strings = array();
		self::walk(
			$data,
			static function ( string $text ) use ( &$strings ): string {
				$strings[] = $text;
				return $text;
			}
		);
		return array_values( array_unique( $strings ) );
	}

	/**
	 * Decoded template files by id.
	 *
	 * @return array<string,array<string,mixed>>
	 */
	public static function files(): array {
		$out   = array();
		$files = glob( PLUGIN_DIR . '/' . self::DIR . '/*.json' );
		foreach ( false !== $files ? $files : array() as $file ) {
			$json = file_get_contents( $file ); // phpcs:ignore WordPress.WP.AlternativeFunctions.file_get_contents_file_get_contents -- Local plugin file.
			$data = false !== $json ? json_decode( $json, true ) : null;
			if ( is_array( $data ) ) {
				$out[ basename( $file, '.json' ) ] = $data;
			}
		}
		return $out;
	}

	/**
	 * A template with its text translated.
	 *
	 * @param array<string,mixed> $data Template data.
	 * @return array<string,mixed>
	 */
	private static function translate( array $data ): array {
		$map = Template_Strings::all();
		return self::walk( $data, static fn( string $text ): string => $map[ $text ] ?? $text );
	}

	/**
	 * Applies a callback to each translated text of a template.
	 *
	 * @param array<string,mixed>      $data Template data.
	 * @param callable(string): string $callback Callback.
	 * @return array<string,mixed>
	 */
	private static function walk( array $data, callable $callback ): array {
		$text = static function ( array $item, array $keys ) use ( $callback ): array {
			foreach ( $keys as $key ) {
				if ( isset( $item[ $key ] ) && is_string( $item[ $key ] ) && '' !== $item[ $key ] ) {
					$item[ $key ] = $callback( $item[ $key ] );
				}
			}
			return $item;
		};

		$data = $text( $data, array( 'title', 'description' ) );
		if ( isset( $data['fields'] ) && is_array( $data['fields'] ) ) {
			foreach ( $data['fields'] as $i => $field ) {
				if ( ! is_array( $field ) ) {
					continue;
				}
				$field = $text( $field, array( 'label', 'help', 'placeholder', 'text', 'firstLabel' ) );
				// A section heading's text (other HTML is not translated).
				if ( isset( $field['content'] ) && is_string( $field['content'] ) && 1 === preg_match( self::HEADING, $field['content'], $m ) ) {
					$field['content'] = '<h' . $m[1] . ' class="tflexforms-heading">' . esc_html( $callback( html_entity_decode( $m[2], ENT_QUOTES ) ) ) . '</h' . $m[1] . '>';
				}
				if ( isset( $field['choices'] ) && is_array( $field['choices'] ) ) {
					foreach ( $field['choices'] as $c => $choice ) {
						$field['choices'][ $c ] = is_array( $choice ) ? $text( $choice, array( 'label' ) ) : $choice;
					}
				}
				$data['fields'][ $i ] = $field;
			}
		}
		if ( isset( $data['mail'] ) && is_array( $data['mail'] ) ) {
			$data['mail'] = $text( $data['mail'], array( 'subject', 'body', 'autoreply_subject', 'autoreply_body' ) );
		}
		if ( isset( $data['messages'] ) && is_array( $data['messages'] ) ) {
			$data['messages'] = $text( $data['messages'], array_keys( $data['messages'] ) );
		}
		return $data;
	}

	/**
	 * A checked template, or null when its fields are not a valid schema.
	 *
	 * @param string               $id         Template id.
	 * @param array<string,mixed>  $data       Translated template data.
	 * @param array<string,string> $categories Known categories.
	 * @return array<string,mixed>|null
	 */
	private static function normalize( string $id, array $data, array $categories ): ?array {
		$doc = array(
			'schemaVersion' => Form_Schema::VERSION,
			'fields'        => isset( $data['fields'] ) && is_array( $data['fields'] ) ? $data['fields'] : array(),
		);
		if ( isset( $data['layout'] ) && is_array( $data['layout'] ) ) {
			$doc['layout'] = $data['layout'];
		}
		$schema = array() !== $doc['fields'] ? Form_Schema::from_array( $doc ) : null;
		if ( null === $schema ) {
			return null;
		}
		$category = isset( $data['category'] ) ? sanitize_key( (string) $data['category'] ) : '';
		return array(
			'id'          => $id,
			'title'       => sanitize_text_field( (string) ( $data['title'] ?? $id ) ),
			'description' => sanitize_text_field( (string) ( $data['description'] ?? '' ) ),
			'category'    => isset( $categories[ $category ] ) ? $category : (string) array_key_first( $categories ),
			'order'       => (int) ( $data['order'] ?? 100 ),
			'schema'      => $schema,
			'mail'        => Form::sanitize_mail_settings( array_merge( Form::default_mail_settings(), isset( $data['mail'] ) && is_array( $data['mail'] ) ? $data['mail'] : array() ) ),
			'messages'    => isset( $data['messages'] ) && is_array( $data['messages'] ) ? Form::sanitize_messages( $data['messages'] ) : array(),
		);
	}
}