<?php
/**
 * Builds the widget URL and renders the iframe. Shared by the shortcode and
 * the block: both end up here, so there is a single place where parameters are
 * sanitised and a single place where markup is produced.
 *
 * @package PiazzaInFesta
 */

defined( 'ABSPATH' ) || exit;

/**
 * Default values for every supported parameter.
 *
 * @return array<string, string>
 */
function pinfesta_defaults() {
	return array(
		'comuni'    => '',
		'regione'   => '',
		'categoria' => '',
		'limite'    => '5',
		'formato'   => 'lista',
		'tema'      => 'chiaro',
		'colore'    => '',
		'titolo'    => '',
		'altezza'   => '320',
		'dal'       => '',
		'al'        => '',
		'cerca'     => '',
		'font'      => '',
		'lingua'    => '',
	);
}

/**
 * Categories accepted by the service. Anything else is dropped instead of
 * being forwarded, so a typo shows every event rather than none.
 *
 * @return string[]
 */
function pinfesta_categorie() {
	return array(
		'religioso',
		'sagra_enogastronomica',
		'musica_concerto',
		'culturale_mostra',
		'incontro_conferenza',
		'fiera_mercato',
		'mercatini',
		'sportivo',
		'natura_escursione',
		'spettacolo',
		'teatro',
		'cinema',
		'bambini_famiglie',
		'istituzionale',
		'altro',
	);
}

/**
 * Cleans a comma separated list of town identifiers (the slug you see in the
 * address of a town page, for instance "la-morra").
 *
 * The hard limit is the service's, not ours: twelve towns on the free plan,
 * fifty with a key. Here we only cut at the higher of the two, so a site with
 * a key is not trimmed by the plugin; the extra towns are simply ignored by
 * the service when the key is missing.
 *
 * @param string $raw Raw attribute value.
 * @return string Normalised list, empty when nothing survives.
 */
function pinfesta_clean_comuni( $raw ) {
	$out = array();

	foreach ( explode( ',', (string) $raw ) as $item ) {
		$slug = sanitize_title( trim( $item ) );

		if ( '' !== $slug ) {
			$out[] = $slug;
		}
	}

	return implode( ',', array_slice( array_unique( $out ), 0, 50 ) );
}

/**
 * Turns the parameters into the URL of the widget page on the service.
 *
 * @param array $args Parameters, already merged with the defaults.
 * @return string
 */
function pinfesta_build_url( $args ) {
	$query = array();

	$comuni = pinfesta_clean_comuni( $args['comuni'] );

	if ( '' !== $comuni ) {
		$query['comune'] = $comuni;
	} elseif ( '' !== $args['regione'] ) {
		$query['regione'] = sanitize_text_field( $args['regione'] );
	}

	// One category or several, comma separated. Unknown ones are dropped, so a
	// typo widens the widget instead of emptying it.
	$categorie = array();

	foreach ( explode( ',', (string) $args['categoria'] ) as $item ) {
		$item = trim( $item );

		if ( in_array( $item, pinfesta_categorie(), true ) ) {
			$categorie[] = $item;
		}
	}

	if ( $categorie ) {
		$query['categoria'] = implode( ',', array_unique( $categorie ) );
	}

	// Period: only events that start between these two dates (YYYY-MM-DD), for
	// a page about Christmas or the summer. Anything that is not a date is
	// ignored.
	foreach ( array( 'dal', 'al' ) as $chiave_data ) {
		$data = trim( (string) $args[ $chiave_data ] );

		if ( preg_match( '/^\d{4}-\d{2}-\d{2}$/', $data ) ) {
			$query[ $chiave_data ] = $data;
		}
	}

	// A word in the title, for instance "natale" inside the markets.
	$cerca = sanitize_text_field( $args['cerca'] );

	if ( mb_strlen( $cerca ) >= 3 ) {
		$query['cerca'] = mb_substr( $cerca, 0, 40 );
	}

	// Language of the widget: event texts (when translated), labels and links.
	// Empty means "follow the site": the current locale, which multilingual
	// plugins such as WPML or Polylang switch page by page. The service speaks
	// Italian, English, German and French; any other language gets English,
	// which a foreign visitor reads better than Italian.
	$lingua = sanitize_key( (string) $args['lingua'] );

	if ( '' === $lingua ) {
		$lingua = substr( function_exists( 'determine_locale' ) ? determine_locale() : get_locale(), 0, 2 );
	}

	if ( ! in_array( $lingua, array( 'it', 'en', 'de', 'fr' ), true ) ) {
		$lingua = 'en';
	}

	if ( 'it' !== $lingua ) {
		$query['lingua'] = $lingua;
	}

	// The widget lives in an iframe and cannot inherit the site's font: the
	// service offers a few safe stacks to pick from.
	if ( in_array( $args['font'], array( 'helvetica', 'serif' ), true ) ) {
		$query['font'] = $args['font'];
	}

	$limite = absint( $args['limite'] );

	if ( $limite > 0 ) {
		$query['limite'] = min( $limite, 20 );
	}

	// Elenco, schede con la locandina, o carosello che scorre da solo.
	if ( in_array( $args['formato'], array( 'schede', 'carosello' ), true ) ) {
		$query['formato'] = $args['formato'];
	}

	if ( 'scuro' === $args['tema'] ) {
		$query['tema'] = 'scuro';
	}

	$colore = sanitize_hex_color( $args['colore'] );

	if ( $colore ) {
		// Without the hash: add_query_arg() leaves "#" as it is, and a bare "#"
		// in a URL opens the fragment, which would swallow this parameter and
		// every parameter after it. The service accepts the six digits alone.
		$query['accent'] = ltrim( $colore, '#' );
	}

	$titolo = sanitize_text_field( $args['titolo'] );

	if ( '' !== $titolo ) {
		$query['titolo'] = $titolo;
	}

	// Service key: optional. It only tells the service that this site may ask
	// for the version without the Piazza in Festa credit line; every feature of
	// this plugin works exactly the same with or without it.
	$chiave = pinfesta_get_option( 'chiave' );

	if ( '' !== $chiave ) {
		$query['chiave']  = $chiave;
		$query['marchio'] = '0';
	}

	return add_query_arg( $query, pinfesta_base_url() . '/embed' );
}

/**
 * Renders the widget.
 *
 * An iframe, on purpose: the CSS of the host site cannot break the widget and
 * the widget cannot break the host site. The height arrives from the framed
 * page via postMessage (assets/js/resize.js), so nobody has to guess it; the
 * `altezza` parameter is only the starting height, and what visitors see when
 * JavaScript is off.
 *
 * @param array $args Parameters, already merged with the defaults.
 * @return string HTML.
 */
function pinfesta_render_iframe( $args ) {
	$args = wp_parse_args( $args, pinfesta_defaults() );

	if ( '' === pinfesta_clean_comuni( $args['comuni'] ) && '' === trim( (string) $args['regione'] ) ) {
		if ( ! current_user_can( 'edit_posts' ) ) {
			return '';
		}

		return '<p class="pinfesta-empty">' . esc_html__( 'Piazza in Festa: set at least one town or a region.', 'piazza-in-festa' ) . '</p>';
	}

	wp_enqueue_style( 'pinfesta-widget' );
	wp_enqueue_script( 'pinfesta-resize' );

	$altezza = absint( $args['altezza'] );
	$altezza = ( $altezza >= 120 && $altezza <= 4000 ) ? $altezza : 320;

	return sprintf(
		'<iframe class="pinfesta-embed" src="%1$s" title="%2$s" height="%3$d" loading="lazy" scrolling="no" referrerpolicy="no-referrer-when-downgrade"></iframe>',
		esc_url( pinfesta_build_url( $args ) ),
		esc_attr__( 'Upcoming local events', 'piazza-in-festa' ),
		$altezza
	);
}