<?php
/**
 * A dashboard's list of feeds.
 *
 * @package PulseCast
 */

namespace PulseCast\Domain;

use PulseCast\Feeds\Feed_Normalizer;
use PulseCast\Support\Url_Validator;

/**
 * Validates and reads a list of `{ url, label }` feeds. Pure PHP.
 */
final class Feed_List {

	public const MAX_LABEL = 60;

	/**
	 * Validates feeds submitted by an administrator.
	 *
	 * Rows with neither a URL nor a label are ignored. Duplicate URLs are dropped. Each URL is
	 * checked with the validator, including name resolution.
	 *
	 * @param mixed         $raw       Submitted value.
	 * @param Url_Validator $validator URL validator.
	 * @return array{feeds: array<int,array{url:string,label:string}>, errors: array<int,string>} Valid feeds, and an error code per rejected row index.
	 */
	public static function sanitize( $raw, Url_Validator $validator ): array {
		$feeds  = array();
		$errors = array();
		$seen   = array();

		foreach ( is_array( $raw ) ? array_values( $raw ) : array() as $index => $row ) {
			$url   = is_array( $row ) && is_string( $row['url'] ?? null ) ? trim( $row['url'] ) : '';
			$label = is_array( $row ) && is_string( $row['label'] ?? null ) ? Feed_Normalizer::plain_text( $row['label'], self::MAX_LABEL ) : '';
			$color = is_array( $row ) ? self::sanitize_color( $row['color'] ?? '' ) : '';

			if ( '' === $url && '' === $label ) {
				continue;
			}

			$error = '' === $url ? Url_Validator::INVALID_URL : $validator->check_feed_url( $url );

			if ( null !== $error ) {
				$errors[ $index ] = $error;
				continue;
			}

			if ( isset( $seen[ $url ] ) ) {
				continue;
			}

			$seen[ $url ] = true;
			$feeds[]      = self::feed( $url, $label, $color );
		}//end foreach

		return array(
			'feeds'  => $feeds,
			'errors' => $errors,
		);
	}

	/**
	 * Validates an optional source colour: `#rgb` or `#rrggbb`, returned as lower-case `#rrggbb`.
	 * Anything else, including CSS functions and named colours, becomes an empty string, which
	 * means "assign automatically".
	 *
	 * @param mixed $value Submitted value.
	 */
	public static function sanitize_color( $value ): string {
		if ( ! is_string( $value ) ) {
			return '';
		}

		$value = strtolower( trim( $value ) );

		if ( 1 === preg_match( '/^#([0-9a-f])([0-9a-f])([0-9a-f])\z/', $value, $m ) ) {
			return '#' . $m[1] . $m[1] . $m[2] . $m[2] . $m[3] . $m[3];
		}

		return 1 === preg_match( '/^#[0-9a-f]{6}\z/', $value ) ? $value : '';
	}

	/**
	 * Builds a feed row. The colour key is only present when a colour is set.
	 *
	 * @param string $url   URL.
	 * @param string $label Label.
	 * @param string $color Validated colour or an empty string.
	 * @return array{url:string,label:string,color?:string}
	 */
	public static function feed( string $url, string $label, string $color ): array {
		$feed = array(
			'url'   => $url,
			'label' => $label,
		);

		if ( '' !== $color ) {
			$feed['color'] = $color;
		}

		return $feed;
	}

	/**
	 * Reads feeds that were stored earlier. Structure only: no URL checks and no DNS, because
	 * the fetcher validates every URL again before each request.
	 *
	 * @param mixed $stored Stored value.
	 * @return array<int,array{url:string,label:string}>
	 */
	public static function from_storage( $stored ): array {
		$feeds = array();

		foreach ( is_array( $stored ) ? $stored : array() as $row ) {
			if ( is_array( $row ) && is_string( $row['url'] ?? null ) && '' !== $row['url'] ) {
				$feeds[] = self::feed( $row['url'], is_string( $row['label'] ?? null ) ? $row['label'] : '', self::sanitize_color( $row['color'] ?? '' ) );
			}
		}

		return $feeds;
	}
}