<?php
/**
 * Scene fields that arrive from a request and are used to build CSS.
 *
 * Breakpoints decide the media queries the compiler emits, so the identifier and the width
 * are both checked here rather than written into a selector as they arrive.
 *
 * @package Aumframe
 */

namespace Aumframe\Css;

defined('ABSPATH') || exit;

final class Scene
{
    /** What a scene with no breakpoints of its own compiles against. */
    public const DEFAULT_BREAKPOINTS = [['id' => 'desktop', 'max' => null]];

    /** The widest breakpoint a media query will be emitted for. */
    private const MAX_WIDTH = 20000;

    /**
     * Validate a breakpoint list.
     *
     * The first entry is the base and carries no width. Every later entry needs a width,
     * because that is what its media query is built from; one without is dropped rather
     * than defaulted, so a malformed list cannot widen a rule's reach.
     *
     * @param mixed $raw
     * @return array<int,array{id:string,max:int|null}>
     */
    public static function breakpoints($raw): array
    {
        if (!is_array($raw) || !Value::isList($raw) || $raw === []) {
            return self::DEFAULT_BREAKPOINTS;
        }

        $out  = [];
        $seen = [];
        foreach ($raw as $bp) {
            $id = Value::get($bp, 'id');
            if (!is_string($id) || !preg_match('/^[a-z][a-z0-9_-]{0,31}$/', $id) || isset($seen[$id])) {
                continue;
            }
            $max = Value::get($bp, 'max');
            if ($out === []) {
                /* The base breakpoint: no media query, so no width. */
                $seen[$id] = true;
                $out[]     = ['id' => $id, 'max' => null];
                continue;
            }
            if (!is_int($max) && !is_float($max) && !(is_string($max) && preg_match('/^\d{1,5}$/', $max))) {
                continue;
            }
            $max = (int) $max;
            if ($max < 1 || $max > self::MAX_WIDTH) {
                continue;
            }
            $seen[$id] = true;
            $out[]     = ['id' => $id, 'max' => $max];
        }

        return $out === [] ? self::DEFAULT_BREAKPOINTS : $out;
    }
}