<?php

declare(strict_types=1);

namespace LIT\MCP;

/**
 * Admin-configurable limits (settings tab "Limits", spec §8.4).
 */
final class Limits
{
    public const OPTION = 'lit_mcp_limits';
    public const DEFAULTS = ['upload_mb' => 5, 'log_retention_days' => 90, 'snapshot_count' => 20];
    /**
     * Hard cap for transfers held in memory as a whole and passed through the MCP response or
     * request as Base64 (lit-media-download, lit/media-upload): above it, PHP memory and the
     * JSON payload become the problem, whatever upload_mb says. URL imports stream to disk
     * and only use upload_mb.
     */
    public const INLINE_MAX_MB = 10;
    private const BOUNDS = ['upload_mb' => [1, 32], 'log_retention_days' => [1, 3650], 'snapshot_count' => [1, 100]];

    public function uploadBytes(): int
    {
        return $this->uploadMegabytes() * 1024 * 1024;
    }

    public function uploadMegabytes(): int
    {
        return $this->all()['upload_mb'];
    }

    /** Limit for Base64 transfers: the upload limit, at most INLINE_MAX_MB. */
    public function inlineBytes(): int
    {
        return $this->inlineMegabytes() * 1024 * 1024;
    }

    public function inlineMegabytes(): int
    {
        return min($this->uploadMegabytes(), self::INLINE_MAX_MB);
    }

    public function logRetentionDays(): int
    {
        return $this->all()['log_retention_days'];
    }

    /** Reserved for design-system snapshots (Etappe 3); LimitsTab keeps the field hidden until then. */
    public function snapshotCount(): int
    {
        return $this->all()['snapshot_count'];
    }

    /** @return array{upload_mb: int, log_retention_days: int, snapshot_count: int} */
    public function all(): array
    {
        return self::sanitize(get_option(self::OPTION, []));
    }

    /**
     * The [min, max] each field is clamped to by sanitize() – for admin UI form attributes,
     * so they can't drift from the actual bounds.
     *
     * @return array<string, array{int, int}>
     */
    public static function bounds(): array
    {
        return self::BOUNDS;
    }

    /**
     * Settings API sanitize callback: always returns all keys, clamped to their bounds.
     *
     * @return array{upload_mb: int, log_retention_days: int, snapshot_count: int}
     */
    public static function sanitize(mixed $input): array
    {
        $input = is_array($input) ? $input : [];
        $clean = self::DEFAULTS;
        foreach (self::BOUNDS as $key => [$min, $max]) {
            if (isset($input[$key]) && is_numeric($input[$key])) {
                $clean[$key] = max($min, min($max, (int) $input[$key]));
            }
        }

        return $clean;
    }
}