<?php

namespace App\Features;

use App\Models\User;
use Carbon\CarbonImmutable;

/**
 * A/B/C assignment for the trial/pricing experiment.
 *
 * Users who registered before `subscriptions.experiment.started_at` (or any user
 * while it is null) are "legacy" and behave like the control group. Everyone who
 * registered on or after the start is split evenly into the three variants by a
 * stable hash of their id, so the bucket never changes for a given user.
 *
 * The split is deterministic (crc32(id) % 3); the funnel report mirrors the same
 * formula in SQL. Manual overrides via `feature:enable` are honoured at runtime
 * but are not reflected in that report — keep overrides to QA accounts.
 *
 * @api
 */
class SubscriptionExperiment
{
    public const LEGACY = 'legacy';

    public const CONTROL = 'control';

    public const REDUCED_TRIAL = 'reduced_trial';

    public const PAY_NOW = 'pay_now';

    public function resolve(User $user): string
    {
        $startedAt = config('subscriptions.experiment.started_at');

        if ($startedAt === null || $user->created_at?->lt(CarbonImmutable::parse($startedAt))) {
            return self::LEGACY;
        }

        return match (crc32((string) $user->getKey()) % 3) {
            0 => self::CONTROL,
            1 => self::REDUCED_TRIAL,
            default => self::PAY_NOW,
        };
    }
}