<?php

namespace App\Services\PBX;

use Illuminate\Support\Facades\Log;
use Illuminate\Support\Facades\Redis;

/**
 * Persists the first queue of a call for the lifetime of the call.
 *
 * GLN runs on the channel that entered the queue, but Survey can run on a
 * different channel (agent transfer to the Survey destination) that shares
 * only the LINKEDID. Queue logs and CDR rows cannot map those channels while
 * the call is still up, so the queue resolved by the first AGI is stored under
 * the LINKEDID and reused by every later AGI of the same call.
 *
 * The key is written with SET NX: the original queue is never overwritten by
 * a later queue the call enters.
 */
class FirstQueueRegistry
{
    public const TTL_SECONDS = 86400;

    private const KEY_PREFIX = 'call-first-queue:';

    /** @var callable(string): mixed|null */
    private $reader;

    /** @var callable(string, string): void|null */
    private $writer;

    public function __construct(?callable $reader = null, ?callable $writer = null)
    {
        $this->reader = $reader;
        $this->writer = $writer;
    }

    public static function key(string $linkedId): string
    {
        return self::KEY_PREFIX . $linkedId;
    }

    public function get(?string $linkedId): ?string
    {
        if (!is_string($linkedId) || $linkedId === '') {
            return null;
        }

        try {
            $reader = $this->reader ?? static fn (string $key) => Redis::get($key);
            $queueNumber = $reader(self::key($linkedId));

            return is_string($queueNumber) && $queueNumber !== '' ? $queueNumber : null;
        } catch (\Throwable $e) {
            Log::warning('First queue cache read failed', [
                'linkedid' => $linkedId,
                'error' => $e->getMessage(),
            ]);

            return null;
        }
    }

    public function remember(?string $linkedId, string $queueNumber): void
    {
        if (!is_string($linkedId) || $linkedId === '' || $queueNumber === '') {
            return;
        }

        try {
            $writer = $this->writer ?? static function (string $key, string $value): void {
                Redis::set($key, $value, 'EX', self::TTL_SECONDS, 'NX');
            };

            $writer(self::key($linkedId), $queueNumber);
        } catch (\Throwable $e) {
            Log::warning('First queue cache write failed', [
                'linkedid' => $linkedId,
                'queue_number' => $queueNumber,
                'error' => $e->getMessage(),
            ]);
        }
    }
}