<?php

declare(strict_types=1);

namespace Monitor\Api\Repository;

use InvalidArgumentException;
use Monitor\Api\Auth\ApiKeyGenerator;
use Monitor\Api\Db\Database;
use Monitor\Api\Http\NotFoundException;

final class AgentRepository
{
    /** @var string[] */
    public const ROLES = ['entwickler', 'product_owner', 'qa', 'user'];

    public function __construct(private readonly Database $db, private readonly int $deskCount = 8)
    {
    }

    /**
     * Registriert einen neuen Agenten und weist ihm bei der Registrierung fest einen
     * Schreibtisch zu (F1/F2: "Agenten erhalten bei der Registrierung eine feste Zuordnung").
     * Die Rolle "user" bekommt nie einen Schreibtisch (kein fester Sitzplatz, F2). Sind alle
     * Schreibtische belegt, registriert sich der Agent trotzdem, aber ohne Schreibtisch
     * ("kommen durch die Tuer, machen ihre Aufgaben und gehen wieder").
     *
     * @return array{agent: array<string, mixed>, api_key: string}
     */
    public function register(string $displayName, string $role): array
    {
        if (!in_array($role, self::ROLES, true)) {
            throw new InvalidArgumentException('Unbekannte Rolle: ' . $role);
        }

        $deskIndex = $role === 'user' ? null : $this->findFreeDesk();

        $apiKey = ApiKeyGenerator::generate();
        $now = $this->db->now();

        $stmt = $this->db->pdo()->prepare(
            'INSERT INTO agents (display_name, role, api_key_hash, desk_index, state, created_at, last_seen_at)
             VALUES (:display_name, :role, :api_key_hash, :desk_index, :state, :created_at, :created_at)'
        );
        $stmt->execute([
            'display_name' => $displayName,
            'role' => $role,
            'api_key_hash' => ApiKeyGenerator::hash($apiKey),
            'desk_index' => $deskIndex,
            'state' => 'idle',
            'created_at' => $now,
        ]);

        $agent = $this->findById((int) $this->db->pdo()->lastInsertId());

        return ['agent' => $agent, 'api_key' => $apiKey];
    }

    private function findFreeDesk(): ?int
    {
        $stmt = $this->db->pdo()->query(
            'SELECT desk_index FROM agents WHERE desk_index IS NOT NULL'
        );
        $occupied = array_map('intval', array_column($stmt->fetchAll(), 'desk_index'));

        for ($i = 0; $i < $this->deskCount; $i++) {
            if (!in_array($i, $occupied, true)) {
                return $i;
            }
        }

        return null;
    }

    /** @return array<string, mixed>|null */
    public function findById(int $id): ?array
    {
        $stmt = $this->db->pdo()->prepare('SELECT * FROM agents WHERE id = :id');
        $stmt->execute(['id' => $id]);
        $row = $stmt->fetch();

        return $row === false ? null : $this->hidingKey($row);
    }

    /** @return array<string, mixed>|null */
    public function findByApiKey(string $apiKey): ?array
    {
        $stmt = $this->db->pdo()->prepare('SELECT * FROM agents WHERE api_key_hash = :hash');
        $stmt->execute(['hash' => ApiKeyGenerator::hash($apiKey)]);
        $row = $stmt->fetch();

        return $row === false ? null : $this->hidingKey($row);
    }

    /** @return array<int, array<string, mixed>> */
    public function all(): array
    {
        $stmt = $this->db->pdo()->query('SELECT * FROM agents ORDER BY id ASC');

        return array_map(fn (array $row) => $this->hidingKey($row), $stmt->fetchAll());
    }

    /** @return array<string, mixed> */
    public function updateActivity(int $id, string $state, ?int $currentTicketId): array
    {
        $stmt = $this->db->pdo()->prepare(
            'UPDATE agents SET state = :state, current_ticket_id = :ticket_id, last_seen_at = :now WHERE id = :id'
        );
        $stmt->execute([
            'state' => $state,
            'ticket_id' => $currentTicketId,
            'now' => $this->db->now(),
            'id' => $id,
        ]);

        $agent = $this->findById($id);
        if ($agent === null) {
            throw new NotFoundException('Agent nicht gefunden: ' . $id);
        }

        return $agent;
    }

    /** @param array<string, mixed> $row @return array<string, mixed> */
    private function hidingKey(array $row): array
    {
        unset($row['api_key_hash']);

        return $row;
    }
}