<?php

namespace App\Services;

use App\Contracts\DatabaseListerInterface;
use Illuminate\Support\Facades\DB;
use InvalidArgumentException;
use Throwable;

class SqlServerDatabaseService implements DatabaseListerInterface
{
    private const PROTECTED_DATABASES = ['master', 'model', 'msdb', 'tempdb'];

    private const QUERY = <<<'SQL'
SELECT
    d.name AS db_name,
    CONVERT(varchar(19), d.create_date, 120) AS created,
    DATEDIFF(day, d.create_date, GETDATE()) AS active_days,
    d.state_desc AS state,
    CONVERT(varchar(19), act.last_activity, 120) AS last_index_activity,
    CONVERT(varchar(19), bak.last_backup, 120) AS last_backup
FROM sys.databases d
OUTER APPLY (
    SELECT MAX(v) AS last_activity
    FROM (
        SELECT last_user_seek AS v FROM sys.dm_db_index_usage_stats WHERE database_id = d.database_id
        UNION ALL
        SELECT last_user_scan FROM sys.dm_db_index_usage_stats WHERE database_id = d.database_id
        UNION ALL
        SELECT last_user_lookup FROM sys.dm_db_index_usage_stats WHERE database_id = d.database_id
        UNION ALL
        SELECT last_user_update FROM sys.dm_db_index_usage_stats WHERE database_id = d.database_id
    ) x
) act
OUTER APPLY (
    SELECT MAX(backup_finish_date) AS last_backup
    FROM msdb.dbo.backupset
    WHERE database_name = d.name AND type = 'D'
) bak
SQL;

    private string $connection = 'sqlsrv';

    public function using(string $connection): self
    {
        $clone = clone $this;
        $clone->connection = $connection;

        return $clone;
    }

    public function listDatabases(string $sort, string $dir, string $search = ''): array
    {
        try {
            $rows = collect(DB::connection($this->connection)->select(self::QUERY))
                ->map(fn ($row) => (array) $row);

            if ($search !== '') {
                $needle = mb_strtolower($search);
                $rows = $rows->filter(function (array $row) use ($needle) {
                    return str_contains(mb_strtolower($row['db_name'] ?? ''), $needle)
                        || str_contains(mb_strtolower($row['state'] ?? ''), $needle);
                });
            }

            $rows = $rows->sortBy(function (array $row) use ($sort) {
                if ($sort === 'active_days') {
                    return (int) ($row['active_days'] ?? 0);
                }

                return $row[$sort] ?? '';
            }, SORT_REGULAR, $dir === 'desc');

            $uptime = DB::connection($this->connection)->selectOne(
                'SELECT CONVERT(varchar(19), sqlserver_start_time, 120) AS started, DATEDIFF(day, sqlserver_start_time, GETDATE()) AS uptime_days FROM sys.dm_os_sys_info'
            );

            $host = config('database.connections.' . $this->connection . '.host');

            return [
                'rows' => $rows->values()->all(),
                'meta' => [
                    'total' => $rows->count(),
                    'server' => $host,
                    'driver' => 'sqlsrv',
                    'sql_started' => $uptime->started ?? null,
                    'uptime_days' => $uptime->uptime_days ?? null,
                ],
                'error' => null,
            ];
        } catch (Throwable) {
            return [
                'rows' => [],
                'meta' => [
                    'total' => 0,
                    'server' => config('database.connections.' . $this->connection . '.host'),
                    'driver' => 'sqlsrv',
                    'sql_started' => null,
                    'uptime_days' => null,
                ],
                'error' => 'Unable to load databases. Please check SQL Server connectivity.',
            ];
        }
    }

    public function makeOffline(string $databaseName): void
    {
        $databaseName = $this->validateName($databaseName);

        if ($this->isProtected($databaseName)) {
            throw new InvalidArgumentException('System databases cannot be taken offline.');
        }

        $exists = DB::connection($this->connection)->selectOne(
            'SELECT name, state_desc FROM sys.databases WHERE name = ?',
            [$databaseName]
        );

        if (! $exists) {
            throw new InvalidArgumentException('Database not found.');
        }

        if (($exists->state_desc ?? '') === 'OFFLINE') {
            throw new InvalidArgumentException('Database is already offline.');
        }

        $quoted = str_replace(']', ']]', $databaseName);
        DB::connection($this->connection)->statement(
            "ALTER DATABASE [{$quoted}] SET OFFLINE WITH ROLLBACK IMMEDIATE"
        );
    }

    public function isProtected(string $databaseName): bool
    {
        return in_array(mb_strtolower($databaseName), self::PROTECTED_DATABASES, true);
    }

    public function supportsOffline(): bool
    {
        return true;
    }

    private function validateName(string $databaseName): string
    {
        $databaseName = trim($databaseName);

        if (! preg_match('/^[a-zA-Z0-9_\-]+$/', $databaseName)) {
            throw new InvalidArgumentException('Invalid database name.');
        }

        return $databaseName;
    }
}