<?php

namespace App\Jobs\VirtualMachine\Provision\Concerns;

use App\Models\IpPool;
use App\Models\ModuleIpAddress;
use App\Models\IpPoolLog;
use App\Models\ModuleVmware;
use App\Models\Service;
use App\Models\VirtualMachines;
use App\Services\VirtualMachine\VmProvisionLogger;
use Illuminate\Support\Facades\DB;

trait ManagesIpReservation
{
    /**
     * Reserve a free IP from the pool inside a DB transaction with row-level locks.
     *
     * Strategy:
     *   1. Lock all existing ModuleIpAddress rows for the network → prevents double-pick
     *   2. Lock the chosen IpPool row → prevents concurrent reservations
     *   3. Create a pending ModuleIpAddress (status=0) to hold the slot
     *
     * Returns the pending ModuleIpAddress record, or null if pool is exhausted.
     */
    /**
     * @return array{reservation:ModuleIpAddress,ip_pool_id:int,gateway:string,cidr:int}|null
     */
    private function reserveIp(
        int    $networkId,
        int    $hostId,
        string $dns,
    ): ?array {
        return DB::transaction(function () use ($networkId, $hostId, $dns) {
            // ip_pools.status is the single source of truth for availability.
            $ipPool = IpPool::where('module_network_id', $networkId)
                ->whereIn('status', ['free', 'reserved'])
                ->lockForUpdate()
                ->inRandomOrder()
                ->first();

            if (!$ipPool) {
                return null;
            }

            // Hold the pool slot
            $ipPool->update(['status' => 'reserved']);

            $cidr    = (int) ($ipPool->cidr ?: 24);
            $gateway = (string) ($ipPool->gateway ?? '');
            $netmask = $ipPool->netmask ?: $this->cidrToNetmask($cidr);

            // module_ip_address mirrors ip_pools — update the existing synced row
            // (created when the IP was added to ip_pools) instead of inserting a new one.
            $reservation = ModuleIpAddress::where('ip', $ipPool->ip_address)
                ->where('module_network_id', $networkId)
                ->lockForUpdate()
                ->first();

            $attrs = [
                'vm_name'           => '__pending__',
                'module_host_id'    => $hostId,
                'module_network_id' => $networkId,
                'ip'                => $ipPool->ip_address,
                'gateway'           => $gateway,
                'netmask'           => $netmask,
                'dns'               => $dns,
                'status'            => 0, // 0 = pending/reserved, not yet confirmed
            ];

            if ($reservation) {
                $reservation->update($attrs);
            } else {
                $reservation = ModuleIpAddress::create($attrs);
            }

            return [
                'reservation' => $reservation,
                'ip_pool_id'  => $ipPool->id,
                'gateway'     => $gateway,
                'cidr'        => $cidr,
            ];
        });
    }

    /**
     * Load a reservation that was created upstream (e.g. by CreateVirtualMachineJob).
     * Returns the same shape as reserveIp() so the rest of the flow is identical.
     *
     * @return array{reservation:ModuleIpAddress,ip_pool_id:int,gateway:string,cidr:int}|null
     */
    private function loadReservation(int $reservationId, ?int $ipPoolId, VmProvisionLogger $logger): ?array
    {
        $reservation = ModuleIpAddress::find($reservationId);
        if (!$reservation) {
            $logger->error('upstream reservation missing', [
                'reservation_id' => $reservationId,
            ]);
            return null;
        }

        $ipPool = $ipPoolId ? IpPool::find($ipPoolId) : null;
        $cidr   = (int) ($ipPool->cidr ?? 24);
        $gateway = (string) ($reservation->gateway ?: ($ipPool->gateway ?? ''));

        return [
            'reservation' => $reservation,
            'ip_pool_id'  => $ipPoolId ?? 0,
            'gateway'     => $gateway,
            'cidr'        => $cidr ?: 24,
        ];
    }

    /**
     * Release a failed reservation by resetting the mirrored ModuleIpAddress row.
     * This returns the IP to the available pool.
     */
    private function releaseIp(ModuleIpAddress $reservation, ?int $ipPoolId, VmProvisionLogger $logger): void
    {
        try {
            $reservation->update(['vm_name' => null, 'status' => 0]);
            if ($ipPoolId) {
                IpPool::where('id', $ipPoolId)->update(['status' => 'free']);
            }
            $logger->step('IP reservation released', ['ip' => $reservation->ip]);
        } catch (\Throwable $e) {
            $logger->warning('could not release IP reservation', [
                'ip'    => $reservation->ip,
                'error' => $e->getMessage(),
            ]);
        }
    }

    /**
     * Confirm a successful IP assignment:
     *   - Update ModuleIpAddress: status → 1 (assigned), vm_name → real name
     *   - Update ModuleVmware: ip, dns, module_ip_address FK
     *   - Update VirtualMachines: ip, ip_pool_id FK (matched by vmId)
     *
     * IP is only written to DB AFTER guest-side verification passes.
     */
    private function persistIp(
        ModuleIpAddress $reservation,
        ModuleVmware $moduleVmware,
        ?int $ipPoolId,
        ?int $serviceId,
    ): void {
        DB::transaction(function () use ($reservation, $moduleVmware, $ipPoolId, $serviceId) {
            $reservation->update([
                'vm_name' => $moduleVmware->name ?? ('VM-' . $this->vmId),
                'status'  => 1, // assigned
            ]);

            $moduleVmware->update([
                'ip'                => $reservation->ip,
                'dns'               => $reservation->dns,
                'module_ip_address' => $reservation->id,
            ]);

            // Sync to virtual_machines — matched by vSphere vmId
            VirtualMachines::where('vm_id', $this->vmId)->update([
                'ip'         => $reservation->ip,
                'ip_pool_id' => $ipPoolId,
            ]);

            // Flip ip_pools row to assigned and link service
            if ($ipPoolId) {
                $statusFrom = (string) IpPool::whereKey($ipPoolId)->value('status');
                IpPool::where('id', $ipPoolId)->update([
                    'status'     => 'assigned',
                    'service_id' => $serviceId,
                ]);
                IpPoolLog::recordVm($ipPoolId, IpPoolLog::VM_ASSIGNED, $statusFrom, $moduleVmware, 'Tạo VM');
            }

            // Touch services row so server_name reflects the provisioned VM.
            // Note: services.vm_id is an FK to module_vmware.id (already set by VmServiceSyncService) — do not overwrite with vSphere vmId string.
            if ($serviceId) {
                Service::where('id', $serviceId)->update([
                    'server_name' => $moduleVmware->name,
                ]);
            }
        });
    }

    /** Convert CIDR prefix length to dotted-decimal netmask (e.g. 24 → 255.255.255.0). */
    private function cidrToNetmask(int $cidr): string
    {
        $cidr = max(0, min(32, $cidr));
        return long2ip(-1 << (32 - $cidr));
    }
}