<?php

namespace App\Livewire\Admin;

use App\Models\VpnPeer;
use App\Provisioning\Jobs\ApplyVpnPeer;
use App\Provisioning\Jobs\SyncVpnPeers;
use App\Services\Wireguard\Keypair;
use App\Services\Wireguard\WireguardHub;
use Illuminate\Database\QueryException;
use Illuminate\Support\Facades\Cache;
use Livewire\Attributes\Layout;
use Livewire\Attributes\On;
use Livewire\Component;

/**
 * VPN access management. The console container has no wg0, so live state is
 * read from the database and refreshed by SyncVpnPeers on the provisioning
 * queue — the poll below only nudges that job, it never talks to WireGuard.
 */
#[Layout('layouts.admin')]
class Vpn extends Component
{
    public string $name = '';

    /** Optional: a peer that generated its own key never hands us the private half. */
    public string $publicKey = '';

    /** Shown once, right after creation — the private key is never stored. */
    public ?string $newConfig = null;

    public ?string $newConfigName = null;

    public function mount(): void
    {
        $this->authorize('vpn.manage');
    }

    /**
     * mount() runs once; every later request — including the five-second poll —
     * only hydrates. Without this, revoking vpn.manage would not take effect
     * until the operator happened to reload the page, and the open tab would
     * keep serving fresh peer state.
     */
    public function hydrate(): void
    {
        $this->authorize('vpn.manage');
    }

    public function create(): void
    {
        $this->authorize('vpn.manage');

        $this->validate([
            'name' => 'required|string|max:255',
            'publicKey' => 'nullable|string|max:64',
        ]);

        $ownKey = trim($this->publicKey) !== '';
        if ($ownKey && ! Keypair::isValidKey(trim($this->publicKey))) {
            $this->addError('publicKey', __('vpn.invalid_key'));

            return;
        }

        $keypair = $ownKey ? null : Keypair::generate();
        $publicKey = $ownKey ? trim($this->publicKey) : $keypair->publicKey;

        $hub = app(WireguardHub::class);

        // Same lock the host pipeline holds while it reserves an address
        // (ConfigureWireguard). Addresses come from one subnet but live in two
        // tables, so neither unique index can catch the other's insert — the
        // shared lock is what keeps a host and an access off the same tunnel IP.
        try {
            $peer = Cache::lock('wireguard:allocate', 30)->block(10, function () use ($hub, $publicKey) {
                // Inside the lock: checking before it would let two concurrent
                // requests both pass and the loser hit the unique index as a
                // 500. withTrashed, because a revoked peer keeps its key until
                // the hub confirms removal.
                $existing = VpnPeer::withTrashed()->where('public_key', $publicKey)->first();
                if ($existing !== null) {
                    return $existing->trashed() ? 'pending_removal' : 'duplicate_key';
                }

                return VpnPeer::create([
                    'name' => trim($this->name),
                    'public_key' => $publicKey,
                    'allowed_ip' => $hub->allocateIp(),
                    'enabled' => true,
                    'present' => false,
                    'created_by' => auth()->id(),
                ]);
            });
        } catch (QueryException) {
            // Backstop: the unique index caught a writer that did not take this
            // lock. Report it like any other duplicate instead of a 500.
            $this->addError('publicKey', __('vpn.duplicate_key'));

            return;
        }

        if (is_string($peer)) {
            $this->addError('publicKey', __('vpn.'.$peer));

            return;
        }

        ApplyVpnPeer::dispatch($peer->public_key, $peer->allowed_ip, true);

        // Only a key we generated can be turned into a ready-to-use config.
        $this->newConfig = $keypair === null ? null : $this->clientConfig($keypair, $peer->allowed_ip);
        $this->newConfigName = $peer->name;

        $this->reset('name', 'publicKey');
        $this->dispatch('notify', message: __('vpn.created'));
    }

    public function toggle(string $uuid): void
    {
        $this->authorize('vpn.manage');

        $peer = VpnPeer::query()->where('uuid', $uuid)->first();
        if ($peer === null) {
            return;
        }

        $peer->update(['enabled' => ! $peer->enabled]);
        ApplyVpnPeer::dispatch($peer->public_key, $peer->allowed_ip, $peer->enabled);

        $this->dispatch('notify', message: $peer->enabled ? __('vpn.unblocked') : __('vpn.blocked'));
    }

    #[On('vpn-peer-deleted')]
    public function peerDeleted(): void
    {
        $this->dispatch('notify', message: __('vpn.deleted'));
    }

    public function dismissConfig(): void
    {
        $this->reset('newConfig', 'newConfigName');
    }

    /** Polled by the view; throttled so a room full of open tabs cannot flood the queue. */
    public function refreshPeers(): void
    {
        if (Cache::add('vpn:sync-dispatched', true, 8)) {
            SyncVpnPeers::dispatch();
        }
    }

    private function clientConfig(Keypair $keypair, string $ip): string
    {
        $hub = app(WireguardHub::class);

        return implode("\n", [
            '[Interface]',
            'PrivateKey = '.$keypair->privateKey,
            'Address = '.$ip.'/32',
            '',
            '[Peer]',
            'PublicKey = '.$hub->publicKey(),
            'Endpoint = '.$hub->endpoint(),
            'AllowedIPs = '.config('provisioning.wireguard.subnet', '10.66.0.0/24'),
            'PersistentKeepalive = 25',
            '',
        ]);
    }

    public function render()
    {
        $hub = app(WireguardHub::class);

        return view('livewire.admin.vpn', [
            'peers' => VpnPeer::query()->with('host')->orderByDesc('present')->orderBy('name')->get(),
            'hubEndpoint' => $hub->endpoint(),
            'hubPublicKey' => $hub->publicKey(),
            'lastSync' => VpnPeer::query()->max('observed_at'),
        ]);
    }
}