<?php

declare(strict_types=1);

namespace Mod\Names\Controllers;

use Illuminate\Http\JsonResponse;
use Illuminate\Http\Request;
use Illuminate\Routing\Controller;
use Illuminate\Support\Facades\Cache;
use Mod\Chain\Services\DaemonRpc;
use Mod\Chain\Services\WalletRpc;

/**
 * .lthn TLD registrar API.
 *
 *   GET  /v1/names/available/{name}  — check if name is available
 *   GET  /v1/names/lookup/{name}     — look up a registered name
 *   GET  /v1/names/search?q={query}  — search names
 *   POST /v1/names/register          — request name registration
 *   GET  /v1/names/directory         — list all names grouped by type
 */
class NamesController extends Controller
{
    public function __construct(
        private readonly DaemonRpc $rpc,
        private readonly WalletRpc $wallet,
    ) {}

    /**
     *   GET /v1/names/available/myname
     */
    public function available(string $name): JsonResponse
    {
        $name = strtolower(trim($name));

        if (! $this->isValidName($name)) {
            return response()->json([
                'available' => false,
                'reason' => 'Invalid name. Use 1-63 lowercase alphanumeric characters.',
            ]);
        }

        $alias = $this->rpc->getAliasByName($name);
        $reserved = Cache::has("name_lock:{$name}");

        return response()->json([
            'name' => $name,
            'available' => $alias === null && ! $reserved,
            'reserved' => $reserved,
            'fqdn' => "{$name}.lthn",
        ]);
    }

    /**
     *   GET /v1/names/lookup/charon
     */
    public function lookup(string $name): JsonResponse
    {
        $alias = $this->rpc->getAliasByName(strtolower(trim($name)));

        if (! $alias) {
            return response()->json(['error' => 'Name not registered'], 404);
        }

        return response()->json([
            'name' => $name,
            'fqdn' => "{$name}.lthn",
            'address' => $alias['address'] ?? '',
            'comment' => $alias['comment'] ?? '',
            'registered' => true,
        ]);
    }

    /**
     *   GET /v1/names/search?q=gate
     */
    public function search(Request $request): JsonResponse
    {
        $query = strtolower(trim((string) $request->get('q')));
        $result = $this->rpc->getAllAliases();
        $aliases = $result['aliases'] ?? [];

        $matches = array_filter($aliases, function ($alias) use ($query) {
            return str_contains($alias['alias'] ?? '', $query)
                || str_contains($alias['comment'] ?? '', $query);
        });

        return response()->json([
            'query' => $query,
            'results' => array_values($matches),
            'count' => count($matches),
        ]);
    }

    /**
     *   GET /v1/names/directory
     */
    public function directory(): JsonResponse
    {
        $result = $this->rpc->getAllAliases();
        $aliases = $result['aliases'] ?? [];

        // Group by type from comment metadata
        $grouped = ['gateway' => [], 'service' => [], 'exit' => [], 'reserved' => [], 'user' => []];

        foreach ($aliases as $alias) {
            $comment = $alias['comment'] ?? '';
            if (str_contains($comment, 'type=gateway')) {
                $grouped['gateway'][] = $alias;
            } elseif (str_contains($comment, 'type=exit')) {
                $grouped['exit'][] = $alias;
            } elseif (str_contains($comment, 'type=service')) {
                $grouped['service'][] = $alias;
            } elseif (str_contains($comment, 'type=reserved')) {
                $grouped['reserved'][] = $alias;
            } else {
                $grouped['user'][] = $alias;
            }
        }

        return response()->json([
            'total' => count($aliases),
            'directory' => $grouped,
        ]);
    }

    /**
     *   POST /v1/names/register  {"name": "mysite", "address": "iTHN..."}
     */
    public function register(Request $request): JsonResponse
    {
        $name = strtolower(trim((string) $request->input('name')));
        $address = trim((string) $request->input('address'));
        $comment = trim((string) $request->input('comment', 'v=lthn1;type=user'));

        if (! $this->isValidName($name)) {
            return response()->json([
                'error' => 'Invalid name. Use 1-63 lowercase alphanumeric characters.',
            ], 422);
        }

        if (empty($address) || ! str_starts_with($address, 'iTHN')) {
            return response()->json([
                'error' => 'Invalid Lethean address.',
            ], 422);
        }

        // Pre-flight: check wallet has funds
        $balance = $this->wallet->getBalance();
        $unlocked = ($balance['unlocked_balance'] ?? 0) / 1e12;
        if ($unlocked < 0.01) {
            return response()->json([
                'error' => 'Registrar wallet has insufficient funds. Please try again later.',
                'name' => $name,
            ], 503);
        }

        // Check availability on chain + reservation lock
        $existing = $this->rpc->getAliasByName($name);
        if ($existing !== null) {
            return response()->json([
                'error' => 'Name already registered.',
                'name' => $name,
            ], 409);
        }

        // Atomic reservation — prevent race condition
        $lockKey = "name_lock:{$name}";
        if (Cache::has($lockKey)) {
            return response()->json([
                'error' => 'This name is being registered by another customer. Please try a different name.',
                'name' => $name,
            ], 409);
        }
        Cache::put($lockKey, true, 600); // 10 minute reservation

        // Register via wallet RPC
        $result = $this->wallet->registerAlias($name, $address, $comment);

        if (isset($result['code']) || isset($result['error'])) {
            $message = $result['message'] ?? ($result['error'] ?? 'Unknown error');
            $code = 502;

            if (str_contains($message, 'NOT_ENOUGH_MONEY')) {
                $message = 'Registrar wallet has insufficient funds. Please try again later.';
                $code = 503;
            }

            // Release lock on permanent failure so name can be retried
            Cache::forget($lockKey);

            return response()->json([
                'error' => $message,
                'name' => $name,
            ], $code);
        }

        if (isset($result['tx_id'])) {
            return response()->json([
                'name' => $name,
                'fqdn' => "{$name}.lthn",
                'address' => $address,
                'tx_id' => $result['tx_id'],
                'status' => 'pending',
            ], 201);
        }

        return response()->json([
            'error' => 'Unexpected response from chain',
            'details' => $result,
        ], 500);
    }

    /**
     *   GET /v1/names/records/charon
     *
     * Reads DNS records from the LNS sidechain.
     */
    public function records(string $name): JsonResponse
    {
        $name = strtolower(trim($name));
        $lnsUrl = config('chain.lns_url', 'http://127.0.0.1:5553');

        $records = [];
        foreach (['A', 'AAAA', 'CNAME', 'MX', 'TXT', 'SRV'] as $type) {
            $response = @file_get_contents("{$lnsUrl}/resolve?name={$name}&type={$type}");
            if ($response) {
                $data = json_decode($response, true);
                if (! empty($data[$type])) {
                    foreach ($data[$type] as $value) {
                        $records[] = [
                            'type' => $type,
                            'host' => '@',
                            'value' => $value,
                            'ttl' => 3600,
                        ];
                    }
                }
            }
        }

        return response()->json([
            'name' => $name,
            'fqdn' => "{$name}.lthn",
            'records' => $records,
        ]);
    }

    /**
     *   POST /v1/names/records/charon  {"records": [{"type":"A","host":"@","value":"1.2.3.4"}]}
     *
     * Updates DNS records by calling update_alias on the wallet RPC.
     * Encodes records into the alias comment field for LNS to parse.
     */
    public function updateRecords(Request $request, string $name): JsonResponse
    {
        $name = strtolower(trim($name));
        $records = $request->input('records', []);

        // Look up the current alias to get the address
        $alias = $this->rpc->getAliasByName($name);
        if (! $alias) {
            return response()->json(['error' => 'Name not registered'], 404);
        }

        $address = $alias['address'] ?? '';

        // Build the comment with DNS records encoded for LNS
        // Format: v=lthn1;type=user;dns=TYPE:HOST:VALUE,TYPE:HOST:VALUE
        $dnsEntries = [];
        foreach ($records as $record) {
            $type = $record['type'] ?? 'A';
            $host = $record['host'] ?? '@';
            $value = $record['value'] ?? '';
            if ($value) {
                $dnsEntries[] = "{$type}:{$host}:{$value}";
            }
        }

        $comment = 'v=lthn1;type=user';
        if ($dnsEntries) {
            $comment .= ';dns=' . implode(',', $dnsEntries);
        }

        // Try to update the alias on chain via wallet RPC
        $result = $this->wallet->updateAlias($name, $address, $comment);
        $ticketId = substr(md5($name . time()), 0, 12);

        // Track ticket ID for background retry
        $ticketIds = Cache::get('dns_ticket_ids', []);
        $ticketIds[] = $ticketId;
        Cache::put('dns_ticket_ids', array_unique($ticketIds), 86400);

        if (isset($result['tx_id'])) {
            // Immediate success — tx submitted
            Cache::put("dns_ticket:{$ticketId}", [
                'name' => $name,
                'status' => 'pending',
                'tx_id' => $result['tx_id'],
                'records' => $records,
                'created_at' => now()->toIso8601String(),
            ], 3600);

            return response()->json([
                'name' => $name,
                'ticket' => $ticketId,
                'tx_id' => $result['tx_id'],
                'status' => 'pending',
                'message' => 'DNS update submitted. Awaiting chain confirmation.',
            ]);
        }

        // Chain busy — queue for retry
        Cache::put("dns_ticket:{$ticketId}", [
            'name' => $name,
            'status' => 'queued',
            'records' => $records,
            'comment' => $comment,
            'address' => $address,
            'error' => $result['message'] ?? ($result['error'] ?? 'Chain busy'),
            'created_at' => now()->toIso8601String(),
        ], 3600);

        return response()->json([
            'name' => $name,
            'ticket' => $ticketId,
            'status' => 'queued',
            'message' => 'DNS update queued. Will be processed when chain is ready.',
        ], 202);
    }

    /**
     *   GET /v1/names/ticket/{id}
     *
     * Check the status of a DNS change ticket.
     */
    public function ticket(string $id): JsonResponse
    {
        $ticket = Cache::get("dns_ticket:{$id}");

        if (! $ticket) {
            return response()->json(['error' => 'Ticket not found'], 404);
        }

        // If pending, check if the tx has confirmed
        if ($ticket['status'] === 'pending' && ! empty($ticket['tx_id'])) {
            $alias = $this->rpc->getAliasByName($ticket['name']);
            if ($alias && str_contains($alias['comment'] ?? '', 'dns=')) {
                $ticket['status'] = 'confirmed';
                Cache::put("dns_ticket:{$id}", $ticket, 3600);
            }
        }

        return response()->json([
            'ticket' => $id,
            'name' => $ticket['name'],
            'status' => $ticket['status'],
            'tx_id' => $ticket['tx_id'] ?? null,
            'created_at' => $ticket['created_at'] ?? null,
        ]);
    }

    /**
     *   GET /v1/names/health
     *
     * Registrar health — wallet balance, chain status, readiness.
     */
    public function health(): JsonResponse
    {
        $balance = $this->wallet->getBalance();
        $info = $this->rpc->getInfo();

        $walletOffline = isset($balance['error']);
        $daemonOffline = isset($info['_offline']);
        $daemonStale = isset($info['_stale']);
        $unlocked = ($balance['unlocked_balance'] ?? 0) / 1e12;
        $fee = 0.01;

        $registrationsRemaining = (int) floor($unlocked / $fee);
        $lowFunds = $registrationsRemaining < 10;
        $criticalFunds = $registrationsRemaining < 2;

        $status = 'healthy';
        if ($daemonOffline || $walletOffline) {
            $status = 'offline';
        } elseif ($criticalFunds) {
            $status = 'critical';
        } elseif ($lowFunds) {
            $status = 'low_funds';
        } elseif ($daemonStale) {
            $status = 'degraded';
        }

        $httpCode = match ($status) {
            'offline' => 503,
            'critical' => 503,
            'degraded' => 200,
            default => 200,
        };

        return response()->json([
            'status' => $status,
            'registrar' => [
                'balance' => round($unlocked, 4),
                'registrations_remaining' => $registrationsRemaining,
                'low_funds' => $lowFunds,
                'wallet_online' => ! $walletOffline,
            ],
            'chain' => [
                'height' => $info['height'] ?? 0,
                'aliases' => $info['alias_count'] ?? 0,
                'pool_size' => $info['tx_pool_size'] ?? 0,
                'synced' => ($info['daemon_network_state'] ?? 0) == 2,
                'daemon_online' => ! $daemonOffline,
                'stale' => $daemonStale,
            ],
        ], $httpCode);
    }

    private function isValidName(string $name): bool
    {
        return (bool) preg_match('/^[a-z0-9][a-z0-9-]{0,62}$/', $name);
    }
}