import 'dart:async';

import 'package:nyxx/nyxx.dart';
import 'package:prometheus_client/prometheus_client.dart';
import 'package:prometheus_client_shelf/shelf_handler.dart';
import 'package:shelf/shelf.dart';
import 'package:shelf/shelf_io.dart' as io;
import 'package:shelf_router/shelf_router.dart';
import 'package:prometheus_client_shelf/shelf_metrics.dart' as shelf_metrics;
import 'package:prometheus_client/runtime_metrics.dart' as runtime_metrics;

// final logger = Logger('Analytics');

/// A global instance of the [Analytics] plugin.
final analytics = Analytics();

class Analytics extends NyxxPlugin<NyxxRest> {
  @override
  String get name => 'Analytics';

  /// Whether to include runtime metrics in the analytics.
  final bool includeDefaultMetrics;

  /// The port to bind the analytics server to.
  final int port;

  /// The analytics route.
  final String route;

  /// The refresh interval for the analytics.
  final Duration refreshInterval;

  /// Custom gauges for the analytics. It's up to you to update these.
  final List<Gauge> gauges;

  /// Custom counters for the analytics.
  final List<Counter> counters;

  /// Custom summaries for the analytics.
  final List<Summary> summaries;

  /// Custom histograms for the analytics.
  final List<Histogram> histograms;

  Analytics({
    this.includeDefaultMetrics = true,
    this.port = 4242,
    this.route = '/analytics',
    this.refreshInterval = const Duration(seconds: 5),
    this.gauges = const [],
    this.counters = const [],
    this.summaries = const [],
    this.histograms = const [],
  });

  @override
  Future<void> beforeConnect(
    ApiOptions apiOptions,
    ClientOptions clientOptions,
  ) async {
    final router = Router();

    router.get('/', (req) => Response.found(route));
    router.get(route, prometheusHandler());

    final pipeline = const Pipeline();

    if (includeDefaultMetrics) {
      runtime_metrics.register();
      pipeline.addMiddleware(shelf_metrics.register());
    }

    final server = await io.serve(
      pipeline.addHandler(router.call),
      '0.0.0.0',
      port,
    );

    // this.s

    logger.info('Serving analytics at http://${server.address.host}:${server.port}$route');
  }

  @override
  NyxxPluginState<NyxxRest, Analytics> createState() => AnalyticsPluginState(this);
}

class AnalyticsPluginState extends NyxxPluginState<NyxxRest, Analytics> {
  late final Timer timer;

  AnalyticsPluginState(super.plugin);

  @override
  Future<void> afterConnect(NyxxRest client) async {
    await super.afterConnect(client);
    registerPeriodicMetrics(client);
    registerCustomMetrics();
  }

  void registerCustomMetrics() {
    final m = [plugin.gauges, plugin.counters, plugin.summaries, plugin.histograms].expand((e) => e);

    if (m.isEmpty) return;

    for (dynamic metric in m) {
      metric.register();
    }
  }

  void registerPeriodicMetrics(NyxxRest client) {
    final cachedUsers = Gauge(name: 'nyxx_analytics_cached_users', help: 'The number of cached users')..register();
    final cachedGuilds = Gauge(name: 'nyxx_analytics_cached_guilds', help: 'The number of cached guilds')..register();
    final cachedChannels = Gauge(name: 'nyxx_analytics_cached_channels', help: 'The number of cached channels')
      ..register();
    final cachedMessages = Gauge(name: 'nyxx_analytics_cached_messages', help: 'The total number of cached messages')
      ..register();
    final restLatency = Gauge(
      name: 'nyxx_analytics_rest_latency',
      help: 'The average REST latency',
      labelNames: ['client_id'],
    )..register();
    final realRestLatency = Gauge(
      name: 'nyxx_analytics_real_rest_latency',
      help: 'The real average REST latency',
      labelNames: ['client_id'],
    )..register();

    Gauge? gatewayLatency;
    Gauge? shardGatewayLatency;

    if (client is NyxxGateway) {
      gatewayLatency = Gauge(
        name: 'nyxx_analytics_gateway_latency',
        help: 'The average gateway latency',
        labelNames: ['client_id'],
      )..register();
      shardGatewayLatency = Gauge(
        name: 'nyxx_analytics_shard_gateway_latency',
        help: 'The average gateway latency per shard',
        labelNames: ['client_id', 'shard_id'],
      )..register();
    }

    Timer.periodic(plugin.refreshInterval, (timer) {
      cachedUsers.value = client.users.cache.length.toDouble();
      cachedGuilds.value = client.guilds.cache.length.toDouble();
      cachedChannels.value = client.channels.cache.length.toDouble();
      cachedMessages.value = client.channels.cache.values
          .whereType<TextChannel>()
          .fold(0, (count, channel) => count + channel.messages.cache.length)
          .toDouble();
      restLatency.labels([client.user.id.toString()]).value = client.httpHandler.latency.inMilliseconds.toDouble();
      realRestLatency.labels([client.user.id.toString()]).value =
          client.httpHandler.realLatency.inMilliseconds.toDouble();

      if (client case final NyxxGateway client) {
        gatewayLatency!.labels([client.user.id.toString()]).value = client.gateway.latency.inMilliseconds.toDouble();
        for (final shard in client.gateway.shards) {
          shardGatewayLatency!.labels([client.user.id.toString(), shard.id.toString()]).value =
              shard.latency.inMilliseconds.toDouble();
        }
      }
    });
  }
}