import { randomUUID } from 'crypto';

import { mediaConfig } from '../config';
import { SfuSessionRegistry } from './registry';
import type {
  SfuConnectTransportInput,
  SfuConsumeInput,
  SfuConsumerDescriptor,
  SfuIceServer,
  SfuProduceInput,
  SfuProducerDescriptor,
  SfuPublishTransportRequest,
  SfuPublishTransportResult,
  SfuService,
  SfuSessionDescriptor,
  SfuSessionStartInput,
  SfuSubscribeTransportRequest,
  SfuSubscribeTransportResult,
  SfuTransportDescriptor,
} from './types';

const toIceServers = (): SfuIceServer[] => {
  if (mediaConfig.turn.urls.length === 0) {
    return [];
  }

  return mediaConfig.turn.urls.map((urls) => ({
    urls,
    ...(mediaConfig.turn.username ? { username: mediaConfig.turn.username } : {}),
    ...(mediaConfig.turn.credential ? { credential: mediaConfig.turn.credential } : {}),
  }));
};

export class NoopSfuService implements SfuService {
  mode: 'single_server_sfu' = 'single_server_sfu';
  private readonly registry = new SfuSessionRegistry();

  async startSession(input: SfuSessionStartInput): Promise<SfuSessionDescriptor> {
    const now = new Date().toISOString();
    const existing = this.registry.get(input.streamSessionId);
    if (existing) return existing;

    const descriptor: SfuSessionDescriptor = {
      streamSessionId: input.streamSessionId,
      ownerUserId: input.ownerUserId,
      cameraDeviceId: input.cameraDeviceId,
      requesterDeviceId: input.requesterDeviceId,
      state: 'starting',
      createdAt: now,
    };
    return this.registry.set(descriptor);
  }

  async setSessionState(streamSessionId: string, state: SfuSessionDescriptor['state']): Promise<void> {
    this.registry.updateState(streamSessionId, state);
  }

  async endSession(streamSessionId: string): Promise<void> {
    this.registry.updateState(streamSessionId, 'ending');
    this.registry.updateState(streamSessionId, 'ended');
  }

  async getSession(streamSessionId: string): Promise<SfuSessionDescriptor | null> {
    return this.registry.get(streamSessionId);
  }

  async getRouterRtpCapabilities(_streamSessionId: string): Promise<Record<string, unknown> | null> {
    return {
      codecs: [{ mimeType: 'video/VP8', clockRate: 90000, kind: 'video' }],
      headerExtensions: [],
    };
  }

  async listSessions(): Promise<SfuSessionDescriptor[]> {
    return this.registry.list();
  }

  async listTransports(streamSessionId: string): Promise<SfuTransportDescriptor[]> {
    return this.registry.listTransports(streamSessionId);
  }

  async listProducers(streamSessionId: string): Promise<SfuProducerDescriptor[]> {
    return this.registry.listProducers(streamSessionId);
  }

  async listConsumers(streamSessionId: string): Promise<SfuConsumerDescriptor[]> {
    return this.registry.listConsumers(streamSessionId);
  }

  async createPublishTransport(input: SfuPublishTransportRequest): Promise<SfuPublishTransportResult> {
    const transportId = `pub_${randomUUID()}`;
    this.registry.addTransport({
      transportId,
      streamSessionId: input.streamSessionId,
      ownerDeviceId: input.cameraDeviceId,
      direction: 'publish',
    });
    return {
      transportId,
      iceServers: toIceServers(),
      transportOptions: {
        id: transportId,
        iceParameters: {},
        iceCandidates: [],
        dtlsParameters: {},
      },
    };
  }

  async createSubscribeTransport(input: SfuSubscribeTransportRequest): Promise<SfuSubscribeTransportResult> {
    const transportId = `sub_${randomUUID()}`;
    this.registry.addTransport({
      transportId,
      streamSessionId: input.streamSessionId,
      ownerDeviceId: input.viewerDeviceId,
      direction: 'subscribe',
    });
    return {
      transportId,
      iceServers: toIceServers(),
      transportOptions: {
        id: transportId,
        iceParameters: {},
        iceCandidates: [],
        dtlsParameters: {},
      },
    };
  }

  async connectPublishTransport(input: SfuConnectTransportInput): Promise<SfuTransportDescriptor> {
    const transport = this.registry.getTransport(input.transportId);
    if (!transport) throw new Error('Publish transport not found');
    if (transport.streamSessionId !== input.streamSessionId) throw new Error('Transport does not belong to stream');
    if (transport.direction !== 'publish') throw new Error('Transport is not a publish transport');
    if (transport.ownerDeviceId !== input.deviceId) throw new Error('Device does not own this publish transport');

    const connected = this.registry.connectTransport(input.transportId);
    if (!connected) throw new Error('Publish transport connect failed');
    return connected;
  }

  async connectSubscribeTransport(input: SfuConnectTransportInput): Promise<SfuTransportDescriptor> {
    const transport = this.registry.getTransport(input.transportId);
    if (!transport) throw new Error('Subscribe transport not found');
    if (transport.streamSessionId !== input.streamSessionId) throw new Error('Transport does not belong to stream');
    if (transport.direction !== 'subscribe') throw new Error('Transport is not a subscribe transport');
    if (transport.ownerDeviceId !== input.deviceId) throw new Error('Device does not own this subscribe transport');

    const connected = this.registry.connectTransport(input.transportId);
    if (!connected) throw new Error('Subscribe transport connect failed');
    return connected;
  }

  async produce(input: SfuProduceInput): Promise<SfuProducerDescriptor> {
    const transport = this.registry.getTransport(input.transportId);
    if (!transport) throw new Error('Publish transport not found');
    if (transport.streamSessionId !== input.streamSessionId) throw new Error('Transport does not belong to stream');
    if (transport.direction !== 'publish') throw new Error('Transport is not a publish transport');
    if (transport.ownerDeviceId !== input.cameraDeviceId) throw new Error('Device does not own this publish transport');
    if (transport.state !== 'connected') throw new Error('Publish transport must be connected before producing');

    return this.registry.addProducer({
      producerId: `prod_${randomUUID()}`,
      streamSessionId: input.streamSessionId,
      transportId: input.transportId,
      cameraDeviceId: input.cameraDeviceId,
      kind: input.kind,
      rtpParameters: input.rtpParameters,
    });
  }

  async consume(input: SfuConsumeInput): Promise<SfuConsumerDescriptor> {
    const transport = this.registry.getTransport(input.transportId);
    if (!transport) throw new Error('Subscribe transport not found');
    if (transport.streamSessionId !== input.streamSessionId) throw new Error('Transport does not belong to stream');
    if (transport.direction !== 'subscribe') throw new Error('Transport is not a subscribe transport');
    if (transport.ownerDeviceId !== input.viewerDeviceId) throw new Error('Device does not own this subscribe transport');
    if (transport.state !== 'connected') throw new Error('Subscribe transport must be connected before consuming');

    const selectedProducer =
      (input.producerId ? this.registry.getProducer(input.producerId) : null) ??
      this.registry
        .listProducers(input.streamSessionId)
        .slice()
        .reverse()
        .find((producer) => producer.kind === 'video');

    if (!selectedProducer) throw new Error('No producer available for consume');
    if (selectedProducer.streamSessionId !== input.streamSessionId) throw new Error('Producer does not belong to stream');

    return this.registry.addConsumer({
      consumerId: `cons_${randomUUID()}`,
      streamSessionId: input.streamSessionId,
      transportId: input.transportId,
      viewerDeviceId: input.viewerDeviceId,
      producerId: selectedProducer.producerId,
      kind: selectedProducer.kind,
      rtpParameters: selectedProducer.rtpParameters,
    });
  }
}