import { randomUUID } from "node:crypto"
import {
  AccessToken,
  RoomAgentDispatch,
  RoomConfiguration,
} from "livekit-server-sdk"
import {
  getVoiceAssistantAgentName,
  getVoiceAssistantBootstrap,
  getVoiceAssistantSiteUrl,
} from "@/lib/voice-assistant/shared"
import type {
  LiveKitTokenResponse,
  VoiceAssistantVisitorMetadata,
} from "@/lib/voice-assistant/types"
import { VOICE_ASSISTANT_SOURCE } from "@/lib/voice-assistant/types"

function readRequiredEnv(name: string) {
  const value = process.env[name]

  if (!value) {
    throw new Error(
      `Missing required voice assistant environment variable: ${name}`
    )
  }

  return value
}

export function getVoiceAssistantServerEnv() {
  const livekitUrl = readRequiredEnv("LIVEKIT_URL")
  const livekitApiKey = readRequiredEnv("LIVEKIT_API_KEY")
  const livekitApiSecret = readRequiredEnv("LIVEKIT_API_SECRET")
  const xaiApiKey = readRequiredEnv("XAI_API_KEY")
  const realtimeModel =
    process.env.XAI_REALTIME_MODEL || "grok-4-1-fast-non-reasoning"

  return {
    livekitUrl,
    livekitApiKey,
    livekitApiSecret,
    xaiApiKey,
    realtimeModel,
    siteUrl: getVoiceAssistantSiteUrl(),
  }
}

function buildRoomName() {
  return `rmv-voice-${randomUUID().slice(0, 8)}`
}

function buildParticipantIdentity() {
  return `website-visitor-${randomUUID().slice(0, 10)}`
}

function buildVisitorMetadata(pathname: string): VoiceAssistantVisitorMetadata {
  const siteUrl = getVoiceAssistantSiteUrl()
  const safePathname = pathname.startsWith("/") ? pathname : `/${pathname}`

  return {
    source: VOICE_ASSISTANT_SOURCE,
    pathname: safePathname,
    pageUrl: new URL(safePathname, siteUrl).toString(),
    startedAt: new Date().toISOString(),
  }
}

export async function createVoiceAssistantTokenResponse(
  pathname: string
): Promise<LiveKitTokenResponse> {
  const env = getVoiceAssistantServerEnv()
  const roomName = buildRoomName()
  const participantIdentity = buildParticipantIdentity()
  const visitorMetadata = buildVisitorMetadata(pathname)
  const agentName = getVoiceAssistantAgentName()

  const token = new AccessToken(env.livekitApiKey, env.livekitApiSecret, {
    identity: participantIdentity,
    name: "Website visitor",
    metadata: JSON.stringify(visitorMetadata),
    ttl: "1 hour",
  })

  token.addGrant({
    roomJoin: true,
    room: roomName,
    canPublish: true,
    canPublishData: true,
    canSubscribe: true,
  })

  token.roomConfig = new RoomConfiguration({
    agents: [
      new RoomAgentDispatch({
        agentName,
        metadata: JSON.stringify(visitorMetadata),
      }),
    ],
  })

  return {
    serverUrl: env.livekitUrl,
    participantToken: await token.toJwt(),
    roomName,
    participantIdentity,
    bootstrap: getVoiceAssistantBootstrap(),
  }
}