/**
 * In-memory store for live sharing sessions (camera + location).
 * Sessions expire after TTL_MS without an update.
 */

import { closeRouter, getProducer, getTransport } from './mediasoup.js'

const TTL_MS = 60_000 // 60 seconds without update = inactive

const sessions = new Map()

/**
 * @typedef {{
 *   id: string
 *   userId: string
 *   label: string
 *   lat: number
 *   lng: number
 *   updatedAt: number
 *   routerId: string | null
 *   producerId: string | null
 *   transportId: string | null
 * }} LiveSession
 */

/**
 * @param {string} userId
 * @param {string} [label]
 * @returns {LiveSession} The created live session.
 */
export function createSession(userId, label = '') {
  const id = crypto.randomUUID()
  const now = Date.now()
  const session = {
    id,
    userId,
    label: (label || 'Live').trim() || 'Live',
    lat: 0,
    lng: 0,
    updatedAt: now,
    routerId: null,
    producerId: null,
    transportId: null,
  }
  sessions.set(id, session)
  return session
}

/**
 * @param {string} id
 * @returns {LiveSession | undefined} The session or undefined.
 */
export function getLiveSession(id) {
  return sessions.get(id)
}

/**
 * Get an existing active session for a user (for replacing with a new one).
 * @param {string} userId
 * @returns {LiveSession | undefined} The first active session for the user, or undefined.
 */
export function getActiveSessionByUserId(userId) {
  const now = Date.now()
  for (const [, s] of sessions) {
    if (s.userId === userId && now - s.updatedAt <= TTL_MS) {
      return s
    }
  }
  return undefined
}

/**
 * @param {string} id
 * @param {{ lat?: number, lng?: number, routerId?: string | null, producerId?: string | null, transportId?: string | null }} updates
 */
export function updateLiveSession(id, updates) {
  const session = sessions.get(id)
  if (!session) return
  const now = Date.now()
  if (Number.isFinite(updates.lat)) session.lat = updates.lat
  if (Number.isFinite(updates.lng)) session.lng = updates.lng
  if (updates.routerId !== undefined) session.routerId = updates.routerId
  if (updates.producerId !== undefined) session.producerId = updates.producerId
  if (updates.transportId !== undefined) session.transportId = updates.transportId
  session.updatedAt = now
}

/**
 * @param {string} id
 */
export function deleteLiveSession(id) {
  sessions.delete(id)
}

/**
 * Clear all sessions (for tests only).
 */
export function clearSessions() {
  sessions.clear()
}

/**
 * Returns sessions updated within TTL_MS (active only).
 * Also cleans up expired sessions.
 * @returns {Promise<Array<{ id: string, userId: string, label: string, lat: number, lng: number, updatedAt: number, hasStream: boolean }>>} Active sessions with hasStream flag.
 */
export async function getActiveSessions() {
  const now = Date.now()
  const result = []
  const expiredIds = []
  for (const [id, s] of sessions) {
    if (now - s.updatedAt <= TTL_MS) {
      result.push({
        id: s.id,
        userId: s.userId,
        label: s.label,
        lat: s.lat,
        lng: s.lng,
        updatedAt: s.updatedAt,
        hasStream: Boolean(s.producerId),
      })
    }
    else {
      expiredIds.push(id)
    }
  }
  // Clean up expired sessions and their WebRTC resources
  for (const id of expiredIds) {
    const session = sessions.get(id)
    if (session) {
      // Clean up producer if it exists
      if (session.producerId) {
        const producer = getProducer(session.producerId)
        if (producer) {
          producer.close()
        }
      }

      // Clean up transport if it exists
      if (session.transportId) {
        const transport = getTransport(session.transportId)
        if (transport) {
          transport.close()
        }
      }

      // Clean up router
      if (session.routerId) {
        await closeRouter(id).catch((err) => {
          console.error(`[liveSessions] Error closing router for expired session ${id}:`, err)
        })
      }

      sessions.delete(id)
    }
  }
  return result
}