/**
 * In-memory CoT entity store: upsert by id, prune on read by TTL.
 * Single source of truth; getActiveEntities returns new objects (no mutation of returned refs).
 */

import { acquire } from './asyncLock.js'
import { COT_ENTITY_TTL_MS } from './constants.js'

const entities = new Map()

/**
 * Upsert entity by id. Input is not mutated; stored value is a new object.
 * @param {{ id: string, lat: number, lng: number, label?: string, eventType?: string, type?: string }} parsed
 */
export async function updateFromCot(parsed) {
  if (!parsed || typeof parsed.id !== 'string') return
  const lat = Number(parsed.lat)
  const lng = Number(parsed.lng)
  if (!Number.isFinite(lat) || !Number.isFinite(lng)) return

  await acquire(`cot-${parsed.id}`, async () => {
    const now = Date.now()
    const existing = entities.get(parsed.id)
    const label = typeof parsed.label === 'string' ? parsed.label : (existing?.label ?? parsed.id)
    const type = typeof parsed.eventType === 'string' ? parsed.eventType : (typeof parsed.type === 'string' ? parsed.type : (existing?.type ?? ''))

    entities.set(parsed.id, {
      id: parsed.id,
      lat,
      lng,
      label,
      type,
      updatedAt: now,
    })
  })
}

/**
 * Active entities (updated within ttlMs). Prunes expired. Returns new array of new objects.
 * @param {number} [ttlMs]
 * @returns {Promise<Array<{ id: string, lat: number, lng: number, label: string, type: string, updatedAt: number }>>} Snapshot of active entities.
 */
export async function getActiveEntities(ttlMs = COT_ENTITY_TTL_MS) {
  return acquire('cot-prune', async () => {
    const now = Date.now()
    const active = []
    const expired = []
    for (const entity of entities.values()) {
      if (now - entity.updatedAt <= ttlMs) {
        active.push({
          id: entity.id,
          lat: entity.lat,
          lng: entity.lng,
          label: entity.label ?? entity.id,
          type: entity.type ?? '',
          updatedAt: entity.updatedAt,
        })
      }
      else {
        expired.push(entity.id)
      }
    }
    for (const id of expired) entities.delete(id)
    return active
  })
}

/** Clear store (tests only). */
export function clearCotStore() {
  entities.clear()
}