import { LRUCache as LRU } from 'lru-cache'
import { CallRequestDTO } from '../CallRequestDTO'
import { CallResponseDTO } from '../CallResponseDTO'
import { Cache } from './Cache'
import { makeCallRequestKey } from '../utils/cache-utils'
import { GetDebugLogger } from '../utils/debug-logger'

const debug = GetDebugLogger('rpc:InMemoryCache')

interface InMemoryCacheOptions {
  cacheMaxSize?: number
  cacheMaxAgeMs?: number
}

export class InMemoryCache implements Cache {
  static DEFAULT_CACHE_MAX_AGE_MS = 1000 * 60 * 15
  static DEFAULT_CACHE_MAX_SIZE = 200

  private cachedResponseByParams: LRU<string, any> | undefined

  constructor(cacheOptions?: InMemoryCacheOptions) {
    this.cachedResponseByParams = new LRU({
      max: cacheOptions?.cacheMaxSize || InMemoryCache.DEFAULT_CACHE_MAX_SIZE,
      ttl:
        cacheOptions?.cacheMaxAgeMs || InMemoryCache.DEFAULT_CACHE_MAX_AGE_MS,
    })
  }

  clearCache = (request?: CallRequestDTO): void => {
    debug('clearCache')
    if (request) {
      this.cachedResponseByParams?.delete(makeCallRequestKey(request))

      return
    }
    this.cachedResponseByParams?.clear()
  }

  getCachedResponse = (
    request: CallRequestDTO,
  ): CallResponseDTO | undefined => {
    debug('getCachedResponse, key: ', request)

    let cachedResponse = this.cachedResponseByParams?.get(
      makeCallRequestKey(request),
    )

    if (typeof cachedResponse === 'string') {
      cachedResponse = JSON.parse(cachedResponse)
    }

    return cachedResponse
  }

  setCachedResponse = (request: CallRequestDTO, response: CallResponseDTO) => {
    debug('setCachedResponse', request, response)

    const requestKey = makeCallRequestKey(request)

    if (!response) {
      return this.cachedResponseByParams?.delete(requestKey)
    }

    // Strip correlationId from cached response - it's request-specific and will
    // be restored during deduplication (see ClientManager.manageClientRequest).
    // This ensures each caller gets their unique correlationId even for cached responses.
    const cachedResponse = { ...response }
    delete cachedResponse.correlationId

    this.cachedResponseByParams?.set(
      requestKey,
      cachedResponse ? JSON.stringify(cachedResponse) : undefined,
    )
  }
}