import type {
  ICache,
  KeyManifestEntry,
  MaybePromise,
} from './shared'
import {
  CACHE_KEY_PREFIX,
} from './shared'

export class CacheKeyManifest {
  private readonly manifestKey: string

  constructor(private cache: ICache, private clientId: string) {
    this.manifestKey = this.createManifestKeyFrom(this.clientId)
  }

  async add(key: string): Promise<void> {
    const keys = new Set(
      (await this.cache.get<KeyManifestEntry>(this.manifestKey))?.keys || [],
    )

    keys.add(key)

    await this.cache.set<KeyManifestEntry>(this.manifestKey, {
      keys: [...keys],
    })
  }

  async remove(key: string): Promise<void> {
    const entry = await this.cache.get<KeyManifestEntry>(this.manifestKey)

    if (entry) {
      const keys = new Set(entry.keys)
      keys.delete(key)

      if (keys.size > 0)
        return await this.cache.set(this.manifestKey, { keys: [...keys] })

      return await this.cache.remove(this.manifestKey)
    }
  }

  get(): MaybePromise<KeyManifestEntry> {
    return this.cache.get<KeyManifestEntry>(this.manifestKey)
  }

  clear(): MaybePromise<void> {
    return this.cache.remove(this.manifestKey)
  }

  private createManifestKeyFrom(clientId: string): string {
    return `${CACHE_KEY_PREFIX}::${clientId}`
  }
}