import { JsonQLQuery } from "@mwater/jsonql"
import DataSource from "./DataSource"
import PriorityDataQueue from "./PriorityDataQueue"
import { Row } from "./types"

/** 
 * Behaves like a DataSource
 * Created by a PriorityDataQueue
 * Forwards performQuery call to the PriorityDataQueue that will forward them to the DataSource 
 */
export default class PriorityDataSource extends DataSource {
  priorityDataQueue: PriorityDataQueue
  priority: number

  constructor(priorityDataQueue: PriorityDataQueue, priority: number) {
    super()
    this.priorityDataQueue = priorityDataQueue
    this.priority = priority
  }

  performQuery(query: JsonQLQuery): Promise<Row[]>
  performQuery(query: JsonQLQuery, cb: (error: any, rows?: Row[]) => void): void
  performQuery(query: JsonQLQuery, cb?: (err: any, results?: Row[]) => void): Promise<Row[]> | void {
    if (cb) {
      this.priorityDataQueue.performQuery(query, cb, this.priority)
      return
    }

    return new Promise<Row[]>((resolve, reject) => {
      this.priorityDataQueue.performQuery(
        query,
        (err, results) => {
          if (err) {
            reject(err)
          } else {
            resolve(results!)
          }
        },
        this.priority
      )
    })
  }

  getImageUrl(imageId: string, height?: number) {
    return this.priorityDataQueue.getImageUrl(imageId, height)
  }

  getFileUrl(fileId: string, filename?: string) {
    return this.priorityDataQueue.getFileUrl(fileId, filename)
  }

  /** Clears the cache if possible with this data source */
  clearCache() {
    return this.priorityDataQueue.clearCache()
  }

  /** Get the cache expiry time in ms from epoch. No cached items before this time will be used */
  getCacheExpiry() {
    return this.priorityDataQueue.getCacheExpiry()
  }
}