import {Queue} from './Queue'
import {Inject, Injectable} from '../../../di'
import {Cache, Maybe} from '../../../util'
import {Queueable, ShouldQueue} from '../types'
import {Serialization} from '../serial/Serialization'

/**
 * Queue implementation that uses the configured cache driver as a queue.
 */
@Injectable()
export class CacheQueue extends Queue {
    @Inject()
    protected readonly cache!: Cache

    @Inject()
    protected readonly serial!: Serialization

    protected get queueIdentifier(): string {
        return `extollo__queue__${this.name}`
    }

    protected async push<T extends Queueable>(item: ShouldQueue<T>): Promise<void> {
        const json = await this.serial.encodeJSON(item)
        await this.cache.arrayPush(this.queueIdentifier, json)
    }

    async pop(): Promise<Maybe<ShouldQueue<Queueable>>> {
        const popped = await this.cache.arrayPop(this.queueIdentifier)
        if ( popped ) {
            return this.serial.decodeJSON(popped)
        }
    }
}