import {BusQueue, Queueable, shouldQueue, ShouldQueue} from '../types'
import {Inject, Injectable} from '../../../di'
import {Awaitable, Maybe} from '../../../util'
import {Bus} from '../Bus'
import {PushingToQueue} from './event/PushingToQueue'
import {PushedToQueue} from './event/PushedToQueue'

@Injectable()
export abstract class Queue implements BusQueue {
    @Inject()
    protected readonly bus!: Bus

    constructor(
        public readonly name: string,
    ) {}

    async dispatch<T extends Queueable>(item: T): Promise<void> {
        if ( shouldQueue(item) ) {
            await this.bus.push(new PushingToQueue(item, this.name))
            await this.push(item)
            await this.bus.push(new PushedToQueue(item, this.name))
            return
        }

        await item.execute()
    }

    protected abstract push<T extends Queueable>(item: ShouldQueue<T>): Awaitable<void>

    abstract pop(): Promise<Maybe<ShouldQueue<Queueable>>>
}