import {Awaitable, JSONState, Maybe, Pipeline, TypeTag, uuid4} from '../../util'
import {Instantiable, StaticInstantiable} from '../../di'

// eslint-disable-next-line @typescript-eslint/no-unused-vars
export interface SerialPayload<TActual, TSerial extends JSONState> extends JSONState {
    serializer: string
    payload: TSerial
}

export interface Serializer<TActual, TSerial extends JSONState> {
    matchActual(some: TActual): boolean

    matchSerial(serial: SerialPayload<TActual, TSerial>): boolean

    encode(actual: TActual): Awaitable<SerialPayload<TActual, TSerial>>

    decode(serial: SerialPayload<TActual, TSerial>): Awaitable<TActual>
}

export interface Event {
    eventUuid: string
    eventName: string
    originBusUuid?: string
    shouldBroadcast?: boolean | (() => Awaitable<boolean>)
}

export abstract class BaseEvent implements Event {
    public readonly eventUuid = uuid4()

    public abstract eventName: string

    public shouldBroadcast(): Awaitable<boolean> {
        return true
    }
}

export type EventHandlerReturn = Awaitable<boolean | void | undefined>

export type EventHandler<T extends Event> = (event: T) => EventHandlerReturn

export interface EventHandlerSubscription {
    unsubscribe(): Awaitable<void>
}

export interface Queueable {
    execute(): Awaitable<void>

    shouldQueue?: boolean | (() => boolean)

    defaultQueue?: string | (() => string)
}

export type ShouldQueue<T extends Queueable> = T & TypeTag<'@extollo/lib:ShouldQueue'>

export function shouldQueue<T extends Queueable>(something: T): something is ShouldQueue<T> {
    if ( typeof something.shouldQueue === 'function' ) {
        return something.shouldQueue()
    }

    return (
        typeof something.shouldQueue === 'undefined'
        || something.shouldQueue
    )
}

export interface EventBus<TEvent extends Event = Event> {
    readonly uuid: string

    subscribe<T extends TEvent>(eventKey: StaticInstantiable<T>, handler: EventHandler<T>): Awaitable<EventHandlerSubscription>

    pipe<T extends TEvent>(eventKey: StaticInstantiable<T>, line: Pipeline<T, EventHandlerReturn>): Awaitable<EventHandlerSubscription>

    push(event: TEvent): Awaitable<void>

    up(): Awaitable<void>

    down(): Awaitable<void>

    isConnected(): boolean
}

/** Internal storage format for local event bus subscribers. */
export interface BusSubscriber<T extends Event> {
    uuid: string
    eventName: string
    eventKey: StaticInstantiable<T>
    handler: EventHandler<T>
}

export interface BusQueue {
    readonly name: string

    dispatch<T extends Queueable>(item: T): Promise<void>

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

export interface RedisBusConnectorConfig {
    type: 'redis'
}

export type BusConnectorConfig = RedisBusConnectorConfig

export interface QueueConfig {
    driver?: Instantiable<BusQueue>,
    /* queues?: ({
        name: string,
        driver: Instantiable<BusQueue>,
    })[] */
}