import { Subject, Observable } from 'rxjs'

import { take } from 'rxjs/operators'

import { addDisposer } from 'mobx-state-tree'

import type { AnyInstance, IsEmptyPayload, PayloadFunc } from '../types'

import type { ValidEffectActions } from './action'

import { subscribe } from './utils'

export type DollEffectFactory<P, R = void> = (

payload$: Observable<P>,

dollSignal: PayloadFunc<R, void>,

) => Observable<ValidEffectActions>

export type DollEffectDispatcher<P, R> = IsEmptyPayload<P> extends true

? <T = R>(

payload?: undefined,

handler?: (result$: Observable<R>) => Observable<T>,

) => Promise<T | undefined>

: <T = R>(

payload: P,

handler?: (result$: Observable<R>) => Observable<T>,

) => Promise<T | undefined>

export function dollEffect<P, R = unknown>(

self: AnyInstance,

factory: DollEffectFactory<P, R>,

): DollEffectDispatcher<P, R>

export function dollEffect(

self: AnyInstance,

factory: DollEffectFactory<any, any>,

): DollEffectDispatcher<any, any> {

const payloadSource = new Subject()

const signalSource = new Subject()

const effect$ = factory(payloadSource.asObservable(), (value) => signalSource.next(value))

const subscription = subscribe(self, factory, effect$)

addDisposer(self, () => {

payloadSource.complete()

signalSource.complete()

subscription.unsubscribe()

})

return (payload: any, handler: any) => {

const promise = (

typeof handler === 'function' ? handler(signalSource.asObservable()) : signalSource

)

.pipe(take(1))

.toPromise()

payloadSource.next(payload)

return promise

}

}