//
//  LinphoneAsyncWrapper.swift
//  CallKitTutorial
//
//  Created by CD on 13/09/2023.
//  Copyright © 2023 BelledonneCommunications. All rights reserved.
//

import Foundation
import Combine
import linphonesw

var coreQueue : DispatchQueue = DispatchQueue(label:"core.queue")
var cancellables = Set<AnyCancellable>()

// A publisher object that can old one or many LinphoneObject objects.

public class LinphoneObjectsPublisher <T> : Publisher {
	public typealias Output = T
	public typealias Failure = Error
	let passThroughSubject = PassthroughSubject<Output, Failure>()
	public func receive<S>(subscriber: S) where S : Subscriber, S.Failure == Failure, S.Input == Output {
			passThroughSubject.receive(subscriber: subscriber)
	}
	
	public func send(completion: Subscribers.Completion<Failure>) {
		passThroughSubject.send(completion: completion)
	}
	
	@discardableResult
	public func postOnMainQueue(onError :@escaping ((Error) -> Void) = {_ in }, receiveValue:@escaping ((Output) -> Void)) ->  LinphoneObjectsPublisher <T>{
		doOnQueue(onError,receiveValue,queue: DispatchQueue.main)
		return self
	}
	
	@discardableResult
	public func postOnCoreQueue(onError :@escaping ((Error) -> Void) = {_ in }, receiveValue:@escaping ((Output) -> Void)) -> LinphoneObjectsPublisher <T>{
		doOnQueue(onError,receiveValue,queue: coreQueue)
		return self
	}
	
	
	private func doOnQueue(_ onError :@escaping ((Error) -> Void) = {_ in }, _ receiveValue:@escaping ((Output) -> Void), queue:DispatchQueue) {
		passThroughSubject.receive(on:queue)
		.sink { error in
			onError(error as! Error)
		} receiveValue: { result in
			receiveValue(result)
		}.store(in: &cancellables)
	}
		
	var savedReference : Any? = nil // Used when a reference is needed to avoid object from beeing GCd (example delegate stubs)
	convenience init (reference: Any) {
		self.init()
		savedReference = reference
	}
}

public class LinphoneAsyncHelper {
	
	func postOnCoreQueue(lambda : @escaping ()->()) {
		coreQueue.async {
			lambda()
		}
	}
	
	func postOnMainQueue(lambda : @escaping()->()) {
		DispatchQueue.main.async {
			lambda()
		}
	}
	
	// Creates a publisher from the object created by the action passed as parameter
	// For example if passed a create core call this function will create the LinphoneObject Core on core queue, and created object will be published through the built publisher
	func createLinphoneObjectWithPublisher<LinphoneObject>(createAction:@escaping()throws -> LinphoneObject ) -> LinphoneObjectsPublisher<LinphoneObject> {
		let publisher = LinphoneObjectsPublisher<LinphoneObject>()
		coreQueue.async {
			do {
				publisher.passThroughSubject.send(try createAction())
			} catch {
				publisher.send(completion: .failure(error))
			}
		}
		return publisher
	}

}

extension Core {

	// Methods below would generated by a script similar to the one that creates LinphoneWrapper

	public func createAccountRegistrationStateChangedPublisher() -> LinphoneObjectsPublisher<(core:Core, account:Account, state:RegistrationState, message:String)> {
		let publisher = LinphoneObjectsPublisher<(core:Core, account:Account, state:RegistrationState, message:String)>()
		let coreDelegate = CoreDelegateStub (
		onAccountRegistrationStateChanged: { (core: Core, account: Account, state: RegistrationState, message: String) in
			publisher.passThroughSubject.send((core,account,state,message))
		})
		publisher.savedReference = coreDelegate
		addDelegate(delegate: coreDelegate)
		return publisher
	}
	
	public func createOnCallStateChangedPublisher() -> LinphoneObjectsPublisher<(core: Core, call: Call, state: Call.State, message: String)> {
		let publisher = LinphoneObjectsPublisher<(core: Core, call: Call, state: Call.State, message: String)>()
		let coreDelegate = CoreDelegateStub (
			onCallStateChanged: { (core: Core, call: Call, state: Call.State, message: String) in
				publisher.passThroughSubject.send((core,call,state,message))
		})
		publisher.savedReference = coreDelegate
		addDelegate(delegate: coreDelegate)
		return publisher
	}
	
	
	
	// ...
}