//
//  LocationsListViewModel.swift
//  Locations
//
//  Created by Javier Cicchelli on 11/04/2023.
//  Copyright © 2023 Röck+Cöde. All rights reserved.
//

import Combine
import Dependency
import Foundation
import Persistence

class LocationsListViewModel: ObservableObject {
    
    // MARK: Dependencies
    
    @Dependency(\.persistence) private var persistence

    // MARK: Properties
    
    weak var coordinator: LocationsListCoordination?

    private lazy var locationProvider = LocationProvider(managedContext: persistence.container.viewContext)
    
    @Published private var viewStatus: LocationsListViewStatus = .initialised

    private let loadRemoteLocations = LoadRemoteLocationsUseCase()
    
    // MARK: Initialisers
    
    init(coordinator: LocationsListCoordination) {
        self.coordinator = coordinator
    }

}

// MARK: - LocationsListViewModeling

extension LocationsListViewModel: LocationsListViewModeling {

    // MARK: Properties

    var locationsDidChangePublisher: PassthroughSubject<[Persistence.Change], Never> { locationProvider.didChangePublisher }
    var numberOfLocationSections: Int { locationProvider.numberOfSections }
    var viewStatusPublisher: Published<LocationsListViewStatus>.Publisher { $viewStatus }

    // MARK: Functions

    func loadLocations() {
        Task {
            do {
                viewStatus = .loading
                
                try await loadRemoteLocations()
                
                try locationProvider.fetch()

                viewStatus = .loaded
            } catch {
                viewStatus = .error
            }
        }
    }
    

    func location(at indexPath: IndexPath) -> Location {
        locationProvider.location(at: indexPath)
    }
    
    func numberOfLocations(in section: Int) -> Int {
        locationProvider.numberOfLocationsInSection(section)
    }
    
    func openLocationsAdd() {
        coordinator?.openLocationsAddScreen()
    }
    
    }
    
}

// MARK: - Enumerations

enum LocationsListViewStatus {
    case initialised
    case loading
    case loaded
    case error
}