//
// Copyright 2022 New Vector Ltd
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
//

import SwiftUI

class NavigationRootCoordinator: ObservableObject, CoordinatorProtocol, CustomStringConvertible {
    @Published fileprivate var rootModule: NavigationModule? {
        didSet {
            if let oldValue {
                oldValue.coordinator.stop()
                oldValue.dismissalCallback?()
            }
            
            if let rootModule {
                logPresentationChange("Set root", rootModule)
                rootModule.coordinator.start()
            }
        }
    }
    
    /// The currently displayed coordinator
    var rootCoordinator: (any CoordinatorProtocol)? {
        rootModule?.coordinator
    }
    
    /// Sets or replaces the presented coordinator
    /// - Parameter coordinator: the coordinator to display
    func setRootCoordinator(_ coordinator: (any CoordinatorProtocol)?, dismissalCallback: (() -> Void)? = nil) {
        guard let coordinator else {
            rootModule = nil
            return
        }
        
        rootModule = NavigationModule(coordinator, dismissalCallback: dismissalCallback)
    }
        
    // MARK: - CoordinatorProtocol
    
    func toPresentable() -> AnyView {
        AnyView(NavigationRootCoordinatorView(rootCoordinator: self))
    }
    
    // MARK: - CustomStringConvertible
    
    var description: String {
        if let rootCoordinator = rootModule?.coordinator {
            return "SingleScreenCoordinator(\(rootCoordinator)"
        } else {
            return "SingleScreenCoordinator(Empty)"
        }
    }
    
    // MARK: - Private
    
    private func logPresentationChange(_ change: String, _ module: NavigationModule) {
        MXLog.info("\(self) \(change): \(module.coordinator)")
    }
}

private struct NavigationRootCoordinatorView: View {
    @ObservedObject var rootCoordinator: NavigationRootCoordinator
    
    var body: some View {
        ZStack {
            rootCoordinator.rootModule?.coordinator.toPresentable()
        }
        .animation(.elementDefault, value: rootCoordinator.rootModule)
    }
}