NetNewsWire/Multiplatform/Shared/Add/AddFeedView.swift

//
//  AddFeedView.swift
//  NetNewsWire
//
//  Created by Stuart Breckenridge on 3/7/20.
//  Copyright © 2020 Ranchero Software. All rights reserved.
//

import SwiftUI
import Account
import RSCore

fileprivate enum AddFeedError: LocalizedError {
	
	case none, alreadySubscribed, initialDownload, noFeeds
	
	var errorDescription: String? {
		switch self {
		case .alreadySubscribed:
			return NSLocalizedString("Can’t add this feed because you’ve already subscribed to it.", comment: "Feed finder")
		case .initialDownload:
			return NSLocalizedString("Can’t add this feed because of a download error.", comment: "Feed finder")
		case .noFeeds:
			return NSLocalizedString("Can’t add a feed because no feed was found.", comment: "Feed finder")
		default:
			return nil
		}
	}
	
}

fileprivate class AddFeedViewModel: ObservableObject {
	
	@Published var providedURL: String = ""
	@Published var providedName: String = ""
	@Published var selectedFolderIndex: Int = 0
	@Published var addFeedError: AddFeedError? {
		didSet {
			addFeedError != .none ? (showError = true) : (showError = false)
		}
	}
	@Published var showError: Bool = false
	@Published var containers: [Container] = []
	@Published var showProgressIndicator: Bool = false
	
	init() {
		for account in AccountManager.shared.sortedActiveAccounts {
			containers.append(account)
			if let sortedFolders = account.sortedFolders {
				containers.append(contentsOf: sortedFolders)
			}
		}
	}
	
}

struct AddFeedView: View {
	
	@Environment(\.presentationMode) private var presentationMode
	@ObservedObject private var viewModel = AddFeedViewModel()
	
    @ViewBuilder var body: some View {
		#if os(iOS)
			iosForm
		#else
			macForm
				.onAppear {
					pasteUrlFromPasteboard()
				}.alert(isPresented: $viewModel.showError) {
					Alert(title: Text("Oops"), message: Text(viewModel.addFeedError!.localizedDescription), dismissButton: Alert.Button.cancel({
						viewModel.addFeedError = .none
					}))
				}
		#endif
    }
	
	#if os(macOS)
	var macForm: some View {
		VStack(alignment: .leading) {
			urlTextField
				.textFieldStyle(RoundedBorderTextFieldStyle())
			providedNameTextField
				.textFieldStyle(RoundedBorderTextFieldStyle())
			folderPicker
			buttonStack
		}
		.padding()
		.frame(minWidth: 400)
	}
	#endif
	
	#if os(iOS)
	var iosForm: some View {
		NavigationLink {
			List {
				Text("PLACEHOLDER")
			}.listStyle(InsetGroupedListStyle())
		}
	}
	#endif
	
	var urlTextField: some View {
		HStack {
			Text("Feed URL:")
			TextField("URL", text: $viewModel.providedURL)
		}
	}
	
	var providedNameTextField: some View {
		HStack(alignment: .lastTextBaseline) {
			Text("Name:")
			TextField("Optional", text: $viewModel.providedName)
		}
	}
	
	var folderPicker: some View {
		Picker("Folder", selection: $viewModel.selectedFolderIndex, content: {
			ForEach(0..<viewModel.containers.count, id: \.self, content: { index in
				if let containerName = (viewModel.containers[index] as? DisplayNameProvider)?.nameForDisplay {
					if viewModel.containers[index] is Folder {
						Text("\(viewModel.containers[index].account?.nameForDisplay ?? "") / \(containerName)").tag(index)
					} else {
						Text(containerName).tag(index)
					}
				}
			})
		})
	}
	
	var buttonStack: some View {
		HStack {
			if viewModel.showProgressIndicator == true {
				ProgressView()
					.frame(width: 25, height: 25)
			}
			Spacer()
			Button("Cancel", action: {
				presentationMode.wrappedValue.dismiss()
			})
			Button("Add", action: {
				addWebFeed()
			}).disabled(!viewModel.providedURL.isValidURL)
		}
	}
	
	#if os(macOS)
	func pasteUrlFromPasteboard() {
		guard let stringFromPasteboard = urlStringFromPasteboard, stringFromPasteboard.isValidURL else {
			return
		}
		viewModel.providedURL = stringFromPasteboard
	}
	#endif
	
}

private extension AddFeedView {

	var urlStringFromPasteboard: String? {
		if let urlString = NSPasteboard.urlString(from: NSPasteboard.general) {
			return urlString.normalizedURL
		}
		return nil
	}
	
	struct AccountAndFolderSpecifier {
		let account: Account
		let folder: Folder?
	}

	func accountAndFolderFromContainer(_ container: Container) -> AccountAndFolderSpecifier? {
		if let account = container as? Account {
			return AccountAndFolderSpecifier(account: account, folder: nil)
		}
		if let folder = container as? Folder, let account = folder.account {
			return AccountAndFolderSpecifier(account: account, folder: folder)
		}
		return nil
	}
	
	func addWebFeed() {
		if let account = accountAndFolderFromContainer(viewModel.containers[viewModel.selectedFolderIndex])?.account {
			
			viewModel.showProgressIndicator = true
			
			let container = viewModel.containers[viewModel.selectedFolderIndex]
			
			if account.hasWebFeed(withURL: viewModel.providedURL) {
				viewModel.addFeedError = .alreadySubscribed
				viewModel.showProgressIndicator = false
				return
			}
			
			account.createWebFeed(url: viewModel.providedURL, name: viewModel.providedName, container: container, completion: { result in
				viewModel.showProgressIndicator = false
				switch result {
				case .success(let feed):
					NotificationCenter.default.post(name: .UserDidAddFeed, object: self, userInfo: [UserInfoKey.webFeed: feed])
					presentationMode.wrappedValue.dismiss()
				case .failure(let error):
					switch error {
					case AccountError.createErrorAlreadySubscribed:
						self.viewModel.addFeedError = .alreadySubscribed
						return
					case AccountError.createErrorNotFound:
						self.viewModel.addFeedError = .noFeeds
						return
					default:
						print("Error")
					}
				}
			})
		}
	}
}


struct AddFeedView_Previews: PreviewProvider {
    static var previews: some View {
        AddFeedView()
    }
}