//
// Copyright 2021-2024 New Vector Ltd.
//
// SPDX-License-Identifier: AGPL-3.0-only OR LicenseRef-Element-Commercial
// Please see LICENSE files in the repository root for full details.
//

import SwiftUI

struct AuthenticationLoginScreen: View {
    // MARK: - Properties
    
    // MARK: Private
    private enum CustomText {
        case username, submit
    }
    
    @Environment(\.theme) private var theme: ThemeSwiftUI
    
    /// A boolean that can be toggled to give focus to the password text field.
    /// This must be manually set back to `false` when the text field finishes editing.
    @State private var isPasswordFocused = false
    
    // BWI #7555 migration part 3
    @State private var showMigrationView = BWIBuildSettings.shared.BuMXMigrationInfoLevel == 3
    // BWI #7555 END
    
    // MARK: Public
    
    @ObservedObject var viewModel: AuthenticationLoginViewModel.Context
    
    var body: some View {
        VStack {
            ScrollView {
                VStack(spacing: 0) {
                    if BWIBuildSettings.shared.bumLoginFlowLayout || BWIBuildSettings.shared.bwiLoginFlowLayout {
                        ServerIcon(image: nil, size: OnboardingMetrics.iconSize)
                            .padding(.top, OnboardingMetrics.topPaddingToNavigationBar)
                            .padding(.bottom, 16)
                    } else {
                        header
                            .padding(.top, OnboardingMetrics.topPaddingToNavigationBar)
                            .padding(.bottom, 28)
                    }
                    
                    if !BWIBuildSettings.shared.bwiLoginFlowLayout {
                        serverInfo
                            .padding(.leading, 12)
                            .padding(.bottom, 16)
                    
                        Rectangle()
                            .fill(theme.colors.quinaryContent)
                            .frame(height: 1)
                            .padding(.bottom, 22)
                    } else {
                        // bwi: show cutom header
                        authLoginHeaderlineText
                    }
                    
                    if BWIBuildSettings.shared.bumLoginFlowLayout {
                        loginDescription
                            .padding(.bottom, 22)
                    }
                    
                    if viewModel.viewState.homeserver.showLoginForm {
                        loginForm
                    }

                    if viewModel.viewState.homeserver.showQRLogin && BWIBuildSettings.shared.allowLoginWithQR {
                        qrLoginButton
                    }
                    
                    if viewModel.viewState.homeserver.showLoginForm && viewModel.viewState.showSSOButtons && BWIBuildSettings.shared.isOIDCEnabled {
                        Text(VectorL10n.or)
                            .foregroundColor(theme.colors.secondaryContent)
                            .padding(.top, 16)
                    }
                    
                    if viewModel.viewState.showSSOButtons && BWIBuildSettings.shared.isOIDCEnabled {
                        ssoButtons
                            .padding(.top, 16)
                    }
                    
                    VStack(spacing: 14) {
                        if BWIBuildSettings.shared.authScreenShowForgotPassword {
                            forgotPasswordButton
                        }
                        if BWIBuildSettings.shared.bwiEnableRegisterInfo {
                            registerButton
                        }
                    }
                    .padding([.vertical], BWIBuildSettings.shared.bwiLoginFlowLayout ? 36 : 0)

                    if !viewModel.viewState.homeserver.showLoginForm && !viewModel.viewState.showSSOButtons {
                        fallbackButton
                    }
                }
                .readableFrame()
                .padding(.horizontal, 16)
            }
            
            if BWIBuildSettings.shared.bumLoginFlowLayout && BWIBuildSettings.shared.bwiShowAccessibilityDeclaration {
                accessibilityDeclaration
                    .frame(alignment: .bottom)
                    .padding(.bottom, 10)
            }
            
            if BWIBuildSettings.shared.bumLoginFlowLayout {
                dataPrivacyForm
                    .frame(alignment: .bottom)
                    .padding(.bottom, 10)
            }
        }
        .background(theme.colors.background.ignoresSafeArea())
        .alert(item: $viewModel.alertInfo) { $0.alert }
        .accentColor(theme.colors.accent)
        // BWI #7555 migration part 3
        .sheet(isPresented: $showMigrationView) {
            MigrationInfoView(username: "", getUserName: nil)
                .environmentObject(BWIThemeService.shared)
                .interactiveDismissDisabled(true)
        }
        // BWI #7555 END
    }

    /// The header containing a Welcome Back title.
    var header: some View {
        Text(VectorL10n.authenticationLoginTitle)
            .font(theme.fonts.title2B)
            .multilineTextAlignment(.center)
            .foregroundColor(theme.colors.primaryContent)
    }
    
    /// The sever information section that includes a button to select a different server.
    var serverInfo: some View {
        AuthenticationServerInfoSection(address: viewModel.viewState.homeserver.address,
                                        flow: .login) {
            viewModel.send(viewAction: .selectServer)
        }
    }
    
    /// The form with text fields for username and password, along with a submit button.
    var loginForm: some View {
        VStack(spacing: 14) {
            RoundedBorderTextField(placeHolder: getCustomText(text: .username),
                                   text: $viewModel.username,
                                   isFirstResponder: false,
                                   configuration: UIKitTextInputConfiguration(returnKeyType: .next,
                                                                              autocapitalizationType: .none,
                                                                              autocorrectionType: .no),
                                   onEditingChanged: usernameEditingChanged,
                                   onCommit: { isPasswordFocused = true })
                .accessibilityIdentifier("usernameTextField")
                .padding(.bottom, 7)
            
            RoundedBorderTextField(placeHolder: VectorL10n.authPasswordPlaceholder,
                                   text: $viewModel.password,
                                   isFirstResponder: isPasswordFocused,
                                   configuration: UIKitTextInputConfiguration(returnKeyType: .done,
                                                                              isSecureTextEntry: true),
                                   onEditingChanged: passwordEditingChanged,
                                   onCommit: submit)
                .accessibilityIdentifier("passwordTextField")
            // bwi: hide nv forgot password button
            if !BWIBuildSettings.shared.bumLoginFlowLayout && !BWIBuildSettings.shared.bwiLoginFlowLayout {
                Button { viewModel.send(viewAction: .forgotPassword) } label: {
                    Text(VectorL10n.authenticationLoginForgotPassword)
                        .font(theme.fonts.body)
                }
                .frame(maxWidth: .infinity, alignment: .trailing)
                .padding(.bottom, 8)
            }

            Button(action: submit) {
                Text(getCustomText(text: .submit))
            }
            .disabled(BWIBuildSettings.shared.BuMXMigrationInfoLevel > 2)   // BWI #7555 migration part 3
            .buttonStyle(PrimaryActionButtonStyle())
            .disabled(!viewModel.viewState.canSubmit)
            .accessibilityIdentifier("nextButton")
            .padding([.top], BWIBuildSettings.shared.bwiLoginFlowLayout ? 36 : 0)
        }
    }

    /// A QR login button that can be used for login.
    var qrLoginButton: some View {
        Button(action: qrLogin) {
            Label {
                Text(VectorL10n.authenticationLoginWithQr)
            } icon: {
                Image(uiImage: Asset.Images.qr.image)
                    .resizable()
                    .frame(width: 24, height: 24)
            }
        }
        .buttonStyle(SecondaryActionButtonStyle(font: theme.fonts.bodySB))
        .padding(.vertical)
        .accessibilityIdentifier("qrLoginButton")
    }
    
    /// A list of SSO buttons that can be used for login.
    var ssoButtons: some View {
        VStack(spacing: 16) {
            ForEach(viewModel.viewState.homeserver.ssoIdentityProviders) { provider in
                AuthenticationSSOButton(provider: provider) {
                    viewModel.send(viewAction: .continueWithSSO(provider))
                }
                .accessibilityIdentifier("ssoButton")
            }
        }
    }

    /// A fallback button that can be used for login.
    var fallbackButton: some View {
        Button(action: fallback) {
            Text(VectorL10n.login)
        }
        .buttonStyle(PrimaryActionButtonStyle())
        .accessibilityIdentifier("fallbackButton")
    }
    
    var dataPrivacyForm: some View {
        VStack() {
            if viewModel.viewState.dataPrivacyString != nil {
                Button(action: {
                    guard let urlString = viewModel.viewState.dataPrivacyString else {
                        return
                    }
                    let tosURL = URL.init(string: urlString)! // add your link here
                    
                    UIApplication.shared.vc_open(tosURL, completionHandler: nil)
                }, label: {
                    Text(BWIL10n.authenticationDataprivacyText)
                        .font(theme.fonts.footnote)
                        .foregroundColor(theme.colors.primaryContent)
                    +
                    Text(BWIL10n.authenticationDataprivacyLink)
                        .font(theme.fonts.footnote)
                        .foregroundColor(.blue)
                        .underline()
                })
                .padding([.horizontal], 20)
            } else {
                EmptyView()
            }
        }
    }
    
    var loginDescription: some View {
        HStack(spacing: 0) {
            Text(BWIL10n.authenticationLoginDescription)
                .font(theme.fonts.callout)
                .foregroundColor(theme.colors.primaryContent)
        }
    }
    
    /// Parses the username for a homeserver.
    func usernameEditingChanged(isEditing: Bool) {
        guard !isEditing, !viewModel.username.isEmpty else { return }
        
        viewModel.send(viewAction: .parseUsername)
    }
    
    /// Resets the password field focus.
    func passwordEditingChanged(isEditing: Bool) {
        guard !isEditing else { return }
        isPasswordFocused = false
    }
    
    /// Sends the `next` view action so long as the form is ready to submit.
    func submit() {
        guard viewModel.viewState.canSubmit else { return }
        viewModel.send(viewAction: .next)
    }

    /// Sends the `fallback` view action.
    func fallback() {
        viewModel.send(viewAction: .fallback)
    }

    /// Sends the `qrLogin` view action.
    func qrLogin() {
        viewModel.send(viewAction: .qrLogin)
    }
    
    // bwi: custom forgot password button
    var forgotPasswordButton: some View {
        Button {
            viewModel.send(viewAction: .forgotPassword)
        } label: {
            Text(BWIL10n.authForgotPassword)
                .font(theme.fonts.body)
        }
        .frame(maxWidth: .infinity, alignment: .center)
        .padding(.bottom, 8)
    }
    
    // bwi: custom register button
    var registerButton: some View {
        Button {
            viewModel.send(viewAction: .register)
        } label: {
            Text(BWIL10n.bwiAuthRegisterButtonTitle)
                .font(theme.fonts.body)
        }
        .frame(maxWidth: .infinity, alignment: .center)
        .padding(.bottom, 8)
    }
    
    // bwi: custom header
    var authLoginHeaderlineText: some View {
        VStack(alignment: .leading) {
            Text(BWIL10n.authLoginHeadlineText)
                .font(theme.fonts.body)
                .foregroundColor(theme.colors.primaryContent)
            Text(BWIL10n.authLoginSubheadlineText)
                .font(theme.fonts.subheadline)
                .foregroundColor(theme.colors.secondaryContent)
        }
        .frame(maxWidth: .infinity, alignment: .leading)
        .padding([.vertical], 36)
    }
    
    
    // bwi: get app specific text
    private func getCustomText(text: CustomText) -> String {
        switch text {
        case .submit:
            return BWIBuildSettings.shared.bwiLoginFlowLayout ? BWIL10n.authenticationServerSelectionSubmitButtonTitle : VectorL10n.next
        case .username:
            return BWIBuildSettings.shared.bwiLoginFlowLayout ? BWIL10n.authUserIdPlaceholder : BWIL10n.authenticationLoginUsername
        }
    }
    
    // bwi: Accessibility declaration
    var accessibilityDeclaration: some View {
        Button(action: {
            viewModel.send(viewAction: .accessibilityDeclaration)
        }, label: {
            Text(BWIL10n.bwiAccessibilityDeclarationButtonTitle)
                .font(theme.fonts.footnote)
                .foregroundColor(.blue)
            .underline()
        })
            .padding([.horizontal], 20)
    }
}

// MARK: - Previews

@available(iOS 15.0, *)
struct AuthenticationLogin_Previews: PreviewProvider {
    static let stateRenderer = MockAuthenticationLoginScreenState.stateRenderer
    static var previews: some View {
        stateRenderer.screenGroup(addNavigation: true)
            .navigationViewStyle(.stack)
    }
}