// Copyright © 2023 Rangeproof Pty Ltd. All rights reserved.

import SwiftUI
import Sodium
import SessionUIKit
import SignalUtilitiesKit
import SessionUtilitiesKit

struct LandingScreen: View {
    @EnvironmentObject var host: HostWrapper

    var body: some View {
        ZStack(alignment: .center) {
            if #available(iOS 14.0, *) {
                ThemeManager.currentTheme.colorSwiftUI(for: .backgroundPrimary).ignoresSafeArea()
            } else {
                ThemeManager.currentTheme.colorSwiftUI(for: .backgroundPrimary)
            }
            
            VStack(
                alignment: .center,
                spacing: 0
            ) {
                Spacer(minLength: 0)
                
                Text("onboarding_landing_title".localized())
                    .bold()
                    .font(.system(size: Values.veryLargeFontSize))
                    .foregroundColor(themeColor: .textPrimary)
                
                Spacer(minLength: 0)
                    .frame(maxHeight: 2 * Values.mediumSpacing)
                
                FakeChat()
                
                Spacer(minLength: 0)
                    .frame(maxHeight: Values.massiveSpacing)
                
                Spacer(minLength: 0)
            }
            .padding(.vertical, Values.mediumSpacing)
            .padding(.bottom, 3 * Values.largeButtonHeight)
            
            VStack(
                alignment: .center,
                spacing: Values.mediumSpacing
            ) {
                Spacer()
                
                Button {
                    register()
                } label: {
                    Text("onboarding_landing_register_button_title".localized())
                        .bold()
                        .font(.system(size: Values.smallFontSize))
                        .foregroundColor(themeColor: .sessionButton_primaryFilledText)
                        .frame(
                            maxWidth: .infinity,
                            maxHeight: Values.largeButtonHeight,
                            alignment: .center
                        )
                        .backgroundColor(themeColor: .sessionButton_primaryFilledBackground)
                        .cornerRadius(Values.largeButtonHeight / 2)
                }
                .padding(.horizontal, Values.massiveSpacing)
                
                Button {
                    restore()
                } label: {
                    Text("onboarding_landing_restore_button_title".localized())
                        .bold()
                        .font(.system(size: Values.smallFontSize))
                        .foregroundColor(themeColor: .sessionButton_text)
                        .frame(
                            maxWidth: .infinity,
                            maxHeight: Values.largeButtonHeight,
                            alignment: .center
                        )
                        .overlay(
                            Capsule()
                                .stroke(themeColor: .sessionButton_border)
                        )
                }
                .padding(.horizontal, Values.massiveSpacing)
                
                Button {
                    openLegalUrl()
                } label: {
                    let attributedText: NSAttributedString = {
                        let text = String(format: "onboarding_T&C".localized(), "terms_of_service".localized(), "privacy_policy".localized())
                        let result = NSMutableAttributedString(
                            string: text,
                            attributes: [ .font : UIFont.systemFont(ofSize: Values.verySmallFontSize)]
                        )
                        result.addAttribute(.font, value: UIFont.boldSystemFont(ofSize: Values.verySmallFontSize), range: (text as NSString).range(of: "terms_of_service".localized()))
                        result.addAttribute(.font, value: UIFont.boldSystemFont(ofSize: Values.verySmallFontSize), range: (text as NSString).range(of: "privacy_policy".localized()))
                        
                        return result
                    }()
                    AttributedText(attributedText)
                        .foregroundColor(themeColor: .textPrimary)
                }
                .padding(.horizontal, Values.massiveSpacing)
            }
        }
    }
    
    private func register() {
        let seed: Data! = try! Randomness.generateRandomBytes(numberBytes: 16)
        let (ed25519KeyPair, x25519KeyPair): (KeyPair, KeyPair) = try! Identity.generate(from: seed)
        Onboarding.Flow.register
            .preregister(
                with: seed,
                ed25519KeyPair: ed25519KeyPair,
                x25519KeyPair: x25519KeyPair
            )
        
        let viewController: SessionHostingViewController = SessionHostingViewController(rootView: DisplayNameScreen(flow: .register))
        viewController.setUpNavBarSessionIcon()
        self.host.controller?.navigationController?.pushViewController(viewController, animated: true)
    }
    
    private func restore() {
        Onboarding.Flow.register.unregister()
        
        let viewController: SessionHostingViewController = SessionHostingViewController(rootView: LoadAccountScreen())
        viewController.setNavBarTitle("onboarding_load_account_title".localized())
        self.host.controller?.navigationController?.pushViewController(viewController, animated: true)
    }
    
    private func openLegalUrl() {
        let modal: ConfirmationModal = ConfirmationModal(
            info: ConfirmationModal.Info(
                title: "modal_open_url_title_2".localized(),
                body: .text("modal_open_url_explanation_2".localized()),
                confirmTitle: "terms_of_service".localized(),
                confirmStyle: .textPrimary,
                cancelTitle: "privacy_policy".localized(),
                cancelStyle: .textPrimary,
                onConfirm: { _ in
                    if let url: URL = URL(string: "https://getsession.org/terms-of-service") {
                        UIApplication.shared.open(url)
                    }
                },
                onCancel: { _ in
                    if let url: URL = URL(string: "https://getsession.org/privacy-policy") {
                        UIApplication.shared.open(url)
                    }
                }
            )
        )
        self.host.controller?.present(modal, animated: true)
    }
}

struct ChatBubble: View {
    let text: String
    let outgoing: Bool
    
    var body: some View {
        let backgroundColor: Color? = ThemeManager.currentTheme.colorSwiftUI(for: (outgoing ? .messageBubble_outgoingBackground : .messageBubble_incomingBackground))
        Text(text)
            .foregroundColor(themeColor: (outgoing ? .messageBubble_outgoingText : .messageBubble_incomingText))
            .font(.system(size: 16))
            .padding(.all, 12)
            .background(backgroundColor)
            .cornerRadius(13)
            .frame(
                maxWidth: 230,
                alignment: (outgoing ? .trailing : .leading)
            )
    }
}

struct FakeChat: View {
    @State var numberOfBubblesShown: Int = 0
    
    let chatBubbles: [ChatBubble] = [
        ChatBubble(text: "onboarding_chat_bubble_1".localized(), outgoing: false),
        ChatBubble(text: "onboarding_chat_bubble_2".localized(), outgoing: true),
        ChatBubble(text: "onboarding_chat_bubble_3".localized(), outgoing: false),
        ChatBubble(text: "onboarding_chat_bubble_4".localized(), outgoing: true),
    ]
    
    var body: some View {
        VStack(
            alignment: .leading,
            spacing: 18
        ) {
            ForEach(
                0...(chatBubbles.count - 1),
                id: \.self
            ) { index in
                let chatBubble: ChatBubble = chatBubbles[index]
                let bubble = chatBubble
                    .frame(
                        maxWidth: .infinity,
                        alignment: chatBubble.outgoing ? .trailing : .leading
                    )
                if index < numberOfBubblesShown {
                    bubble
                        .transition(
                            AnyTransition
                                .move(edge: .bottom)
                                .combined(with:.opacity.animation(.easeIn(duration: 0.68)))
                        )
                }
            }
        }
        .frame(
            height: 320,
            alignment: .bottom
        )
        .padding(.horizontal, 36)
        .onAppear {
            guard numberOfBubblesShown < 4 else { return }
            
            Timer.scheduledTimerOnMainThread(withTimeInterval: 0.2, repeats: false) { _ in
                withAnimation(.spring().speed(0.68)) {
                    numberOfBubblesShown = 1
                }
                Timer.scheduledTimerOnMainThread(withTimeInterval: 1.5, repeats: true) { timer in
                    withAnimation(.spring().speed(0.68)) {
                        numberOfBubblesShown += 1
                        if numberOfBubblesShown >= 4 {
                            timer.invalidate()
                        }
                    }
                }
            }
        }
    }
}

struct LandingView_Previews: PreviewProvider {
    static var previews: some View {
        LandingScreen()
    }
}