//
//  LockScreenView.swift
//  Feels
//
//  Lock screen shown when privacy lock is enabled and app needs authentication.
//

import SwiftUI

struct LockScreenView: View {

    @ObservedObject var authManager: BiometricAuthManager
    @State private var showError = false

    var body: some View {
        ZStack {
            // Background gradient
            LinearGradient(
                colors: [
                    Color(.systemBackground),
                    Color(.systemGray6)
                ],
                startPoint: .top,
                endPoint: .bottom
            )
            .ignoresSafeArea()

            VStack(spacing: 40) {
                Spacer()

                // App icon / lock icon
                VStack(spacing: 20) {
                    Image(systemName: "lock.fill")
                        .font(.largeTitle)
                        .foregroundStyle(.secondary)

                    Text("Feels is Locked")
                        .font(.title2)
                        .fontWeight(.semibold)

                    Text("Authenticate to access your mood data")
                        .font(.subheadline)
                        .foregroundStyle(.secondary)
                        .multilineTextAlignment(.center)
                }

                Spacer()

                // Unlock button
                Button {
                    Task {
                        let success = await authManager.authenticate()
                        if !success {
                            showError = true
                        }
                    }
                } label: {
                    HStack(spacing: 12) {
                        Image(systemName: authManager.biometricIcon)
                            .font(.title2)

                        Text("Unlock with \(authManager.biometricName)")
                            .fontWeight(.medium)
                    }
                    .frame(maxWidth: .infinity)
                    .padding(.vertical, 16)
                    .background(Color.accentColor)
                    .foregroundColor(.white)
                    .clipShape(RoundedRectangle(cornerRadius: 14))
                }
                .disabled(authManager.isAuthenticating)
                .padding(.horizontal, 40)

                // Passcode fallback hint
                if authManager.canUseDevicePasscode {
                    Text("Or use your device passcode")
                        .font(.caption)
                        .foregroundStyle(.tertiary)
                }

                Spacer()
                    .frame(height: 60)
            }
            .padding()
        }
        .alert("Authentication Failed", isPresented: $showError) {
            Button("Try Again") {
                Task {
                    await authManager.authenticate()
                }
            }
            Button("Cancel", role: .cancel) { }
        } message: {
            Text("Unable to verify your identity. Please try again.")
        }
        .onAppear {
            // Auto-trigger authentication on appear
            if !authManager.isUnlocked && !authManager.isAuthenticating {
                Task {
                    await authManager.authenticate()
                }
            }
        }
    }
}