// ── Login / Register View ─────────────────────────────────────
// Authentication form for ChronoMind via platform-service.

import SwiftUI

struct CMLoginView: View {
    @ObservedObject var authService = CMAuthService.shared

    @State private var isRegister = false
    @State private var name = ""
    @State private var email = ""
    @State private var password = ""

    private var isLoading: Bool {
        if case .loading = authService.state { return true }
        return false
    }

    private var errorMessage: String? {
        if case .error(let msg) = authService.state { return msg }
        return nil
    }

    private var isValidEmail: Bool {
        let p = "[A-Z0-9a-z._%+-]+@[A-Za-z0-9.-]+\\.[A-Za-z]{2,}"
        return email.range(of: p, options: .regularExpression) != nil
    }

    private var isValidPassword: Bool {
        password.count >= 8
            && password.rangeOfCharacter(from: .uppercaseLetters) != nil
            && password.rangeOfCharacter(from: .lowercaseLetters) != nil
            && password.rangeOfCharacter(from: .decimalDigits) != nil
    }

    private var isValid: Bool {
        isValidEmail && isValidPassword && (!isRegister || !name.trimmingCharacters(in: .whitespaces).isEmpty)
    }

    var body: some View {
        ZStack {
            CMColors.bg.ignoresSafeArea()

            ScrollView {
                VStack(spacing: 24) {
                    Spacer(minLength: 60)

                    Image(systemName: "clock.badge.checkmark")
                        .font(.system(size: 48))
                        .foregroundColor(CMColors.accent)

                    Text("ChronoMind")
                        .font(CMFonts.display(size: 28))
                        .foregroundColor(CMColors.text)

                    Text(isRegister ? "Create your account" : "Sign in to your account")
                        .font(CMFonts.body(size: 15))
                        .foregroundColor(CMColors.textSecondary)

                    VStack(spacing: 14) {
                        if isRegister {
                            TextField("Full Name", text: $name)
                                .textContentType(.name)
                                .autocapitalization(.words)
                                .padding(14)
                                .background(CMColors.surface)
                                .cornerRadius(CMRadius.md)
                                .foregroundColor(CMColors.text)
                        }

                        TextField("Email", text: $email)
                            .textContentType(.emailAddress)
                            .keyboardType(.emailAddress)
                            .autocapitalization(.none)
                            .disableAutocorrection(true)
                            .padding(14)
                            .background(CMColors.surface)
                            .cornerRadius(CMRadius.md)
                            .foregroundColor(CMColors.text)

                        SecureField("Password", text: $password)
                            .textContentType(isRegister ? .newPassword : .password)
                            .padding(14)
                            .background(CMColors.surface)
                            .cornerRadius(CMRadius.md)
                            .foregroundColor(CMColors.text)

                        if !password.isEmpty && isRegister && !isValidPassword {
                            Text("Password needs: 8+ chars, uppercase, lowercase, digit")
                                .font(.caption)
                                .foregroundColor(CMColors.warning)
                        }
                    }
                    .padding(.horizontal, 24)

                    if let errorMessage {
                        Text(errorMessage)
                            .font(.caption)
                            .foregroundColor(CMColors.error)
                            .padding(.horizontal, 24)
                    }

                    Button {
                        Task {
                            if isRegister {
                                await authService.register(name: name, email: email, password: password)
                            } else {
                                await authService.login(email: email, password: password)
                            }
                        }
                    } label: {
                        if isLoading {
                            ProgressView()
                                .tint(.white)
                                .frame(maxWidth: .infinity)
                                .frame(height: 48)
                        } else {
                            Text(isRegister ? "Create Account" : "Sign In")
                                .fontWeight(.semibold)
                                .frame(maxWidth: .infinity)
                                .frame(height: 48)
                        }
                    }
                    .buttonStyle(.borderedProminent)
                    .tint(CMColors.accent)
                    .disabled(!isValid || isLoading)
                    .padding(.horizontal, 24)

                    HStack {
                        Text(isRegister ? "Already have an account?" : "Don't have an account?")
                            .font(.caption)
                            .foregroundColor(CMColors.textSecondary)
                        Button(isRegister ? "Sign In" : "Register") {
                            withAnimation { isRegister.toggle() }
                        }
                        .font(.caption)
                        .foregroundColor(CMColors.accent)
                    }

                    Spacer(minLength: 40)
                }
            }
        }
        .preferredColorScheme(.dark)
    }
}