import SwiftUI

/// Modal Sheet allowing logged-in users to change their password.
struct ChangePasswordModalView: View {
    @Environment(\.dismiss) private var dismiss
    @ObservedObject var authManager: AuthManager = .shared
    
    @State private var oldPasswordInput: String = ""
    @State private var newPasswordInput: String = ""
    @State private var confirmPasswordInput: String = ""
    @State private var errorMessage: String?
    @State private var successToast: String?
    
    var body: some View {
        ZStack {
            Color.spaceBlack.ignoresSafeArea()
            
            VStack(spacing: 20) {
                // Header
                HStack {
                    Text("修改密码")
                        .font(.system(size: 18, weight: .bold))
                        .foregroundStyle(Color.primary)
                    Spacer()
                    Button {
                        dismiss()
                    } label: {
                        Image(systemName: "xmark.circle.fill")
                            .font(.system(size: 22))
                            .foregroundStyle(Color.secondary.opacity(0.6))
                    }
                }
                .padding(.horizontal, 20)
                .padding(.top, 20)
                
                VStack(spacing: 14) {
                    passwordField(label: "当前原密码", text: $oldPasswordInput, placeholder: "请输入当前账号原密码")
                    passwordField(label: "新密码", text: $newPasswordInput, placeholder: "请输入新密码 (不少于 6 位)")
                    passwordField(label: "确认新密码", text: $confirmPasswordInput, placeholder: "请再次输入新密码")
                    
                    if let error = errorMessage {
                        Text(error)
                            .font(.system(size: 12))
                            .foregroundStyle(Color.recordingRed)
                            .frame(maxWidth: .infinity, alignment: .leading)
                    }
                    
                    if let toast = successToast {
                        Text(toast)
                            .font(.system(size: 12))
                            .foregroundStyle(Color.green)
                            .frame(maxWidth: .infinity, alignment: .leading)
                    }
                }
                .padding(.horizontal, 20)
                .padding(.top, 10)
                
                Spacer()
                
                Button {
                    handleChangePassword()
                } label: {
                    if authManager.isProcessing {
                        ProgressView()
                            .tint(Color.spaceBlack)
                    } else {
                        Text("确认修改密码")
                            .font(.system(size: 15, weight: .semibold))
                            .foregroundStyle(Color.spaceBlack)
                    }
                }
                .frame(maxWidth: .infinity)
                .padding(.vertical, 14)
                .background(Color.primary)
                .cornerRadius(8)
                .padding(.horizontal, 20)
                .padding(.bottom, 24)
                .disabled(authManager.isProcessing)
            }
        }
    }
    
    private func passwordField(label: String, text: Binding<String>, placeholder: String) -> some View {
        VStack(alignment: .leading, spacing: 6) {
            Text(label)
                .font(.system(size: 12))
                .foregroundStyle(Color.secondary)
            
            HStack(spacing: 12) {
                Image(systemName: "lock")
                    .font(.system(size: 14))
                    .foregroundStyle(Color.secondary)
                    .frame(width: 20)
                
                SecureField(placeholder, text: text)
                    .font(.system(size: 14))
            }
            .padding(.horizontal, 14)
            .padding(.vertical, 12)
            .background(Color.cardBackground.opacity(0.3))
            .businessBorder(cornerRadius: 8)
        }
    }
    
    private func handleChangePassword() {
        errorMessage = nil
        successToast = nil
        
        guard !oldPasswordInput.isEmpty else {
            errorMessage = "请输入原密码"
            return
        }
        guard newPasswordInput.count >= 6 else {
            errorMessage = "新密码长度不能少于 6 位"
            return
        }
        guard newPasswordInput == confirmPasswordInput else {
            errorMessage = "两次输入的无缝新密码不一致"
            return
        }
        
        authManager.changePassword(oldPassword: oldPasswordInput, newPassword: newPasswordInput) { success, err in
            if success {
                successToast = "密码修改成功！请记牢新密码"
                DispatchQueue.main.asyncAfter(deadline: .now() + 1.0) {
                    dismiss()
                }
            } else {
                errorMessage = err ?? "原密码错误或修改失败"
            }
        }
    }
}