using System.Windows.Input;
using JdeScoping.ConfigManager.Core.Constants;

namespace JdeScoping.ConfigManager.Ui.ViewModels.Dialogs;

/// <summary>
/// View model for unlocking an existing secure store.
/// </summary>
public class UnlockStoreDialogViewModel : ViewModelBase
{
    private readonly string _storePath;
    private string _keyFilePath = string.Empty;

    /// <summary>
    /// Initializes a new instance of the <see cref="UnlockStoreDialogViewModel"/> class.
    /// </summary>
    /// <param name="storePath">The path to the store file to unlock.</param>
    public UnlockStoreDialogViewModel(string storePath)
    {
        _storePath = storePath ?? throw new ArgumentNullException(nameof(storePath));
        BrowseKeyFilePathCommand = new RelayCommand(BrowseKeyFilePath);
    }

    /// <summary>
    /// Gets the path to the store file to unlock (read-only).
    /// </summary>
    public string StorePath => _storePath;

    /// <summary>
    /// Gets or sets the path to the key file for decryption.
    /// </summary>
    public string KeyFilePath
    {
        get => _keyFilePath;
        set
        {
            if (SetProperty(ref _keyFilePath, value))
                NotifyValidationChanged();
        }
    }

    /// <summary>
    /// Gets the command to browse for key file path location.
    /// </summary>
    public ICommand BrowseKeyFilePathCommand { get; }

    /// <summary>
    /// Gets a value indicating whether the dialog input is valid.
    /// </summary>
    public bool IsValid
    {
        get
        {
            if (string.IsNullOrWhiteSpace(KeyFilePath))
                return false;

            return System.IO.File.Exists(KeyFilePath);
        }
    }

    /// <summary>
    /// Gets the validation error message, or null if valid.
    /// </summary>
    public string? ValidationError
    {
        get
        {
            if (string.IsNullOrWhiteSpace(KeyFilePath))
                return SecureStoreStrings.KeyFilePathRequired;

            if (!System.IO.File.Exists(KeyFilePath))
                return SecureStoreStrings.KeyFileNotFound;

            return null;
        }
    }

    /// <summary>
    /// Event raised to request open file dialog for key file path.
    /// Parameters: title, fileTypeName, pattern
    /// Returns: selected file path or null
    /// </summary>
    public event Func<string, string, string, Task<string?>>? OnShowOpenFileDialog;

    private void NotifyValidationChanged()
    {
        OnPropertyChanged(nameof(IsValid));
        OnPropertyChanged(nameof(ValidationError));
    }

    private async void BrowseKeyFilePath()
    {
        if (OnShowOpenFileDialog == null)
            return;

        var path = await OnShowOpenFileDialog(
            SecureStoreStrings.SelectKeyFile,
            SecureStoreFileExtensions.KeyTypeName,
            SecureStoreFileExtensions.KeyPattern);

        if (!string.IsNullOrEmpty(path))
        {
            KeyFilePath = path;
        }
    }
}