using System;
using Avalonia.Data;

namespace Material.Dialog.ViewModels.Elements.TextField
{
    public class TextFieldViewModel : DialogViewModelBase
    {
        private readonly TextFieldDialogViewModel _parent;

        public TextFieldDialogViewModel Parent => _parent;

        public TextFieldViewModel(TextFieldDialogViewModel parent, string defaultText = default,
            Func<string, Tuple<bool, string>> validateHandler = null)
        {
            _parent = parent;
            _text = defaultText;

            ValidateHandler = validateHandler;

            var result = DoValidate(defaultText);
            IsValid = result.Item1;
        }

        public event EventHandler<bool> OnValidateRequired;

        public Func<string, Tuple<bool, string>> ValidateHandler;

        private string _placeholderText;

        public string PlaceholderText
        {
            get => _placeholderText;
            set
            {
                _placeholderText = value;
                OnPropertyChanged();
            }
        }

        private string _text;

        public string Text
        {
            get => _text;
            set
            {
                _text = value;
                OnPropertyChanged();
                OnTextChanged(value);
            }
        }

        private string _classes;

        public string Classes
        {
            get => _classes;
            set
            {
                _classes = value;
                OnPropertyChanged();
            }
        }

        private string _label;

        public string Label
        {
            get => _label;
            set
            {
                _label = value;
                OnPropertyChanged();
            }
        }

        private char _maskChar;

        public char MaskChar
        {
            get => _maskChar;
            set
            {
                _maskChar = value;
                OnPropertyChanged();
            }
        }

        private int _maxCountChars;

        public int MaxCountChars
        {
            get => _maxCountChars;
            set
            {
                _maxCountChars = value;
                OnPropertyChanged();
            }
        }

        private bool _isValid;

        public bool IsValid
        {
            get => _isValid;
            set
            {
                _isValid = value;
                OnPropertyChanged();
            }
        }

        private string _assistiveText;

        public string AssistiveText
        {
            get => _assistiveText;
            set
            {
                _assistiveText = value;
                OnPropertyChanged();
            }
        }

        private void OnTextChanged(string text)
        {
            var result = DoValidate(text);

            var isSuccessful = result.Item1;

            IsValid = isSuccessful;
            OnValidateRequired?.Invoke(this, true);

            if (!isSuccessful)
                throw new DataValidationException(result.Item2);
        }

        private Tuple<bool, string> DoValidate(string text)
        {
            try
            {
                return ValidateHandler?.Invoke(text) ?? new Tuple<bool, string>(true, null);
            }
            catch (Exception e)
            {
                return new Tuple<bool, string>(false, e.Message);
            }
        }
    }
}