using System;
using System.Runtime.Serialization;

namespace WingCloudServer.GeneralDocTools.Model.Parameters
{
    /// <summary>
    /// parameter base type
    /// </summary>
    /// <typeparam name="T"></typeparam>
    [DataContract]
    public abstract class ParameterBase<T> : IParameter
    {
        private T _initialValue;

        private T _value;

        /// <summary>
        /// The value saved in setting file.Some times the value will be set but not saved to setting file.
        /// </summary>
        public T SavedValue { get; private set; }

        /// <summary>
        /// parameter value
        /// </summary>
        [DataMember]
        public T Value
        {
            get
            {
                return _value;
            }
            set
            {
                if (!Equals(_value, value))
                {
                    _value = value;
                    OnValueChanged();
                }
            }
        }

        /// <summary>
        /// parameter name
        /// </summary>
        public string Name { get; set; } = string.Empty;

        /// <summary>
        /// parameter section
        /// </summary>
        public string Section { get; set; } = string.Empty;

        /// <summary>
        /// parameter value changed state
        /// </summary>
        public bool IsChanged => !Equals(_initialValue, Value);

        /// <summary>
        /// value changed event
        /// </summary>
        public event EventHandler ValueChanged;

        /// <summary>
        /// notify value changed
        /// </summary>
        private void OnValueChanged()
        {
            ValueChanged?.Invoke(this, EventArgs.Empty);
        }

        /// <summary>
        /// change initial value
        /// </summary>
        public void ChangeInitialValue()
        {
            _initialValue = Value;
            SavedValue = Value;
        }

        public void ChangeSavedValue()
        {
            SavedValue = Value;
        }

        public void ChangeParameterValue(object value)
        {
            var newParameter = value as ParameterBase<T>;
            if (newParameter != null)
            {
                Value = newParameter.Value;
                SavedValue = Value;
            }
        }
    }
}