using System;
using System.ComponentModel;
using System.Windows;
using System.Windows.Threading;
using JetBrains.Annotations;
using TeaBox.Macros;

namespace JDSongConverter.Tasks
{
    public enum TaskResult
    {
        Ok,
        Error,
        ParametersError,
        FileMissing
    }

    /// <summary>
    /// A task is a piece of work that can be run independentaly from any other task
    /// </summary>
    public abstract class Task : INotifyPropertyChanged
    {
        #region Variables
        
        private bool _enabled = true;
        
        #endregion

        #region Properties

        /// <summary>
        /// Indicates whether the task is active or not
        /// </summary>
        public bool Enabled
        {
            get { return _enabled; }
            set
            {
                if (_enabled != value)
                {
                    _enabled = value;
                    OnPropertyChanged("Enabled");
                }
            }
        }

        /// <summary>
        /// The name of the task
        /// </summary>
        public abstract string Name
        {
            get; set;
        }

        /// <summary>
        /// The text displayed during execution of task
        /// </summary>
        public abstract string ProgressText
        {
            get;
        }

        /// <summary>
        /// The context of the task, containing some useful informations like the current song being converted
        /// </summary>
        public TaskContext Context
        {
            get; set;
        }
        
        #endregion
        
        #region Methods

        /// <summary>
        /// The method where task execution takes place
        /// </summary>
        /// <param name="executionContext">the logger to log errors/warnings</param>
        /// <returns>the result of the task</returns>
        public abstract TaskResult Process(IExecutionContext executionContext);

        #endregion

        public event PropertyChangedEventHandler PropertyChanged;

        [NotifyPropertyChangedInvocator]
        protected virtual void OnPropertyChanged(string propertyName)
        {
            Application.Current.Dispatcher.BeginInvoke(DispatcherPriority.Normal, new Action(() =>
            {
                PropertyChangedEventHandler handler = PropertyChanged;
                if (handler != null) handler(this, new PropertyChangedEventArgs(propertyName));
            }));
        }
    }
}