// --------------------------------------------------------------------------------------------------------------------
// <copyright file="QueueViewModel.cs" company="HandBrake Project (http://handbrake.fr)">
//   This file is part of the HandBrake source code - It may be used under the terms of the GNU General Public License.
// </copyright>
// <summary>
//   The Preview View Model
// </summary>
// --------------------------------------------------------------------------------------------------------------------

namespace HandBrakeWPF.ViewModels
{
    using System;
    using System.Collections.Generic;
    using System.ComponentModel;
    using System.IO;
    using System.Linq;
    using System.Windows;

    using Caliburn.Micro;

    using HandBrakeWPF.EventArgs;
    using HandBrakeWPF.Properties;
    using HandBrakeWPF.Services.Interfaces;
    using HandBrakeWPF.Services.Queue.Interfaces;
    using HandBrakeWPF.Services.Queue.Model;
    using HandBrakeWPF.ViewModels.Interfaces;

    using Microsoft.Win32;

    using EncodeCompletedEventArgs = HandBrakeWPF.Services.Encode.EventArgs.EncodeCompletedEventArgs;
    using EncodeProgressEventArgs = HandBrakeWPF.Services.Encode.EventArgs.EncodeProgressEventArgs;
    using EncodeTask = HandBrakeWPF.Services.Encode.Model.EncodeTask;

    /// <summary>
    /// The Preview View Model
    /// </summary>
    public class QueueViewModel : ViewModelBase, IQueueViewModel
    {
        #region Constants and Fields

        private readonly IErrorService errorService;
        private readonly IUserSettingService userSettingService;
        private readonly IQueueProcessor queueProcessor;
        private bool isEncoding;
        private string jobStatus;
        private string jobsPending;
        private string whenDoneAction;

        private bool isQueueRunning;

        #endregion

        #region Constructors and Destructors

        /// <summary>
        /// Initializes a new instance of the <see cref="QueueViewModel"/> class.
        /// </summary>
        /// <param name="userSettingService">
        /// The user Setting Service.
        /// </param>
        /// <param name="queueProcessor">
        /// The Queue Processor Service 
        /// </param>
        /// <param name="errorService">
        /// The Error Service 
        /// </param>
        public QueueViewModel(IUserSettingService userSettingService, IQueueProcessor queueProcessor, IErrorService errorService)
        {
            this.userSettingService = userSettingService;
            this.queueProcessor = queueProcessor;
            this.errorService = errorService;
            this.Title = Resources.QueueViewModel_Queue;
            this.JobsPending = Resources.QueueViewModel_NoEncodesPending;
            this.JobStatus = Resources.QueueViewModel_NoJobsPending;
            this.SelectedItems = new BindingList<QueueTask>();
            this.DisplayName = "Queue";
            this.IsQueueRunning = false;
            
            this.WhenDoneAction = this.userSettingService.GetUserSetting<string>(UserSettingConstants.WhenCompleteAction);
        }

        #endregion

        #region Properties

        /// <summary>
        /// Gets or sets a value indicating whether the Queue is paused or not..
        /// </summary>
        public bool IsQueueRunning
        {
            get
            {
                return this.isQueueRunning;
            }
            set
            {
                if (value == this.isQueueRunning) return;
                this.isQueueRunning = value;
                this.NotifyOfPropertyChange(() => this.IsQueueRunning);
            }
        }

        /// <summary>
        /// Gets or sets JobStatus.
        /// </summary>
        public string JobStatus
        {
            get
            {
                return this.jobStatus;
            }

            set
            {
                this.jobStatus = value;
                this.NotifyOfPropertyChange(() => this.JobStatus);
            }
        }

        /// <summary>
        /// Gets or sets JobsPending.
        /// </summary>
        public string JobsPending
        {
            get
            {
                return this.jobsPending;
            }

            set
            {
                this.jobsPending = value;
                this.NotifyOfPropertyChange(() => this.JobsPending);
            }
        }

        /// <summary>
        /// Gets or sets WhenDoneAction.
        /// </summary>
        public string WhenDoneAction
        {
            get
            {
                return this.whenDoneAction;
            }
            set
            {
                this.whenDoneAction = value;
                this.NotifyOfPropertyChange(() => this.WhenDoneAction);
            }
        }

        /// <summary>
        /// Gets the queue tasks.
        /// </summary>
        public BindingList<QueueTask> QueueTasks
        {
            get
            {
                return this.queueProcessor.Queue;
            }
        }

        /// <summary>
        /// Gets or sets the selected items.
        /// </summary>
        public BindingList<QueueTask> SelectedItems { get; set; }

        #endregion

        #region Public Methods

        /// <summary>
        /// Update the When Done Setting
        /// </summary>
        /// <param name="action">
        /// The action.
        /// </param>
        public void WhenDone(string action)
        {
            this.WhenDoneAction = action;
            this.userSettingService.SetUserSetting(UserSettingConstants.WhenCompleteAction, action);
        }

        /// <summary>
        /// Clear the Queue
        /// </summary>
        public void Clear()
        {
            MessageBoxResult result = this.errorService.ShowMessageBox(
                Resources.QueueViewModel_ClearQueueConfrimation, Resources.Confirm, MessageBoxButton.YesNo, MessageBoxImage.Warning);
            if (result == MessageBoxResult.Yes)
            {
                this.queueProcessor.Clear();
            }
        }

        /// <summary>
        /// Clear Completed Items
        /// </summary>
        public void ClearCompleted()
        {
            this.queueProcessor.ClearCompleted();
        }

        /// <summary>
        /// Close this window.
        /// </summary>
        public void Close()
        {
            this.TryClose();
        }

        /// <summary>
        /// Handle the On Window Load
        /// </summary>
        public override void OnLoad()
        {
            // Setup the window to the correct state.
            this.IsQueueRunning = this.queueProcessor.EncodeService.IsEncoding;
            this.JobsPending = string.Format(Resources.QueueViewModel_JobsPending, this.queueProcessor.Count);

            base.OnLoad();
        }

        /// <summary>
        /// Can Pause the Queue.
        /// Used by Caliburn Micro to enable/disable the context menu item.
        /// </summary>
        /// <returns>
        /// True when we can pause the queue.
        /// </returns>
        public bool CanPauseQueue()
        {
            return this.IsQueueRunning;
        }

        /// <summary>
        /// Pause the Queue
        /// </summary>
        public void PauseQueue()
        {
            this.queueProcessor.Pause();

            this.JobStatus = Resources.QueueViewModel_QueuePending;
            this.JobsPending = string.Format(Resources.QueueViewModel_JobsPending, this.queueProcessor.Count);
            this.IsQueueRunning = false;

            MessageBox.Show(Resources.QueueViewModel_QueuePauseNotice, Resources.QueueViewModel_Queue, 
                MessageBoxButton.OK, MessageBoxImage.Information);
        }

        /// <summary>
        /// Pause the Queue
        /// </summary>
        /// <remarks>
        /// Prevents evaluation of CanPauseQueue
        /// </remarks>
        public void PauseQueueToolbar()
        {
            this.PauseQueue();
        }

        /// <summary>
        /// The remove selected jobs.
        /// </summary>
        public void RemoveSelectedJobs()
        {
            MessageBoxResult result =
                  this.errorService.ShowMessageBox(
                      Resources.QueueViewModel_DelSelectedJobConfirmation,
                      Resources.Question,
                      MessageBoxButton.YesNo,
                      MessageBoxImage.Question);

            if (result == MessageBoxResult.No)
            {
                return;
            }

            List<QueueTask> tasksToRemove = this.SelectedItems.ToList();
            foreach (QueueTask job in tasksToRemove)
            {
                this.RemoveJob(job);
            }
        }

        /// <summary>
        /// Remove a Job from the queue
        /// </summary>
        /// <param name="queueTask">
        /// The Job to remove from the queue
        /// </param>
        public void RemoveJob(object queueTask)
        {
            QueueTask task = queueTask as QueueTask;
            if (task == null)
            {
                return;
            }

            if (task.Status == QueueItemStatus.InProgress)
            {
                MessageBoxResult result =
                    this.errorService.ShowMessageBox(
                        Resources.QueueViewModel_JobCurrentlyRunningWarning, 
                        Resources.Warning, 
                        MessageBoxButton.YesNo, 
                        MessageBoxImage.Question);

                if (result == MessageBoxResult.Yes)
                {
                    this.queueProcessor.EncodeService.Stop();
                    this.queueProcessor.Remove(task);
                }
            }
            else
            {
                this.queueProcessor.Remove(task);
            }
        }

        /// <summary>
        /// Reset the job state to waiting.
        /// </summary>
        /// <param name="task">
        /// The task.
        /// </param>
        public void RetryJob(QueueTask task)
        {
            task.Status = QueueItemStatus.Waiting;
            this.queueProcessor.BackupQueue(null);
            this.JobsPending = string.Format(Resources.QueueViewModel_JobsPending, this.queueProcessor.Count);
        }

        /// <summary>
        /// Can Start Encoding.
        /// Used by Caliburn Micro to enable/disable the context menu item.
        /// </summary>
        /// <returns>
        /// True when we can start encoding.
        /// </returns>
        public bool CanStartQueue()
        {
            return !this.IsQueueRunning;
        }

        /// <summary>
        /// Start Encode
        /// </summary>
        public void StartQueue()
        {
            if (this.queueProcessor.Count == 0)
            {
                this.errorService.ShowMessageBox(
                    Resources.QueueViewModel_NoPendingJobs, Resources.Error, MessageBoxButton.OK, MessageBoxImage.Error);
                return;
            }

            this.JobStatus = Resources.QueueViewModel_QueueStarted;
            this.JobsPending = string.Format(Resources.QueueViewModel_JobsPending, this.queueProcessor.Count);
            this.IsQueueRunning = true;

            this.queueProcessor.Start(userSettingService.GetUserSetting<bool>(UserSettingConstants.ClearCompletedFromQueue));
        }

        /// <summary>
        /// Export the Queue to a file.
        /// </summary>
        public void Export()
        {
            SaveFileDialog dialog = new SaveFileDialog
                {
                    Filter = "Legacy Queue Files (*.hbq)|*.hbq|Json for CLI (*.json)|*.json", 
                    OverwritePrompt = true, 
                    DefaultExt = ".hbq", 
                    AddExtension = true
                };

            if (dialog.ShowDialog() == true)
            {
                if (Path.GetExtension(dialog.FileName).ToLower().Trim() == ".json")
                {
                    this.queueProcessor.ExportJson(dialog.FileName);
                }
                else
                {
                    this.queueProcessor.BackupQueue(dialog.FileName);
                }
            }
        }

        /// <summary>
        /// Import a saved queue
        /// </summary>
        public void Import()
        {
            OpenFileDialog dialog = new OpenFileDialog { Filter = "Legacy Queue Files (*.hbq)|*.hbq", CheckFileExists = true };
            if (dialog.ShowDialog() == true)
            {
                this.queueProcessor.RestoreQueue(dialog.FileName);
            }
        }

        /// <summary>
        /// Edit this Job
        /// </summary>
        /// <param name="task">
        /// The task.
        /// </param>
        public void EditJob(QueueTask task)
        {
            MessageBoxResult result = this.errorService.ShowMessageBox(
                Resources.QueueViewModel_EditConfrimation, 
                "Modify Job?", 
                MessageBoxButton.YesNo, 
                MessageBoxImage.Question);

            if (result != MessageBoxResult.Yes)
            {
                return;
            }

            // Remove the job if it is not already encoding. Let the user decide if they want to cancel or not.
            this.RemoveJob(task);

            // Pass a copy of the job back to the Main Screen
            IMainViewModel mvm = IoC.Get<IMainViewModel>();
            mvm.EditQueueJob(new EncodeTask(task.Task));
        }

        #endregion

        #region Methods

        public void Activate()
        {
            this.queueProcessor.QueueCompleted += this.queueProcessor_QueueCompleted;
            this.queueProcessor.QueueChanged += this.QueueManager_QueueChanged;
            this.queueProcessor.JobProcessingStarted += this.QueueProcessorJobProcessingStarted;

        }

        public void Deactivate()
        {
            this.queueProcessor.QueueCompleted -= this.queueProcessor_QueueCompleted;
            this.queueProcessor.QueueChanged -= this.QueueManager_QueueChanged;
            this.queueProcessor.JobProcessingStarted -= this.QueueProcessorJobProcessingStarted;
        }

        /// <summary>
        /// Override the OnActive to run the Screen Loading code in the view model base.
        /// </summary>
        protected override void OnActivate()
        {
            this.Load();

            this.queueProcessor.QueueCompleted += this.queueProcessor_QueueCompleted;
            this.queueProcessor.QueueChanged += this.QueueManager_QueueChanged;
            this.queueProcessor.EncodeService.EncodeStatusChanged += this.EncodeService_EncodeStatusChanged;
            this.queueProcessor.EncodeService.EncodeCompleted += this.EncodeService_EncodeCompleted;
            this.queueProcessor.JobProcessingStarted += this.QueueProcessorJobProcessingStarted;
            this.queueProcessor.LowDiskspaceDetected += this.QueueProcessor_LowDiskspaceDetected;

            this.JobsPending = string.Format(Resources.QueueViewModel_JobsPending, this.queueProcessor.Count);
            this.JobStatus = Resources.QueueViewModel_QueueReady;

            base.OnActivate();
        }

        /// <summary>
        /// Override the Deactivate
        /// </summary>
        /// <param name="close">
        /// The close.
        /// </param>
        protected override void OnDeactivate(bool close)
        {
            this.queueProcessor.QueueCompleted -= this.queueProcessor_QueueCompleted;
            this.queueProcessor.QueueChanged -= this.QueueManager_QueueChanged;
            this.queueProcessor.EncodeService.EncodeStatusChanged -= this.EncodeService_EncodeStatusChanged;
            this.queueProcessor.EncodeService.EncodeCompleted -= this.EncodeService_EncodeCompleted;
            this.queueProcessor.JobProcessingStarted -= this.QueueProcessorJobProcessingStarted;
            this.queueProcessor.LowDiskspaceDetected -= this.QueueProcessor_LowDiskspaceDetected;

            base.OnDeactivate(close);
        }

        /// <summary>
        /// Handle the Encode Status Changed Event.
        /// </summary>
        /// <param name="sender">
        /// The sender.
        /// </param>
        /// <param name="e">
        /// The EncodeProgressEventArgs.
        /// </param>
        private void EncodeService_EncodeStatusChanged(object sender, EncodeProgressEventArgs e)
        {
            Execute.OnUIThread(() =>
            {
                this.JobStatus =
                    string.Format(
                        Resources.QueueViewModel_QueueStatusDisplay, 
                        e.Task, 
                        e.TaskCount, 
                        e.PercentComplete, 
                        e.CurrentFrameRate, 
                        e.AverageFrameRate, 
                        e.EstimatedTimeLeft, 
                        e.ElapsedTime);
            });
        }

        /// <summary>
        /// Detect Low Disk Space before starting new queue tasks.
        /// </summary>
        /// <param name="sender">Event invoker. </param>
        /// <param name="e">Event Args.</param>
        private void QueueProcessor_LowDiskspaceDetected(object sender, EventArgs e)
        {
            Execute.OnUIThreadAsync(
                () =>
                {
                    this.queueProcessor.Pause();
                    this.JobStatus = Resources.QueueViewModel_QueuePending;
                    this.JobsPending = string.Format(Resources.QueueViewModel_JobsPending, this.queueProcessor.Count);
                    this.IsQueueRunning = false;

                    this.errorService.ShowMessageBox(
                        Resources.MainViewModel_LowDiskSpaceWarning,
                        Resources.MainViewModel_LowDiskSpace,
                        MessageBoxButton.OK,
                        MessageBoxImage.Warning);
                });
        }

        /// <summary>
        /// Handle the Queue Changed Event.
        /// </summary>
        /// <param name="sender">
        /// The sender.
        /// </param>
        /// <param name="e">
        /// The e.
        /// </param>
        private void QueueManager_QueueChanged(object sender, EventArgs e)
        {
            this.JobsPending = string.Format(Resources.QueueViewModel_JobsPending, this.queueProcessor.Count);

            if (!queueProcessor.IsProcessing)
            {
                this.JobStatus = Resources.QueueViewModel_QueueNotRunning;
                this.IsQueueRunning = false;
            }
        }

        /// <summary>
        /// Handle the Queue Completed Event
        /// </summary>
        /// <param name="sender">
        /// The sender.
        /// </param>
        /// <param name="e">
        /// The EventArgs.
        /// </param>
        private void queueProcessor_QueueCompleted(object sender, EventArgs e)
        {
            this.JobStatus = Resources.QueueViewModel_QueueCompleted;
            this.JobsPending = string.Format(Resources.QueueViewModel_JobsPending, this.queueProcessor.Count);
            this.IsQueueRunning = false;
        }

        /// <summary>
        /// The encode service_ encode completed.
        /// </summary>
        /// <param name="sender">
        /// The sender.
        /// </param>
        /// <param name="e">
        /// The e.
        /// </param>
        private void EncodeService_EncodeCompleted(object sender, EncodeCompletedEventArgs e)
        {
            if (!this.queueProcessor.IsProcessing)
            {
                this.JobStatus = Resources.QueueViewModel_LastJobFinished;
            }
        }

        /// <summary>
        /// The queue processor job processing started.
        /// </summary>
        /// <param name="sender">
        /// The sender.
        /// </param>
        /// <param name="e">
        /// The QueueProgressEventArgs.
        /// </param>
        private void QueueProcessorJobProcessingStarted(object sender, QueueProgressEventArgs e)
        {
            this.JobStatus = Resources.QueueViewModel_QueueStarted;
            this.JobsPending = string.Format(Resources.QueueViewModel_JobsPending, this.queueProcessor.Count);
            this.IsQueueRunning = true; 
        }

        #endregion
    }
}