// --------------------------------------------------------------------------------------------------------------------
// <copyright file="ChaptersViewModel.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 Chapters View Model
// </summary>
// --------------------------------------------------------------------------------------------------------------------

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

    using Caliburn.Micro;

    using HandBrakeWPF.EventArgs;
    using HandBrakeWPF.Properties;
    using HandBrakeWPF.Services.Interfaces;
    using HandBrakeWPF.Services.Presets.Model;
    using HandBrakeWPF.Services.Scan.Model;
    using HandBrakeWPF.Utilities.Input;
    using HandBrakeWPF.Utilities.Output;
    using HandBrakeWPF.ViewModels.Interfaces;

    using ChapterMarker = HandBrakeWPF.Services.Encode.Model.Models.ChapterMarker;
    using EncodeTask = HandBrakeWPF.Services.Encode.Model.EncodeTask;
    using GeneralApplicationException = HandBrakeWPF.Exceptions.GeneralApplicationException;

    /// <summary>
    /// The Chapters View Model
    /// </summary>
    public class ChaptersViewModel : ViewModelBase, IChaptersViewModel
    {
        #region Constants and Fields

        private readonly IErrorService errorService;

        /// <summary>
        /// The source chapters backing field
        /// </summary>
        private List<Chapter> sourceChaptersList;

        #endregion

        #region Constructors and Destructors

        /// <summary>
        /// Initializes a new instance of the <see cref="ChaptersViewModel"/> class.
        /// </summary>
        /// <param name="windowManager">
        /// The window manager.
        /// </param>
        /// <param name="userSettingService">
        /// The user Setting Service.
        /// </param>
        /// <param name="errorService">
        /// The Error Service 
        /// </param>
        public ChaptersViewModel(IWindowManager windowManager, IUserSettingService userSettingService, IErrorService errorService)
        {
            this.Task = new EncodeTask();
            this.errorService = errorService;
        }

        public event EventHandler<TabStatusEventArgs> TabStatusChanged;

        #endregion

        #region Public Properties

        /// <summary>
        /// Gets or sets Task.
        /// </summary>
        public EncodeTask Task { get; set; }

        /// <summary>
        /// Gets or sets a value indicating whether chapter markers are enabled.
        /// </summary>
        public bool IncludeChapterMarkers
        {
            get
            {
                return this.Task.IncludeChapterMarkers;
            }
            set
            {
                this.Task.IncludeChapterMarkers = value;
                this.NotifyOfPropertyChange(() => this.IncludeChapterMarkers);
                this.OnTabStatusChanged(null);
            }
        }

        public ObservableCollection<ChapterMarker> Chapters
        {
            get
            {
                return this.Task.ChapterNames;
            }

            set
            {
                this.Task.ChapterNames = value;
                this.NotifyOfPropertyChange(() => this.Chapters);
            }
        }

        #endregion

        #region Properties

        /// <summary>
        /// Gets or sets SourceChapterList.
        /// </summary>
        private ObservableCollection<Chapter> SourceChapterList { get; set; }

        #endregion

        #region Public Methods

        /// <summary>
        /// Export the Chapter Markers to a CSV file
        /// </summary>
        /// <exception cref="GeneralApplicationException">
        /// Thrown if exporting fails.
        /// </exception>
        public void Export()
        {
            string fileName = null;
            using (var saveFileDialog = new SaveFileDialog()
                                        {
                                            Filter = "Csv File|*.csv",
                                            DefaultExt = "csv",
                                            CheckPathExists = true,
                                            OverwritePrompt = true
                                        })
            {
                var dialogResult = saveFileDialog.ShowDialog();
                fileName = saveFileDialog.FileName;

                // Exit early if the user cancelled or the filename is invalid
                if (dialogResult != DialogResult.OK || string.IsNullOrWhiteSpace(fileName))
                    return;
            }

            try
            {
                using (var csv = new StreamWriter(fileName))
                {
                    foreach (ChapterMarker row in this.Chapters)
                    {
                        csv.Write("{0},{1}{2}", row.ChapterNumber, CsvHelper.Escape(row.ChapterName), Environment.NewLine);
                    }
                }
            }
            catch (Exception exc)
            {
                throw new GeneralApplicationException(
                    Resources.ChaptersViewModel_UnableToExportChaptersWarning,
                    Resources.ChaptersViewModel_UnableToExportChaptersMsg,
                    exc);
            }
        }

        /// <summary>
        /// Imports a Chapter marker file
        /// </summary>
        /// <exception cref="GeneralApplicationException">
        /// Thrown if importing fails.
        /// </exception>
        public void Import()
        {
            string filename = null;
            string fileExtension = null;
            using (var dialog = new OpenFileDialog()
                    {
                        Filter = string.Join("|", "All Supported Formats (*.csv;*.tsv,*.xml,*.txt)|*.csv;*.tsv;*.xml;*.txt", ChapterImporterCsv.FileFilter, ChapterImporterXml.FileFilter, ChapterImporterTxt.FileFilter),
                        FilterIndex = 1,  // 1 based, the index value of the first filter entry is 1
                        CheckFileExists = true
                    })
            {
                var dialogResult = dialog.ShowDialog();
                filename = dialog.FileName;

                // Exit if the user didn't press the OK button or the file name is invalid
                if (dialogResult != DialogResult.OK || string.IsNullOrWhiteSpace(filename))
                    return;

                // Retrieve the file extension after we've confirmed that the user selected something to open
                fileExtension = Path.GetExtension(filename)?.ToLowerInvariant();
            }

            var importedChapters = new Dictionary<int, Tuple<string, TimeSpan>>();

            // Execute the importer based on the file extension
            switch (fileExtension)
            {
                case ".csv": // comma separated file
                case ".tsv": // tab separated file
                    ChapterImporterCsv.Import(filename, ref importedChapters);
                    break;
                case ".xml":
                    ChapterImporterXml.Import(filename, ref importedChapters);
                    break;
                case ".txt":
                    ChapterImporterTxt.Import(filename, ref importedChapters);
                    break;
                default:
                    throw new GeneralApplicationException(
                        Resources.ChaptersViewModel_UnsupportedFileFormatWarning,
                        string.Format(Resources.ChaptersViewModel_UnsupportedFileFormatMsg, fileExtension));
            }
            
            // Exit early if no chapter information was extracted
            if (importedChapters == null || importedChapters.Count <= 0)
                return;

            // Validate the chaptermap against the current chapter list extracted from the source
            bool hasTimestamps = importedChapters.Select(importedChapter => importedChapter.Value.Item2).Any(t => t != TimeSpan.Zero);

            string validationErrorMessage;
            if (!this.ValidateImportedChapters(importedChapters, out validationErrorMessage, hasTimestamps))
            {
                if (!string.IsNullOrEmpty(validationErrorMessage))
                {
                    throw new GeneralApplicationException(
                              Resources.ChaptersViewModel_ValidationFailedWarning,
                              validationErrorMessage);
                }

                // The user has cancelled the import, so exit
                return;
            }

            // Now iterate over each chatper we have, and set it's name
            foreach (ChapterMarker item in this.Chapters)
            {
                // If we don't have a chapter name for this chapter then 
                // fallback to the value that is already set for the chapter
                string chapterName = item.ChapterName;

                // Attempt to retrieve the imported chapter name
                Tuple<string, TimeSpan> chapterInfo;
                if (importedChapters.TryGetValue(item.ChapterNumber, out chapterInfo))
                    chapterName = chapterInfo.Item1;

                // Assign the chapter name unless the name is not set or only whitespace characters
                item.ChapterName = !string.IsNullOrWhiteSpace(chapterName) ? chapterName : string.Empty;
            }
        }

        /// <summary>
        /// Setup this window for a new source
        /// </summary>
        /// <param name="source">
        /// The source.
        /// </param>
        /// <param name="title">
        /// The title.
        /// </param>
        /// <param name="preset">
        /// The preset.
        /// </param>
        /// <param name="task">
        /// The task.
        /// </param>
        public void SetSource(Source source, Title title, Preset preset, EncodeTask task)
        {
            this.Task = task;

            if (preset != null)
            {
                this.IncludeChapterMarkers = preset.Task.IncludeChapterMarkers;
            }

            this.sourceChaptersList = title.Chapters;
            this.SetSourceChapters(title.Chapters);
        }

        /// <summary>
        /// Setup this tab for the specified preset.
        /// </summary>
        /// <param name="preset">
        /// The preset.
        /// </param>
        /// <param name="task">
        /// The task.
        /// </param>
        public void SetPreset(Preset preset, EncodeTask task)
        {
            this.Task = task;
            this.IncludeChapterMarkers = preset.Task.IncludeChapterMarkers;
            this.NotifyOfPropertyChange(() => this.Chapters);
        }

        /// <summary>
        /// Update all the UI controls based on the encode task passed in.
        /// </summary>
        /// <param name="task">
        /// The task.
        /// </param>
        public void UpdateTask(EncodeTask task)
        {
            this.Task = task;

            this.NotifyOfPropertyChange(() => this.IncludeChapterMarkers);
            this.NotifyOfPropertyChange(() => this.Chapters);
        }

        public bool MatchesPreset(Preset preset)
        {
            if (preset.Task.IncludeChapterMarkers != this.IncludeChapterMarkers)
            {
                return false;
            }

            return true;
        }

        /// <summary>
        /// Reset Chapter Names
        /// </summary>
        public void Reset()
        {
            if (this.sourceChaptersList != null)
            {
                this.SetSourceChapters(this.sourceChaptersList);
            }
        }

        /// <summary>
        /// Set the Source Chapters List
        /// </summary>
        /// <param name="sourceChapters">
        /// The source chapters.
        /// </param>
        public void SetSourceChapters(IEnumerable<Chapter> sourceChapters)
        {
            // Cache the chapters in this screen
            this.SourceChapterList = new ObservableCollection<Chapter>(sourceChapters);
            this.Chapters.Clear();

            // Then Add new Chapter Markers.
            int counter = 1;

            foreach (Chapter chapter in this.SourceChapterList)
            {
                string chapterName = string.IsNullOrEmpty(chapter.ChapterName) ? string.Format(Resources.ChapterViewModel_Chapter, counter) : chapter.ChapterName;
                var marker = new ChapterMarker(chapter.ChapterNumber, chapterName, chapter.Duration);
                this.Chapters.Add(marker);

                counter += 1;
            }
        }

        #endregion

        #region Private Methods

        protected virtual void OnTabStatusChanged(TabStatusEventArgs e)
        {
            this.TabStatusChanged?.Invoke(this, e);
        }

        /// <summary>
        /// Validates any imported chapter information against the currently detected chapter information in the 
        /// source media. If validation fails then an error message is returned via the out parameter <see cref="validationErrorMessage"/>
        /// </summary>
        /// <param name="importedChapters">The list of imported chapter information</param>
        /// <param name="validationErrorMessage">In case of a validation error this variable will hold 
        ///                                      a detailed message that can be presented to the user</param>
        /// <returns>True if there are no errors with imported chapters, false otherwise</returns>
        private bool ValidateImportedChapters(Dictionary<int, Tuple<string, TimeSpan>> importedChapters, out string validationErrorMessage, bool hasTimestamps)
        {
            validationErrorMessage = null;

            // If the number of chapters don't match, prompt for confirmation
            if (importedChapters.Count != this.Chapters.Count)
            {
                if (this.errorService.ShowMessageBox(
                        string.Format(Resources.ChaptersViewModel_ValidateImportedChapters_ChapterCountMismatchMsg, this.Chapters.Count, importedChapters.Count),
                        Resources.ChaptersViewModel_ValidateImportedChapters_ChapterCountMismatchWarning,
                        MessageBoxButton.YesNo,
                        MessageBoxImage.Question) !=
                    MessageBoxResult.Yes)
                {
                    return false;
                }
            }

            // If the average discrepancy in timings between chapters is either:
            //   a) more than 15 sec for more than 2 chapters
            //      (I chose 15sec based on empirical evidence from testing a few DVDs and comparing to chapter-marker files I downloaded)
            //      => This check will not be performed for the first and last chapter as they're very likely to differ significantly due to language and region
            //         differences (e.g. longer title sequences and different distributor credits)
            if (hasTimestamps)
            {
                List<TimeSpan> diffs = new List<TimeSpan>();
                foreach (KeyValuePair<int, Tuple<string, TimeSpan>> import in importedChapters)
                {
                    ChapterMarker sourceMarker = this.Chapters[import.Key - 1];
                    TimeSpan source = sourceMarker.Duration;

                    TimeSpan diff = source - import.Value.Item2;
                    diffs.Add(diff);

                }


               // var diffs = importedChapters.Zip(this.Chapters, (import, source) => source.Duration - import.Value.Item2);
                if (diffs.Count(diff => Math.Abs(diff.TotalSeconds) > 15) > 2)
                {
                    if (this.errorService.ShowMessageBox(
                            Resources.ChaptersViewModel_ValidateImportedChapters_ChapterDurationMismatchMsg,
                            Resources.ChaptersViewModel_ValidateImportedChapters_ChapterDurationMismatchWarning,
                            MessageBoxButton.YesNo,
                            MessageBoxImage.Question) != MessageBoxResult.Yes)
                    {
                        return false;
                    }
                }
            }

            // All is well, we should import chapters
            return true;
        }

        #endregion
    }
}