using System.Runtime.InteropServices;
using System.Text.RegularExpressions;
using System.Xml.Linq;
using static System.IO.UnixFileMode;

namespace Tranga;

/// <summary>
/// Has to be Part of a publication
/// Includes the Chapter-Name, -VolumeNumber, -ChapterNumber, the location of the chapter on the internet and the saveName of the local file.
/// </summary>
public readonly struct Chapter : IComparable
{
    // ReSharper disable once MemberCanBePrivate.Global
    public Manga parentManga { get; }
    public string? name { get; }
    public float volumeNumber { get; }
    public float chapterNumber { get; }
    public string url { get; }
    // ReSharper disable once MemberCanBePrivate.Global
    public string fileName { get; }
    public string? id { get; }
    
    private static readonly Regex LegalCharacters = new (@"([A-z]*[0-9]* *\.*-*,*\]*\[*'*\'*\)*\(*~*!*)*");
    private static readonly Regex IllegalStrings = new(@"(Vol(ume)?|Ch(apter)?)\.?", RegexOptions.IgnoreCase);

    public Chapter(Manga parentManga, string? name, string? volumeNumber, string chapterNumber, string url, string? id = null)
        : this(parentManga, name, float.Parse(volumeNumber??"0", GlobalBase.numberFormatDecimalPoint),
            float.Parse(chapterNumber, GlobalBase.numberFormatDecimalPoint), url, id)
    {
    }
    
    public Chapter(Manga parentManga, string? name, float? volumeNumber, float chapterNumber, string url, string? id = null)
    {
        this.parentManga = parentManga;
        this.name = name;
        this.volumeNumber = volumeNumber??0;
        this.chapterNumber = chapterNumber;
        this.url = url;
        this.id = id;
        
        string chapterVolNumStr = $"Vol.{this.volumeNumber} Ch.{chapterNumber}";

        if (name is not null && name.Length > 0)
        {
            string chapterName = IllegalStrings.Replace(string.Concat(LegalCharacters.Matches(name)), "");
            this.fileName = chapterName.Length > 0 ? $"{chapterVolNumStr} - {chapterName}" : chapterVolNumStr;
        }
        else
            this.fileName = chapterVolNumStr;
    }

    public override string ToString()
    {
        return $"Chapter {parentManga.sortName} {parentManga.internalId} {chapterNumber} {name}";
    }

    public override bool Equals(object? obj)
    {
        if (obj is not Chapter)
            return false;
        return CompareTo(obj) == 0;
    }

    public int CompareTo(object? obj)
    {
        if(obj is not Chapter otherChapter)
            throw new ArgumentException($"{obj} can not be compared to {this}");
        return volumeNumber.CompareTo(otherChapter.volumeNumber) switch
        {
            <0 => -1,
            >0 => 1,
            _ => chapterNumber.CompareTo(otherChapter.chapterNumber)
        };
    }

    /// <summary>
    /// Checks if a chapter-archive is already present
    /// </summary>
    /// <returns>true if chapter is present</returns>
    internal bool CheckChapterIsDownloaded()
    {
        string mangaDirectory = Path.Join(TrangaSettings.downloadLocation, parentManga.folderName);
        if (!Directory.Exists(mangaDirectory))
            return false;
        FileInfo? mangaArchive = null;
        string markerPath = Path.Join(mangaDirectory, $".{id}");
        if (this.id is not null && File.Exists(markerPath))
        {
            if(File.Exists(File.ReadAllText(markerPath)))
                mangaArchive = new FileInfo(File.ReadAllText(markerPath));
            else
                File.Delete(markerPath);
        }
        
        if(mangaArchive is null)
        {
            FileInfo[] archives = new DirectoryInfo(mangaDirectory).GetFiles("*.cbz");
            Regex volChRex = new(@"(?:Vol(?:ume)?\.([0-9]+)\D*)?Ch(?:apter)?\.([0-9]+(?:\.[0-9]+)*)(?: - (.*))?.cbz");

            Chapter t = this;
            mangaArchive = archives.FirstOrDefault(archive =>
            {
                Match m = volChRex.Match(archive.Name);
                /*
                 * 1. If the volumeNumber is not present in the filename, it is not checked.
                 * 2. Check the chapterNumber in the chapter against the one in the filename.
                 * 3. The chpaterName has to either be absent both in the chapter and the filename or match.
                 */
                return (!m.Groups[1].Success || m.Groups[1].Value == t.volumeNumber.ToString(GlobalBase.numberFormatDecimalPoint)) &&
                       m.Groups[2].Value == t.chapterNumber.ToString(GlobalBase.numberFormatDecimalPoint) &&
                       ((!m.Groups[3].Success && string.IsNullOrEmpty(t.name)) || m.Groups[3].Value == t.name);
            });
        }
        
        string correctPath = GetArchiveFilePath();
        if(mangaArchive is not null && mangaArchive.FullName != correctPath)
            mangaArchive.MoveTo(correctPath, true);
        return (mangaArchive is not null);
    }
    
    public void CreateChapterMarker()
    {
        if (this.id is null)
            return;
        string path = Path.Join(TrangaSettings.downloadLocation, parentManga.folderName, $".{id}");
        File.WriteAllText(path, GetArchiveFilePath());
        File.SetAttributes(path, FileAttributes.Hidden);
        if (RuntimeInformation.IsOSPlatform(OSPlatform.Linux))  
            File.SetUnixFileMode(path, UserRead | UserWrite | UserExecute | GroupRead | GroupWrite | GroupExecute | OtherRead | OtherExecute);
    }
    
    /// <summary>
    /// Creates full file path of chapter-archive
    /// </summary>
    /// <returns>Filepath</returns>
    internal string GetArchiveFilePath()
    {
        return Path.Join(TrangaSettings.downloadLocation, parentManga.folderName, $"{parentManga.folderName} - {this.fileName}.cbz");
    }

    /// <summary>
    /// Creates a string containing XML of publication and chapter.
    /// See ComicInfo.xml
    /// </summary>
    /// <returns>XML-string</returns>
    internal string GetComicInfoXmlString()
    {
        XElement comicInfo = new XElement("ComicInfo",
            new XElement("Tags", string.Join(',', parentManga.tags)),
            new XElement("LanguageISO", parentManga.originalLanguage),
            new XElement("Title", this.name),
            new XElement("Writer", string.Join(',', parentManga.authors)),
            new XElement("Volume", this.volumeNumber),
            new XElement("Number", this.chapterNumber)
        );
        return comicInfo.ToString();
    }
}