using MangaReader.Core.Data;
using MangaReader.Core.Metadata;
using Microsoft.EntityFrameworkCore;
using System.Text.RegularExpressions;

namespace MangaReader.Core.Pipeline;

public partial class MangaPipeline(MangaContext context) : IMangaPipeline
{
    enum TitleType
    {
        Primary,
        Secondary
    }

    public async Task RunAsync(MangaPipelineRequest request)
    {
        string sourceName = request.SourceName;
        string sourceUrl = request.SourceUrl;
        SourceManga sourceManga = request.SourceManga;

        Source source = await GetOrAddSourceAsync(sourceName);
        Manga manga = await GetOrAddMangaAsync(sourceManga);

        await AddMangaSourceAsync(sourceUrl, manga, source);
        await AddTitleAsync(manga, sourceManga.Title, TitleType.Primary);
        await AddDescriptionAsync(manga, sourceManga.Description);

        foreach (SourceMangaTitle alternateTitle in sourceManga.AlternateTitles)
        {
            await AddTitleAsync(manga, alternateTitle, TitleType.Secondary);
        }

        foreach (string genre in sourceManga.Genres)
        {
            await LinkGenreAsync(manga, genre);
        }

        foreach (SourceMangaChapter chapter in sourceManga.Chapters)
        {
            await AddChapterAsync(manga, chapter);
        }

        context.SaveChanges();
    }

    private async Task<Source> GetOrAddSourceAsync(string sourceName)
    {
        Source? source = await context.Sources.FirstOrDefaultAsync(s => s.Name == sourceName);

        if (source != null)
            return source;

        source = new()
        {
            Name = sourceName
        };

        context.Sources.Add(source);

        return source;
    }

    private async Task<Manga> GetOrAddMangaAsync(SourceManga sourceManga)
    {
        Manga? manga = await context.Mangas.FirstOrDefaultAsync(manga =>
            manga.Titles.Any(mangaTitle => mangaTitle.Name == sourceManga.Title.Name));

        if (manga != null)
            return manga;

        manga = new()
        {
            Slug = GenerateSlug(sourceManga.Title.Name),
        };

        context.Add(manga);

        return manga;
    }

    private static string GenerateSlug(string title)
    {
        title = title.ToLowerInvariant();
        title = RemoveInvalidCharsRegex().Replace(title, ""); // remove invalid chars
        title = RemoveSpacesWithDashRegex().Replace(title, "-");         // replace spaces with dash

        return title.Trim('-');
    }

    [GeneratedRegex(@"[^a-z0-9\s-]")]
    private static partial Regex RemoveInvalidCharsRegex();

    [GeneratedRegex(@"\s+")]
    private static partial Regex RemoveSpacesWithDashRegex();

    private async Task AddMangaSourceAsync(string sourceUrl, Manga manga, Source source)
    {
        MangaSource? mangaSource = await context.MangaSources.FirstOrDefaultAsync(ms =>
            ms.Manga == manga && ms.Source == source && ms.Url == sourceUrl);

        if (mangaSource != null)
            return;

        mangaSource = new()
        {
            Manga = manga,
            Source = source,
            Url = sourceUrl
        };

        context.MangaSources.Add(mangaSource);
    }

    private async Task AddTitleAsync(Manga manga, SourceMangaTitle sourceMangaTitle, TitleType titleType)
    {
        MangaTitle? mangaTitle = await context.MangaTitles.FirstOrDefaultAsync(mt =>
            mt.Manga == manga && mt.Name == sourceMangaTitle.Name);

        if (mangaTitle != null)
            return;

        mangaTitle = new()
        {
            Manga = manga,
            Name = sourceMangaTitle.Name,
            Language = sourceMangaTitle.Language,
            IsPrimary = titleType == TitleType.Primary
        };

        context.MangaTitles.Add(mangaTitle);
    }

    private async Task AddDescriptionAsync(Manga manga, SourceMangaDescription? sourceMangaDescription)
    {
        if (sourceMangaDescription == null)
            return;

        MangaDescription? mangaDescription = await context.MangaDescriptions.FirstOrDefaultAsync(md =>
            md.Manga == manga && md.Name == sourceMangaDescription.Name);

        if (mangaDescription != null)
            return;

        mangaDescription = new()
        {
            Manga = manga,
            Name = sourceMangaDescription.Name,
            Language = sourceMangaDescription.Language
        };

        context.MangaDescriptions.Add(mangaDescription);
    }

    private async Task LinkGenreAsync(Manga manga, string genreName)
    {
        Genre genre = await GetOrAddGenreAsync(genreName);

        MangaGenre? mangaGenre = await context.MangaGenres.FirstOrDefaultAsync(x => x.Manga == manga && x.Genre == genre);

        if (mangaGenre != null)
            return;

        mangaGenre = new()
        {
            Manga = manga,
            Genre = genre
        };

        context.MangaGenres.Add(mangaGenre);
    }

    private async Task<Genre> GetOrAddGenreAsync(string genreName)
    {
        Genre? genre = await context.Genres.FirstOrDefaultAsync(x => x.Name == genreName);

        if (genre != null)
            return genre;

        genre = new()
        {
            Name = genreName,
        };

        await context.Genres.AddAsync(genre);

        return genre;
    }

    private async Task AddChapterAsync(Manga manga, SourceMangaChapter sourceMangaChapter)
    {
        MangaChapter mangaChapter = await context.MangaChapters.FirstOrDefaultAsync(x => x.ChapterNumber == sourceMangaChapter.Number)
            ?? AddMangaChapter(manga, sourceMangaChapter);

        if (mangaChapter.VolumeNumber is null && sourceMangaChapter.Volume is not null)
        {
            mangaChapter.VolumeNumber = sourceMangaChapter.Volume;
        }

        if (mangaChapter.Title is null && sourceMangaChapter.Title is not null)
        {
            mangaChapter.Title = sourceMangaChapter.Title;
        }
    }

    private MangaChapter AddMangaChapter(Manga manga, SourceMangaChapter sourceMangaChapter)
    {
        MangaChapter mangaChapter = new()
        {
            Manga = manga,
            ChapterNumber = sourceMangaChapter.Number
        };

        context.MangaChapters.Add(mangaChapter);

        return mangaChapter;
    }
}