// <copyright file="ChapterRepository.cs" company="PlaceholderCompany">
// Copyright (c) PlaceholderCompany. All rights reserved.
// </copyright>

namespace Jellyfin.Server.Implementations.Item;

using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading;
using System.Threading.Tasks;
using Jellyfin.Database.Implementations;
using Jellyfin.Database.Implementations.Entities;
using MediaBrowser.Controller.Drawing;
using MediaBrowser.Controller.Persistence;
using MediaBrowser.Model.Entities;
using Microsoft.EntityFrameworkCore;

/// <summary>
/// The Chapter manager.
/// </summary>
public class ChapterRepository : IChapterRepository
{
    private readonly IDbContextFactory<JellyfinDbContext> _dbProvider;
    private readonly IImageProcessor _imageProcessor;

    /// <summary>
    /// Initializes a new instance of the <see cref="ChapterRepository"/> class.
    /// </summary>
    /// <param name="dbProvider">The EFCore provider.</param>
    /// <param name="imageProcessor">The Image Processor.</param>
    public ChapterRepository(IDbContextFactory<JellyfinDbContext> dbProvider, IImageProcessor imageProcessor)
    {
        _dbProvider = dbProvider;
        _imageProcessor = imageProcessor;
    }

    /// <inheritdoc />
    public async Task<ChapterInfo?> GetChapterAsync(Guid baseItemId, int index, CancellationToken cancellationToken = default)
    {
        await using var context = _dbProvider.CreateDbContext();
        var chapter = await context.Chapters.AsNoTracking()
            .Select(e => new
            {
                chapter = e,
                baseItemPath = e.Item.Path
            })
            .FirstOrDefaultAsync(e => e.chapter.ItemId.Equals(baseItemId) && e.chapter.ChapterIndex == index, cancellationToken)
            .ConfigureAwait(false);

        if (chapter is not null)
        {
            return Map(chapter.chapter, chapter.baseItemPath!);
        }

        return null;
    }

    /// <inheritdoc />
    public async Task<IReadOnlyList<ChapterInfo>> GetChaptersAsync(Guid baseItemId, CancellationToken cancellationToken = default)
    {
        await using var context = _dbProvider.CreateDbContext();
        var chapters = await context.Chapters.AsNoTracking()
            .Where(e => e.ItemId.Equals(baseItemId))
            .Select(e => new
            {
                chapter = e,
                baseItemPath = e.Item.Path
            })
            .ToArrayAsync(cancellationToken)
            .ConfigureAwait(false);

        return chapters.Select(e => Map(e.chapter, e.baseItemPath!)).ToArray();
    }

    /// <inheritdoc />
    public async Task SaveChaptersAsync(Guid itemId, IReadOnlyList<ChapterInfo> chapters, CancellationToken cancellationToken = default)
    {
        await using var context = _dbProvider.CreateDbContext();

        // Use the execution strategy to handle transactional consistency and retries
        // This is required for PostgreSQL NpgsqlRetryingExecutionStrategy
        var executionStrategy = context.Database.CreateExecutionStrategy();
        await executionStrategy.ExecuteAsync(async () =>
        {
            await context.Chapters
                .Where(e => e.ItemId.Equals(itemId))
                .ExecuteDeleteAsync(cancellationToken)
                .ConfigureAwait(false);

            for (var i = 0; i < chapters.Count; i++)
            {
                var chapter = chapters[i];
                await context.Chapters.AddAsync(Map(chapter, i, itemId), cancellationToken).ConfigureAwait(false);
            }

            await context.SaveChangesAsync(cancellationToken).ConfigureAwait(false);
        }).ConfigureAwait(false);
    }

    /// <inheritdoc />
    public async Task DeleteChaptersAsync(Guid itemId, CancellationToken cancellationToken)
    {
        var dbContext = await _dbProvider.CreateDbContextAsync(cancellationToken).ConfigureAwait(false);
        await using (dbContext.ConfigureAwait(false))
        {
            await dbContext.Chapters.Where(c => c.ItemId.Equals(itemId)).ExecuteDeleteAsync(cancellationToken).ConfigureAwait(false);
            await dbContext.SaveChangesAsync(cancellationToken).ConfigureAwait(false);
        }
    }

    private Chapter Map(ChapterInfo chapterInfo, int index, Guid itemId)
    {
        return new Chapter()
        {
            ChapterIndex = index,
            StartPositionTicks = chapterInfo.StartPositionTicks,
            ImageDateModified = chapterInfo.ImageDateModified,
            ImagePath = chapterInfo.ImagePath,
            ItemId = itemId,
            Name = chapterInfo.Name,
            Item = null!
        };
    }

    private ChapterInfo Map(Chapter chapterInfo, string baseItemPath)
    {
        var chapterEntity = new ChapterInfo()
        {
            StartPositionTicks = chapterInfo.StartPositionTicks,
            ImageDateModified = chapterInfo.ImageDateModified.GetValueOrDefault(),
            ImagePath = chapterInfo.ImagePath,
            Name = chapterInfo.Name,
        };

        if (!string.IsNullOrEmpty(chapterInfo.ImagePath))
        {
            chapterEntity.ImageTag = _imageProcessor.GetImageCacheTag(baseItemPath, chapterEntity.ImageDateModified);
        }

        return chapterEntity;
    }
}