// <copyright file="KeyframeRepository.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.Persistence;
using Microsoft.EntityFrameworkCore;

/// <summary>
/// Repository for obtaining Keyframe data.
/// </summary>
public class KeyframeRepository : IKeyframeRepository
{
    private readonly IDbContextFactory<JellyfinDbContext> _dbProvider;

    /// <summary>
    /// Initializes a new instance of the <see cref="KeyframeRepository"/> class.
    /// </summary>
    /// <param name="dbProvider">The EFCore db factory.</param>
    public KeyframeRepository(IDbContextFactory<JellyfinDbContext> dbProvider)
    {
        _dbProvider = dbProvider;
    }

    private static MediaEncoding.Keyframes.KeyframeData Map(KeyframeData entity)
    {
        return new MediaEncoding.Keyframes.KeyframeData(
            entity.TotalDuration,
            (entity.KeyframeTicks ?? []).ToList());
    }

    private KeyframeData Map(MediaEncoding.Keyframes.KeyframeData dto, Guid itemId)
    {
        return new()
        {
            ItemId = itemId,
            TotalDuration = dto.TotalDuration,
            KeyframeTicks = dto.KeyframeTicks.ToList()
        };
    }

    /// <inheritdoc />
    public async Task<IReadOnlyList<MediaEncoding.Keyframes.KeyframeData>> GetKeyframeDataAsync(Guid itemId, CancellationToken cancellationToken = default)
    {
        await using var context = _dbProvider.CreateDbContext();

        return await context.KeyframeData
            .AsNoTracking()
            .Where(e => e.ItemId.Equals(itemId))
            .Select(e => Map(e))
            .ToListAsync(cancellationToken)
            .ConfigureAwait(false);
    }

    /// <inheritdoc />
    public async Task SaveKeyframeDataAsync(Guid itemId, MediaEncoding.Keyframes.KeyframeData data, 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.KeyframeData.Where(e => e.ItemId.Equals(itemId)).ExecuteDeleteAsync(cancellationToken).ConfigureAwait(false);
            await context.KeyframeData.AddAsync(Map(data, itemId), cancellationToken).ConfigureAwait(false);
            await context.SaveChangesAsync(cancellationToken).ConfigureAwait(false);
        }).ConfigureAwait(false);
    }

    /// <inheritdoc />
    public async Task DeleteKeyframeDataAsync(Guid itemId, CancellationToken cancellationToken = default)
    {
        await using var context = _dbProvider.CreateDbContext();
        await context.KeyframeData.Where(e => e.ItemId.Equals(itemId)).ExecuteDeleteAsync(cancellationToken).ConfigureAwait(false);
        await context.SaveChangesAsync(cancellationToken).ConfigureAwait(false);
    }
}
