using DotBased.Monads;
using Manager.App.Models.Library;
using Manager.App.Models.Settings;
using Manager.App.Models.System;
using Manager.Data.Contexts;
using Manager.Data.Entities.LibraryContext;
using Microsoft.EntityFrameworkCore;
using Microsoft.Extensions.Options;

namespace Manager.App.Services;

public class LibraryService : ILibraryService
{
    private readonly ILogger<LibraryService> _logger;
    private readonly LibrarySettings _librarySettings;
    private readonly IDbContextFactory<LibraryDbContext> _dbContextFactory;
    private readonly DirectoryInfo _libraryDirectory;
    private const string SubDirMedia = "Media";
    private const string SubDirChannels = "Channels";

    public LibraryService(ILogger<LibraryService> logger, IOptions<LibrarySettings> librarySettings, IDbContextFactory<LibraryDbContext> contextFactory)
    {
        _logger = logger;
        _librarySettings = librarySettings.Value;
        _dbContextFactory = contextFactory;
        _libraryDirectory = Directory.CreateDirectory(_librarySettings.Path);
        logger.LogDebug("Working dir for library: {LibraryWorkingDir}", _libraryDirectory.FullName);
        Directory.CreateDirectory(Path.Combine(_librarySettings.Path, SubDirMedia));
        Directory.CreateDirectory(Path.Combine(_librarySettings.Path, SubDirChannels));
    }

    public async Task<Result<ChannelEntity>> GetChannelByIdAsync(string id, CancellationToken cancellationToken = default)
    {
        if (string.IsNullOrWhiteSpace(id))
        {
            return ResultError.Fail("Channel id cannot be null or empty!");
        }

        try
        {
            await using var context = await _dbContextFactory.CreateDbContextAsync(cancellationToken);
            var channel = await context.Channels.Include(c => c.ClientAccount).FirstOrDefaultAsync(c => c.Id == id, cancellationToken);
            if (channel == null)
            {
                return ResultError.Fail("Channel not found!");
            }

            return channel;
        }
        catch (Exception e)
        {
            return HandleException(e);
        }
    }

    public async Task<Result> SaveChannelAsync(ChannelEntity channel, CancellationToken cancellationToken = default)
    {
        try
        {
            await using var context = await _dbContextFactory.CreateDbContextAsync(cancellationToken);
            if (context.Channels.Any(c => c.Id == channel.Id))
            {
                context.Channels.Update(channel);
            }
            else
            {
                context.Channels.Add(channel);
            }
            
            var changed = await context.SaveChangesAsync(cancellationToken);
            return changed <= 0 ? Result.Success() : ResultError.Fail("Failed to save channel!");
        }
        catch (Exception e)
        {
            return ResultError.Error(e);
        }
    }

    public async Task<Result<LibraryInformation>> GetLibraryInfoAsync(CancellationToken cancellationToken = default)
    {
        try
        {
            await using var context = await _dbContextFactory.CreateDbContextAsync(cancellationToken);
            var libInfo = new LibraryInformation
            {
                LibraryPath = _libraryDirectory.FullName,
                CreatedAtUtc = _libraryDirectory.CreationTimeUtc,
                LastModifiedUtc = _libraryDirectory.LastWriteTimeUtc,
                TotalChannels = await context.Channels.CountAsync(cancellationToken: cancellationToken),
                TotalMedia = await context.Media.CountAsync(cancellationToken: cancellationToken),
                TotalSizeBytes = GetDirectorySize(_libraryDirectory)
            };
            return libInfo;
        }
        catch (Exception e)
        {
            return HandleException(e);
        }
    }

    public async Task<ListResult<ChannelEntity>> GetChannelAccountsAsync(int total = 20, int offset = 0, CancellationToken cancellationToken = default)
    {
        try
        {
            await using var context = await _dbContextFactory.CreateDbContextAsync(cancellationToken);
            var orderedAccounts = context.Channels.Include(x => x.ClientAccount).Where(x => x.ClientAccount != null).OrderBy(x => x.Id);
            return new ListResultReturn<ChannelEntity>(orderedAccounts.Skip(offset).Take(total).ToList(),orderedAccounts.Count());
        }
        catch (Exception e)
        {
            return HandleException(e);
        }
    }

    private long GetDirectorySize(DirectoryInfo dir)
    {
        try
        {
            var size = dir.EnumerateFiles("*", SearchOption.AllDirectories).Select(f => f.Length).Sum();
            return size;
        }
        catch (Exception e)
        {
            _logger.LogError(e, "Error while getting directory size.");
            throw;
        }
    }

    private ResultError HandleException(Exception exception)
    {
        if (exception is OperationCanceledException)
        {
            return ResultError.Fail("Library service operation cancelled");
        }

        _logger.LogError(exception, "Failed to get library information");
        return ResultError.Fail("Failed to get library information");
    }
}