using Fragalytics.Web.Infrastructure;
using Fragalytics.Web.Models;
using Microsoft.Extensions.Options;

namespace Fragalytics.Web.Services;

public sealed class ClipMediaService
{
    private readonly JsonAppStore _store;
    private readonly FragalyticsOptions _options;

    public ClipMediaService(JsonAppStore store, IOptions<FragalyticsOptions> options)
    {
        _store = store;
        _options = options.Value;
    }

    public async Task<int> AttachClipAssetAsync(
        int clipJobId,
        string fileName,
        string? contentType,
        Stream input,
        CancellationToken cancellationToken)
    {
        var extension = Path.GetExtension(fileName);
        if (!ClipMediaFormats.AllowedExtensions.Contains(extension))
        {
            throw new InvalidOperationException($"Only {ClipMediaFormats.Mp4Extension} and {ClipMediaFormats.WebMExtension} clip uploads are supported.");
        }

        var clipsDirectory = Path.Combine(Path.GetFullPath(_options.DataDirectory), "clips");
        Directory.CreateDirectory(clipsDirectory);

        var safeFileName = Path.GetFileName(fileName);
        var storedName = $"{DateTimeOffset.UtcNow.ToUnixTimeMilliseconds()}_{clipJobId}{extension}";
        var storedPath = Path.Combine(clipsDirectory, storedName);

        long fileSize;
        await using (var output = File.Create(storedPath))
        {
            await input.CopyToAsync(output, cancellationToken);
            fileSize = output.Length;
        }

        return await _store.UpdateAsync(state =>
        {
            var clipJob = state.ClipJobs.FirstOrDefault(item => item.Id == clipJobId)
                ?? throw new InvalidOperationException("Clip job not found.");

            if (clipJob.ClipAssetId is int existingAssetId)
            {
                var existingAsset = state.ClipAssets.FirstOrDefault(item => item.Id == existingAssetId);
                if (existingAsset is not null && File.Exists(existingAsset.StoredPath))
                {
                    File.Delete(existingAsset.StoredPath);
                }
                state.ClipAssets.RemoveAll(item => item.Id == existingAssetId);
            }

            var asset = new ClipAssetRecord
            {
                Id = state.NextClipAssetId++,
                ClipJobId = clipJobId,
                FileName = safeFileName,
                StoredPath = storedPath,
                ContentType = string.IsNullOrWhiteSpace(contentType) ? ClipMediaFormats.InferContentType(extension) : contentType,
                FileSizeBytes = fileSize
            };

            state.ClipAssets.Add(asset);
            clipJob.ClipAssetId = asset.Id;
            clipJob.Status = ClipJobStatuses.Rendered;
            clipJob.ErrorMessage = null;
            clipJob.CompletedAtUtc = DateTime.UtcNow;
            return asset.Id;
        }, cancellationToken);
    }
}