using Beam.Abstractions;
using Beam.Downloaders;
using Beam.Models;
using Microsoft.Playwright;

namespace Beam.Playwright {
    public class PlaywrightUnitDownloader<RawType, OutType>(
        UnitDownloaderOptions<RawType, OutType> options,
        PlaywrightAsyncManipulator puppetManipulator)
        : UnitDownloader<RawType, OutType>(options)
        where RawType : IDocument {
        public PlaywrightAsyncManipulator PuppetManipulator { get; } = puppetManipulator;

        protected override async Task DownloadToStream(string url, int bufferSize, Stream destinationStream, IProgress<IDownloadReport> progress, CancellationToken ct) {
            var page = await PlaywrightContext.Browser.Value.NewPageAsync();
            try {
                await page.GotoAsync(url);
                await PuppetManipulator(page);
                var download = await page.WaitForDownloadAsync();

                await using var stream = await download.CreateReadStreamAsync();
                var buffer = new byte[bufferSize];
                var inBuffer = 0;
                var downloaded = 0;
                while ((inBuffer = stream.Read(buffer)) > 0) {
                    downloaded += inBuffer;
                    progress?.Report(new DownloadReport() {
                        BytesDownloaded = downloaded,
                        BytesRemaining = stream.Length - downloaded
                    });
                    await destinationStream.WriteAsync(buffer.AsMemory(0, inBuffer), ct);
                }
                
            } finally {
                if (!page.IsClosed)
                    await page.CloseAsync();
            }
        }
    }

}