using System.Text;
using DotBased.Monads;

namespace Manager.YouTube.Interpreter;

public class JavaScriptEngineManager
{
    private readonly PlayerEngineCollection _engines = [];
    
    public async Task<Result<PlayerEngine>> GetPlayerEngine(string playerUrl)
    {
        if (string.IsNullOrEmpty(playerUrl))
        {
            return ResultError.Fail("player url is empty or null!");
        }

        var version = GetScriptVersion(playerUrl);
        
        if (_engines.TryGetValue(version, out var engine))
        {
            return engine;
        }

        var playerJsSourceResult = await DownloadPlayerScriptAsync(playerUrl);
        if (!playerJsSourceResult.IsSuccess)
        {
            return playerJsSourceResult.Error ?? ResultError.Fail("Download player script failed!");
        }

        return new PlayerEngine(version, playerJsSourceResult.Value);
    }
    
    private static string GetScriptVersion(string relativePlayerUrl)
    {
        var split = relativePlayerUrl.Split('/', StringSplitOptions.RemoveEmptyEntries | StringSplitOptions.TrimEntries);
        var v = split[2];
        var lang = split[4];
        return $"{v}-{lang}";
    }

    private static async Task<Result<string>> DownloadPlayerScriptAsync(string relativeUrl, YouTubeClient? client = null)
    {
        var downloadRequest = new HttpRequestMessage(HttpMethod.Get, new Uri($"{NetworkService.Origin}/{relativeUrl}"));
        var downloadResponse = await NetworkService.DownloadBytesAsync(downloadRequest, client);
        if (!downloadResponse.IsSuccess)
        {
            return downloadResponse.Error ?? ResultError.Fail($"Failed to download script from url: {relativeUrl}");
        }

        var playerJs = Encoding.UTF8.GetString(downloadResponse.Value.Data);
        if (string.IsNullOrWhiteSpace(playerJs))
        {
            return ResultError.Fail("Script value is empty!");
        }
        
        return playerJs;
    }
}