namespace podcast_agent
{
    using System.Xml.Linq;
    using Newtonsoft.Json;

    class Program
    {
        static async Task Main(string[] args)
        {
            var conf = Configure();
            var downloader = new HttpClient();
            downloader.DefaultRequestHeaders.UserAgent.ParseAdd(conf.UserAgent);

            XNamespace ns = "http://www.itunes.com/dtds/podcast-1.0.dtd";
            foreach (var feed in conf.FeedCommands)
            {
                try
                {
                    var xml = XDocument.Load(feed.Url);

                    foreach (var item in xml.Descendants("item"))
                    {
                        var title = item.Element("title")?.Value;
                        var ext = ".wav";
                        var attachmentLink = item.Element("enclosure")?.Attribute("url")?.Value.ToString();
                        var probableFilename = attachmentLink.Substring(0, attachmentLink.IndexOf('?'));
                        if (probableFilename.LastIndexOf('.') > 0)
                        {
                            ext = probableFilename.Substring(probableFilename.LastIndexOf('.'));
                        }

                        Console.WriteLine($"{title}, {attachmentLink}");
                        var downloadPath = Path.Combine(feed.OutputDir, title + ext);
                        var dlResult = (await downloader.GetAsync(attachmentLink));
                        if(dlResult.IsSuccessStatusCode)
                        {
                            if(feed.KeepCount != null && feed.KeepCount > 0)
                            {
                                var files = Directory.GetFiles(feed.OutputDir, "*" + ext);
                                if(files.Length > feed.KeepCount -1)
                                {
                                    files = files.Order().Take((int)feed.KeepCount -1).ToArray();
                                    foreach(var f in files)
                                    {
                                        File.Delete(f);
                                    }
                                }
                            }
                            File.WriteAllBytes(downloadPath, await dlResult.Content.ReadAsByteArrayAsync());
                        }
                    }
                }
                catch (Exception e)
                {
                    Console.Error.WriteLine($"failed attempting to dl {feed} -");
                    Console.Error.WriteLine(e);
                }
            }
        }
        static Configuration Configure(string configurationPath = "appsettings.json")
        {
            if (!File.Exists(configurationPath))
            {
                Console.Error.WriteLine($"could not find configuration at {configurationPath}! copying sample to that spot.");
                File.Copy("sample-appsettings.json", configurationPath); //and you know what, if that explodes at the OS level, the OS should give you an error
                return null;
            }
            var fileContents = File.ReadAllText(configurationPath);
            if (string.IsNullOrWhiteSpace(fileContents))
            {
                Console.Error.WriteLine($"configuration file at {configurationPath} was empty! overwriting with sample settings.");
                File.Copy("sample-appsettings.json", configurationPath, true);
                return null;
            }

            var conf = JsonConvert.DeserializeObject<Configuration>(fileContents);

            if (conf == null)
            {
                Console.Error.WriteLine($"configuration file at {configurationPath} was empty! overwriting with sample settings.");
                File.Copy("sample-appsettings.json", configurationPath, true);
                return null;
            }

            return conf;
        }
    }
}