using System.Net.Http.Headers;
using System.Xml.Linq;

namespace ChrisKaczor.ApplicationUpdate;

public class VersionInfo
{
    private static readonly HttpClient HttpClient = new() { DefaultRequestHeaders = { UserAgent = { ProductInfoHeaderValue.Parse(UpdateCheck.ApplicationName) } } };

    public Version? Version { get; set; }
    public string? InstallFile { get; set; }
    public DateTimeOffset? InstallCreated { get; set; }
    public bool? Prerelease { get; set; }

    public static async Task<VersionInfo?> Load(ServerType updateServerType, string url, string file, bool includePrerelease)
    {
        return updateServerType switch
        {
            ServerType.Generic => LoadFile(url, file, includePrerelease),
            ServerType.GitHub => await LoadGitHub(url, includePrerelease),
            _ => null
        };
    }

    private static VersionInfo? LoadFile(string url, string file, bool includePrerelease)
    {
        try
        {
            if (includePrerelease)
                throw new NotSupportedException("Prerelease not currently supported for generic server type");

            var document = XDocument.Load(url + file);

            var versionInformationElement = document.Element("versionInformation");

            if (versionInformationElement == null)
                return null;

            var versionElement = versionInformationElement.Element("version");
            var installFileElement = versionInformationElement.Element("installFile");
            var installCreatedElement = versionInformationElement.Element("installCreated");

            if (versionElement == null || installFileElement == null || installCreatedElement == null)
                return null;

            var versionInfo = new VersionInfo
            {
                Version = Version.Parse(versionElement.Value),
                InstallFile = installFileElement.Value,
                InstallCreated = DateTimeOffset.Parse(installCreatedElement.Value)
            };

            return versionInfo;
        }
        catch (Exception)
        {
            return null;
        }
    }

    private static async Task<VersionInfo?> LoadGitHub(string baseUrl, bool includePrerelease)
    {
        var versionInfo = includePrerelease ? await GitHubRelease.GetLatestPrereleaseAsync(baseUrl) : await GitHubRelease.GetLatestAsync(baseUrl);
        
        return versionInfo;
    }

    internal static VersionInfo? CreateFromGitHubRelease(GitHubRelease? release)
    {
        if (release?.TagName == null || release.Assets == null || release.Assets.Count == 0)
            return null;

        var versionInfo = new VersionInfo
        {
            Version = Version.Parse(release.TagName),
            InstallFile = release.Assets[0].BrowserDownloadUrl,
            InstallCreated = release.Assets[0].CreatedAt?.UtcDateTime,
            Prerelease = release.Prerelease
        };

        return versionInfo;
    }
}