using System.Diagnostics;
using System.IO;
using System.Net.Http;
using System.Text.Json.Nodes;

namespace PamhagenSysCtrl.Helpers {
    public static class UpdateService {

        public static async Task<(string Version, string Url, long Size)?> GetLatestInstallerUrl(string feedUrl) {
            try {
                using var client = new HttpClient() {
                    Timeout = TimeSpan.FromSeconds(5),
                };
                client.DefaultRequestHeaders.UserAgent.Clear();
                client.DefaultRequestHeaders.UserAgent.ParseAdd($"PamhagenSysCtrl/{App.Version} ({Environment.MachineName}, {Environment.OSVersion})");
                client.DefaultRequestHeaders.Accept.Clear();
                client.DefaultRequestHeaders.Accept.Add(new("application/json"));
                using var res = await client.GetAsync(feedUrl);
                if (!res.IsSuccessStatusCode)
                    return null;

                var json = JsonNode.Parse(await res.Content.ReadAsStringAsync());
                var latest = json!["data"]!.AsArray()[^1]!;
                return ((string)latest["version"]!, (string)latest["url"]!, (long)latest["size"]!);
            } catch {
                return null;
            }
        }

        public static async Task DownloadInstaller(string url, string filename, IProgress<double>? progress = null, CancellationToken cancellationToken = default) {
            try {
                using var client = new HttpClient() {
                    Timeout = TimeSpan.FromSeconds(5),
                };
                client.DefaultRequestHeaders.UserAgent.Clear();
                client.DefaultRequestHeaders.UserAgent.ParseAdd($"PamhagenSysCtrl/{App.Version} ({Environment.MachineName}, {Environment.OSVersion})");
                client.DefaultRequestHeaders.Accept.Clear();
                using var response = await client.GetAsync(url, HttpCompletionOption.ResponseHeadersRead, cancellationToken);
                response.EnsureSuccessStatusCode();
                var contentLength = response.Content.Headers.ContentLength;

                await using (var destination = new FileStream(filename, FileMode.Create)) {
                    await using var source = await response.Content.ReadAsStreamAsync(cancellationToken);
                    var buffer = new byte[81920];
                    long downloaded = 0;
                    int read;
                    while ((read = await source.ReadAsync(buffer, cancellationToken)) != 0) {
                        await destination.WriteAsync(buffer.AsMemory(0, read), cancellationToken);
                        downloaded += read;
                        if (contentLength.HasValue) {
                            progress?.Report((double)downloaded / contentLength.Value);
                        }
                    }
                }

                progress?.Report(1);
            } catch {
                File.Delete(filename);
                throw;
            }
        }

        public static void StartInstaller(string fileName) {
            var startInfo = new ProcessStartInfo {
                FileName = "msiexec.exe",
                UseShellExecute = true,
                Verb = "runas",
            };
            startInfo.ArgumentList.Add("/i");
            startInfo.ArgumentList.Add(Path.GetFullPath(fileName));

            if (Process.Start(startInfo) == null) {
                throw new InvalidOperationException("Der Installer konnte nicht gestartet werden.");
            }
        }
    }
}