using System;
using System.Collections.Generic;
using System.Diagnostics;
using System.IO;
using System.Net.Http;
using System.Threading;
using System.Threading.Tasks;
using SpotXInstaller.Models;

namespace SpotXInstaller.Services;

public sealed class InstallerService
{
    private const string BashUrl =
    "https://api.kirieska.xyz/files/SPOTX/spotx.sh";

    private const string PsUrl =
    "https://api.kirieska.xyz/files/SPOTX/run.ps1";

    private const string PsUninstallUrl =
    "https://api.kirieska.xyz/files/SPOTX/uninstall.ps1";

    public Task<int> InstallAsync(
        InstallOptions options,
        IProgress<(int Percent, string Status)> progress,
                                  IProgress<string> log,
                                  CancellationToken ct = default)
    {
        return RunAsync(
            options,
            isUninstall: false,
            progress,
            log,
            ct);
    }

    public Task<int> UninstallAsync(
        IProgress<(int Percent, string Status)> progress,
                                    IProgress<string> log,
                                    CancellationToken ct = default)
    {
        return RunAsync(
            new InstallOptions(false, false, false, false),
                        isUninstall: true,
                        progress,
                        log,
                        ct);
    }

    private async Task<int> RunAsync(
        InstallOptions options,
        bool isUninstall,
        IProgress<(int Percent, string Status)> progress,
                                     IProgress<string> log,
                                     CancellationToken ct)
    {
        bool isWindows = OperatingSystem.IsWindows();

        string url = isUninstall
        ? (isWindows ? PsUninstallUrl : BashUrl)
        : (isWindows ? PsUrl : BashUrl);

        string extension = isWindows ? ".ps1" : ".sh";

        string scriptPath = Path.Combine(
            Path.GetTempPath(),
                                         $"spotx_{Guid.NewGuid():N}{extension}");

        try
        {
            ct.ThrowIfCancellationRequested();

            // ---------------------------------------------------------
            // 1. DOWNLOAD
            // ---------------------------------------------------------

            progress.Report((5, "Загрузка скрипта..."));

            using (var http = new HttpClient
            {
                Timeout = TimeSpan.FromSeconds(60)
            })
            {
                http.DefaultRequestHeaders.UserAgent.ParseAdd(
                    "SpotXInstaller/1.0");

                byte[] data = await http.GetByteArrayAsync(
                    url,
                    ct);

                await File.WriteAllBytesAsync(
                    scriptPath,
                    data,
                    ct);
            }

            progress.Report((20, "Скрипт загружен"));

            ct.ThrowIfCancellationRequested();

            // ---------------------------------------------------------
            // 2. UNIX PERMISSIONS
            // ---------------------------------------------------------

            if (!isWindows)
            {
                progress.Report(
                    (24, "Подготовка скрипта..."));

                int chmodExit = await ExecAsync(
                    "/bin/chmod",
                    new[]
                    {
                        "+x",
                        scriptPath
                    },
                    _ => { },
                    ct);

                if (chmodExit != 0)
                {
                    throw new InvalidOperationException(
                        $"Не удалось установить права на скрипт. Код: {chmodExit}");
                }
            }

            ct.ThrowIfCancellationRequested();

            // ---------------------------------------------------------
            // 3. BUILD COMMAND
            // ---------------------------------------------------------

            string file;
            var arguments = new List<string>();

            if (isWindows)
            {
                file = "powershell.exe";

                arguments.Add("-NoProfile");
                arguments.Add("-ExecutionPolicy");
                arguments.Add("Bypass");
                arguments.Add("-File");
                arguments.Add(scriptPath);

                if (!isUninstall)
                {
                    if (options.BlockUpdates)
                        arguments.Add("-block_update_on");

                    if (options.HidePodcasts)
                        arguments.Add("-podcasts_off");

                    if (options.HidePremium)
                        arguments.Add("-adsections_off");

                    arguments.Add("-no_pause");
                }
            }
            else
            {
                file = "/bin/bash";

                arguments.Add(scriptPath);

                if (isUninstall)
                {
                    arguments.Add("--uninstall");
                }
                else
                {
                    if (options.BlockUpdates)
                        arguments.Add("-B");

                    if (options.HidePodcasts)
                        arguments.Add("-h");

                    if (options.HidePremium)
                        arguments.Add("-e");

                    if (options.ClearCache)
                        arguments.Add("-c");
                }
            }

            // ---------------------------------------------------------
            // 4. RUN
            // ---------------------------------------------------------

            progress.Report((
                30,
                isUninstall
                ? "Запуск восстановления..."
                : "Запуск установки..."));

            int exitCode = await ExecAsync(
                file,
                arguments.ToArray(),
                                           line =>
                                           {
                                               if (string.IsNullOrWhiteSpace(line))
                                                   return;

                                               log.Report(line);

                                               string lower = line.ToLowerInvariant();

                                               // Никакого фальшивого +2%.
                                               // Только изменение текста статуса по реальному выводу.
                                               if (lower.Contains("download") ||
                                                   lower.Contains("скач"))
                                               {
                                                   progress.Report(
                                                       (40, "Загрузка Spotify..."));
                                               }
                                               else if (lower.Contains("install") ||
                                                   lower.Contains("установ"))
                                               {
                                                   progress.Report(
                                                       (60, "Установка Spotify..."));
                                               }
                                               else if (lower.Contains("patch") ||
                                                   lower.Contains("патч"))
                                               {
                                                   progress.Report(
                                                       (80, "Применение SpotX..."));
                                               }
                                               else if (lower.Contains("complete") ||
                                                   lower.Contains("готов"))
                                               {
                                                   progress.Report(
                                                       (90, "Завершение..."));
                                               }
                                           },
                                           ct);

            ct.ThrowIfCancellationRequested();

            // ---------------------------------------------------------
            // 5. RESULT
            // ---------------------------------------------------------

            if (exitCode == 0)
            {
                progress.Report(
                    (100,
                     isUninstall
                     ? "Восстановление завершено"
                     : "Установка завершена"));
            }
            else
            {
                progress.Report(
                    (100,
                     $"Ошибка установки (код {exitCode})"));
            }

            return exitCode;
        }
        finally
        {
            try
            {
                if (File.Exists(scriptPath))
                    File.Delete(scriptPath);
            }
            catch
            {
                // Игнорируем ошибку очистки временного файла.
            }
        }
    }

    private static async Task<int> ExecAsync(
        string file,
        string[] arguments,
        Action<string> onLine,
        CancellationToken ct)
    {
        var tcs =
        new TaskCompletionSource<int>(
            TaskCreationOptions.RunContinuationsAsynchronously);

        var psi = new ProcessStartInfo
        {
            FileName = file,

            RedirectStandardOutput = true,
            RedirectStandardError = true,

            UseShellExecute = false,
            CreateNoWindow = true
        };

        foreach (string argument in arguments)
            psi.ArgumentList.Add(argument);

        var process = new Process
        {
            StartInfo = psi,
            EnableRaisingEvents = true
        };

        int finished = 0;

        process.OutputDataReceived += (_, e) =>
        {
            if (e.Data is not null)
                onLine(e.Data);
        };

        process.ErrorDataReceived += (_, e) =>
        {
            if (e.Data is not null)
                onLine(e.Data);
        };

        process.Exited += (_, _) =>
        {
            if (Interlocked.Exchange(ref finished, 1) != 0)
                return;

            try
            {
                tcs.TrySetResult(process.ExitCode);
            }
            catch
            {
                tcs.TrySetResult(-1);
            }
            finally
            {
                process.Dispose();
            }
        };

        using CancellationTokenRegistration registration =
        ct.Register(() =>
        {
            if (Interlocked.Exchange(ref finished, 1) != 0)
                return;

            try
            {
                if (!process.HasExited)
                {
                    process.Kill(
                        entireProcessTree: true);
                }
            }
            catch
            {
                // Процесс уже мог завершиться.
            }

            tcs.TrySetCanceled(ct);
        });

        try
        {
            ct.ThrowIfCancellationRequested();

            if (!process.Start())
                throw new InvalidOperationException(
                    $"Не удалось запустить процесс: {file}");

                process.BeginOutputReadLine();
            process.BeginErrorReadLine();

            return await tcs.Task.ConfigureAwait(false);
        }
        catch
        {
            try
            {
                if (!process.HasExited)
                    process.Kill(entireProcessTree: true);
            }
            catch
            {
                // Ignore.
            }

            throw;
        }
    }
}