// Copyright (c) .NET Foundation and contributors. All rights reserved.
// Licensed under the MIT license. See LICENSE file in the project root for full license information.

using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Runtime.InteropServices;
using Microsoft.DotNet.Cli;
using Microsoft.DotNet.Cli.Utils;
using Microsoft.DotNet.PlatformAbstractions;
using Microsoft.DotNet.Tools;
using Microsoft.DotNet.Tools.Common;
using Microsoft.Extensions.EnvironmentAbstractions;
using Newtonsoft.Json;

namespace Microsoft.DotNet.ShellShim
{
    internal class ShellShimRepository : IShellShimRepository
    {
        private const string ApphostNameWithoutExtension = "apphost";

        private readonly DirectoryPath _shimsDirectory;
        private readonly IFileSystem _fileSystem;
        private readonly IAppHostShellShimMaker _appHostShellShimMaker;
        private readonly IFilePermissionSetter _filePermissionSetter;

        public ShellShimRepository(
            DirectoryPath shimsDirectory,
            string appHostSourceDirectory = null,
            IFileSystem fileSystem = null,
            IAppHostShellShimMaker appHostShellShimMaker = null,
            IFilePermissionSetter filePermissionSetter = null)
        {
            _shimsDirectory = shimsDirectory;
            _fileSystem = fileSystem ?? new FileSystemWrapper();
            _appHostShellShimMaker = appHostShellShimMaker ?? new AppHostShellShimMaker(appHostSourceDirectory: appHostSourceDirectory);
            _filePermissionSetter = filePermissionSetter ?? new FilePermissionSetter();
        }

        public void CreateShim(FilePath targetExecutablePath, string commandName, IReadOnlyList<FilePath> packagedShims = null)
        {
            if (string.IsNullOrEmpty(targetExecutablePath.Value))
            {
                throw new ShellShimException(CommonLocalizableStrings.CannotCreateShimForEmptyExecutablePath);
            }
            if (string.IsNullOrEmpty(commandName))
            {
                throw new ShellShimException(CommonLocalizableStrings.CannotCreateShimForEmptyCommand);
            }

            if (ShimExists(commandName))
            {
                throw new ShellShimException(
                    string.Format(
                        CommonLocalizableStrings.ShellShimConflict,
                        commandName));
            }

            TransactionalAction.Run(
                action: () =>
                {
                    try
                    {
                        if (!_fileSystem.Directory.Exists(_shimsDirectory.Value))
                        {
                            _fileSystem.Directory.CreateDirectory(_shimsDirectory.Value);
                        }

                        if (TryGetPackagedShim(packagedShims, commandName, out FilePath? packagedShim))
                        {
                            _fileSystem.File.Copy(packagedShim.Value.Value, GetShimPath(commandName).Value);
                            _filePermissionSetter.SetUserExecutionPermission(GetShimPath(commandName).Value);
                        }
                        else
                        {
                            _appHostShellShimMaker.CreateApphostShellShim(
                                targetExecutablePath,
                                GetShimPath(commandName));
                        }
                    }
                    catch (FilePermissionSettingException ex)
                    {
                        throw new ShellShimException(
                                string.Format(CommonLocalizableStrings.FailedSettingShimPermissions, ex.Message));
                    }
                    catch (Exception ex) when (ex is UnauthorizedAccessException || ex is IOException)
                    {
                        throw new ShellShimException(
                            string.Format(
                                CommonLocalizableStrings.FailedToCreateShellShim,
                                commandName,
                                ex.Message
                            ),
                            ex);
                    }
                },
                rollback: () => {
                    foreach (var file in GetShimFiles(commandName).Where(f => _fileSystem.File.Exists(f.Value)))
                    {
                        File.Delete(file.Value);
                    }
                });
        }

        public void RemoveShim(string commandName)
        {
            var files = new Dictionary<string, string>();
            TransactionalAction.Run(
                action: () => {
                    try
                    {
                        foreach (var file in GetShimFiles(commandName).Where(f => _fileSystem.File.Exists(f.Value)))
                        {
                            var tempPath = Path.Combine(Path.GetTempPath(), Path.GetRandomFileName());
                            _fileSystem.File.Move(file.Value, tempPath);
                            files[file.Value] = tempPath;
                        }
                    }
                    catch (Exception ex) when (ex is UnauthorizedAccessException || ex is IOException)
                    {
                        throw new ShellShimException(
                            string.Format(
                                CommonLocalizableStrings.FailedToRemoveShellShim,
                                commandName,
                                ex.Message
                            ),
                            ex);
                    }
                },
                commit: () => {
                    foreach (var value in files.Values)
                    {
                        _fileSystem.File.Delete(value);
                    }
                },
                rollback: () => {
                    foreach (var kvp in files)
                    {
                        _fileSystem.File.Move(kvp.Value, kvp.Key);
                    }
                });
        }

        private class StartupOptions
        {
            public string appRoot { get; set; }
        }

        private class RootObject
        {
            public StartupOptions startupOptions { get; set; }
        }

        private bool ShimExists(string commandName)
        {
            return GetShimFiles(commandName).Any(p => _fileSystem.File.Exists(p.Value));
        }

        private IEnumerable<FilePath> GetShimFiles(string commandName)
        {
            if (string.IsNullOrEmpty(commandName))
            {
                yield break;
            }

            yield return GetShimPath(commandName);
        }

        private FilePath GetShimPath(string commandName)
        {
            if (RuntimeInformation.IsOSPlatform(OSPlatform.Windows))
            {
                return new FilePath(_shimsDirectory.WithFile(commandName).Value +".exe");
            }
            else
            {
                return _shimsDirectory.WithFile(commandName);
            }
        }

        private bool TryGetPackagedShim(
            IReadOnlyList<FilePath> packagedShims,
            string commandName,
            out FilePath? packagedShim)
        {
            packagedShim = null;

            if (packagedShims != null && packagedShims.Count > 0)
            {
                FilePath[] candidatepackagedShim =
                    packagedShims
                        .Where(s => string.Equals(
                            Path.GetFileName(s.Value),
                            Path.GetFileName(GetShimPath(commandName).Value))).ToArray();

                if (candidatepackagedShim.Length > 1)
                {
                    throw new ShellShimException(
                        string.Format(
                            CommonLocalizableStrings.MoreThanOnePackagedShimAvailable,
                            string.Join(';', candidatepackagedShim)));
                }

                if (candidatepackagedShim.Length == 1)
                {
                    packagedShim = candidatepackagedShim.Single();
                    return true;
                }
            }

            return false;
        }
    }
}