using System;
using System.Collections.Generic;
using System.Diagnostics;
using System.Globalization;
using System.IO;
using System.Reflection;
using Microsoft.Build.Framework;
using Microsoft.Build.Utilities;
using Microsoft.Win32;

namespace YekNebTasks
{
    public static class Utilities
    {
        private static string cmake = string.Empty;
        private static string git = string.Empty;
        private static string patch = string.Empty;
        private static string python = string.Empty;
        private static string VSWhere = string.Empty;

        public static string FindFileOnPath(string fileName)
        {
            if (string.IsNullOrEmpty(fileName))
            {
                return string.Empty;
            }
            string FoundFile = string.Empty;
            fileName = Environment.ExpandEnvironmentVariables(fileName);
            if (File.Exists(fileName))
            {
                FoundFile = Path.GetFullPath(fileName);
            }
            else if (string.IsNullOrEmpty(Path.GetDirectoryName(fileName)))
            {
                var path = Environment.GetEnvironmentVariable("PATH") ?? string.Empty;
                foreach (var dir in path.Split(Path.PathSeparator))
                {
                    var dirL = dir.Trim();
                    var fullPath = Path.GetFullPath(Path.Combine(dirL, fileName));
                    if (File.Exists(fullPath))
                    {
                        FoundFile = fullPath;
                        break;
                    }
                }
            }
            return FoundFile;
        }

        public static string FindFileUsingCandidates(
            string[] candidates)
        {
            if (candidates == null || candidates.Length == 0)
            {
                return string.Empty;
            }
            string FoundFile = string.Empty;
            foreach (string candidate in candidates)
            {
                string candidateL = Environment.ExpandEnvironmentVariables(
                    candidate);
                if (File.Exists(candidateL))
                {
                    FoundFile = candidateL;
                    break;
                }
            }
            return FoundFile;
        }

        public static string FindCMake()
        {
            if (!string.IsNullOrEmpty(cmake))
            {
                return cmake;
            }
            const string FileName = "cmake.exe";
            string[] candidates = new string[]{
                @"%ProgramFiles(x86)%\Microsoft Visual Studio\2019\Community\Common7\IDE\CommonExtensions\Microsoft\CMake\CMake\bin\cmake.exe",
                @"%ProgramFiles(x86)%\Microsoft Visual Studio\2019\BuildTools\Common7\IDE\CommonExtensions\Microsoft\CMake\CMake\bin\cmake.exe",
                @"%ProgramFiles(x86)%\Microsoft Visual Studio\2019\Professional\Common7\IDE\CommonExtensions\Microsoft\CMake\CMake\bin\cmake.exe",
                @"%ProgramFiles(x86)%\Microsoft Visual Studio\2017\Professional\Common7\IDE\CommonExtensions\Microsoft\CMake\CMake\bin\cmake.exe",
                @"%ProgramFiles%\CMake\bin\cmake.exe",
                @"%ProgramW6432%\CMake\bin\cmake.exe",
                @"%SystemDrive%\msys64\mingw64\bin\cmake.exe",
                @"%SystemDrive%\msys64\mingw32\bin\cmake.exe",
                @"%SystemDrive%\msys64\usr\bin\cmake.exe"
            };
            cmake = FindFileUsingCandidates(candidates);
            if (!string.IsNullOrEmpty(cmake))
            {
                return cmake;
            }
            cmake = FindFileOnPath(FileName);
            return cmake;
        }

        public static string FindGit()
        {
            if (!string.IsNullOrEmpty(git))
            {
                return git;
            }
            const string FileName = "git.exe";
            string[] candidates = new String[]{
                @"%ProgramFiles%\Git\cmd\git.exe",
                @"%ProgramW6432%\Git\cmd\git.exe",
                @"%SystemDrive%\msys64\mingw64\bin\git.exe",
                @"%SystemDrive%\msys64\mingw32\bin\git.exe",
                @"%SystemDrive%\msys64\usr\bin\git.exe",
                @"%SystemDrive%\MinGW\msys\1.0\bin\git.exe"
            };
            git = FindFileUsingCandidates(candidates);
            if (!string.IsNullOrEmpty(git))
            {
                return git;
            }
            git = FindFileOnPath(FileName);
            return git;
        }

        public static string FindNMake()
        {
            string nmake = FindFileOnPath("nmake.exe");
            if (!string.IsNullOrEmpty(nmake))
            {
                return nmake;
            }
            string visualStudioDir = GetVisualStudioInstallDirectory("16.0");
            if (string.IsNullOrEmpty(visualStudioDir) || !Directory.Exists(visualStudioDir))
            {
                visualStudioDir = GetVisualStudioInstallDirectory("15.0");
            }
            if (string.IsNullOrEmpty(visualStudioDir) || !Directory.Exists(visualStudioDir))
            {
                visualStudioDir = GetVisualStudioInstallDirectory("14.0");
            }
            if (string.IsNullOrEmpty(visualStudioDir) || !Directory.Exists(visualStudioDir))
            {
                return string.Empty;
            }
            string vcDir = Path.Combine(visualStudioDir, "VC");
            if (!Directory.Exists(vcDir))
            {
                return string.Empty;
            }
            string[] foundFiles = Directory.GetFiles(
                vcDir, "nmake.exe", SearchOption.AllDirectories);
            if (foundFiles.Length == 0)
            {
                return string.Empty;
            }
            CultureInfo culture = CultureInfo.CurrentCulture;
            foreach (var candidate in foundFiles)
            {
                if (culture.CompareInfo.IndexOf(candidate, "x64", CompareOptions.IgnoreCase) >= 0)
                {
                    nmake = candidate;
                }
            }
            return nmake;
        }

        public static string FindPatch()
        {
            if (!string.IsNullOrEmpty(patch))
            {
                return patch;
            }
            const string FileName = "patch.exe";
            string[] candidates = new string[]{
                @"%SystemDrive%\msys64\mingw64\bin\patch.exe",
                @"%SystemDrive%\msys64\mingw32\bin\patch.exe",
                @"%SystemDrive%\msys64\usr\bin\patch.exe",
                @"%SystemDrive%\MinGW\msys\1.0\bin\patch.exe"
            };
            patch = FindFileUsingCandidates(candidates);
            if (string.IsNullOrEmpty(patch))
            {
                patch = FindFileOnPath(FileName);
            }
            return patch;
        }

        public static string FindPython()
        {
            if (!string.IsNullOrEmpty(python))
            {
                return python;
            }
            const string FileName = "python.exe";
            string[] candidates = new string[]{
                @"%ProgramFiles%\Python39\python.exe",
                @"%ProgramW6432%\Python39\python.exe",
                @"%ProgramFiles%\Python38\python.exe",
                @"%ProgramW6432%\Python38\python.exe",
                @"%ProgramFiles(x86)%\Microsoft Visual Studio\Shared\Python37_64\python.exe",
                @"%ProgramFiles(x86)%\Microsoft Visual Studio\Shared\Python36_64\python.exe",
                @"%ProgramFiles%\Python36\python.exe",
                @"%ProgramW6432%\Python36\python.exe",
                @"%SystemDrive%\Python36\python3.6.exe",
                @"%SystemDrive%\Python36\python3.exe",
                @"%SystemDrive%\Python36\python.exe",
                @"%SystemDrive%\Python35\python3.5.exe",
                @"%SystemDrive%\Python35\python3.exe",
                @"%SystemDrive%\Python35\python.exe",
                @"%SystemDrive%\Python34\python3.4.exe",
                @"%SystemDrive%\Python34\python3.exe",
                @"%SystemDrive%\Python34\python.exe",
                @"%SystemDrive%\msys64\mingw64\bin\python3.8.exe",
                @"%SystemDrive%\msys64\mingw64\bin\python3.7.exe",
                @"%SystemDrive%\msys64\mingw64\bin\python3.6.exe",
                @"%SystemDrive%\msys64\mingw64\bin\python3.5.exe",
                @"%SystemDrive%\msys64\mingw64\bin\python3.exe",
                @"%SystemDrive%\msys64\mingw32\bin\python3.6.exe",
                @"%SystemDrive%\msys64\mingw32\bin\python3.5.exe",
                @"%SystemDrive%\msys64\mingw32\bin\python3.exe",
                @"%SystemDrive%\msys64\usr\bin\python3.6.exe",
                @"%SystemDrive%\msys64\usr\bin\python3.5.exe",
                @"%SystemDrive%\msys64\usr\bin\python3.exe"
            };
            python = FindFileUsingCandidates(candidates);
            if (!string.IsNullOrEmpty(python))
            {
                return python;
            }
            python = FindFileOnPath(FileName);
            return python;
        }

        private static string FindVSWhereUsingRegistry()
        {
            const string regKeyName = @"SOFTWARE\Microsoft\VisualStudio\Setup";
            const string valueName = @"SharedInstallationPath";
            string ret = string.Empty;
            using (RegistryKey regKey = Registry.LocalMachine.OpenSubKey(regKeyName))
            {
                if (regKey == null)
                {
                    return string.Empty;
                }
                ret = regKey.GetValue(valueName) as string;
            }
            if (string.IsNullOrEmpty(ret))
            {
                return string.Empty;
            }
            DirectoryInfo info = Directory.GetParent(ret);
            if (info == null)
            {
                return string.Empty;
            }
            ret = Path.Combine(info.FullName, @"Installer\vswhere.exe");
            if (!File.Exists(ret))
            {
                return string.Empty;
            }
            return ret;
        }

        public static string FindVSWhere()
        {
            if (!string.IsNullOrEmpty(VSWhere))
            {
                return VSWhere;
            }
            VSWhere = FindVSWhereUsingRegistry();
            if (!string.IsNullOrEmpty(VSWhere))
            {
                return VSWhere;
            }
            const string FileName = "vswhere.exe";
            string[] candidates = new string[]{
                @"%ProgramFiles(x86)%\Microsoft Visual Studio\Installer\vswhere.exe",
                @"%ProgramFiles%\Microsoft Visual Studio\Installer\vswhere.exe"
            };
            VSWhere = FindFileUsingCandidates(candidates);
            if (!string.IsNullOrEmpty(VSWhere))
            {
                return VSWhere;
            }
            VSWhere = FindFileOnPath(FileName);
            return VSWhere;
        }

        private static string RunProcessAndGetStandardOutput(string fileName, string arguments)
        {
            string ret = string.Empty;
            Process p = null;
            try
            {
                p = new Process();
                p.StartInfo.UseShellExecute = false;
                p.StartInfo.RedirectStandardOutput = true;
                p.StartInfo.FileName = fileName;
                p.StartInfo.Arguments = arguments;
                p.Start();
                // Read the output stream first and then wait.
                ret = p.StandardOutput.ReadToEnd();
                p.WaitForExit();
            }
            finally
            {
                if (p != null)
                {
                    p.Dispose();
                }
            }
            return ret;
        }

        private static string GetVisualStudioInstallDirectoryUsingRegistry(string version)
        {
            const string VS7RegKeyName = @"SOFTWARE\Microsoft\VisualStudio\SxS\VS7";
            const string VS7RegKeyX64Name = @"SOFTWARE\WOW6432Node\Microsoft\VisualStudio\SxS\VS7";
            string regKeyName;
            if (Environment.Is64BitOperatingSystem)
            {
                regKeyName = VS7RegKeyX64Name;
            }
            else
            {
                regKeyName = VS7RegKeyName;
            }
            string installDirectory = string.Empty;
            using (RegistryKey regKey = Registry.LocalMachine.OpenSubKey(regKeyName))
            {
                if (regKey != null)
                {
                    installDirectory = regKey.GetValue(version) as string;
                }
            }
            return installDirectory;
        }

        private static string GetVisualStudioInstallDirectoryUsingVSWhere(string version)
        {
            string vsWhere = FindVSWhere();
            if (string.IsNullOrEmpty(vsWhere))
            {
                return string.Empty;
            }
            string output = RunProcessAndGetStandardOutput(
                vsWhere, $"-version {version} -property installationPath");
            vsWhere = output.Trim();
            return vsWhere;
        }

        public static string GetVisualStudioInstallDirectory(string version)
        {
            string ret = GetVisualStudioInstallDirectoryUsingVSWhere(version);
            if (string.IsNullOrEmpty(ret))
            {
                ret = GetVisualStudioInstallDirectoryUsingRegistry(version);
            }
            return ret;
        }

    }

}