using System;
using System.Collections.Generic;
using System.Linq;
using System.IO;
using Umbraco.Core.IO;
using Umbraco.Web.PublishedCache;

namespace Umbraco.Web.Install
{
    internal class FilePermissionHelper
    {
        // ensure that these directories exist and Umbraco can write to them
        private static readonly string[] PermissionDirs = { SystemDirectories.Css, SystemDirectories.Config, SystemDirectories.Data, SystemDirectories.Media, SystemDirectories.Masterpages, SystemDirectories.Xslt, SystemDirectories.UserControls, SystemDirectories.Preview };
        private static readonly string[] PackagesPermissionsDirs = { SystemDirectories.Bin, SystemDirectories.Umbraco, SystemDirectories.UserControls, SystemDirectories.Packages };

        // ensure Umbraco can write to these files (the directories must exist)
        private static readonly string[] PermissionFiles = { };

        public static bool RunFilePermissionTestSuite(out Dictionary<string, IEnumerable<string>> report)
        {
            report = new Dictionary<string, IEnumerable<string>>();

            IEnumerable<string> errors;

            if (EnsureDirectories(PermissionDirs, out errors) == false)
                report["Folder creation failed"] = errors.ToList();

            if (EnsureDirectories(PackagesPermissionsDirs, out errors) == false)
                report["File writing for packages failed"] = errors.ToList();

            if (EnsureFiles(PermissionFiles, out errors) == false)
                report["File writing failed"] = errors.ToList();

            if (TestFacade(out errors) == false)
                report["Facade environment check failed"] = errors.ToList();

            if (EnsureCanCreateSubDirectory(SystemDirectories.Media, out errors) == false)
                report["Media folder creation failed"] = errors.ToList();

            return report.Count == 0;
        }

        public static bool EnsureDirectories(string[] dirs, out IEnumerable<string> errors)
        {
            List<string> temp = null;
            var success = true;
            foreach (var dir in dirs)
            {
                // we don't want to create/ship unnecessary directories, so
                // here we just ensure we can access the directory, not create it
                var tryAccess = TryAccessDirectory(dir);
                if (tryAccess) continue;

                if (temp == null) temp = new List<string>();
                temp.Add(dir);
                success = false;
            }

            errors = success ? Enumerable.Empty<string>() : temp;
            return success;
        }

        public static bool EnsureFiles(string[] files, out IEnumerable<string> errors)
        {
            List<string> temp = null;
            var success = true;
            foreach (var file in files)
            {
                var canWrite = TryWriteFile(file);
                if (canWrite) continue;

                if (temp == null) temp = new List<string>();
                temp.Add(file);
                success = false;
            }

            errors = success ? Enumerable.Empty<string>() : temp;
            return success;
        }

        public static bool EnsureCanCreateSubDirectory(string dir, out IEnumerable<string> errors)
        {
            return EnsureCanCreateSubDirectories(new[] { dir }, out errors);
        }

        public static bool EnsureCanCreateSubDirectories(IEnumerable<string> dirs, out IEnumerable<string> errors)
        {
            List<string> temp = null;
            var success = true;
            foreach (var dir in dirs)
            {
                var canCreate = TryCreateSubDirectory(dir);
                if (canCreate) continue;

                if (temp == null) temp = new List<string>();
                temp.Add(dir);
                success = false;
            }

            errors = success ? Enumerable.Empty<string>() : temp;
            return success;
        }

        public static bool TestFacade(out IEnumerable<string> errors)
        {
            var facadeService = FacadeServiceResolver.Current.Service;
            return facadeService.EnsureEnvironment(out errors);
        }

        // tries to create a sub-directory
        // if successful, the sub-directory is deleted
        // creates the directory if needed - does not delete it
        private static bool TryCreateSubDirectory(string dir)
        {
            try
            {
                var path = IOHelper.MapPath(dir + "/" + CreateRandomName());
                Directory.CreateDirectory(path);
                Directory.Delete(path);
                return true;
            }
            catch
            {
                return false;
            }
        }

        // tries to create a file
        // if successful, the file is deleted
        // creates the directory if needed - does not delete it
        public static bool TryCreateDirectory(string dir)
        {
            try
            {
                var dirPath = IOHelper.MapPath(dir);

                if (Directory.Exists(dirPath) == false)
                    Directory.CreateDirectory(dirPath);

                var filePath = dirPath + "/" + CreateRandomName() + ".tmp";
                File.WriteAllText(filePath, "This is an Umbraco internal test file. It is safe to delete it.");
                File.Delete(filePath);
                return true;
            }
            catch
            {
                return false;
            }
        }

        // tries to create a file
        // if successful, the file is deleted
        // if the directory does not exist, do nothing & success
        public static bool TryAccessDirectory(string dir)
        {
            try
            {
                var dirPath = IOHelper.MapPath(dir);

                if (Directory.Exists(dirPath) == false)
                    return true;

                var filePath = dirPath + "/" + CreateRandomName() + ".tmp";
                File.WriteAllText(filePath, "This is an Umbraco internal test file. It is safe to delete it.");
                File.Delete(filePath);
                return true;
            }
            catch
            {
                return false;
            }
        }

        // tries to write into a file
        // fails if the directory does not exist
        private static bool TryWriteFile(string file)
        {
            try
            {
                var path = IOHelper.MapPath(file);
                File.AppendText(path).Close();
                return true;
            }
            catch
            {
                return false;
            }
        }

        private static string CreateRandomName()
        {
            return "umbraco-test." + Guid.NewGuid().ToString("N").Substring(0, 8);
        }
    }
}