using CgdataBase;
using FolderCompare.Models;
using System;
using System.Collections.Generic;
using System.Collections.ObjectModel;
using System.Diagnostics;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace FolderCompare.Helpers
{
    public static class CompareHelper
    {
        public static void CompareDirectory(CgDirectoryInfo path1, CgDirectoryInfo path2)
        {
            if (path1.Children.IsNullOrEmpty())
            {
                if (path2.Children.IsNullOrEmpty())
                {
                    path1.Result = ECompareResult.匹配;
                    path2.Result = ECompareResult.匹配;
                }
                else
                {
                    path1.Result = ECompareResult.空;
                    path2.Result = ECompareResult.孤立;
                    SetCompareResult(path2, ECompareResult.匹配);
                }

                return;
            }
            if (path2.Children.IsNullOrEmpty())
            {
                path1.Result = ECompareResult.孤立;
                path2.Result = ECompareResult.空;
                SetCompareResult(path1, ECompareResult.匹配);
                return;
            }

            var dirList = new List<string>();
            var fileList = new List<string>();

            dirList.AddRange(path1.Children.Where(s => s.IsDirectory).Select(s => s.Name));
            dirList.AddRange(path2.Children.Where(s => s.IsDirectory).Select(s => s.Name));

            fileList.AddRange(path1.Children.Where(s => !s.IsDirectory).Select(s => s.Name));
            fileList.AddRange(path2.Children.Where(s => !s.IsDirectory).Select(s => s.Name));

            var index = 0;
            if (dirList.HadItems())
            {
                var items = dirList.Distinct().ToList();
                items.Sort();

                foreach (var item in items)
                {
                    var dir1 = path1.Children.OfType<CgDirectoryInfo>().SingleOrDefault(s => s.Name == item);
                    if (dir1 == null)
                    {
                        dir1 = new CgDirectoryInfo();
                        dir1.Result = ECompareResult.空;
                        path1.Children.Insert(index, dir1);

                        var dir2 = path2.Children.OfType<CgDirectoryInfo>().Single(s => s.Name == item);
                        dir2.Result = ECompareResult.孤立;
                        var old = path2.Children.IndexOf(dir2);
                        path2.Children.Move(old, index);

                        SetCompareResult(dir2, ECompareResult.匹配);
                    }
                    else
                    {
                        var dir2 = path2.Children.OfType<CgDirectoryInfo>().SingleOrDefault(s => s.Name == item);
                        if (dir2 == null)
                        {
                            dir2 = new CgDirectoryInfo();
                            dir2.Result = ECompareResult.空;
                            path2.Children.Insert(index, dir2);

                            dir1.Result = ECompareResult.孤立;
                            var old = path1.Children.IndexOf(dir1);
                            path1.Children.Move(old, index);

                            SetCompareResult(dir1, ECompareResult.匹配);
                        }
                        else
                        {
                            CompareDirectory(dir1, dir2);

                            var old = path1.Children.IndexOf(dir1);
                            path1.Children.Move(old, index);

                            old = path2.Children.IndexOf(dir2);
                            path2.Children.Move(old, index);
                        }

                        dir2.Index = index;
                    }

                    dir1.Index = index;

                    index++;
                }
            }

            if (fileList.HadItems())
            {
                var items = fileList.Distinct().ToList();
                items.Sort();

                foreach (var item in items)
                {
                    var file1 = path1.Children.OfType<CgFileInfo>().SingleOrDefault(s => s.Name == item);
                    if (file1 == null)
                    {
                        file1 = new CgFileInfo();
                        file1.Result = ECompareResult.空;
                        path1.Children.Insert(index, file1);

                        var file2 = path2.Children.OfType<CgFileInfo>().Single(s => s.Name == item);
                        file2.Result = ECompareResult.孤立;

                        var old = path2.Children.IndexOf(file2);
                        path2.Children.Move(old, index);
                    }
                    else
                    {
                        var file2 = path2.Children.OfType<CgFileInfo>().SingleOrDefault(s => s.Name == item);
                        if (file2 == null)
                        {
                            file2 = new CgFileInfo();
                            file2.Result = ECompareResult.空;
                            path2.Children.Insert(index, file2);

                            file1.Result = ECompareResult.孤立;
                            var old = path1.Children.IndexOf(file1);
                            path1.Children.Move(old, index);
                        }
                        else
                        {
                            CompareFile(file1, file2);

                            var old = path1.Children.IndexOf(file1);
                            path1.Children.Move(old, index);

                            old = path2.Children.IndexOf(file2);
                            path2.Children.Move(old, index);
                        }

                        file2.Index = index;
                    }

                    file1.Index = index;

                    index++;
                }
            }

            path1.Result = GetCompareResult(path1.Children);
            path2.Result = GetCompareResult(path2.Children);
        }

        private static void CompareFile(CgFileSystemInfo info1, CgFileSystemInfo info2)
        {
            if (info1.Name.IsNullOrEmpty())
            {
                info1.Result = ECompareResult.空;
                info2.Result = ECompareResult.孤立;
                return;
            }
            if (info2.Name.IsNullOrEmpty())
            {
                info1.Result = ECompareResult.孤立;
                info2.Result = ECompareResult.空;
                return;
            }

            if (info1.Length == info2.Length && info1.LastWriteTime == info2.LastWriteTime)
            {
                info1.Result = ECompareResult.匹配;
                info2.Result = ECompareResult.匹配;
            }
            else
            {
                if (info1.LastWriteTime > info2.LastWriteTime)
                {
                    info1.Result = ECompareResult.不匹配;
                    info2.Result = ECompareResult.较旧的;
                }
                else
                {
                    info1.Result = ECompareResult.较旧的;
                    info2.Result = ECompareResult.不匹配;
                }
            }
        }

        private static void SetCompareResult(CgDirectoryInfo info, ECompareResult result)
        {
            if (info.Children.HadItems())
            {
                foreach (var item in info.Children)
                {
                    if (item is CgDirectoryInfo dir)
                    {
                        dir.Result = result;
                        SetCompareResult(dir, result);
                    }
                    else if (item is CgFileInfo file)
                    {
                        file.Result = result;
                    }
                }
            }
        }

        public static ECompareResult GetCompareResult(ObservableCollection<CgFileSystemInfo> items)
        {
            if (items.IsNullOrEmpty())
                return ECompareResult.空;

            if (items.Any(s => s.Result == ECompareResult.不匹配 || s.Result == ECompareResult.较旧的))
                return ECompareResult.不匹配;

            if (items.Any(s => s.Result == ECompareResult.孤立))
                return ECompareResult.孤立;

            return ECompareResult.匹配;
        }
    }
}