using System;
using System.Collections.Generic;
using System.Linq;
using Microsoft.SharePoint;

namespace Taloyhtio.CustomNavigationCommon
{
    // It sortes the folders based on SortOrder column added to content type.
    // OTB Folder content type is sealed, so in order to be able manually rearrange
    // folders sorting order custom content type should be created based on Folder content type.
    // See http://sharepoint-guru.blogspot.com/2007/06/adding-metadata-to-folder.html for details
    public static class FolderSorter
    {
        private const string ORDERED_FOLDER_CONTENT_TYPE_NAME = "Ordered Folder";
        private const int DEFAULT_ORDER = 0;
        private const string SORT_ORDER_FIELD_NAME = "SortOrder";

        public static List<SPFolder> Sort(List<SPFolder> folders)
        {
            try
            {
                if (folders.IsNullOrEmpty())
                {
                    return new List<SPFolder>();
                }

                // containts pairs (sortOrder, list of folders with that sortOrder)
                var sortDict = new Dictionary<int, List<SPFolder>>();
                int order;
                foreach (var folder in folders)
                {
                    var isOrdered = isOrderedFolder(folder);
                    if (isOrdered.HasValue && isOrdered.Value)
                    {
                        order = getOrder(folder);
                    }
                    else
                    {
                        // OTB folders are treated as having 0 order. They will be sorted after
                        // ordered folders
                        order = DEFAULT_ORDER;
                    }
                    addFolderWithOrder(sortDict, order, folder);
                }

                if (sortDict.IsNullOrEmpty())
                {
                    // it should not happen
                    return new List<SPFolder>();
                }

                var result = sortFolders(sortDict);
                return result;
            }
            catch (Exception x)
            {
                LogUtils.LogError("Error occured during sorting folders:\n{0}\n{1}",
                    x.Message, x.StackTrace);
                return folders;
            }
        }

        private static List<SPFolder> sortFolders(Dictionary<int, List<SPFolder>> sortDict)
        {
            if (sortDict.IsNullOrEmpty())
            {
                return new List<SPFolder>();
            }

            var result = new List<SPFolder>();
            var orders = sortDict.Keys.ToList();
            orders.Sort();
            foreach (var order in orders)
            {
                if (order == DEFAULT_ORDER)
                {
                    // folders with DEFAULT_ORDER are going last
                    continue;
                }

                addFoldersRange(sortDict, order, result);
            }

            if (orders.Contains(DEFAULT_ORDER))
            {
                addFoldersRange(sortDict, DEFAULT_ORDER, result);
            }

            return result;
        }

        private static void addFoldersRange(Dictionary<int, List<SPFolder>> sortDict, int order, List<SPFolder> result)
        {
            var folders = sortDict[order];
            if (folders.IsNullOrEmpty())
            {
                return;
            }
            // within the same order folders are sorted alphabetically
            var sortedFolders = folders.OrderBy(f => f.Name);
            result.AddRange(sortedFolders);
        }

        private static void addFolderWithOrder(Dictionary<int, List<SPFolder>> sortDict, int order, SPFolder folder)
        {
            if (sortDict == null)
            {
                return;
            }
            if (!sortDict.ContainsKey(order))
            {
                sortDict[order] = new List<SPFolder>();
            }
            sortDict[order].Add(folder);
        }

        private static int getOrder(SPFolder folder)
        {
            try
            {
                if (folder == null)
                {
                    return DEFAULT_ORDER;
                }
                if (!folder.Item.Fields.ContainsField(SORT_ORDER_FIELD_NAME))
                {
                    return DEFAULT_ORDER;
                }
                var val = folder.Item[SORT_ORDER_FIELD_NAME] as double?;
                if (!val.HasValue)
                {
                    return DEFAULT_ORDER;
                }
                int order = Convert.ToInt32(val.Value);
                if (order < 0)
                {
                    order = 0;
                }
                return order;
            }
            catch (Exception x)
            {
                //LogUtils.LogError(x);
                return DEFAULT_ORDER;
            }
        }

        private static bool? isOrderedFolder(SPFolder folder)
        {
            try
            {
                if (folder == null)
                {
                    return null;
                }
                string contentTypeName = (string)folder.Item[SPBuiltInFieldId.ContentType];
                return (contentTypeName == ORDERED_FOLDER_CONTENT_TYPE_NAME);
            }
            catch (Exception x)
            {
                //LogUtils.LogError(x);
                return null;
            }
        }
    }
}