using System;
using System.Collections.Generic;
using System.Linq;
using System.Net;
using System.Net.Http;
using System.Net.Http.Formatting;
using System.Web.Http;
using Umbraco.Core;
using Umbraco.Core.Logging;
using Umbraco.Core.Models;
using Umbraco.Core.Models.EntityBase;
using Umbraco.Core.Persistence;
using Umbraco.Web.Models.Trees;
using Umbraco.Web.WebApi.Filters;
using umbraco;
using umbraco.BusinessLogic.Actions;
using System.Globalization;

namespace Umbraco.Web.Trees
{
    public abstract class ContentTreeControllerBase : TreeController
    {

        #region Actions

        /// <summary>
        /// Gets an individual tree node
        /// </summary>
        /// <param name="id"></param>
        /// <param name="queryStrings"></param>
        /// <returns></returns>
        [HttpQueryStringFilter("queryStrings")]
        public TreeNode GetTreeNode(string id, FormDataCollection queryStrings)
        {
            int asInt;
            if (int.TryParse(id, out asInt) == false)
            {
                throw new HttpResponseException(Request.CreateResponse(HttpStatusCode.NotFound));
            }

            var entity = Services.EntityService.Get(asInt, UmbracoObjectType);
            if (entity == null)
            {
                throw new HttpResponseException(Request.CreateResponse(HttpStatusCode.NotFound));
            }

            var node = GetSingleTreeNode(entity, entity.ParentId.ToInvariantString(), queryStrings);

            //add the tree alias to the node since it is standalone (has no root for which this normally belongs)
            node.AdditionalData["treeAlias"] = TreeAlias;
            return node;
        }

        #endregion

        protected abstract TreeNode GetSingleTreeNode(IUmbracoEntity e, string parentId, FormDataCollection queryStrings);

        /// <summary>
        /// Returns the 
        /// </summary>
        protected abstract int RecycleBinId { get; }

        /// <summary>
        /// Returns true if the recycle bin has items in it
        /// </summary>
        protected abstract bool RecycleBinSmells { get; }

        /// <summary>
        /// Returns the user's start node for this tree
        /// </summary>
        protected abstract int[] UserStartNodes { get; }

        /// <summary>
        /// Gets the tree nodes for the given id
        /// </summary>
        /// <param name="id"></param>
        /// <param name="queryStrings"></param>
        /// <returns></returns>        
        protected virtual TreeNodeCollection PerformGetTreeNodes(string id, FormDataCollection queryStrings)
        {
            var nodes = new TreeNodeCollection();

            var altStartId = string.Empty;
            if (queryStrings.HasKey(TreeQueryStringParameters.StartNodeId))
                altStartId = queryStrings.GetValue<string>(TreeQueryStringParameters.StartNodeId);

            //check if a request has been made to render from a specific start node
            if (string.IsNullOrEmpty(altStartId) == false && altStartId != "undefined" && altStartId != Constants.System.Root.ToString(CultureInfo.InvariantCulture))
            {
                id = altStartId;

                //we need to verify that the user has access to view this node, otherwise we'll render an empty tree collection
                // TODO: in the future we could return a validation statement so we can have some UI to notify the user they don't have access                
                if (HasPathAccess(id, queryStrings) == false)
                {
                    LogHelper.Warn<ContentTreeControllerBase>("The user " + Security.CurrentUser.Username + " does not have access to the tree node " + id);
                    return new TreeNodeCollection();
                }

                // So there's an alt id specified, it's not the root node and the user has access to it, great! But there's one thing we
                // need to consider: 
                // If the tree is being rendered in a dialog view we want to render only the children of the specified id, but
                // when the tree is being rendered normally in a section and the current user's start node is not -1, then 
                // we want to include their start node in the tree as well.
                // Therefore, in the latter case, we want to change the id to -1 since we want to render the current user's root node
                // and the GetChildEntities method will take care of rendering the correct root node.
                // If it is in dialog mode, then we don't need to change anything and the children will just render as per normal.
                if (IsDialog(queryStrings) == false && UserStartNodes.Contains(Constants.System.Root) == false)
                {
                    id = Constants.System.Root.ToString(CultureInfo.InvariantCulture);
                }
            }

            var entities = GetChildEntities(id);
            nodes.AddRange(entities.Select(entity => GetSingleTreeNode(entity, id, queryStrings)).Where(node => node != null));
            return nodes;
        }

        protected abstract MenuItemCollection PerformGetMenuForNode(string id, FormDataCollection queryStrings);

        protected abstract UmbracoObjectTypes UmbracoObjectType { get; }

        protected IEnumerable<IUmbracoEntity> GetChildEntities(string id)
        {
            // use helper method to ensure we support both integer and guid lookups
            int iid;

            // look up from GUID if it's not an integer
            if (int.TryParse(id, out iid) == false)
            {
                var idEntity = GetEntityFromId(id);
                if (idEntity == null)
                {
                    throw new HttpResponseException(HttpStatusCode.NotFound);
                }
                iid = idEntity.Id;
            }

            // if a request is made for the root node but user has no access to
            // root node, return start nodes instead
            if (iid == Constants.System.Root && UserStartNodes.Contains(Constants.System.Root) == false)
            {
                return UserStartNodes.Length > 0
                    ? Services.EntityService.GetAll(UmbracoObjectType, UserStartNodes)
                    : Enumerable.Empty<IUmbracoEntity>();
            }

            return Services.EntityService.GetChildren(iid, UmbracoObjectType).ToArray();
        }

        /// <summary>
        /// Returns true or false if the current user has access to the node based on the user's allowed start node (path) access
        /// </summary>
        /// <param name="id"></param>
        /// <param name="queryStrings"></param>
        /// <returns></returns>
        protected abstract bool HasPathAccess(string id, FormDataCollection queryStrings);

        /// <summary>
        /// Ensures the recycle bin is appended when required (i.e. user has access to the root and it's not in dialog mode)
        /// </summary>
        /// <param name="id"></param>
        /// <param name="queryStrings"></param>
        /// <returns></returns>
        /// <remarks>
        /// This method is overwritten strictly to render the recycle bin, it should serve no other purpose
        /// </remarks>
        protected sealed override TreeNodeCollection GetTreeNodes(string id, FormDataCollection queryStrings)
        {
            //check if we're rendering the root
            if (id == Constants.System.Root.ToInvariantString() && UserStartNodes.Contains(Constants.System.Root))
            {
                var altStartId = string.Empty;

                if (queryStrings.HasKey(TreeQueryStringParameters.StartNodeId))
                    altStartId = queryStrings.GetValue<string>(TreeQueryStringParameters.StartNodeId);

                //check if a request has been made to render from a specific start node                
                if (string.IsNullOrEmpty(altStartId) == false && altStartId != "undefined" && altStartId != Constants.System.Root.ToString(CultureInfo.InvariantCulture))
                {
                    id = altStartId;
                }

                var nodes = GetTreeNodesInternal(id, queryStrings);

                //only render the recycle bin if we are not in dialog and the start id id still the root
                if (IsDialog(queryStrings) == false && id == Constants.System.Root.ToInvariantString())
                {
                    nodes.Add(CreateTreeNode(
                        RecycleBinId.ToInvariantString(),
                        id,
                        queryStrings,
                        ui.GetText("general", "recycleBin"),
                        "icon-trash",
                        RecycleBinSmells,
                        queryStrings.GetValue<string>("application") + TreeAlias.EnsureStartsWith('/') + "/recyclebin"));

                }

                return nodes;
            }

            return GetTreeNodesInternal(id, queryStrings);
        }

        /// <summary>
        /// Before we make a call to get the tree nodes we have to check if they can actually be rendered
        /// </summary>
        /// <param name="id"></param>
        /// <param name="queryStrings"></param>
        /// <returns></returns>
        /// <remarks>
        /// Currently this just checks if it is a container type, if it is we cannot render children. In the future this might check for other things.
        /// </remarks>
        private TreeNodeCollection GetTreeNodesInternal(string id, FormDataCollection queryStrings)
        {
            IUmbracoEntity current = GetEntityFromId(id);

            //before we get the children we need to see if this is a container node

            //test if the parent is a listview / container
            if (current != null && current.IsContainer())
            {
                //no children!
                return new TreeNodeCollection();
            }

            return PerformGetTreeNodes(id, queryStrings);
        }

        /// <summary>
        /// Checks if the menu requested is for the recycle bin and renders that, otherwise renders the result of PerformGetMenuForNode
        /// </summary>
        /// <param name="id"></param>
        /// <param name="queryStrings"></param>
        /// <returns></returns>
        protected sealed override MenuItemCollection GetMenuForNode(string id, FormDataCollection queryStrings)
        {
            if (RecycleBinId.ToInvariantString() == id)
            {
                var menu = new MenuItemCollection();
                menu.Items.Add<ActionEmptyTranscan>(ui.Text("actions", "emptyTrashcan"));
                menu.Items.Add<ActionRefresh>(ui.Text("actions", ActionRefresh.Instance.Alias), true);
                return menu;
            }
            return PerformGetMenuForNode(id, queryStrings);
        }

        /// <summary>
        /// Based on the allowed actions, this will filter the ones that the current user is allowed
        /// </summary>
        /// <param name="menuWithAllItems"></param>
        /// <param name="userAllowedMenuItems"></param>
        /// <returns></returns>
        protected void FilterUserAllowedMenuItems(MenuItemCollection menuWithAllItems, IEnumerable<MenuItem> userAllowedMenuItems)
        {
            var userAllowedActions = userAllowedMenuItems.Where(x => x.Action != null).Select(x => x.Action).ToArray();

            var notAllowed = menuWithAllItems.Items.Where(
                a => (a.Action != null
                      && a.Action.CanBePermissionAssigned
                      && (a.Action.CanBePermissionAssigned == false || userAllowedActions.Contains(a.Action) == false)))
                                             .ToArray();

            //remove the ones that aren't allowed.
            foreach (var m in notAllowed)
            {
                menuWithAllItems.Items.Remove(m);
            }
        }

        internal IEnumerable<MenuItem> GetAllowedUserMenuItemsForNode(IUmbracoEntity dd)
        {
            var actions = global::umbraco.BusinessLogic.Actions.Action.FromString(UmbracoUser.GetPermissions(dd.Path));

            // A user is allowed to delete their own stuff
            if (dd.CreatorId == UmbracoUser.Id && actions.Contains(ActionDelete.Instance) == false)
                actions.Add(ActionDelete.Instance);

            return actions.Select(x => new MenuItem(x));
        }

        /// <summary>
        /// Determins if the user has access to view the node/document
        /// </summary>
        /// <param name="doc">The Document to check permissions against</param>
        /// <param name="allowedUserOptions">A list of MenuItems that the user has permissions to execute on the current document</param>
        /// <remarks>By default the user must have Browse permissions to see the node in the Content tree</remarks>
        /// <returns></returns>        
        internal bool CanUserAccessNode(IUmbracoEntity doc, IEnumerable<MenuItem> allowedUserOptions)
        {
            return allowedUserOptions.Select(x => x.Action).OfType<ActionBrowse>().Any();
        }

        /// <summary>
        /// Get an entity via an id that can be either an integer, Guid or UDI
        /// </summary>
        /// <param name="id"></param>
        /// <returns></returns>
        internal IUmbracoEntity GetEntityFromId(string id)
        {
            IUmbracoEntity entity;

            Guid idGuid;
            int idInt;
            Udi idUdi;

            if (Guid.TryParse(id, out idGuid))
            {
                entity = Services.EntityService.GetByKey(idGuid, UmbracoObjectType);
            }
            else if (int.TryParse(id, out idInt))
            {
                entity = Services.EntityService.Get(idInt, UmbracoObjectType);
            }
            else if (Udi.TryParse(id, out idUdi))
            {
                var guidUdi = idUdi as GuidUdi;
                entity = guidUdi != null ? Services.EntityService.GetByKey(guidUdi.Guid, UmbracoObjectType) : null;
            }
            else
            {
                return null;
            }

            return entity;
        }
    }
}