using System;
using System.Collections.Concurrent;
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.Services;
using Umbraco.Core.Logging;
using Umbraco.Core.Models;
using Umbraco.Web.Models.Trees;
using Umbraco.Web.WebApi.Filters;
using System.Globalization;
using Umbraco.Core.Models.Entities;
using Umbraco.Core.Services;
using Umbraco.Web.Actions;
using Umbraco.Web.Composing;


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;
            Guid asGuid = Guid.Empty;
            if (int.TryParse(id, out asInt) == false)
            {
                if (Guid.TryParse(id, out asGuid) == false)
                {
                    throw new HttpResponseException(Request.CreateResponse(HttpStatusCode.NotFound));
                }
            }

            var entity = asGuid == Guid.Empty
                    ? Services.EntityService.Get(asInt, UmbracoObjectType)
                    : Services.EntityService.Get(asGuid, 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

        /// <summary>
        /// Ensure the noAccess metadata is applied for the root node if in dialog mode and the user doesn't have path access to it
        /// </summary>
        /// <param name="queryStrings"></param>
        /// <returns></returns>
        protected override TreeNode CreateRootNode(FormDataCollection queryStrings)
        {
            var node = base.CreateRootNode(queryStrings);

            if (IsDialog(queryStrings) && UserStartNodes.Contains(Constants.System.Root) == false)
            {
                node.AdditionalData["noAccess"] = true;
            }

            return node;
        }

        protected abstract TreeNode GetSingleTreeNode(IEntitySlim entity, string parentId, FormDataCollection queryStrings);

        /// <summary>
        /// Returns a <see cref="TreeNode"/> for the <see cref="IUmbracoEntity"/> and
        /// attaches some meta data to the node if the user doesn't have start node access to it when in dialog mode
        /// </summary>
        /// <param name="e"></param>
        /// <param name="parentId"></param>
        /// <param name="queryStrings"></param>
        /// <returns></returns>
        internal TreeNode GetSingleTreeNodeWithAccessCheck(IEntitySlim e, string parentId, FormDataCollection queryStrings)
        {
            var entityIsAncestorOfStartNodes = Security.CurrentUser.IsInBranchOfStartNode(e, Services.EntityService, RecycleBinId, out var hasPathAccess);
            if (entityIsAncestorOfStartNodes == false)
                return null;

            var treeNode = GetSingleTreeNode(e, parentId, queryStrings);
            if (hasPathAccess == false)
            {
                treeNode.AdditionalData["noAccess"] = true;
            }
            return treeNode;
        }

        /// <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; }

        protected virtual TreeNodeCollection PerformGetTreeNodes(string id, FormDataCollection queryStrings)
        {
            var nodes = new TreeNodeCollection();

            var rootIdString = Constants.System.Root.ToString(CultureInfo.InvariantCulture);
            var hasAccessToRoot = UserStartNodes.Contains(Constants.System.Root);

            var startNodeId = queryStrings.HasKey(TreeQueryStringParameters.StartNodeId)
                ? queryStrings.GetValue<string>(TreeQueryStringParameters.StartNodeId)
                : string.Empty;

            if (string.IsNullOrEmpty(startNodeId) == false && startNodeId != "undefined" && startNodeId != rootIdString)
            {
                // request has been made to render from a specific, non-root, start node
                id = startNodeId;

                // ensure that the user has access to that node, otherwise return the empty tree nodes 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)
                {
                    Logger.Warn<ContentTreeControllerBase>("User {Username} does not have access to node with id {Id}", Security.CurrentUser.Username, id);
                    return nodes;
                }

                // if the tree is rendered...
                // - in a dialog: render only the children of the specific start node, nothing to do
                // - in a section: if the current user's start nodes do not contain the root node, we need
                //   to include these start nodes in the tree too, to provide some context - i.e. change
                //   start node back to root node, and then GetChildEntities method will take care of the rest.
                if (IsDialog(queryStrings) == false && hasAccessToRoot == false)
                    id = rootIdString;
            }

            // get child entities - if id is root, but user's start nodes do not contain the
            // root node, this returns the start nodes instead of root's children
            var entities = GetChildEntities(id, queryStrings).ToList();
            nodes.AddRange(entities.Select(x => GetSingleTreeNodeWithAccessCheck(x, id, queryStrings)).Where(x => x != null));

            // if the user does not have access to the root node, what we have is the start nodes,
            // but to provide some context we also need to add their topmost nodes when they are not
            // topmost nodes themselves (level > 1).
            if (id == rootIdString && hasAccessToRoot == false)
            {
                var topNodeIds = entities.Where(x => x.Level > 1).Select(GetTopNodeId).Where(x => x != 0).Distinct().ToArray();
                if (topNodeIds.Length > 0)
                {
                    var topNodes = Services.EntityService.GetAll(UmbracoObjectType, topNodeIds.ToArray());
                    nodes.AddRange(topNodes.Select(x => GetSingleTreeNodeWithAccessCheck(x, id, queryStrings)).Where(x => x != null));
                }
            }

            return nodes;
        }

        private static readonly char[] Comma = { ',' };

        private int GetTopNodeId(IUmbracoEntity entity)
        {
            int id;
            var parts = entity.Path.Split(Comma, StringSplitOptions.RemoveEmptyEntries);
            return parts.Length >= 2 && int.TryParse(parts[1], out id) ? id : 0;
        }

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

        protected abstract UmbracoObjectTypes UmbracoObjectType { get; }

        protected virtual IEnumerable<IEntitySlim> GetChildEntities(string id, FormDataCollection queryStrings)
        {
            // try to parse id as an integer else use GetEntityFromId
            // which will grok Guids, Udis, etc and let use obtain the id
            if (int.TryParse(id, out var entityId) == false)
            {
                var entity = GetEntityFromId(id);
                if (entity == null)
                    throw new HttpResponseException(HttpStatusCode.NotFound);

                entityId = entity.Id;
            }

            return GetChildrenFromEntityService(entityId);

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

            return result;*/
        }

        /// <summary>
        /// Abstract method to fetch the entities from the entity service
        /// </summary>
        /// <param name="entityId"></param>
        /// <returns></returns>
        internal abstract IEnumerable<IUmbracoEntity> GetChildrenFromEntityService(int entityId);

        /// <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>
        //we should remove this in v8, it's now here for backwards compat only
        protected abstract bool HasPathAccess(string id, FormDataCollection queryStrings);

        /// <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="entity"></param>
        /// <param name="queryStrings"></param>
        /// <returns></returns>
        protected bool HasPathAccess(IUmbracoEntity entity, FormDataCollection queryStrings)
        {
            if (entity == null) return false;
            return Security.CurrentUser.HasPathAccess(entity, Services.EntityService, RecycleBinId);
        }

        /// <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,
                        Services.TextService.Localize("general/recycleBin"),
                        "icon-trash",
                        RecycleBinSmells,
                        queryStrings.GetValue<string>("application") + TreeAlias.EnsureStartsWith('/') + "/recyclebin"));

                }

                return nodes;
            }

            return GetTreeNodesInternal(id, queryStrings);
        }

        /// <summary>
        /// Check to see if we should return children of a container node
        /// </summary>
        /// <param name="e"></param>
        /// <returns></returns>
        /// <remarks>
        /// This is required in case a user has custom start nodes that are children of a list view since in that case we'll need to render the tree node. In normal cases we don't render
        /// children of a list view.
        /// </remarks>
        protected bool ShouldRenderChildrenOfContainer(IEntitySlim e)
        {
            var isContainer = e.IsContainer;

            var renderChildren = e.HasChildren && (isContainer == false);

            //Here we need to figure out if the node is a container and if so check if the user has a custom start node, then check if that start node is a child
            // of this container node. If that is true, the HasChildren must be true so that the tree node still renders even though this current node is a container/list view.
            if (isContainer && UserStartNodes.Length > 0 && UserStartNodes.Contains(Constants.System.Root) == false)
            {                    
                var startNodes = Services.EntityService.GetAll(UmbracoObjectType, UserStartNodes);
                //if any of these start nodes' parent is current, then we need to render children normally so we need to switch some logic and tell
                // the UI that this node does have children and that it isn't a container
                if (startNodes.Any(x => x.ParentId == e.Id))
                {
                    renderChildren = true;
                }
            }

            return renderChildren;
        }

        /// <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)
        {
            var 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 && ShouldRenderChildrenOfContainer(current) == false)
            {
                //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(new MenuItem("emptyRecycleBin", Services.TextService)
                {
                    Icon = "trash",
                    OpensDialog = true
                });
                menu.Items.Add(new RefreshNode(Services.TextService, 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 permission = Services.UserService.GetPermissions(Security.CurrentUser, dd.Path);
            //fixme: inject
            var actions = Current.Actions.FromEntityPermission(permission)
                .ToList();

            var actionDelete = Current.Actions.GetAction<ActionDelete>();

            // A user is allowed to delete their own stuff
            var tryGetCurrentUserId = Security.GetUserId();
            if (tryGetCurrentUserId && dd.CreatorId == tryGetCurrentUserId.Result && actions.Contains(actionDelete) == false)
                actions.Add(actionDelete);

            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, string culture)
        {
            //TODO: At some stage when we implement permissions on languages we'll need to take care of culture
            return allowedUserOptions.Select(x => x.Action).OfType<ActionBrowse>().Any();
        }


        /// <summary>
        /// this will parse the string into either a GUID or INT
        /// </summary>
        /// <param name="id"></param>
        /// <returns></returns>
        internal Tuple<Guid?, int?> GetIdentifierFromString(string id)
        {
            Guid idGuid;
            int idInt;
            Udi idUdi;

            if (Guid.TryParse(id, out idGuid))
            {
                return new Tuple<Guid?, int?>(idGuid, null);
            }
            if (int.TryParse(id, out idInt))
            {
                return new Tuple<Guid?, int?>(null, idInt);
            }
            if (Udi.TryParse(id, out idUdi))
            {
                var guidUdi = idUdi as GuidUdi;
                if (guidUdi != null)
                    return new Tuple<Guid?, int?>(guidUdi.Guid, null);
            }

            return null;
        }

        /// <summary>
        /// Get an entity via an id that can be either an integer, Guid or UDI
        /// </summary>
        /// <param name="id"></param>
        /// <returns></returns>
        /// <remarks>
        /// This object has it's own contextual cache for these lookups
        /// </remarks>
        internal IEntitySlim GetEntityFromId(string id)
        {
            return _entityCache.GetOrAdd(id, s =>
            {
                IEntitySlim entity;

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

                return entity;
            });
        }

        private readonly ConcurrentDictionary<string, IEntitySlim> _entityCache = new ConcurrentDictionary<string, IEntitySlim>();
    }
}