using System;
using System.Collections.Generic;
using System.Linq;
using Microsoft.Extensions.Logging;
using NPoco;
using Umbraco.Core.Cache;
using Umbraco.Core.Models;
using Umbraco.Core.Models.Entities;
using Umbraco.Core.Persistence.Dtos;
using Umbraco.Core.Persistence.Factories;
using Umbraco.Core.Persistence.Querying;
using Umbraco.Core.Persistence.SqlSyntax;
using Umbraco.Core.Scoping;
using Umbraco.Core.Services;
using static Umbraco.Core.Persistence.SqlExtensionsStatics;

namespace Umbraco.Core.Persistence.Repositories.Implement
{
    /// <summary>
    /// Represents a repository for doing CRUD operations for <see cref="Relation"/>
    /// </summary>
    internal class RelationRepository : NPocoRepositoryBase<int, IRelation>, IRelationRepository
    {
        private readonly IRelationTypeRepository _relationTypeRepository;
        private readonly IEntityRepository _entityRepository;

        public RelationRepository(IScopeAccessor scopeAccessor, ILogger<RelationRepository> logger, IRelationTypeRepository relationTypeRepository, IEntityRepository entityRepository)
            : base(scopeAccessor, AppCaches.NoCache, logger)
        {
            _relationTypeRepository = relationTypeRepository;
            _entityRepository = entityRepository;
        }

        #region Overrides of RepositoryBase<int,Relation>

        protected override IRelation PerformGet(int id)
        {
            var sql = GetBaseQuery(false);
            sql.Where(GetBaseWhereClause(), new { id });

            var dto = Database.Fetch<RelationDto>(SqlSyntax.SelectTop(sql, 1)).FirstOrDefault();
            if (dto == null)
                return null;

            var relationType = _relationTypeRepository.Get(dto.RelationType);
            if (relationType == null)
                throw new InvalidOperationException(string.Format("RelationType with Id: {0} doesn't exist", dto.RelationType));

            return DtoToEntity(dto, relationType);
        }

        protected override IEnumerable<IRelation> PerformGetAll(params int[] ids)
        {
            var sql = GetBaseQuery(false);
            if (ids.Length > 0)
                sql.WhereIn<RelationDto>(x => x.Id, ids);
            sql.OrderBy<RelationDto>(x => x.RelationType);
            var dtos = Database.Fetch<RelationDto>(sql);
            return DtosToEntities(dtos);
        }

        protected override IEnumerable<IRelation> PerformGetByQuery(IQuery<IRelation> query)
        {
            var sqlClause = GetBaseQuery(false);
            var translator = new SqlTranslator<IRelation>(sqlClause, query);
            var sql = translator.Translate();
            sql.OrderBy<RelationDto>(x => x.RelationType);
            var dtos = Database.Fetch<RelationDto>(sql);
            return DtosToEntities(dtos);
        }

        private IEnumerable<IRelation> DtosToEntities(IEnumerable<RelationDto> dtos)
        {
            //NOTE: This is N+1, BUT ALL relation types are cached so shouldn't matter

            return dtos.Select(x => DtoToEntity(x, _relationTypeRepository.Get(x.RelationType))).ToList();
        }

        private static IRelation DtoToEntity(RelationDto dto, IRelationType relationType)
        {
            var entity = RelationFactory.BuildEntity(dto, relationType);

            // reset dirty initial properties (U4-1946)
            entity.ResetDirtyProperties(false);

            return entity;
        }

        #endregion

        #region Overrides of NPocoRepositoryBase<int,Relation>

        protected override Sql<ISqlContext> GetBaseQuery(bool isCount)
        {
            if (isCount)
            {
                return Sql().SelectCount().From<RelationDto>();
            }

            var sql = Sql().Select<RelationDto>()
                .AndSelect<NodeDto>("uchild", x => Alias(x.NodeObjectType, "childObjectType"))
                .AndSelect<NodeDto>("uparent", x => Alias(x.NodeObjectType, "parentObjectType"))
                .From<RelationDto>()
                .InnerJoin<NodeDto>("uchild").On<RelationDto, NodeDto>((rel, node) => rel.ChildId == node.NodeId, aliasRight: "uchild")
                .InnerJoin<NodeDto>("uparent").On<RelationDto, NodeDto>((rel, node) => rel.ParentId == node.NodeId, aliasRight: "uparent");


            return sql;
        }

        protected override string GetBaseWhereClause()
        {
            return "umbracoRelation.id = @id";
        }

        protected override IEnumerable<string> GetDeleteClauses()
        {
            var list = new List<string>
                           {
                               "DELETE FROM umbracoRelation WHERE id = @id"
                           };
            return list;
        }

        protected override Guid NodeObjectTypeId
        {
            get { throw new NotImplementedException(); }
        }

        #endregion

        #region Unit of Work Implementation

        protected override void PersistNewItem(IRelation entity)
        {
            entity.AddingEntity();

            var dto = RelationFactory.BuildDto(entity);

            var id = Convert.ToInt32(Database.Insert(dto));

            entity.Id = id;
            PopulateObjectTypes(entity);

            entity.ResetDirtyProperties();
        }

        protected override void PersistUpdatedItem(IRelation entity)
        {
            entity.UpdatingEntity();

            var dto = RelationFactory.BuildDto(entity);
            Database.Update(dto);

            PopulateObjectTypes(entity);

            entity.ResetDirtyProperties();
        }

        #endregion

        /// <summary>
        /// Used for joining the entity query with relations for the paging methods
        /// </summary>
        /// <param name="sql"></param>
        private void SqlJoinRelations(Sql<ISqlContext> sql)
        {
            // add left joins for relation tables (this joins on both child or parent, so beware that this will normally return entities for
            // both sides of the relation type unless the IUmbracoEntity query passed in filters one side out).
            sql.LeftJoin<RelationDto>().On<NodeDto, RelationDto>((left, right) => left.NodeId == right.ChildId || left.NodeId == right.ParentId);
            sql.LeftJoin<RelationTypeDto>().On<RelationDto, RelationTypeDto>((left, right) => left.RelationType == right.Id);
        }

        public IEnumerable<IUmbracoEntity> GetPagedParentEntitiesByChildId(int childId, long pageIndex, int pageSize, out long totalRecords, params Guid[] entityTypes)
        {
            // var contentObjectTypes = new[] { Constants.ObjectTypes.Document, Constants.ObjectTypes.Media, Constants.ObjectTypes.Member }
            // we could pass in the contentObjectTypes so that the entity repository sql is configured to do full entity lookups so that we get the full data
            // required to populate content, media or members, else we get the bare minimum data needed to populate an entity. BUT if we do this it
            // means that the SQL is less efficient and returns data that is probably not needed for what we need this lookup for. For the time being we
            // will just return the bare minimum entity data.

            return _entityRepository.GetPagedResultsByQuery(Query<IUmbracoEntity>(), entityTypes, pageIndex, pageSize, out totalRecords, null, null, sql =>
            {
                SqlJoinRelations(sql);

                sql.Where<RelationDto>(rel => rel.ChildId == childId);
                sql.Where<RelationDto, NodeDto>((rel, node) => rel.ParentId == childId || node.NodeId != childId);
            });
        }

        public IEnumerable<IUmbracoEntity> GetPagedChildEntitiesByParentId(int parentId, long pageIndex, int pageSize, out long totalRecords, params Guid[] entityTypes)
        {
            // var contentObjectTypes = new[] { Constants.ObjectTypes.Document, Constants.ObjectTypes.Media, Constants.ObjectTypes.Member }
            // we could pass in the contentObjectTypes so that the entity repository sql is configured to do full entity lookups so that we get the full data
            // required to populate content, media or members, else we get the bare minimum data needed to populate an entity. BUT if we do this it
            // means that the SQL is less efficient and returns data that is probably not needed for what we need this lookup for. For the time being we
            // will just return the bare minimum entity data.

            return _entityRepository.GetPagedResultsByQuery(Query<IUmbracoEntity>(), entityTypes, pageIndex, pageSize, out totalRecords, null, null, sql =>
            {
                SqlJoinRelations(sql);

                sql.Where<RelationDto>(rel => rel.ParentId == parentId);
                sql.Where<RelationDto, NodeDto>((rel, node) => rel.ChildId == parentId || node.NodeId != parentId);
            });
        }

        public void Save(IEnumerable<IRelation> relations)
        {
            foreach (var hasIdentityGroup in relations.GroupBy(r => r.HasIdentity))
            {
                if (hasIdentityGroup.Key)
                {
                    // Do updates, we can't really do a bulk update so this is still a 1 by 1 operation
                    // however we can bulk populate the object types. It might be possible to bulk update
                    // with SQL but would be pretty ugly and we're not really too worried about that for perf,
                    // it's the bulk inserts we care about.
                    var asArray = hasIdentityGroup.ToArray();
                    foreach (var relation in hasIdentityGroup)
                    {
                        relation.UpdatingEntity();
                        var dto = RelationFactory.BuildDto(relation);
                        Database.Update(dto);
                    }
                    PopulateObjectTypes(asArray);
                }
                else
                {
                    // Do bulk inserts
                    var entitiesAndDtos = hasIdentityGroup.ToDictionary(
                        r =>                        // key = entity
                        {
                            r.AddingEntity();
                            return r;
                        },
                        RelationFactory.BuildDto);  // value = DTO


                    foreach (var dto in entitiesAndDtos.Values)
                    {
                        Database.Insert(dto);
                    }

                    // All dtos now have IDs assigned
                    foreach (var de in entitiesAndDtos)
                    {
                        // re-assign ID to the entity
                        de.Key.Id = de.Value.Id;
                    }

                    PopulateObjectTypes(entitiesAndDtos.Keys.ToArray());
                }
            }
        }

        public void SaveBulk(IEnumerable<ReadOnlyRelation> relations)
        {
            foreach (var hasIdentityGroup in relations.GroupBy(r => r.HasIdentity))
            {
                if (hasIdentityGroup.Key)
                {
                    // Do updates, we can't really do a bulk update so this is still a 1 by 1 operation
                    // however we can bulk populate the object types. It might be possible to bulk update
                    // with SQL but would be pretty ugly and we're not really too worried about that for perf,
                    // it's the bulk inserts we care about.
                    foreach (var relation in hasIdentityGroup)
                    {
                        var dto = RelationFactory.BuildDto(relation);
                        Database.Update(dto);
                    }
                }
                else
                {
                    // Do bulk inserts
                    var dtos = hasIdentityGroup.Select(RelationFactory.BuildDto);

                    Database.InsertBulk(dtos);

                }
            }
        }

        public IEnumerable<IRelation> GetPagedRelationsByQuery(IQuery<IRelation> query, long pageIndex, int pageSize, out long totalRecords, Ordering ordering)
        {
            var sql = GetBaseQuery(false);

            if (ordering == null || ordering.IsEmpty)
                ordering = Ordering.By(SqlSyntax.GetQuotedColumn(Constants.DatabaseSchema.Tables.Relation, "id"));

            var translator = new SqlTranslator<IRelation>(sql, query);
            sql = translator.Translate();

            // apply ordering
            ApplyOrdering(ref sql, ordering);

            var pageIndexToFetch = pageIndex + 1;
            var page = Database.Page<RelationDto>(pageIndexToFetch, pageSize, sql);
            var dtos = page.Items;
            totalRecords = page.TotalItems;

            var relTypes = _relationTypeRepository.GetMany(dtos.Select(x => x.RelationType).Distinct().ToArray())
                .ToDictionary(x => x.Id, x => x);

            var result = dtos.Select(r =>
            {
                if (!relTypes.TryGetValue(r.RelationType, out var relType))
                    throw new InvalidOperationException(string.Format("RelationType with Id: {0} doesn't exist", r.RelationType));
                return DtoToEntity(r, relType);
            }).ToList();

            return result;
        }


        public void DeleteByParent(int parentId, params string[] relationTypeAliases)
        {
            var subQuery = Sql().Select<RelationDto>(x => x.Id)
                .From<RelationDto>()
                .InnerJoin<RelationTypeDto>().On<RelationDto, RelationTypeDto>(x => x.RelationType, x => x.Id)
                .Where<RelationDto>(x => x.ParentId == parentId);

            if (relationTypeAliases.Length > 0)
            {
                subQuery.WhereIn<RelationTypeDto>(x => x.Alias, relationTypeAliases);
            }

            Database.Execute(Sql().Delete<RelationDto>().WhereIn<RelationDto>(x => x.Id, subQuery));
        }

        /// <summary>
        /// Used to populate the object types after insert/update
        /// </summary>
        /// <param name="entities"></param>
        private void PopulateObjectTypes(params IRelation[] entities)
        {
            var entityIds = entities.Select(x => x.ParentId).Concat(entities.Select(y => y.ChildId)).Distinct();

            var nodes = Database.Fetch<NodeDto>(Sql().Select<NodeDto>().From<NodeDto>()
                    .WhereIn<NodeDto>(x => x.NodeId, entityIds))
                .ToDictionary(x => x.NodeId, x => x.NodeObjectType);

            foreach (var e in entities)
            {
                if (nodes.TryGetValue(e.ParentId, out var parentObjectType))
                {
                    e.ParentObjectType = parentObjectType.GetValueOrDefault();
                }
                if (nodes.TryGetValue(e.ChildId, out var childObjectType))
                {
                    e.ChildObjectType = childObjectType.GetValueOrDefault();
                }
            }
        }

        private void ApplyOrdering(ref Sql<ISqlContext> sql, Ordering ordering)
        {
            if (sql == null) throw new ArgumentNullException(nameof(sql));
            if (ordering == null) throw new ArgumentNullException(nameof(ordering));

            // TODO: although this works for name, it probably doesn't work for others without an alias of some sort
            var orderBy = ordering.OrderBy;

            if (ordering.Direction == Direction.Ascending)
                sql.OrderBy(orderBy);
            else
                sql.OrderByDescending(orderBy);
        }
    }
}