// /**
//  * File: Query.cs
//  * Author: haraldwolff
//  *
//  * This file and it's content is copyrighted by the Author and / or copyright holder.
//  * Any use wihtout proper permission is illegal and may lead to legal actions.
//  *
//  *
//  **/
using System;
using System.Collections.Generic;
using ln.types.btree;
using System.Linq;
using ln.types.odb.ng.index;
using ln.types.odb.ng.storage;
using ln.objects.catalog;

namespace ln.types.odb.ng
{
    public abstract class Query
    {
        private Query()
        {
        }

        public static Query AND(Query query,params Query[] queries)
        {
            return new IMPL.AND(query, queries);
        }
        public static Query OR(Query query, params Query[] queries)
        {
            return new IMPL.OR(query, queries);
        }
        public static Query NOT(Query query)
        {
            return new IMPL.NOT(query);
        }

        public static Query Equals<T>(string propertyName, object value) => Equals(IndexPath.TranslatePropertyPath(typeof(T), propertyName), Mapper.Default.MapValue(value));
        public static Query Equals(String propertyName, ODBEntity value)
        {
            if (object.ReferenceEquals(value,null))
                value = ODBNull.Instance;

            return IF(propertyName, (v) => value.CompareTo(v)==0);
        }
        public static Query EqualsNot<T>(string propertyName, ODBEntity value) => EqualsNot(IndexPath.TranslatePropertyPath(typeof(T), propertyName), value);
        public static Query EqualsNot(String propertyName, ODBEntity value)
        {
            if (object.ReferenceEquals(value, null))
                value = ODBNull.Instance;

            return IF(propertyName, (v) => value.CompareTo(v)!=0);
        }

        public static Query Equals<T>(string propertyName, ODBEntity[] values) => Equals(IndexPath.TranslatePropertyPath(typeof(T), propertyName), values);
        public static Query Equals(String propertyName, ODBEntity[] values)
        {
            return IF(propertyName, (v) => {
				foreach (ODBEntity value in values)
					if (value.CompareTo(v) == 0)
						return true;
				return false;
			});
        }

        public static Query Contains<T, A>(string propertyName, IEnumerable<A> values)
        {
            ODBEntity[] oValues = values.Select(v => Mapper.Default.MapValue(v)).ToArray();
            return IF(IndexPath.TranslatePropertyPath(typeof(T), propertyName), v => oValues.Contains(v));
        }


        public static Query IF<T>(string propertyName, Predicate<ODBEntity> predicate) => IF(IndexPath.TranslatePropertyPath(typeof(T),propertyName), predicate);
        public static Query IF(string propertyName,Predicate<ODBEntity> predicate)
        {
            return new IMPL.IF(propertyName, predicate);
        }

        public abstract IEnumerable<Guid> Execute(IStorage storage);


        class IMPL
        {
            public class IF : Query
            {
                public string PropertyName { get; }
                public Predicate<ODBEntity> Predicate { get; }

                public IF(string propertyName,Predicate<ODBEntity> predicate)
                {
                    PropertyName = propertyName;
                    Predicate = predicate;
                }

                public override IEnumerable<Guid> Execute(IStorage storage)
                {
                    return storage.GetDocumentIDs(PropertyName,Predicate);
                }
            }

            public class AND : Query
            {
                public Query Query { get; }
                public Query[] Queries { get; }

                public AND(Query query, params Query[] queries)
                {
                    Query = query;
                    Queries = queries;
                }

                public override IEnumerable<Guid> Execute(IStorage storage)
                {
                    BTree<Guid> firstSet = new BTree<Guid>();

					firstSet.AddRange(
						Query.Execute(storage)
                    );

                    foreach (Query aQuery in Queries)
                    {
                        if (firstSet.Count == 0)
                            return new Guid[0];

                        BTree<Guid> nextSet = new BTree<Guid>();

                        foreach (Guid documentID in aQuery.Execute(storage))
                        {
                            if (firstSet.ContainsKey(documentID))
                                nextSet.Add(documentID);
                        }

                        firstSet = nextSet;
                    }

                    return firstSet.Keys;
                }
            }

            public class OR : Query
            {
                public Query Query { get; }
                public Query[] Queries { get; }

                public OR(Query query, params Query[] queries)
                {
                    Query = query;
                    Queries = queries;
                }

                public override IEnumerable<Guid> Execute(IStorage storage)
                {
                    BTree<Guid> result = new BTree<Guid>();

                    result.TryAddRange(
                        Query.Execute(storage)
                    );

                    foreach (Query aQuery in Queries)
                    {
                        foreach (Guid documentID in aQuery.Execute(storage))
                            result.TryAdd(documentID);
                    }

                    return result.Keys;
                }
            }
            public class NOT : Query
            {
                public Query Query { get; }

                public NOT(Query query)
                {
                    Query = query;
                }

                public override IEnumerable<Guid> Execute(IStorage storage)
                {
                    BTree<Guid> notSet = new BTree<Guid>();
                    BTree<Guid> result = new BTree<Guid>();

                    notSet.AddRange(Query.Execute(storage));

                    foreach (Guid documentID in storage.GetDocumentIDs())
                    {
                        if (!notSet.ContainsKey(documentID))
                            result.Add(documentID);
                    }

                    return result.Keys;
                }
            }
        }
    }
}