using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using ln.objects.catalog;

namespace ln.types.odb.ng.diff
{
    public class ListDiff : Diff
    {
        List<ODBValue> remove = new List<ODBValue>();
        List<ODBEntity> add = new List<ODBEntity>();
        Dictionary<ODBValue, Diff> update = new Dictionary<ODBValue, Diff>();

        public ListDiff(ODBList src,ODBList dst)
        {
            HashSet<ODBEntity> srcItems = new HashSet<ODBEntity>(src);
            HashSet<ODBEntity> common = new HashSet<ODBEntity>(srcItems);
            HashSet<ODBEntity> dstItems = new HashSet<ODBEntity>(dst);
            HashSet<ODBEntity> commonDst = new HashSet<ODBEntity>(dstItems);

            common.IntersectWith(dstItems);
            commonDst.IntersectWith(srcItems);

            srcItems.ExceptWith(common);
            dstItems.ExceptWith(common);

            remove.AddRange(srcItems.Select((i) => i.Identity));
            add.AddRange(dstItems);

            Dictionary<ODBValue, ODBEntity> srcLookup = new Dictionary<ODBValue, ODBEntity>();
            foreach (ODBEntity entity in common)
                srcLookup.Add(entity.Identity, entity);

            foreach (ODBEntity entity in commonDst)
            {
                ODBValue identity = entity.Identity;
                ODBEntity srcEntity = srcLookup[identity];

                if (entity.CompareTo(srcEntity) != 0)
                    update.Add(identity, Diff.Construct(srcEntity, entity));
            }
        }

        public override ODBEntity Apply(ODBEntity src)
        {
            ODBList list = src as ODBList;

            foreach (ODBEntity entity in list.ToArray())
            {
                ODBValue identity = entity.Identity;

                if (remove.Contains(identity))
                {
                    list.Remove(entity);
                } else if (update.ContainsKey(identity))
                {
                    update[identity].Apply(entity);
                }
            }

            foreach (ODBEntity entity in add)
            {
                list.Add(entity.Clone());
            }

            return src;
        }

        public override string ToString()
        {
            return base.ToString();
        }

        public override string ToTreeString(int indent)
        {
            indent += 2;
            StringBuilder stringBuilder = new StringBuilder();

            stringBuilder.AppendFormat("ListDiff Remove={0} Change={1} Add={2}",remove.Count,update.Count,add.Count);
            foreach (ODBEntity key in remove)
            {
                stringBuilder.AppendLine();
                stringBuilder.AppendFormat("{0}-{1}", new string(' ', indent), key);
            }
            foreach (ODBValue key in update.Keys)
            {
                stringBuilder.AppendLine();
                stringBuilder.AppendFormat("{0} {1} {2}", new string(' ', indent), key, update[key].ToTreeString(indent));
            }
            foreach (ODBEntity key in add)
            {
                stringBuilder.AppendLine();
                stringBuilder.AppendFormat("{0}+{1}", new string(' ', indent), key.ToTreeString(indent));
            }

            return stringBuilder.ToString();

        }

    }
}