using System.Collections.Generic;
using System.Collections;
using System;

namespace JungleDB {
	public class DefaultTransactionManager : TransactionManager {
		private AtomicReference<TreeContext> repository;
		private TreeContext tip;
		private ChangeListWriter writer;
		private string uuid;


		public DefaultTransactionManager(ChangeListWriter _writer, TreeContext _tip, AtomicReference<TreeContext> _repository, string _uuid) {
			repository = _repository;
			tip = _tip;
			writer = _writer;
			uuid = _uuid;
		}

		public Either<Error, TransactionManager> commit(TreeNode newRoot, TreeOperationLog _log) {
			long currentRevision = tip.getRevision();
			long nextRevision = currentRevision + 1;

			string _treeName = tip.getTreeName();
			// 通信時に必要?
			ChangeList list = new InnerChangeList(_log, _treeName, uuid);

			InterfaceTraverser traverser = new InterfaceTraverser(newRoot, true);
			// traverser.createIndex();
			TreeContext newTreeContext = new DefaultTreeContext(newRoot , tip, list, uuid, _treeName, nextRevision,traverser);
			// compare and setがどういう役割か?Javaで
			if  (repository.CompareAndSet(newTreeContext, newTreeContext.prev())) { // CompareAndSetが成功した場合に処理を実行
				TransactionManager txManager = new DefaultTransactionManager(writer, newTreeContext, repository, uuid);
				return DefaultEither<Error, TransactionManager>.newB(txManager);
			}

			return DefaultEither<Error, TransactionManager>.newA((Error) new DefaultError());
		}

		public Either<Error, TransactionManager> firstcommit(TreeNode _newRoot, TreeOperationLog _log) {
			return commit(_newRoot,_log);
		}

		public string getUUID() {
			return uuid;
		}

		public long getRevision() {
			return tip.getRevision();
		}

		public class InnerChangeList : ChangeList{

			TreeOperationLog log;
			string treeName;
			string uuid;


			IEnumerator IEnumerable.GetEnumerator()
			{
				// call the generic version of the method
				return this.GetEnumerator();
			}

			public IEnumerator<TreeOperation> GetEnumerator()
			{
				return iterator ();
			}


			public InnerChangeList(TreeOperationLog _log, string _treeName, string _uuid){
				this.log = _log;
				this.treeName = _treeName;
				this.uuid = _uuid;
			}

			public IEnumerator<TreeOperation> iterator() {
				return log.GetEnumerator();
			}

			public string getTreeName() {
				return treeName;
			}

			public TreeOperationLog getLog() {
				return log;
			}

			public string uuids() {
				return uuid;
			}
		}
	}
}