package jef.database;

import java.sql.PreparedStatement;
import java.sql.SQLException;
import java.util.ArrayList;
import java.util.List;
import java.util.concurrent.atomic.AtomicInteger;

import jef.database.dialect.DatabaseDialect;
import jef.database.query.JoinElement;
import jef.database.query.SqlContext;
import jef.database.routing.PartitionResult;
import jef.database.support.SqlLog;
import jef.database.wrapper.clause.BindSql;
import jef.database.wrapper.executor.DbTask;
import jef.database.wrapper.variable.BindVariableContext;

/**
 * 基本数据库操作
 * 
 * @author jiyi
 * 
 */
public abstract class DeleteProcessor {
	abstract int processDelete0(OperateTarget db, IQueryableEntity obj, BindSql where, PartitionResult site, SqlLog sb) throws SQLException;

	abstract BindSql toWhereClause(JoinElement joinElement, SqlContext context, DatabaseDialect profile);

	static DeleteProcessor get(DatabaseDialect profile, DbClient parent) {
		return new PreparedImpl(parent.preProcessor);
	}

	final int processDelete(Session session, final IQueryableEntity obj, final BindSql where, PartitionResult[] sites, long parseCost) throws SQLException {
		long parse = System.currentTimeMillis();
		final SqlLog log = ORMConfig.getInstance().newLogger();
		int total = 0;
		String dbname = null;
		if (sites.length >= ORMConfig.getInstance().getParallelSelect()) {
			List<DbTask> tasks = new ArrayList<DbTask>();
			final AtomicInteger count = new AtomicInteger();
			for (final PartitionResult site : sites) {
				final OperateTarget target = session.selectTarget(site.getDatabase());
				dbname = target.getTransactionId();
				tasks.add(new DbTask() {
					@Override
					public void execute() throws SQLException {
						count.addAndGet(processDelete0(target, obj, where, site, log));
					}
				});
			}
			DbUtils.parallelExecute(tasks);
			total = count.get();
		} else {
			for (PartitionResult site : sites) {
				OperateTarget target = session.selectTarget(site.getDatabase());
				dbname = target.getTransactionId();
				total += processDelete0(target, obj, where, site, log);
			}
		}
		log.append("Deleted:", total).append("\t Time cost([ParseSQL]:", parse - parseCost).append("ms, [DbAccess]:", System.currentTimeMillis() - parse).append("ms) |", dbname);
		log.output();
		return total;
	}

	private static final class PreparedImpl extends DeleteProcessor {
		private SqlProcessor parent;

		public PreparedImpl(SqlProcessor parent) {
			this.parent = parent;
		}

		int processDelete0(OperateTarget db, IQueryableEntity obj, BindSql where, PartitionResult site, SqlLog sb) throws SQLException {
			int count = 0;
			for (String tablename : site.getTables()) {
				String sql = "delete from " + DbUtils.escapeColumn(db.getProfile(), tablename) + where.getSql();
				sb.ensureCapacity(sql.length() + 150);
				sb.append(sql).append(db);

				PreparedStatement psmt = null;
				try {
					psmt = db.prepareStatement(sql);
					int deleteTimeout = ORMConfig.getInstance().getDeleteTimeout();
					if (deleteTimeout > 0) {
						psmt.setQueryTimeout(deleteTimeout);
					}
					BindVariableContext context = new BindVariableContext(psmt, db.getProfile(), sb);
					context.setVariables(obj.getQuery(), null, where.getBind());
					psmt.execute();
					count += psmt.getUpdateCount();
				} catch (SQLException e) {
					DbUtils.processError(e, tablename, db);
					db.releaseConnection();// 如果在处理过程中发现异常，方法即中断，就要释放连接，这样就不用在外面再套一层finally
					throw e;
				} catch (RuntimeException e) {
					db.releaseConnection();// 如果在处理过程中发现异常，方法即中断，就要释放连接，这样就不用在外面再套一层finally
				} finally {
					sb.output();
					if (psmt != null)
						psmt.close();
				}
			}
			db.releaseConnection();
			return count;
		}

		@Override
		BindSql toWhereClause(JoinElement joinElement, SqlContext context, DatabaseDialect profile) {
			return parent.toWhereClause(joinElement, context, null, profile,false);
		}
	}
}