/*
 * Copyright 2004, 2005, 2006 Acegi Technology Pty Limited
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.springframework.security.acls.jdbc;

import java.sql.PreparedStatement;
import java.sql.SQLException;
import java.util.List;

import javax.sql.DataSource;

import org.springframework.dao.DataAccessException;
import org.springframework.jdbc.core.BatchPreparedStatementSetter;
import org.springframework.security.acls.domain.AccessControlEntryImpl;
import org.springframework.security.acls.domain.GrantedAuthoritySid;
import org.springframework.security.acls.domain.ObjectIdentityImpl;
import org.springframework.security.acls.domain.PrincipalSid;
import org.springframework.security.acls.model.AccessControlEntry;
import org.springframework.security.acls.model.Acl;
import org.springframework.security.acls.model.AclCache;
import org.springframework.security.acls.model.AlreadyExistsException;
import org.springframework.security.acls.model.ChildrenExistException;
import org.springframework.security.acls.model.MutableAcl;
import org.springframework.security.acls.model.MutableAclService;
import org.springframework.security.acls.model.NotFoundException;
import org.springframework.security.acls.model.ObjectIdentity;
import org.springframework.security.acls.model.Sid;
import org.springframework.security.core.Authentication;
import org.springframework.security.core.context.SecurityContextHolder;
import org.springframework.transaction.support.TransactionSynchronizationManager;
import org.springframework.util.Assert;

/**
 * Provides a base JDBC implementation of {@link MutableAclService}.
 * <p>
 * The default settings are for HSQLDB. If you are using a different database you will
 * probably need to set the {@link #setSidIdentityQuery(String) sidIdentityQuery} and
 * {@link #setClassIdentityQuery(String) classIdentityQuery} properties appropriately. The
 * other queries, SQL inserts and updates can also be customized to accomodate schema
 * variations, but must produce results consistent with those expected by the defaults.
 * <p>
 * See the appendix of the Spring Security reference manual for more information on the
 * expected schema and how it is used. Information on using PostgreSQL is also included.
 *
 * @author Ben Alex
 * @author Johannes Zlattinger
 */
public class JdbcMutableAclService extends JdbcAclService implements MutableAclService {
	// ~ Instance fields
	// ================================================================================================

	private boolean foreignKeysInDatabase = true;
	private final AclCache aclCache;
	private String deleteEntryByObjectIdentityForeignKey = "delete from acl_entry where acl_object_identity=?";
	private String deleteObjectIdentityByPrimaryKey = "delete from acl_object_identity where id=?";
	private String classIdentityQuery = "call identity()";
	private String sidIdentityQuery = "call identity()";
	private String insertClass = "insert into acl_class (class) values (?)";
	private String insertEntry = "insert into acl_entry "
			+ "(acl_object_identity, ace_order, sid, mask, granting, audit_success, audit_failure)"
			+ "values (?, ?, ?, ?, ?, ?, ?)";
	private String insertObjectIdentity = "insert into acl_object_identity "
			+ "(object_id_class, object_id_identity, owner_sid, entries_inheriting) "
			+ "values (?, ?, ?, ?)";
	private String insertSid = "insert into acl_sid (principal, sid) values (?, ?)";
	private String selectClassPrimaryKey = "select id from acl_class where class=?";
	private String selectObjectIdentityPrimaryKey = "select acl_object_identity.id from acl_object_identity, acl_class "
			+ "where acl_object_identity.object_id_class = acl_class.id and acl_class.class=? "
			+ "and acl_object_identity.object_id_identity = ?";
	private String selectSidPrimaryKey = "select id from acl_sid where principal=? and sid=?";
	private String updateObjectIdentity = "update acl_object_identity set "
			+ "parent_object = ?, owner_sid = ?, entries_inheriting = ?"
			+ " where id = ?";

	// ~ Constructors
	// ===================================================================================================

	public JdbcMutableAclService(DataSource dataSource, LookupStrategy lookupStrategy,
			AclCache aclCache) {
		super(dataSource, lookupStrategy);
		Assert.notNull(aclCache, "AclCache required");
		this.aclCache = aclCache;
	}

	// ~ Methods
	// ========================================================================================================

	public MutableAcl createAcl(ObjectIdentity objectIdentity)
			throws AlreadyExistsException {
		Assert.notNull(objectIdentity, "Object Identity required");

		// Check this object identity hasn't already been persisted
		if (retrieveObjectIdentityPrimaryKey(objectIdentity) != null) {
			throw new AlreadyExistsException("Object identity '" + objectIdentity
					+ "' already exists");
		}

		// Need to retrieve the current principal, in order to know who "owns" this ACL
		// (can be changed later on)
		Authentication auth = SecurityContextHolder.getContext().getAuthentication();
		PrincipalSid sid = new PrincipalSid(auth);

		// Create the acl_object_identity row
		createObjectIdentity(objectIdentity, sid);

		// Retrieve the ACL via superclass (ensures cache registration, proper retrieval
		// etc)
		Acl acl = readAclById(objectIdentity);
		Assert.isInstanceOf(MutableAcl.class, acl, "MutableAcl should be been returned");

		return (MutableAcl) acl;
	}

	/**
	 * Creates a new row in acl_entry for every ACE defined in the passed MutableAcl
	 * object.
	 *
	 * @param acl containing the ACEs to insert
	 */
	protected void createEntries(final MutableAcl acl) {
		if (acl.getEntries().isEmpty()) {
			return;
		}
		jdbcTemplate.batchUpdate(insertEntry, new BatchPreparedStatementSetter() {
			public int getBatchSize() {
				return acl.getEntries().size();
			}

			public void setValues(PreparedStatement stmt, int i) throws SQLException {
				AccessControlEntry entry_ = acl.getEntries().get(i);
				Assert.isTrue(entry_ instanceof AccessControlEntryImpl,
						"Unknown ACE class");
				AccessControlEntryImpl entry = (AccessControlEntryImpl) entry_;

				stmt.setLong(1, ((Long) acl.getId()).longValue());
				stmt.setInt(2, i);
				stmt.setLong(3, createOrRetrieveSidPrimaryKey(entry.getSid(), true)
						.longValue());
				stmt.setInt(4, entry.getPermission().getMask());
				stmt.setBoolean(5, entry.isGranting());
				stmt.setBoolean(6, entry.isAuditSuccess());
				stmt.setBoolean(7, entry.isAuditFailure());
			}
		});
	}

	/**
	 * Creates an entry in the acl_object_identity table for the passed ObjectIdentity.
	 * The Sid is also necessary, as acl_object_identity has defined the sid column as
	 * non-null.
	 *
	 * @param object to represent an acl_object_identity for
	 * @param owner for the SID column (will be created if there is no acl_sid entry for
	 * this particular Sid already)
	 */
	protected void createObjectIdentity(ObjectIdentity object, Sid owner) {
		Long sidId = createOrRetrieveSidPrimaryKey(owner, true);
		Long classId = createOrRetrieveClassPrimaryKey(object.getType(), true);
		jdbcTemplate.update(insertObjectIdentity, classId, object.getIdentifier(), sidId,
				Boolean.TRUE);
	}

	/**
	 * Retrieves the primary key from {@code acl_class}, creating a new row if needed and
	 * the {@code allowCreate} property is {@code true}.
	 *
	 * @param type to find or create an entry for (often the fully-qualified class name)
	 * @param allowCreate true if creation is permitted if not found
	 *
	 * @return the primary key or null if not found
	 */
	protected Long createOrRetrieveClassPrimaryKey(String type, boolean allowCreate) {
		List<Long> classIds = jdbcTemplate.queryForList(selectClassPrimaryKey,
				new Object[] { type }, Long.class);

		if (!classIds.isEmpty()) {
			return classIds.get(0);
		}

		if (allowCreate) {
			jdbcTemplate.update(insertClass, type);
			Assert.isTrue(TransactionSynchronizationManager.isSynchronizationActive(),
					"Transaction must be running");
			return jdbcTemplate.queryForObject(classIdentityQuery, Long.class);
		}

		return null;
	}

	/**
	 * Retrieves the primary key from acl_sid, creating a new row if needed and the
	 * allowCreate property is true.
	 *
	 * @param sid to find or create
	 * @param allowCreate true if creation is permitted if not found
	 *
	 * @return the primary key or null if not found
	 *
	 * @throws IllegalArgumentException if the <tt>Sid</tt> is not a recognized
	 * implementation.
	 */
	protected Long createOrRetrieveSidPrimaryKey(Sid sid, boolean allowCreate) {
		Assert.notNull(sid, "Sid required");

		String sidName;
		boolean sidIsPrincipal = true;

		if (sid instanceof PrincipalSid) {
			sidName = ((PrincipalSid) sid).getPrincipal();
		}
		else if (sid instanceof GrantedAuthoritySid) {
			sidName = ((GrantedAuthoritySid) sid).getGrantedAuthority();
			sidIsPrincipal = false;
		}
		else {
			throw new IllegalArgumentException("Unsupported implementation of Sid");
		}

		return createOrRetrieveSidPrimaryKey(sidName, sidIsPrincipal, allowCreate);
	}

	/**
	 * Retrieves the primary key from acl_sid, creating a new row if needed and the
	 * allowCreate property is true.
	 * @param sidName name of Sid to find or to create
	 * @param sidIsPrincipal whether it's a user or granted authority like role
	 * @param allowCreate true if creation is permitted if not found
	 * @return the primary key or null if not found
	 */
	protected Long createOrRetrieveSidPrimaryKey(String sidName, boolean sidIsPrincipal,
			boolean allowCreate) {

		List<Long> sidIds = jdbcTemplate.queryForList(selectSidPrimaryKey, new Object[] {
				Boolean.valueOf(sidIsPrincipal), sidName }, Long.class);

		if (!sidIds.isEmpty()) {
			return sidIds.get(0);
		}

		if (allowCreate) {
			jdbcTemplate.update(insertSid, Boolean.valueOf(sidIsPrincipal), sidName);
			Assert.isTrue(TransactionSynchronizationManager.isSynchronizationActive(),
					"Transaction must be running");
			return jdbcTemplate.queryForObject(sidIdentityQuery, Long.class);
		}

		return null;
	}

	public void deleteAcl(ObjectIdentity objectIdentity, boolean deleteChildren)
			throws ChildrenExistException {
		Assert.notNull(objectIdentity, "Object Identity required");
		Assert.notNull(objectIdentity.getIdentifier(),
				"Object Identity doesn't provide an identifier");

		if (deleteChildren) {
			List<ObjectIdentity> children = findChildren(objectIdentity);
			if (children != null) {
				for (ObjectIdentity child : children) {
					deleteAcl(child, true);
				}
			}
		}
		else {
			if (!foreignKeysInDatabase) {
				// We need to perform a manual verification for what a FK would normally
				// do
				// We generally don't do this, in the interests of deadlock management
				List<ObjectIdentity> children = findChildren(objectIdentity);
				if (children != null) {
					throw new ChildrenExistException("Cannot delete '" + objectIdentity
							+ "' (has " + children.size() + " children)");
				}
			}
		}

		Long oidPrimaryKey = retrieveObjectIdentityPrimaryKey(objectIdentity);

		// Delete this ACL's ACEs in the acl_entry table
		deleteEntries(oidPrimaryKey);

		// Delete this ACL's acl_object_identity row
		deleteObjectIdentity(oidPrimaryKey);

		// Clear the cache
		aclCache.evictFromCache(objectIdentity);
	}

	/**
	 * Deletes all ACEs defined in the acl_entry table belonging to the presented
	 * ObjectIdentity primary key.
	 *
	 * @param oidPrimaryKey the rows in acl_entry to delete
	 */
	protected void deleteEntries(Long oidPrimaryKey) {
		jdbcTemplate.update(deleteEntryByObjectIdentityForeignKey, oidPrimaryKey);
	}

	/**
	 * Deletes a single row from acl_object_identity that is associated with the presented
	 * ObjectIdentity primary key.
	 * <p>
	 * We do not delete any entries from acl_class, even if no classes are using that
	 * class any longer. This is a deadlock avoidance approach.
	 *
	 * @param oidPrimaryKey to delete the acl_object_identity
	 */
	protected void deleteObjectIdentity(Long oidPrimaryKey) {
		// Delete the acl_object_identity row
		jdbcTemplate.update(deleteObjectIdentityByPrimaryKey, oidPrimaryKey);
	}

	/**
	 * Retrieves the primary key from the acl_object_identity table for the passed
	 * ObjectIdentity. Unlike some other methods in this implementation, this method will
	 * NOT create a row (use {@link #createObjectIdentity(ObjectIdentity, Sid)} instead).
	 *
	 * @param oid to find
	 *
	 * @return the object identity or null if not found
	 */
	protected Long retrieveObjectIdentityPrimaryKey(ObjectIdentity oid) {
		try {
			return jdbcTemplate.queryForObject(selectObjectIdentityPrimaryKey, Long.class,
					oid.getType(), oid.getIdentifier());
		}
		catch (DataAccessException notFound) {
			return null;
		}
	}

	/**
	 * This implementation will simply delete all ACEs in the database and recreate them
	 * on each invocation of this method. A more comprehensive implementation might use
	 * dirty state checking, or more likely use ORM capabilities for create, update and
	 * delete operations of {@link MutableAcl}.
	 */
	public MutableAcl updateAcl(MutableAcl acl) throws NotFoundException {
		Assert.notNull(acl.getId(), "Object Identity doesn't provide an identifier");

		// Delete this ACL's ACEs in the acl_entry table
		deleteEntries(retrieveObjectIdentityPrimaryKey(acl.getObjectIdentity()));

		// Create this ACL's ACEs in the acl_entry table
		createEntries(acl);

		// Change the mutable columns in acl_object_identity
		updateObjectIdentity(acl);

		// Clear the cache, including children
		clearCacheIncludingChildren(acl.getObjectIdentity());

		// Retrieve the ACL via superclass (ensures cache registration, proper retrieval
		// etc)
		return (MutableAcl) super.readAclById(acl.getObjectIdentity());
	}

	private void clearCacheIncludingChildren(ObjectIdentity objectIdentity) {
		Assert.notNull(objectIdentity, "ObjectIdentity required");
		List<ObjectIdentity> children = findChildren(objectIdentity);
		if (children != null) {
			for (ObjectIdentity child : children) {
				clearCacheIncludingChildren(child);
			}
		}
		aclCache.evictFromCache(objectIdentity);
	}

	/**
	 * Updates an existing acl_object_identity row, with new information presented in the
	 * passed MutableAcl object. Also will create an acl_sid entry if needed for the Sid
	 * that owns the MutableAcl.
	 *
	 * @param acl to modify (a row must already exist in acl_object_identity)
	 *
	 * @throws NotFoundException if the ACL could not be found to update.
	 */
	protected void updateObjectIdentity(MutableAcl acl) {
		Long parentId = null;

		if (acl.getParentAcl() != null) {
			Assert.isInstanceOf(ObjectIdentityImpl.class, acl.getParentAcl()
					.getObjectIdentity(),
					"Implementation only supports ObjectIdentityImpl");

			ObjectIdentityImpl oii = (ObjectIdentityImpl) acl.getParentAcl()
					.getObjectIdentity();
			parentId = retrieveObjectIdentityPrimaryKey(oii);
		}

		Assert.notNull(acl.getOwner(), "Owner is required in this implementation");

		Long ownerSid = createOrRetrieveSidPrimaryKey(acl.getOwner(), true);
		int count = jdbcTemplate.update(updateObjectIdentity, parentId, ownerSid,
				Boolean.valueOf(acl.isEntriesInheriting()), acl.getId());

		if (count != 1) {
			throw new NotFoundException("Unable to locate ACL to update");
		}
	}

	/**
	 * Sets the query that will be used to retrieve the identity of a newly created row in
	 * the <tt>acl_class</tt> table.
	 *
	 * @param classIdentityQuery the query, which should return the identifier. Defaults
	 * to <tt>call identity()</tt>
	 */
	public void setClassIdentityQuery(String classIdentityQuery) {
		Assert.hasText(classIdentityQuery, "New classIdentityQuery query is required");
		this.classIdentityQuery = classIdentityQuery;
	}

	/**
	 * Sets the query that will be used to retrieve the identity of a newly created row in
	 * the <tt>acl_sid</tt> table.
	 *
	 * @param sidIdentityQuery the query, which should return the identifier. Defaults to
	 * <tt>call identity()</tt>
	 */
	public void setSidIdentityQuery(String sidIdentityQuery) {
		Assert.hasText(sidIdentityQuery, "New sidIdentityQuery query is required");
		this.sidIdentityQuery = sidIdentityQuery;
	}

	public void setDeleteEntryByObjectIdentityForeignKeySql(
			String deleteEntryByObjectIdentityForeignKey) {
		this.deleteEntryByObjectIdentityForeignKey = deleteEntryByObjectIdentityForeignKey;
	}

	public void setDeleteObjectIdentityByPrimaryKeySql(
			String deleteObjectIdentityByPrimaryKey) {
		this.deleteObjectIdentityByPrimaryKey = deleteObjectIdentityByPrimaryKey;
	}

	public void setInsertClassSql(String insertClass) {
		this.insertClass = insertClass;
	}

	public void setInsertEntrySql(String insertEntry) {
		this.insertEntry = insertEntry;
	}

	public void setInsertObjectIdentitySql(String insertObjectIdentity) {
		this.insertObjectIdentity = insertObjectIdentity;
	}

	public void setInsertSidSql(String insertSid) {
		this.insertSid = insertSid;
	}

	public void setClassPrimaryKeyQuery(String selectClassPrimaryKey) {
		this.selectClassPrimaryKey = selectClassPrimaryKey;
	}

	public void setObjectIdentityPrimaryKeyQuery(String selectObjectIdentityPrimaryKey) {
		this.selectObjectIdentityPrimaryKey = selectObjectIdentityPrimaryKey;
	}

	public void setSidPrimaryKeyQuery(String selectSidPrimaryKey) {
		this.selectSidPrimaryKey = selectSidPrimaryKey;
	}

	public void setUpdateObjectIdentity(String updateObjectIdentity) {
		this.updateObjectIdentity = updateObjectIdentity;
	}

	/**
	 * @param foreignKeysInDatabase if false this class will perform additional FK
	 * constrain checking, which may cause deadlocks (the default is true, so deadlocks
	 * are avoided but the database is expected to enforce FKs)
	 */
	public void setForeignKeysInDatabase(boolean foreignKeysInDatabase) {
		this.foreignKeysInDatabase = foreignKeysInDatabase;
	}
}
