package org.apache.ddlutils.model;

/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you 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.
 */

import java.io.Serializable;
import java.sql.Types;
import java.util.ArrayList;
import java.util.Collection;
import java.util.HashSet;
import java.util.Iterator;

import org.apache.commons.beanutils.DynaBean;
import org.apache.commons.lang.builder.EqualsBuilder;
import org.apache.commons.lang.builder.HashCodeBuilder;
import org.apache.ddlutils.dynabean.DynaClassCache;
import org.apache.ddlutils.dynabean.SqlDynaClass;
import org.apache.ddlutils.dynabean.SqlDynaException;

/**
 * Represents the database model, ie. the tables in the database. It also
 * contains the corresponding dyna classes for creating dyna beans for the
 * objects stored in the tables.
 *
 * @version $Revision: 504014 $
 */
public class Database implements Serializable, Cloneable
{
    /** Unique ID for serialization purposes. */
    private static final long serialVersionUID = -3160443396757573868L;

    /** The name of the database model. */
    private String _name;
    /** The method for generating primary keys (currently ignored). */
    private String _idMethod;
    /** The version of the model. */
    private String _version;
    /** The tables. */
    private ArrayList _tables = new ArrayList();
    /** The dyna class cache for this model. */
    private transient DynaClassCache _dynaClassCache = null;

    /**
     * Adds all tables from the other database to this database.
     * Note that the other database is not changed.
     * 
     * @param otherDb The other database model
     */
    public void mergeWith(Database otherDb) throws ModelException
    {
        for (Iterator it = otherDb._tables.iterator(); it.hasNext();)
        {
            Table table = (Table)it.next();

            if (findTable(table.getName()) != null)
            {
                // TODO: It might make more sense to log a warning and overwrite the table (or merge them) ?
                throw new ModelException("Cannot merge the models because table "+table.getName()+" already defined in this model");
            }
            try
            {
                addTable((Table)table.clone());
            }
            catch (CloneNotSupportedException ex)
            {
                // won't happen
            }
        }
    }

    /**
     * Returns the name of this database model.
     * 
     * @return The name
     */
    public String getName()
    {
        return _name;
    }

    /**
     * Sets the name of this database model.
     * 
     * @param name The name
     */
    public void setName(String name)
    {
        _name = name;
    }

    /**
     * Returns the version of this database model.
     * 
     * @return The version
     */
    public String getVersion()
    {
        return _version;
    }

    /**
     * Sets the version of this database model.
     * 
     * @param version The version
     */
    public void setVersion(String version)
    {
        _version = version;
    }

    /**
     * Returns the method for generating primary key values.
     * 
     * @return The method
     */
    public String getIdMethod()
    {
        return _idMethod;
    }

    /**
     * Sets the method for generating primary key values. Note that this
     * value is ignored by DdlUtils and only for compatibility with Torque.
     * 
     * @param idMethod The method
     */
    public void setIdMethod(String idMethod)
    {
        _idMethod = idMethod;
    }

    /**
     * Returns the number of tables in this model.
     * 
     * @return The number of tables
     */
    public int getTableCount()
    {
        return _tables.size();
    }

    /**
     * Returns the tables in this model.
     * 
     * @return The tables
     */
    public Table[] getTables()
    {
        return (Table[])_tables.toArray(new Table[_tables.size()]);
    }

    /**
     * Returns the table at the specified position.
     * 
     * @param idx The index of the table
     * @return The table
     */
    public Table getTable(int idx)
    {
        return (Table)_tables.get(idx);
    }

    /**
     * Adds a table.
     * 
     * @param table The table to add
     */
    public void addTable(Table table)
    {
        if (table != null)
        {
            _tables.add(table);
        }
    }

    /**
     * Adds a table at the specified position.
     * 
     * @param idx   The index where to insert the table
     * @param table The table to add
     */
    public void addTable(int idx, Table table)
    {
        if (table != null)
        {
            _tables.add(idx, table);
        }
    }

    /**
     * Adds the given tables.
     * 
     * @param tables The tables to add
     */
    public void addTables(Collection tables)
    {
        for (Iterator it = tables.iterator(); it.hasNext();)
        {
            addTable((Table)it.next());
        }
    }

    /**
     * Removes the given table.
     * 
     * @param table The table to remove
     */
    public void removeTable(Table table)
    {
        if (table != null)
        {
            _tables.remove(table);
        }
    }

    /**
     * Removes the indicated table.
     * 
     * @param idx The index of the table to remove
     */
    public void removeTable(int idx)
    {
        _tables.remove(idx);
    }

    // Helper methods

    /**
     * Initializes the model by establishing the relationships between elements in this model encoded
     * eg. in foreign keys etc. Also checks that the model elements are valid (table and columns have
     * a name, foreign keys rference existing tables etc.) 
     */
    public void initialize() throws ModelException
    {
        // we have to setup
        // * target tables in foreign keys
        // * columns in foreign key references
        // * columns in indices
        // * columns in uniques
        HashSet namesOfProcessedTables  = new HashSet();
        HashSet namesOfProcessedColumns = new HashSet();
        HashSet namesOfProcessedFks     = new HashSet();
        HashSet namesOfProcessedIndices = new HashSet();
        int     tableIdx = 0;

        if ((getName() == null) || (getName().length() == 0))
        {
            throw new ModelException("The database model has no name");
        }

        for (Iterator tableIt = _tables.iterator(); tableIt.hasNext(); tableIdx++)
        {
            Table curTable = (Table)tableIt.next();

            if ((curTable.getName() == null) || (curTable.getName().length() == 0))
            {
                throw new ModelException("The table nr. "+tableIdx+" has no name");
            }
            if (namesOfProcessedTables.contains(curTable.getName()))
            {
                throw new ModelException("There are multiple tables with the name "+curTable.getName());
            }
            namesOfProcessedTables.add(curTable.getName());

            namesOfProcessedColumns.clear();
            namesOfProcessedFks.clear();
            namesOfProcessedIndices.clear();

            for (int idx = 0; idx < curTable.getColumnCount(); idx++)
            {
                Column column = curTable.getColumn(idx);

                if ((column.getName() == null) || (column.getName().length() == 0))
                {
                    throw new ModelException("The column nr. "+idx+" in table "+curTable.getName()+" has no name");
                }
                if (namesOfProcessedColumns.contains(column.getName()))
                {
                    throw new ModelException("There are multiple column with the name "+column.getName()+" in the table "+curTable.getName());
                }
                namesOfProcessedColumns.add(column.getName());

                if ((column.getType() == null) || (column.getType().length() == 0))
                {
                    throw new ModelException("The column nr. "+idx+" in table "+curTable.getName()+" has no type");
                }
                if ((column.getTypeCode() == Types.OTHER) && !"OTHER".equalsIgnoreCase(column.getType()))
                {
                    throw new ModelException("The column nr. "+idx+" in table "+curTable.getName()+" has an unknown type "+column.getType());
                }
                namesOfProcessedColumns.add(column.getName());
            }

            for (int idx = 0; idx < curTable.getForeignKeyCount(); idx++)
            {
                ForeignKey fk     = curTable.getForeignKey(idx);
                String     fkName = (fk.getName() == null ? "" : fk.getName());
                String     fkDesc = (fkName.length() == 0 ? "nr. " + idx : fkName);

                if (fkName.length() > 0)
                {
                    if (namesOfProcessedFks.contains(fkName))
                    {
                        throw new ModelException("There are multiple foreign keys in table "+curTable.getName()+" with the name "+fkName);
                    }
                    namesOfProcessedFks.add(fkName);
                }

                if (fk.getForeignTable() == null)
                {
                    Table targetTable = findTable(fk.getForeignTableName(), true);

                    if (targetTable == null)
                    {
                        throw new ModelException("The foreignkey "+fkDesc+" in table "+curTable.getName()+" references the undefined table "+fk.getForeignTableName());
                    }
                    else
                    {
                        fk.setForeignTable(targetTable);
                    }
                }
                for (int refIdx = 0; refIdx < fk.getReferenceCount(); refIdx++)
                {
                    Reference ref = fk.getReference(refIdx);

                    if (ref.getLocalColumn() == null)
                    {
                        Column localColumn = curTable.findColumn(ref.getLocalColumnName(), true);

                        if (localColumn == null)
                        {
                            throw new ModelException("The foreignkey "+fkDesc+" in table "+curTable.getName()+" references the undefined local column "+ref.getLocalColumnName());
                        }
                        else
                        {
                            ref.setLocalColumn(localColumn);
                        }
                    }
                    if (ref.getForeignColumn() == null)
                    {
                        Column foreignColumn = fk.getForeignTable().findColumn(ref.getForeignColumnName(), true);

                        if (foreignColumn == null)
                        {
                            throw new ModelException("The foreignkey "+fkDesc+" in table "+curTable.getName()+" references the undefined local column "+ref.getForeignColumnName()+" in table "+fk.getForeignTable().getName());
                        }
                        else
                        {
                            ref.setForeignColumn(foreignColumn);
                        }
                    }
                }
            }

            for (int idx = 0; idx < curTable.getIndexCount(); idx++)
            {
                Index  index     = curTable.getIndex(idx);
                String indexName = (index.getName() == null ? "" : index.getName());
                String indexDesc = (indexName.length() == 0 ? "nr. " + idx : indexName);

                if (indexName.length() > 0)
                {
                    if (namesOfProcessedIndices.contains(indexName))
                    {
                        throw new ModelException("There are multiple indices in table "+curTable.getName()+" with the name "+indexName);
                    }
                    namesOfProcessedIndices.add(indexName);
                }

                for (int indexColumnIdx = 0; indexColumnIdx < index.getColumnCount(); indexColumnIdx++)
                {
                    IndexColumn indexColumn = index.getColumn(indexColumnIdx);
                    Column      column      = curTable.findColumn(indexColumn.getName(), true);

                    if (column == null)
                    {
                        throw new ModelException("The index "+indexDesc+" in table "+curTable.getName()+" references the undefined column "+indexColumn.getName());
                    }
                    else
                    {
                        indexColumn.setColumn(column);
                    }
                }
            }
        }
    }
    
    /**
     * Finds the table with the specified name, using case insensitive matching.
     * Note that this method is not called getTable to avoid introspection
     * problems.
     * 
     * @param name The name of the table to find
     * @return The table or <code>null</code> if there is no such table
     */
    public Table findTable(String name)
    {
        return findTable(name, false);
    }

    /**
     * Finds the table with the specified name, using case insensitive matching.
     * Note that this method is not called getTable) to avoid introspection
     * problems.
     * 
     * @param name          The name of the table to find
     * @param caseSensitive Whether case matters for the names
     * @return The table or <code>null</code> if there is no such table
     */
    public Table findTable(String name, boolean caseSensitive)
    {
        for (Iterator iter = _tables.iterator(); iter.hasNext();)
        {
            Table table = (Table) iter.next();

            if (caseSensitive)
            {
                if (table.getName().equals(name))
                {
                    return table;
                }
            }
            else
            {
                if (table.getName().equalsIgnoreCase(name))
                {
                    return table;
                }
            }
        }
        return null;
    }

    /**
     * Returns the dyna class cache. If none is available yet, a new one will be created.
     * 
     * @return The dyna class cache
     */
    private DynaClassCache getDynaClassCache()
    {
        if (_dynaClassCache == null)
        {
            _dynaClassCache = new DynaClassCache();
        }
        return _dynaClassCache;
    }

    /**
     * Resets the dyna class cache. This should be done for instance when a column
     * has been added or removed to a table.
     */
    public void resetDynaClassCache()
    {
        _dynaClassCache = null;
    }
    
    /**
     * Returns the {@link org.apache.ddlutils.dynabean.SqlDynaClass} for the given table name. If the it does not
     * exist yet, a new one will be created based on the Table definition.
     * 
     * @param tableName The name of the table to create the bean for
     * @return The <code>SqlDynaClass</code> for the indicated table or <code>null</code>
     *         if the model contains no such table
     */
    public SqlDynaClass getDynaClassFor(String tableName)
    {
        Table table = findTable(tableName);

        return table != null ? getDynaClassCache().getDynaClass(table) : null;
    }

    /**
     * Returns the {@link org.apache.ddlutils.dynabean.SqlDynaClass} for the given dyna bean.
     * 
     * @param bean The dyna bean
     * @return The <code>SqlDynaClass</code> for the given bean
     */
    public SqlDynaClass getDynaClassFor(DynaBean bean)
    {
        return getDynaClassCache().getDynaClass(bean);
    }

    /**
     * Creates a new dyna bean for the given table.
     * 
     * @param table The table to create the bean for
     * @return The new dyna bean
     */
    public DynaBean createDynaBeanFor(Table table) throws SqlDynaException
    {
        return getDynaClassCache().createNewInstance(table);
    }

    /**
     * Convenience method that combines {@link #createDynaBeanFor(Table)} and
     * {@link #findTable(String, boolean)}.
     * 
     * @param tableName     The name of the table to create the bean for
     * @param caseSensitive Whether case matters for the names
     * @return The new dyna bean
     */
    public DynaBean createDynaBeanFor(String tableName, boolean caseSensitive) throws SqlDynaException
    {
        return getDynaClassCache().createNewInstance(findTable(tableName, caseSensitive));
    }

    /**
     * {@inheritDoc}
     */
    public Object clone() throws CloneNotSupportedException
    {
        Database result = (Database)super.clone();

        result._name     = _name;
        result._idMethod = _idMethod;
        result._version  = _version;
        result._tables   = (ArrayList)_tables.clone();

        return result;
    }

    /**
     * {@inheritDoc}
     */
    public boolean equals(Object obj)
    {
        if (obj instanceof Database)
        {
            Database other = (Database)obj;

            // Note that this compares case sensitive
            return new EqualsBuilder().append(_name,   other._name)
                                      .append(_tables, other._tables)
                                      .isEquals();
        }
        else
        {
            return false;
        }
    }

    /**
     * {@inheritDoc}
     */
    public int hashCode()
    {
        return new HashCodeBuilder(17, 37).append(_name)
                                          .append(_tables)
                                          .toHashCode();
    }

    /**
     * {@inheritDoc}
     */
    public String toString()
    {
        StringBuffer result = new StringBuffer();

        result.append("Database [name=");
        result.append(getName());
        result.append("; ");
        result.append(getTableCount());
        result.append(" tables]");

        return result.toString();
    }

    /**
     * Returns a verbose string representation of this database.
     * 
     * @return The string representation
     */
    public String toVerboseString()
    {
        StringBuffer result = new StringBuffer();

        result.append("Database [");
        result.append(getName());
        result.append("] tables:");
        for (int idx = 0; idx < getTableCount(); idx++)
        {
            result.append(" ");
            result.append(getTable(idx).toVerboseString());
        }

        return result.toString();
    }
}
