/*
 *    SimpleCollectionDatabase.java
 *    Copyright (C) 2008 New Zealand Digital Library, http://www.nzdl.org
 *
 *    This program is free software; you can redistribute it and/or modify
 *    it under the terms of the GNU General Public License as published by
 *    the Free Software Foundation; either version 2 of the License, or
 *    (at your option) any later version.
 *
 *    This program is distributed in the hope that it will be useful,
 *    but WITHOUT ANY WARRANTY; without even the implied warranty of
 *    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *    GNU General Public License for more details.
 *
 *    You should have received a copy of the GNU General Public License
 *    along with this program; if not, write to the Free Software
 *    Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 */
package org.greenstone.gsdl3.util;

import java.util.Iterator;
import java.util.Set;
import java.util.Vector;

import org.apache.log4j.*;

import org.apache.commons.lang3.StringUtils;

public class SimpleCollectionDatabase implements OID.OIDTranslatable
{

	static Logger logger = Logger.getLogger(org.greenstone.gsdl3.util.SimpleCollectionDatabase.class.getName());

	/* just read access, many readers can share a database */
	public final static int READ = FlatDatabaseWrapper.READ;
	/* read/write, exclusive access */
	public final static int WRITE = FlatDatabaseWrapper.WRITE;

	protected FlatDatabaseWrapper coll_db = null;

	public SimpleCollectionDatabase(String db_type)
	{

		// Access databaseWrapper through reflection (forName) so code
		// can be more dynamic as to the database backends that are
		// supported for this installation of Greenstone

		String dbwrap_name = db_type.toUpperCase() + "Wrapper";
		Class dbwrap_class = null;

		try
		{
			String full_dbwrap_name = "org.greenstone.gsdl3.util." + dbwrap_name;
			dbwrap_class = Class.forName(full_dbwrap_name);
		}
		catch (ClassNotFoundException e)
		{
			try
			{
				//try the dbwrap_name alone in case the package name is
				//already specified
				dbwrap_class = Class.forName(dbwrap_name);
			}
			catch (ClassNotFoundException ae)
			{
				logger.error("Couldn't create SimpleCollectionDatabase of type " + db_type);
				logger.info(ae.getMessage());
			}
		}

		try
		{
			this.coll_db = (FlatDatabaseWrapper) dbwrap_class.newInstance();
		}
		catch (Exception e)
		{
			logger.error("Failed to call the constructor " + dbwrap_name + "()");
		}

	}

	public boolean databaseOK()
	{
		// Previously failed to open database
		// Most likely cause is that this installation of Greenstone3 has not 
		// been compiled with support for this database type
		return coll_db != null;
	}

	/**
	 * open the database filename, with mode mode - uses the FlatDatabaseWrapper
	 * modes
	 */
	public boolean openDatabase(String filename, int mode)
	{
		return this.coll_db.openDatabase(filename, mode);
	}

	/** close the database */
	public void closeDatabase()
	{
		this.coll_db.closeDatabase();
	}

	/**
	 * Returns a DBInfo structure of the key-value pairs associated with a
	 * particular main key in the database
	 */
	public DBInfo getInfo(String main_key)
	{
		//   logger.warn("All the entries of the db are:");
		//   this.coll_db.displayAllEntries();

		if (this.coll_db == null)
		{
			// Most likely cause is that this installation of Greenstone3 has not 
			// been compiled with support for this database type
			return null;
		}

		String key_info = this.coll_db.getValue(main_key);
		if (key_info == null || key_info.equals(""))
		{
			return null;
		}
		
		DBInfo info = new DBInfo();

		String[] lines = StringUtils.split(key_info, "\n");
		String key;
		String value;
		for (int i = 0; i < lines.length; i++)
		{
			logger.debug("line:" + lines[i]);
			int a = lines[i].indexOf('<');
			int b = lines[i].indexOf('>');
			if (a == -1 || b == -1)
			{
				logger.error("bad format in db");
			}
			else
			{
				key = lines[i].substring(a + 1, b);
				value = lines[i].substring(b + 1);
				logger.debug("key=" + key + ", val=" + value);
				info.addInfo(key, value);
			}
		}
		
		return info;
	}
	
	public boolean setInfo(String mainKey, DBInfo info)
	{
		StringBuilder valueToAdd = new StringBuilder();
		Iterator<String> i = info.getKeys().iterator();
		while (i.hasNext())
		{
			String currentKey = i.next();
			Vector<String> currentValues = (Vector<String>)info.getMultiInfo(currentKey);
			
			if(currentValues.size() == 0)
			{
				valueToAdd.append("<" + currentKey + ">\n");
				continue;
			}
			
			for(int j = 0; j < currentValues.size(); j++)
			{
				valueToAdd.append("<" + currentKey + ">" + currentValues.get(j) + "\n");
			}
		}
		
		//Remove the final \n
		if (valueToAdd.length() > 0)
		{
			valueToAdd.delete(valueToAdd.length() - 1, valueToAdd.length());
		}
		
		return this.coll_db.setValue(mainKey, valueToAdd.toString());
	}
	
	public String getValue(String key)
	{
		return this.coll_db.getValue(key);
	}
	
	public boolean setValue(String key, String value)
	{
		return this.coll_db.setValue(key, value);
	}
	
	public boolean deleteKey(String key)
	{
		return this.coll_db.deleteKey(key);
	}

	/** converts a greenstone OID to internal docnum */
	public String OID2Docnum(String OID)
	{
		DBInfo info = getInfo(OID);
		if (info != null)
		{
			return info.getInfo("docnum");
		}
		return null;
	}

	/**
	 * converts a greenstone OID to an internal docnum, returning a Long -
	 * convenience method
	 */
	public long OID2DocnumLong(String OID)
	{
		DBInfo info = getInfo(OID);
		if (info != null)
		{
			long real_num = Long.parseLong(info.getInfo("docnum"));
			return real_num;
		}
		return -1;
	}

	/** converts a docnum to greenstone OID */
	public String docnum2OID(String docnum)
	{
		DBInfo info = getInfo(docnum);
		if (info != null)
		{
			String oid = info.getInfo("section");
			return oid;
		}
		else
		{
			return null;
		}
	}

	/**
	 * converts a docnum to greenstone OID - convenience method
	 */
	public String docnum2OID(long docnum)
	{
		return docnum2OID(Long.toString(docnum));
	}

	/** converts an external id to greenstone OID */
	public String externalId2OID(String extid)
	{
		DBInfo info = getInfo(extid);
		if (info != null)
		{
			String oid = info.getInfo("section");
			return oid;
		}
		return null;
	}

	/**
	 * After OID.translateOID() is through, this method processes OID further to
	 * translate relative oids into proper oids: .pr (parent), .rt (root) .fc
	 * (first child), .lc (last child), .ns (next sibling), .ps (previous
	 * sibling) .np (next page), .pp (previous page) : links sections in the
	 * order that you'd read the document a suffix is expected to be present so
	 * test before using
	 */
	public String processOID(String doc_id, String top, String suff, int sibling_num)
	{
		DBInfo info = getInfo(doc_id);
		if (info == null)
		{
			logger.info("info is null!!");
			return top;
		}

		String contains = info.getInfo("contains");
		if (contains.equals(""))
		{
			// something is wrong
			return top;
		}
		contains = StringUtils.replace(contains, "\"", doc_id);
		String[] children = StringUtils.split(contains, ";");
		if (suff.equals("fc"))
		{
			return children[0];
		}
		else if (suff.equals("lc"))
		{
			return children[children.length - 1];
		}
		else
		{
			if (suff.equals("ss"))
			{
				return children[sibling_num - 1];
			}
			// find the position that we are at.
			int i = 0;
			while (i < children.length)
			{
				if (children[i].equals(top))
				{
					break;
				}
				i++;
			}

			if (suff.equals("ns"))
			{
				if (i == children.length - 1)
				{
					return children[i];
				}
				return children[i + 1];
			}
			else if (suff.equals("ps"))
			{
				if (i == 0)
				{
					return children[i];
				}
				return children[i - 1];
			}
		}

		return top;
	}
}