DBUtils.java

package org.sana.android.db;

import java.util.ArrayList;
import java.util.List;

import org.sana.android.content.Uris;
import org.sana.android.provider.BaseContract;

import android.database.Cursor;
import android.net.Uri;
import android.provider.BaseColumns;
import android.text.TextUtils;

/**
 * Collection of database helper methods.
 * 
 * @author Sana Development
 *
 */
public final class DBUtils {

	private DBUtils(){}
	/**
	 * Returns the selection statement as:<br/>
	 *  ( uuid = "uri.getLastPathSegment()" ) AND ( selection )
	 * 
	 * @param uri
	 * @param whereClause
	 * @return
	 */
	public static String getWhereClauseWithUUID(Uri uri, String whereClause){
		String select = whereClause;
		select = concatenateWhere(whereClause,
					BaseContract.UUID + " = '" + uri.getLastPathSegment() +"'");
		return select;
	}
	
	/**
	 * Returns the selection statement as
	 *  ( _ID = "uri.getPathSegments().get(1)" ) AND ( selection )
	 * or as the original based on whether the uri match was a dir or item.
	 * Relies on matcher values for *.dir being even integers.
	 * @param uri
	 * @param whereClause
	 * @return
	 */
	public static String getWhereClauseWithID(Uri uri, String whereClause){
		return concatenateWhere(whereClause,
				BaseContract._ID + " = " + uri.getLastPathSegment());
	}
	
	/**
	 * Returns the selection statement as
	 *  ( _ID = "uri.getPathSegments().get(1)" ) AND ( selection )
	 * or as the original based on whether the uri match was a dir or item.
	 * Relies on matcher values for *.dir being even integers.
	 * @param uri
	 * @param whereClause
	 * @return
	 */
	public static String getWhereClause(Uri uri, int match, String whereClause){
		String select = whereClause;
		if(Uris.isItemType(uri)){
			if((Uris.getTypeDescriptor(uri) & Uris.ITEM_ID) != 0)
				select = concatenateWhere(whereClause,
					BaseColumns._ID + " LIKE " + uri.getLastPathSegment());
			else
				select = concatenateWhere(whereClause,
						BaseContract.UUID + " LIKE '" + uri.getLastPathSegment() +"'");
		}
		return select;
	}
	
	/**
	 * Constructs a SQL WHERE clause with {@link android.provider.BaseColumns#_ID _ID}
	 * prepended.
	 *  
	 * @param id The value of the _ID column
	 * @param wherClause
	 * @return
	 */
	public static String getWhereClause(long id, String wherClause){
		return concatenateWhere(BaseColumns._ID + " LIKE " + id, wherClause);
	}
	
	/**
	 * 
	 * @param cursor
	 * @param column
	 * @return
	 */
	public static List<String> dumpStringColumn(Cursor cursor, int column){
		List<String> list = new ArrayList<String>();
		while(cursor.moveToNext()){
			list.add(cursor.getString(column));
		}
		return list;
	}
	
	/**
	 * Appends one set of selection args to another. This is useful when adding 
	 * a selection argument to a user provided set.
	 * 
	 * @param originalValues
	 * @param newValues
	 * @return
	 */
	public static String[] appendSelectionArgs(String[] originalValues, 
			String[] newValues)
	{
		int l1 = (originalValues != null)? originalValues.length: 0;
		int l2 = (newValues != null)? newValues.length: 0;
		String[] result = new String[l1 + l2];
		for(int index = 0;index < l1 + l2;index++){
			result[index] = (index < l1)? originalValues[index]: newValues[index];
		}
		return result;
	}
	
	/**
	 * Concatenates two SQL WHERE clauses, handling empty or null values.
	 * 
	 * @param arg1
	 * @param arg2
	 * @return 
	 */
	public static String concatenateWhere(String arg1, String arg2){
		String cat = "";
		// Both non empty concatenate
		if(!TextUtils.isEmpty(arg1) && !TextUtils.isEmpty(arg2))
			cat = String.format("%s AND %s", arg1, arg2);
		else {
		// at least one empty
			if(!TextUtils.isEmpty(arg1))
				cat = arg1;
			else if(!TextUtils.isEmpty(arg2))
				cat = arg2;
		}
		cat.replace("=", " LIKE ");
		return cat;
	}

	/**
	 * Converts any Uri query string into a select statement by taking
	 * every key value pair in the query into "key = 'value'".
	 *  
	 * @param uri
	 * @return
	 */
	public static String convertUriQueryToSelect(Uri uri){
		String qString = uri.getQuery();
		// Shortcut out for null query
		if(TextUtils.isEmpty(qString))
			return null;
		StringBuilder select = new StringBuilder();
		String[] rawQuery = uri.getQuery().split(",");
		for(int index = 0;index < rawQuery.length;index++){
			String[] kv = rawQuery[index].split("=");
			// append space after first key value pair
			if(index > 0) select.append(" ");
			select.append(String.format("%s LIKE '%s'",kv[0],kv[1]));
		}
		return select.toString();
	}
	
}