QueryParserUtils.java

package org.springframework.data.simpledb.query.parser;

import org.springframework.data.simpledb.annotation.Query;
import org.springframework.util.StringUtils;

/**
 * Acts as a Parser for Building the Custom Query based on the given {@link Query} parameters<br/>
 * <br/>
 */
public final class QueryParserUtils {

	private QueryParserUtils() {
	}

	public static String buildQueryFromQueryParameters(String valueParameter, String[] rawSelectParameters,
			String rawWhereParameters, String domainName) {

		if(StringUtils.hasText(valueParameter)) {
			return valueParameter;
		}

		StringBuilder stringBuilder = new StringBuilder();

		appendSelectClause(stringBuilder, rawSelectParameters);
		appendFromClause(stringBuilder, domainName);
		appendWhereClauseIfPresent(stringBuilder, rawWhereParameters);

		return stringBuilder.toString();
	}

	public static String createQueryClause(String clause, String[] rawParameters, String delimiter) {
		StringBuilder query = new StringBuilder(clause);
		int idx = 1;

		for(String rawParameter : rawParameters) {
			query.append(rawParameter);

			if(idx++ != rawParameters.length) {
				query.append(delimiter);
			}
		}

		return query.toString();
	}

	private static void appendWhereClauseIfPresent(StringBuilder stringBuilder, String rawWhereParameters) {
		if(StringUtils.hasText(rawWhereParameters)) {
			stringBuilder.append(" where " + rawWhereParameters);
		}
	}

	private static void appendFromClause(StringBuilder stringBuilder, String domainName) {
		stringBuilder.append(" from `" + domainName + "`");
	}

	private static void appendSelectClause(StringBuilder stringBuilder, String[] rawSelectParameters) {
		if(StringUtils.hasText(rawSelectParameters[0])) {
			stringBuilder.append(createQueryClause("select ", rawSelectParameters, ", "));
		} else {
			stringBuilder.append("select *");
		}
	}

}