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/*******************************************************************
 * © 2019 SAP SE or an SAP affiliate company. All rights reserved. *
 *******************************************************************/
package com.sap.cds.impl.parser;

import java.util.List;

import com.fasterxml.jackson.databind.JsonNode;
import com.fasterxml.jackson.databind.node.ArrayNode;
import com.google.common.collect.Lists;
import com.sap.cds.impl.parser.builder.ExpressionBuilder;
import com.sap.cds.ql.cqn.CqnExpression;
import com.sap.cds.ql.cqn.CqnPredicate;
import com.sap.cds.ql.cqn.CqnSyntaxException;
import com.sap.cds.ql.cqn.CqnToken;

public class ExpressionParser {

	private ExpressionParser() {

	}

	public static CqnExpression parseExpression(ArrayNode xpr) {
		if (xpr != null) {
			return ExpressionBuilder.create(parseTokens(xpr)).xpr();
		}
		return null;
	}

	public static CqnPredicate parsePredicate(String cqnExpr) {
		try {
			ArrayNode expr = CqnParser.getDocumentContext(cqnExpr).read("$");
			return parsePredicate(expr);
		} catch (Exception ex) {
			throw new CqnSyntaxException("Error parsing " + cqnExpr, ex);
		}
	}

	public static List parseTokens(String cqnExpr) {
		ArrayNode expr = CqnParser.getDocumentContext(cqnExpr).read("$");
		return parseTokens(expr);
	}

	public static CqnPredicate parsePredicate(JsonNode expr) {
		if (expr == null) {
			return null;
		}
		if (expr.isArray()) {
			List tokens = parseTokens((ArrayNode) expr);
			return new ExprParser().parsePredicate(tokens);
		}
		return ExpressionBuilder.create(TokenParser.parse(expr)).predicate();
	}

	public static List parseTokens(ArrayNode arrayNode) {
		List tokens = Lists.newArrayList();
		if (arrayNode != null) {
			arrayNode.forEach(n -> tokens.add(TokenParser.parse(n)));
		}
		return tokens;
	}

}