/*
 * Copyright 2002-2015 the original author or authors.
 *
 * Licensed 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.
 */

package org.springframework.expression.spel;

import java.util.Arrays;
import java.util.List;

import org.springframework.expression.EvaluationException;
import org.springframework.expression.Expression;
import org.springframework.expression.ExpressionParser;
import org.springframework.expression.ParseException;
import org.springframework.expression.spel.standard.SpelExpressionParser;
import org.springframework.expression.spel.support.StandardEvaluationContext;

import static org.junit.Assert.*;

/**
 * Common superclass for expression tests.
 *
 * @author Andy Clement
 */
public abstract class AbstractExpressionTests {

	private static final boolean DEBUG = false;

	protected static final boolean SHOULD_BE_WRITABLE = true;

	protected static final boolean SHOULD_NOT_BE_WRITABLE = false;


	protected final ExpressionParser parser = new SpelExpressionParser();

	protected final StandardEvaluationContext eContext = TestScenarioCreator.getTestEvaluationContext();


	/**
	 * Evaluate an expression and check that the actual result matches the
	 * expectedValue and the class of the result matches the expectedClassOfResult.
	 * @param expression the expression to evaluate
	 * @param expectedValue the expected result for evaluating the expression
	 * @param expectedResultType the expected class of the evaluation result
	 */
	public void evaluate(String expression, Object expectedValue, Class<?> expectedResultType) {
		Expression expr = parser.parseExpression(expression);
		if (expr == null) {
			fail("Parser returned null for expression");
		}
		if (DEBUG) {
			SpelUtilities.printAbstractSyntaxTree(System.out, expr);
		}

		Object value = expr.getValue(eContext);

		// Check the return value
		if (value == null) {
			if (expectedValue == null) {
				return;  // no point doing other checks
			}
			assertEquals("Expression returned null value, but expected '" + expectedValue + "'", expectedValue, null);
		}

		Class<?> resultType = value.getClass();
		assertEquals("Type of the actual result was not as expected.  Expected '" + expectedResultType +
				"' but result was of type '" + resultType + "'", expectedResultType, resultType);

		if (expectedValue instanceof String) {
			assertEquals("Did not get expected value for expression '" + expression + "'.", expectedValue,
					AbstractExpressionTests.stringValueOf(value));
		}
		else {
			assertEquals("Did not get expected value for expression '" + expression + "'.", expectedValue, value);
		}
	}

	public void evaluateAndAskForReturnType(String expression, Object expectedValue, Class<?> expectedResultType) {
		Expression expr = parser.parseExpression(expression);
		if (expr == null) {
			fail("Parser returned null for expression");
		}
		if (DEBUG) {
			SpelUtilities.printAbstractSyntaxTree(System.out, expr);
		}

		Object value = expr.getValue(eContext, expectedResultType);
		if (value == null) {
			if (expectedValue == null) {
				return;  // no point doing other checks
			}
			assertEquals("Expression returned null value, but expected '" + expectedValue + "'", expectedValue, null);
		}

		Class<?> resultType = value.getClass();
		assertEquals("Type of the actual result was not as expected.  Expected '" + expectedResultType +
				"' but result was of type '" + resultType + "'", expectedResultType, resultType);
		assertEquals("Did not get expected value for expression '" + expression + "'.", expectedValue, value);
	}

	/**
	 * Evaluate an expression and check that the actual result matches the
	 * expectedValue and the class of the result matches the expectedClassOfResult.
	 * This method can also check if the expression is writable (for example,
	 * it is a variable or property reference).
	 * @param expression the expression to evaluate
	 * @param expectedValue the expected result for evaluating the expression
	 * @param expectedClassOfResult the expected class of the evaluation result
	 * @param shouldBeWritable should the parsed expression be writable?
	 */
	public void evaluate(String expression, Object expectedValue, Class<?> expectedClassOfResult, boolean shouldBeWritable) {
		Expression expr = parser.parseExpression(expression);
		if (expr == null) {
			fail("Parser returned null for expression");
		}
		if (DEBUG) {
			SpelUtilities.printAbstractSyntaxTree(System.out, expr);
		}
		Object value = expr.getValue(eContext);
		if (value == null) {
			if (expectedValue == null) {
				return;  // no point doing other checks
			}
			assertEquals("Expression returned null value, but expected '" + expectedValue + "'", expectedValue, null);
		}
		Class<? extends Object> resultType = value.getClass();
		if (expectedValue instanceof String) {
			assertEquals("Did not get expected value for expression '" + expression + "'.", expectedValue,
					AbstractExpressionTests.stringValueOf(value));
		}
		else {
			assertEquals("Did not get expected value for expression '" + expression + "'.", expectedValue, value);
		}
		assertEquals("Type of the result was not as expected.  Expected '" + expectedClassOfResult +
				"' but result was of type '" + resultType + "'", expectedClassOfResult.equals(resultType), true);

		boolean isWritable = expr.isWritable(eContext);
		if (isWritable != shouldBeWritable) {
			if (shouldBeWritable)
				fail("Expected the expression to be writable but it is not");
			else
				fail("Expected the expression to be readonly but it is not");
		}
	}

	/**
	 * Evaluate the specified expression and ensure the expected message comes out.
	 * The message may have inserts and they will be checked if otherProperties is specified.
	 * The first entry in otherProperties should always be the position.
	 * @param expression the expression to evaluate
	 * @param expectedMessage the expected message
	 * @param otherProperties the expected inserts within the message
	 */
	protected void evaluateAndCheckError(String expression, SpelMessage expectedMessage, Object... otherProperties) {
		evaluateAndCheckError(expression, null, expectedMessage, otherProperties);
	}

	/**
	 * Evaluate the specified expression and ensure the expected message comes out.
	 * The message may have inserts and they will be checked if otherProperties is specified.
	 * The first entry in otherProperties should always be the position.
	 * @param expression the expression to evaluate
	 * @param expectedReturnType ask the expression return value to be of this type if possible
	 * ({@code null} indicates don't ask for conversion)
	 * @param expectedMessage the expected message
	 * @param otherProperties the expected inserts within the message
	 */
	protected void evaluateAndCheckError(String expression, Class<?> expectedReturnType, SpelMessage expectedMessage,
			Object... otherProperties) {
		try {
			Expression expr = parser.parseExpression(expression);
			if (expr == null) {
				fail("Parser returned null for expression");
			}
			if (expectedReturnType != null) {
				expr.getValue(eContext, expectedReturnType);
			}
			else {
				expr.getValue(eContext);
			}
			fail("Should have failed with message " + expectedMessage);
		}
		catch (EvaluationException ee) {
			SpelEvaluationException ex = (SpelEvaluationException) ee;
			if (ex.getMessageCode() != expectedMessage) {
				assertEquals("Failed to get expected message", expectedMessage, ex.getMessageCode());
			}
			if (otherProperties != null && otherProperties.length != 0) {
				// first one is expected position of the error within the string
				int pos = ((Integer) otherProperties[0]).intValue();
				assertEquals("Did not get correct position reported in error ", pos, ex.getPosition());
				if (otherProperties.length > 1) {
					// Check inserts match
					Object[] inserts = ex.getInserts();
					if (inserts == null) {
						inserts = new Object[0];
					}
					if (inserts.length < otherProperties.length - 1) {
						fail("Cannot check " + (otherProperties.length - 1) +
								" properties of the exception, it only has " + inserts.length + " inserts");
					}
					for (int i = 1; i < otherProperties.length; i++) {
						if (otherProperties[i] == null) {
							if (inserts[i - 1] != null) {
								fail("Insert does not match, expected 'null' but insert value was '" +
										inserts[i - 1] + "'");
							}
						}
						else if (inserts[i - 1] == null) {
							if (otherProperties[i] != null) {
								fail("Insert does not match, expected '" + otherProperties[i] +
										"' but insert value was 'null'");
							}
						}
						else if (!inserts[i - 1].equals(otherProperties[i])) {
							fail("Insert does not match, expected '" + otherProperties[i] +
									"' but insert value was '" + inserts[i - 1] + "'");
						}
					}
				}
			}
		}
	}

	/**
	 * Parse the specified expression and ensure the expected message comes out.
	 * The message may have inserts and they will be checked if otherProperties is specified.
	 * The first entry in otherProperties should always be the position.
	 * @param expression the expression to evaluate
	 * @param expectedMessage the expected message
	 * @param otherProperties the expected inserts within the message
	 */
	protected void parseAndCheckError(String expression, SpelMessage expectedMessage, Object... otherProperties) {
		try {
			Expression expr = parser.parseExpression(expression);
			SpelUtilities.printAbstractSyntaxTree(System.out, expr);
			fail("Parsing should have failed!");
		}
		catch (ParseException pe) {
			SpelParseException ex = (SpelParseException)pe;
			if (ex.getMessageCode() != expectedMessage) {
				assertEquals("Failed to get expected message", expectedMessage, ex.getMessageCode());
			}
			if (otherProperties != null && otherProperties.length != 0) {
				// first one is expected position of the error within the string
				int pos = ((Integer) otherProperties[0]).intValue();
				assertEquals("Did not get correct position reported in error ", pos, ex.getPosition());
				if (otherProperties.length > 1) {
					// Check inserts match
					Object[] inserts = ex.getInserts();
					if (inserts == null) {
						inserts = new Object[0];
					}
					if (inserts.length < otherProperties.length - 1) {
						fail("Cannot check " + (otherProperties.length - 1) +
								" properties of the exception, it only has " + inserts.length + " inserts");
					}
					for (int i = 1; i < otherProperties.length; i++) {
						if (!inserts[i - 1].equals(otherProperties[i])) {
							fail("Insert does not match, expected '" + otherProperties[i] +
									"' but insert value was '" + inserts[i - 1] + "'");
						}
					}
				}
			}
		}
	}


	protected static String stringValueOf(Object value) {
		return stringValueOf(value, false);
	}

	/**
	 * Produce a nice string representation of the input object.
	 * @param value object to be formatted
	 * @return a nice string
	 */
	protected static String stringValueOf(Object value, boolean isNested) {
		// do something nice for arrays
		if (value == null) {
			return "null";
		}
		if (value.getClass().isArray()) {
			StringBuilder sb = new StringBuilder();
			if (value.getClass().getComponentType().isPrimitive()) {
				Class<?> primitiveType = value.getClass().getComponentType();
				if (primitiveType == Integer.TYPE) {
					int[] l = (int[]) value;
					sb.append("int[").append(l.length).append("]{");
					for (int j = 0; j < l.length; j++) {
						if (j > 0) {
							sb.append(",");
						}
						sb.append(stringValueOf(l[j]));
					}
					sb.append("}");
				}
				else if (primitiveType == Long.TYPE) {
					long[] l = (long[]) value;
					sb.append("long[").append(l.length).append("]{");
					for (int j = 0; j < l.length; j++) {
						if (j > 0) {
							sb.append(",");
						}
						sb.append(stringValueOf(l[j]));
					}
					sb.append("}");
				}
				else {
					throw new RuntimeException("Please implement support for type " + primitiveType.getName() +
							" in ExpressionTestCase.stringValueOf()");
				}
			}
			else if (value.getClass().getComponentType().isArray()) {
				List<Object> l = Arrays.asList((Object[]) value);
				if (!isNested) {
					sb.append(value.getClass().getComponentType().getName());
				}
				sb.append("[").append(l.size()).append("]{");
				int i = 0;
				for (Object object : l) {
					if (i > 0) {
						sb.append(",");
					}
					i++;
					sb.append(stringValueOf(object, true));
				}
				sb.append("}");
			}
			else {
				List<Object> l = Arrays.asList((Object[]) value);
				if (!isNested) {
					sb.append(value.getClass().getComponentType().getName());
				}
				sb.append("[").append(l.size()).append("]{");
				int i = 0;
				for (Object object : l) {
					if (i > 0) {
						sb.append(",");
					}
					i++;
					sb.append(stringValueOf(object));
				}
				sb.append("}");
			}
			return sb.toString();
		}
		else {
			return value.toString();
		}
	}

}
