/*
 * Copyright 2013 Google Inc.
 *
 * 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 com.google.gwt.dev.jjs.impl;

import com.google.gwt.dev.jjs.SourceInfo;
import com.google.gwt.dev.jjs.ast.Context;
import com.google.gwt.dev.jjs.ast.JBinaryOperation;
import com.google.gwt.dev.jjs.ast.JBinaryOperator;
import com.google.gwt.dev.jjs.ast.JExpression;
import com.google.gwt.dev.jjs.ast.JExpressionStatement;
import com.google.gwt.dev.jjs.ast.JLocal;
import com.google.gwt.dev.jjs.ast.JType;

/**
 * Test for {@link JModVisitorWithTemporaryVariableCreation}.
 */
public class JModVisitorWithTemporaryVariableCreationTest extends JJSTestBase {
  /**
   * Replaces expressions with assignment-to-temp. Does not replace lvalues, or
   * the top level expression in an expression statement.
   */
  private static final class AlwaysReplacer extends JModVisitorWithTemporaryVariableCreation {
    /**
     * Don't bother replacing entire JExpressionStatements with a temp.
     */
    private JExpression dontBother;

    public AlwaysReplacer() {
      super(OptimizerContext.NULL_OPTIMIZATION_CONTEXT);
    }

    @Override
    public boolean visit(JExpressionStatement x, Context ctx) {
      dontBother = x.getExpr();
      return super.visit(x, ctx);
    }

    @Override
    public void endVisit(JExpression x, Context ctx) {
      if (x != dontBother && !ctx.isLvalue()) {
        SourceInfo info = x.getSourceInfo();
        JType type = x.getType();
        JLocal local = createTempLocal(info, type, "$t" + nextIdToAssign++);
        ctx.replaceMe(new JBinaryOperation(info, type, JBinaryOperator.ASG,
            local.makeRef(info), x));
      }
    }
    private int nextIdToAssign;
  }

  public void testBasic() throws Exception {
    assertTransform("int i = 3;", new AlwaysReplacer()).into("int $t0; int i = $t0 = 3;");
  }

  public void testForStatement() throws Exception {
    StringBuilder original = new StringBuilder();
    original.append("for (int i = 0; true; i += 1);");

    StringBuilder expected = new StringBuilder();
    /*
     * TODO(scottb): technically $t1 and $t2 could be part of the for
     * statement's initializer list.
     */
    expected.append("boolean $t1;");
    expected.append("int $t2;");
    expected.append("int $t3;");
    expected.append("for (int $t0, i = $t0 = 0; $t1 = true; $t3 = i += $t2 = 1);");

    assertTransform(original.toString(), new AlwaysReplacer()).into(expected.toString());
  }

  public void testForStatementScoping() throws Exception {
    StringBuilder original = new StringBuilder();
    original.append("boolean f = false;");
    original.append("for (int i = 3; f; );");
    original.append("int j = 4;");

    StringBuilder expected = new StringBuilder();
    expected.append("boolean $t0;");
    expected.append("boolean f = $t0 = false;");
    expected.append("boolean $t2;");
    expected.append("for (int $t1, i = $t1 = 3; $t2 = f; );");
    expected.append("int $t3; int j = $t3 = 4;");

    assertTransform(original.toString(), new AlwaysReplacer()).into(expected.toString());
  }

  /**
   * Test for issue 8304.
   */
  public void testNamingConflict() throws Exception {
    StringBuilder original = new StringBuilder();
    original.append("boolean $type = false;");
    original.append("for (int i = 3; $type; );");

    StringBuilder expected = new StringBuilder();
    expected.append("boolean $t0;");
    expected.append("boolean $type = $t0 = false;");
    expected.append("boolean $t2;");
    expected.append("for (int $t1, i = $t1 = 3; $t2 = $type; );");

    assertTransform(original.toString(), new AlwaysReplacer()).into(expected.toString());
  }

  public void testNested() throws Exception {
    assertTransform("{ int i = 3; }", new AlwaysReplacer()).into("{ int $t0; int i = $t0 = 3; }");
  }

  public void testNestedPost() throws Exception {
    StringBuilder original = new StringBuilder();
    original.append("int i = 3;");
    original.append("{ int j = 4; }");

    StringBuilder expected = new StringBuilder();
    expected.append("int $t0; int i = $t0 = 3;");
    expected.append("{ int $t1; int j = $t1 = 4; }");

    assertTransform(original.toString(), new AlwaysReplacer()).into(expected.toString());
  }

  public void testNestedPre() throws Exception {
    StringBuilder original = new StringBuilder();
    original.append("{ int i = 3; }");
    original.append("int j = 4;");

    StringBuilder expected = new StringBuilder();
    expected.append("{ int $t0; int i = $t0 = 3; }");
    expected.append("int $t1; int j = $t1 = 4;");

    assertTransform(original.toString(), new AlwaysReplacer()).into(expected.toString());
  }

  public void testVeryComplex() throws Exception {
    StringBuilder original = new StringBuilder();
    original.append("int a = 0;");
    original.append("{ int i = 3; int j = 4; }");
    original.append("int b = 1;");
    original.append("{ int i = 3; int j = 4; }");
    original.append("int c = 2;");

    StringBuilder expected = new StringBuilder();
    expected.append("int $t0; int a = $t0 = 0;");
    expected.append("{ int $t1; int i = $t1 = 3; int $t2; int j = $t2 = 4; }");
    expected.append("int $t3; int b = $t3 = 1;");
    expected.append("{ int $t4; int i = $t4 = 3; int $t5; int j = $t5 = 4; }");
    expected.append("int $t6; int c = $t6 = 2;");

    assertTransform(original.toString(), new AlwaysReplacer()).into(expected.toString());
  }
}