// Copyright 2014 The Bazel Authors. All rights reserved.
//
// 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.devtools.build.lib.actions;

/**
 * An exception indication that the execution of an action has failed OR could
 * not be attempted OR could not be finished OR had something else wrong.
 *
 * <p>The four main kinds of failure are broadly defined as follows:
 *
 * <p>USER_INPUT which means it had something to do with what the user told us
 * to do.  This failure should satisfy the invariant that it would happen
 * identically again if all other things are equal.
 *
 * <p>ENVIRONMENT which is loosely defined as anything which is generally out of
 * scope for a blaze evaluation. As a rule of thumb, these are any errors would
 * not necessarily happen again given constant input.
 *
 * <p>INTERRUPTION conditions arise from being unable to complete an evaluation
 * for whatever reason.
 *
 * <p>INTERNAL_ERROR would happen because of anything which arises from within
 * blaze itself but is generally unexpected to ever occur for any user input.
 *
 * <p>The class is a catch-all for both failures of actions and failures to
 * evaluate actions properly.
 *
 * <p>Invariably, all low level ExecExceptions are caught by various specific
 * ConfigurationAction classes and re-raised as ActionExecutionExceptions.
 */
public abstract class ExecException extends Exception {

  private final boolean catastrophe;

  public ExecException(String message, boolean catastrophe) {
    super(message);
    this.catastrophe = catastrophe;
  }

  public ExecException(String message) {
    this(message, false);
  }
  
  public ExecException(Throwable cause) {
    super(cause);
    this.catastrophe = false;
  }

  public ExecException(String message, Throwable cause, boolean catastrophe) {
    super(message + ": " + cause.getMessage(), cause);
    this.catastrophe = catastrophe;
  }

  public ExecException(String message, Throwable cause) {
    this(message, cause, false);
  }

  /**
   * Catastrophic exceptions should stop the build, even if --keep_going.
   */
  public boolean isCatastrophic() {
    return catastrophe;
  }

  /**
   * Returns a new ActionExecutionException without a message prefix.
   * @param action failed action
   * @return ActionExecutionException object describing the action failure
   */
  public ActionExecutionException toActionExecutionException(Action action) {
    // In all ExecException implementations verboseFailures argument used only to determine should
    // we pass ExecException as cause of ActionExecutionException. So use this method only 
    // if you need this information inside of ActionExecutionexception.
    return toActionExecutionException("", true, action);
  }

  /**
   * Returns a new ActionExecutionException given a message prefix describing the action type as a
   * noun. When appropriate (we use some heuristics to decide), produces an abbreviated message
   * incorporating just the termination status if available.
   *
   * @param messagePrefix describes the action type as noun
   * @param verboseFailures true if user requested verbose output with flag --verbose_failures
   * @param action failed action
   * @return ActionExecutionException object describing the action failure
   */
  public abstract ActionExecutionException toActionExecutionException(String messagePrefix,
        boolean verboseFailures, Action action);
}