/*
 * Copyright 2009 The Closure Compiler 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 com.google.javascript.jscomp;

import com.google.common.base.Preconditions;
import com.google.common.collect.Iterables;
import com.google.javascript.jscomp.graph.GraphvizGraph;
import com.google.javascript.jscomp.graph.LinkedDirectedGraph;
import com.google.javascript.rhino.Node;

import java.io.Serializable;
import java.util.Collections;
import java.util.List;
import java.util.Map;
import java.util.Set;

/**
 * Pass factories and meta-data for native Compiler passes.
 *
 * @author nicksantos@google.com (Nick Santos)
 */
public abstract class PassConfig {

  // Used by subclasses in this package.
  final CompilerOptions options;

  /**
   * A memoized version of scopeCreator. It must be memoized so that
   * we can make two separate passes over the AST, one for inferring types
   * and one for checking types.
   */
  private MemoizedScopeCreator typedScopeCreator;

  /**
   * This is the scope creator that {@code TypedScopeCreator} delegates to.
   */
  private TypedScopeCreator internalScopeCreator;

  /** The global typed scope. */
  TypedScope topScope = null;

  public PassConfig(CompilerOptions options) {
    this.options = options;
  }

  /**
   * Regenerates the top scope from scratch.
   *
   * @param compiler The compiler for which the global scope is regenerated.
   * @param root The root of the AST.
   */
  void regenerateGlobalTypedScope(AbstractCompiler compiler, Node root) {
    internalScopeCreator = new TypedScopeCreator(compiler);
    typedScopeCreator = new MemoizedScopeCreator(internalScopeCreator);
    topScope = typedScopeCreator.createScope(root, null);
  }

  void clearTypedScope() {
    internalScopeCreator = null;
    typedScopeCreator = null;
    topScope = null;
  }

  /**
   * Regenerates the top scope potentially only for a sub-tree of AST and then
   * copies information for the old global scope.
   *
   * @param compiler The compiler for which the global scope is generated.
   * @param scriptRoot The root of the AST used to generate global scope.
   */
  void patchGlobalTypedScope(AbstractCompiler compiler, Node scriptRoot) {
    Preconditions.checkNotNull(internalScopeCreator);
    internalScopeCreator.patchGlobalScope(topScope, scriptRoot);
  }

  /**
   * Gets the scope creator for typed scopes.
   */
  MemoizedScopeCreator getTypedScopeCreator() {
    return typedScopeCreator;
  }

  /**
   * Gets the global scope, with type information.
   */
  TypedScope getTopScope() {
    return topScope;
  }

  /**
   * Gets additional checking passes that are run always, even in "whitespace only" mode.
   * For very specific cases where processing is required even in a mode which is intended
   * not to have any processing - specifically introduced to support goog.module() usage.
   */
  protected List<PassFactory> getWhitespaceOnlyPasses() {
    return Collections.emptyList();
  }

  /**
   * Gets the checking passes to run.
   *
   * Checking passes revolve around emitting warnings and errors.
   * They also may include pre-processor passes needed to do
   * error analysis more effectively.
   *
   * Clients that only want to analyze code (like IDEs) and not emit
   * code will only run checks and not optimizations.
   */
  protected abstract List<PassFactory> getChecks();

  /**
   * Gets the optimization passes to run.
   *
   * Optimization passes revolve around producing smaller and faster code.
   * They should always run after checking passes.
   */
  protected abstract List<PassFactory> getOptimizations();

  /**
   * Gets a graph of the passes run. For debugging.
   */
  GraphvizGraph getPassGraph() {
    LinkedDirectedGraph<String, String> graph =
        LinkedDirectedGraph.createWithoutAnnotations();
    Iterable<PassFactory> allPasses =
        Iterables.concat(getChecks(), getOptimizations());
    String lastPass = null;
    String loopStart = null;
    for (PassFactory pass : allPasses) {
      String passName = pass.getName();
      int i = 1;
      while (graph.hasNode(passName)) {
        passName = pass.getName() + (i++);
      }
      graph.createNode(passName);

      if (loopStart == null && !pass.isOneTimePass()) {
        loopStart = passName;
      } else if (loopStart != null && pass.isOneTimePass()) {
        graph.connect(lastPass, "loop", loopStart);
        loopStart = null;
      }

      if (lastPass != null) {
        graph.connect(lastPass, "", passName);
      }
      lastPass = passName;
    }
    return graph;
  }

  /**
   * Create a type inference pass.
   */
  final TypeInferencePass makeTypeInference(AbstractCompiler compiler) {
    return new TypeInferencePass(
        compiler, compiler.getReverseAbstractInterpreter(),
        topScope, typedScopeCreator);
  }

  static final InferJSDocInfo makeInferJsDocInfo(AbstractCompiler compiler) {
    return new InferJSDocInfo(compiler);
  }

  /**
   * Create a type-checking pass.
   */
  final TypeCheck makeTypeCheck(AbstractCompiler compiler) {
    return new TypeCheck(
        compiler,
        compiler.getReverseAbstractInterpreter(),
        compiler.getTypeRegistry(),
        topScope,
        typedScopeCreator,
        options.reportMissingOverride)
        .reportMissingProperties(options.enables(
            DiagnosticGroup.forType(TypeCheck.INEXISTENT_PROPERTY)));
  }

  /**
   * Insert the given pass factory before the factory of the given name.
   */
  static final void addPassFactoryBefore(
      List<PassFactory> factoryList, PassFactory factory, String passName) {
    factoryList.add(
        findPassIndexByName(factoryList, passName), factory);
  }

  /**
   * Find a pass factory with the same name as the given one, and replace it.
   */
  static final void replacePassFactory(
      List<PassFactory> factoryList, PassFactory factory) {
    factoryList.set(
        findPassIndexByName(factoryList, factory.getName()), factory);
  }

  /**
   * Throws an exception if no pass with the given name exists.
   */
  private static int findPassIndexByName(
      List<PassFactory> factoryList, String name) {
    for (int i = 0; i < factoryList.size(); i++) {
      if (factoryList.get(i).getName().equals(name)) {
        return i;
      }
    }

    throw new IllegalArgumentException(
        "No factory named '" + name + "' in the factory list");
  }

  /**
   * Find the first pass provider that does not have a delegate.
   */
  final PassConfig getBasePassConfig() {
    PassConfig current = this;
    while (current instanceof PassConfigDelegate) {
      current = ((PassConfigDelegate) current).delegate;
    }
    return current;
  }

  /**
   * Get intermediate state for a running pass config, so it can
   * be paused and started again later.
   */
  protected abstract State getIntermediateState();

  /**
   * An implementation of PassConfig that just proxies all its method calls
   * into an inner class.
   */
  static class PassConfigDelegate extends PassConfig {

    private final PassConfig delegate;

    PassConfigDelegate(PassConfig delegate) {
      super(delegate.options);
      this.delegate = delegate;
    }

    @Override
    protected List<PassFactory> getWhitespaceOnlyPasses() {
      return delegate.getWhitespaceOnlyPasses();
    }

    @Override protected List<PassFactory> getChecks() {
      return delegate.getChecks();
    }

    @Override protected List<PassFactory> getOptimizations() {
      return delegate.getOptimizations();
    }

    @Override MemoizedScopeCreator getTypedScopeCreator() {
      return delegate.getTypedScopeCreator();
    }

    @Override TypedScope getTopScope() {
      return delegate.getTopScope();
    }

    @Override protected State getIntermediateState() {
      return delegate.getIntermediateState();
    }
  }

  /**
   * Intermediate state for a running pass configuration.
   */
  public static class State implements Serializable {
    private static final long serialVersionUID = 1L;

    final Map<String, Integer> cssNames;
    final VariableMap variableMap;
    final VariableMap propertyMap;
    final VariableMap anonymousFunctionNameMap;
    final VariableMap stringMap;
    final FunctionNames functionNames;
    final String idGeneratorMap;

    public State(Map<String, Integer> cssNames, Set<String> exportedNames,
        CrossModuleMethodMotion.IdGenerator crossModuleIdGenerator,
        VariableMap variableMap, VariableMap propertyMap,
        VariableMap anonymousFunctionNameMap,
        VariableMap stringMap, FunctionNames functionNames,
        String idGeneratorMap) {
      this.cssNames = cssNames;
      this.variableMap = variableMap;
      this.propertyMap = propertyMap;
      this.anonymousFunctionNameMap = anonymousFunctionNameMap;
      this.stringMap = stringMap;
      this.idGeneratorMap = idGeneratorMap;
      this.functionNames = functionNames;
    }
  }
}
