/*
 * Copyright 2008 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 static com.google.common.base.Preconditions.checkNotNull;
import static com.google.common.base.Preconditions.checkState;

import com.google.javascript.jscomp.NodeTraversal.AbstractPostOrderCallback;
import com.google.javascript.rhino.JSDocInfo;
import com.google.javascript.rhino.Node;
import java.util.LinkedHashMap;
import java.util.LinkedHashSet;

/**
 * Records all of the symbols and properties that should be exported.
 *
 * <p>Currently applies to: - function foo() {} - var foo = function() {} - foo.bar = function() {}
 * - var FOO = ...; - foo.BAR = ...;
 *
 * <p>FOO = BAR = 5; and var FOO = BAR = 5; are not supported because the annotation is ambiguous to
 * whether it applies to all the variables or only the first one.
 */
class FindExportableNodes extends AbstractPostOrderCallback {

  static final DiagnosticType NON_GLOBAL_ERROR =
      DiagnosticType.error(
          "JSC_NON_GLOBAL_ERROR",
          "@export only applies to symbols/properties defined in the " + "global scope.");

  static final DiagnosticType EXPORT_ANNOTATION_NOT_ALLOWED =
      DiagnosticType.error(
          "JSC_EXPORT_ANNOTATION_NOT_ALLOWED", "@export is not supported on this expression.");

  private final AbstractCompiler compiler;

  /** The set of node with @export annotations and their associated fully qualified names */
  private final LinkedHashMap<String, Node> exports = new LinkedHashMap<>();

  /**
   * The set of class member function nodes with @export annotations and the fully qualified name of
   * the owning class (not including the member fn name).
   */
  private final LinkedHashMap<Node, String> es6ClassExports = new LinkedHashMap<>();

  /**
   * The set of property names associated with @export annotations that do not have an associated
   * fully qualified name.
   */
  private final LinkedHashSet<String> localExports = new LinkedHashSet<>();

  private final boolean allowLocalExports;

  FindExportableNodes(AbstractCompiler compiler, boolean allowLocalExports) {
    this.compiler = compiler;
    this.allowLocalExports = allowLocalExports;
  }

  @Override
  public void visit(NodeTraversal t, Node n, Node parent) {
    JSDocInfo docInfo = n.getJSDocInfo();
    if (docInfo == null || !docInfo.isExport()) {
      return;
    }

    if (parent.isAssign() && (n.isFunction() || n.isClass())) {
      JSDocInfo parentInfo = parent.getJSDocInfo();
      if (parentInfo != null && parentInfo.isExport()) {
        // ScopedAliases produces export annotations on both the function/class
        // node and assign node, we only want to visit the assign node.
        return;
      }
    }

    Mode mode = null;
    String export = null;
    Node context = null;

    switch (n.getToken()) {
      case FUNCTION:
      case CLASS:
        if (parent.isScript()) {
          export = NodeUtil.getName(n);
          context = n;
          mode = Mode.EXPORT;
        }
        break;

      case ASSIGN:
        Node grandparent = parent.getParent();
        if (parent.isExprResult() && !n.getLastChild().isAssign()) {
          if (grandparent != null
              && grandparent.isScript()
              && n.getFirstChild().isQualifiedName()) {
            export = n.getFirstChild().getQualifiedName();
            context = n;
            mode = Mode.EXPORT;
          } else if (allowLocalExports && n.getFirstChild().isGetProp()) {
            Node target = n.getFirstChild();
            export = target.getString();
            mode = Mode.EXTERN;
          }
        }
        break;

      case VAR:
      case LET:
      case CONST:
        if (parent.isScript()) {
          if (n.getFirstChild().hasChildren() && !n.getFirstFirstChild().isAssign()) {
            export = n.getFirstChild().getString();
            context = n;
            mode = Mode.EXPORT;
          }
        }
        break;

      case GETPROP:
        {
          // TODO(b/63582201): currently, the IF body is executed even for code in the global
          // scope, e.g., when the pass looks at code transpiled from ES6 that uses getters.
          // This means that the top-level code we want to rewrite works by accident, only when
          // allowLocalExports happens to be true.
          if (allowLocalExports && parent.isExprResult()) {
            export = n.getString();
            mode = Mode.EXTERN;
          }
          break;
        }

      case MEMBER_FUNCTION_DEF:
        if (parent.getParent().isClass()) {
          String methodOwnerName =
              NodeUtil.getBestLValueName(NodeUtil.getBestLValue(parent.getParent()));
          if (methodOwnerName == null) {
            t.report(n, EXPORT_ANNOTATION_NOT_ALLOWED);
            return;
          }
          es6ClassExports.put(n, methodOwnerName + (n.isStaticMember() ? "" : ".prototype"));
          return;
        }
        // fallthrough

      case STRING_KEY:
      case GETTER_DEF:
      case SETTER_DEF:
        if (allowLocalExports) {
          export = n.getString();
          mode = Mode.EXTERN;
        }
        break;
      default:
        break;
    }

    if (export != null) {
      if (mode == Mode.EXPORT) {
        checkNotNull(context);
        exports.put(export, context);
      } else {
        checkState(context == null);
        checkState(mode == Mode.EXTERN);
        checkState(!export.isEmpty());
        localExports.add(export);
      }
    } else if (!(n.isGetProp() && parent.isExprResult())) {
      // Silently ignore exports of the form:
      // /** @export */ Foo.prototype.myprop;
      // They are currently used on interfaces and records and have no effect.
      // If we cleanup the code base in the future, we can warn again.

      // Don't produce extra warnings for functions values of object literals
      if (!n.isFunction() || !NodeUtil.mayBeObjectLitKey(parent)) {
        if (allowLocalExports) {
          compiler.report(JSError.make(n, EXPORT_ANNOTATION_NOT_ALLOWED));
        } else {
          compiler.report(JSError.make(n, NON_GLOBAL_ERROR));
        }
      }
    }
  }

  LinkedHashMap<String, Node> getExports() {
    return exports;
  }

  LinkedHashSet<String> getLocalExports() {
    return localExports;
  }

  LinkedHashMap<Node, String> getEs6ClassExports() {
    return es6ClassExports;
  }

  static enum Mode {
    EXPORT,
    EXTERN
  }
}

@@ -1591,25 +1591,25 @@
 t only a
-pplies to
+llowed on
  symbols
@@ -1639,13 +1639,8 @@
 the 
-%22 + %22
 glob
@@ -1648,16 +1648,181 @@
 l scope.
+%5Cn%22%0A              + %22Convert to a global definition or enable --export_local_property_definitions/%22%0A              + %22 options.setExportLocalPropertyDefinitions(true)
 %22);%0A%0A  s

Add more details about how to fix the JSC_NON_GLOBAL_ERROR message