/*
    * Copyright (c) 2002-2026 Gargoyle Software 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
    * https://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.htmlunit.javascript;
  
  import static org.htmlunit.BrowserVersionFeatures.JS_ARRAY_SORT_ACCEPTS_INCONSISTENT_COMPERATOR;
  import static org.htmlunit.BrowserVersionFeatures.JS_PROPERTY_DESCRIPTOR_NAME;
  
  import java.io.Serializable;
  import java.util.function.Consumer;
  
  import org.htmlunit.BrowserVersion;
  import org.htmlunit.ScriptException;
  import org.htmlunit.ScriptPreProcessor;
  import org.htmlunit.WebClient;
  import org.htmlunit.corejs.javascript.Callable;
  import org.htmlunit.corejs.javascript.CompilerEnvirons;
  import org.htmlunit.corejs.javascript.Context;
  import org.htmlunit.corejs.javascript.ContextAction;
  import org.htmlunit.corejs.javascript.ContextFactory;
  import org.htmlunit.corejs.javascript.ErrorReporter;
  import org.htmlunit.corejs.javascript.Evaluator;
  import org.htmlunit.corejs.javascript.EvaluatorException;
  import org.htmlunit.corejs.javascript.Function;
  import org.htmlunit.corejs.javascript.Script;
  import org.htmlunit.corejs.javascript.VarScope;
  import org.htmlunit.corejs.javascript.debug.Debugger;
  import org.htmlunit.html.HtmlElement;
  import org.htmlunit.html.HtmlPage;
  
  /**
   * ContextFactory that supports termination of scripts if they exceed a timeout. Based on example from
   * <a href="http://www.mozilla.org/rhino/apidocs/org/mozilla/javascript/ContextFactory.html">ContextFactory</a>.
   *
   * @author Andre Soereng
   * @author Ahmed Ashour
   * @author Marc Guillemot
   * @author Ronald Brill
   */
  public class HtmlUnitContextFactory extends ContextFactory {
  
      private static final int INSTRUCTION_COUNT_THRESHOLD = 10_000;
  
      private final WebClient webClient_;
      private final BrowserVersion browserVersion_;
      private long timeout_;
      private Debugger debugger_;
      private boolean deminifyFunctionCode_;
  
      /**
       * Creates a new instance of HtmlUnitContextFactory.
       *
       * @param webClient the web client using this factory
       */
      public HtmlUnitContextFactory(final WebClient webClient) {
          super();
          webClient_ = webClient;
          browserVersion_ = webClient.getBrowserVersion();
      }
  
      /**
       * Sets the number of milliseconds a script is allowed to execute before
       * being terminated. A value of 0 or less means no timeout.
       *
       * @param timeout the timeout value
       */
      public void setTimeout(final long timeout) {
          timeout_ = timeout;
      }
  
      /**
       * Returns the number of milliseconds a script is allowed to execute before
       * being terminated. A value of 0 or less means no timeout.
       *
       * @return the timeout value (default value is <code>0</code>)
       */
      public long getTimeout() {
          return timeout_;
      }
  
      /**
       * Sets the JavaScript debugger to use to receive JavaScript execution debugging information.
       * The HtmlUnit default implementation ({@link DebuggerImpl}, {@link DebugFrameImpl}) may be
       * used, or a custom debugger may be used instead. By default, no debugger is used.
       *
       * @param debugger the JavaScript debugger to use (maybe {@code null})
       */
      public void setDebugger(final Debugger debugger) {
         debugger_ = debugger;
     }
 
     /**
      * Returns the JavaScript debugger to use to receive JavaScript execution debugging information.
      * By default, no debugger is used, and this method returns {@code null}.
      *
      * @return the JavaScript debugger to use to receive JavaScript execution debugging information
      */
     public Debugger getDebugger() {
         return debugger_;
     }
 
     /**
      * Configures if the code of <code>new Function("...some code...")</code> should be deminified to be more readable
      * when using the debugger. This is a small performance cost.
      * @param deminify the new value
      */
     public void setDeminifyFunctionCode(final boolean deminify) {
         deminifyFunctionCode_ = deminify;
     }
 
     /**
      * Indicates code of calls like <code>new Function("...some code...")</code> should be deminified to be more
      * readable when using the debugger.
      * @return the de-minify status
      */
     public boolean isDeminifyFunctionCode() {
         return deminifyFunctionCode_;
     }
 
     /**
      * Custom context to store execution time and handle timeouts.
      */
     private class TimeoutContext extends Context {
         private long startTime_;
 
         protected TimeoutContext(final ContextFactory factory) {
             super(factory);
         }
 
         public void startClock() {
             startTime_ = System.currentTimeMillis();
         }
 
         public void terminateScriptIfNecessary() {
             if (timeout_ > 0) {
                 final long currentTime = System.currentTimeMillis();
                 if (currentTime - startTime_ > timeout_) {
                     // Terminate script by throwing an Error instance to ensure that the
                     // script will never get control back through catch or finally.
                     throw new TimeoutError(timeout_, currentTime - startTime_);
                 }
             }
         }
 
         @Override
         protected Script compileString(String source, final Evaluator compiler,
                 final ErrorReporter compilationErrorReporter, final String sourceName,
                 final int lineno, final Object securityDomain,
                 final Consumer<CompilerEnvirons> compilerEnvironsProcessor) {
 
             // this method gets called by Context.compileString and by ScriptRuntime.evalSpecial
             // which is used for window.eval. We have to take care in which case we are.
             final boolean isWindowEval = compiler != null;
 
             // Remove HTML comments around the source if needed
             if (!isWindowEval) {
 
                 // **** Memory Optimization ****
                 // final String sourceCodeTrimmed = source.trim();
                 // if (sourceCodeTrimmed.startsWith("<!--")) {
                 // **** Memory Optimization ****
                 // do not trim because this will create a copy of the
                 // whole string (usually large for libs like jQuery
                 // if there is whitespace to trim (e.g. cr at end)
                 final int length = source.length();
                 int start = 0;
                 while ((start < length) && (source.charAt(start) <= ' ')) {
                     start++;
                 }
                 if (start + 3 < length
                         && source.charAt(start++) == '<'
                         && source.charAt(start++) == '!'
                         && source.charAt(start++) == '-'
                         && source.charAt(start++) == '-') {
                     source = source.replaceFirst("<!--", "// <!--");
                 }
             }
 
             // Pre process the source code
             final HtmlPage page = (HtmlPage) Context.getCurrentContext()
                 .getThreadLocal(JavaScriptEngine.KEY_STARTING_PAGE);
             source = preProcess(page, source, sourceName, lineno, null);
 
             return super.compileString(source, compiler, compilationErrorReporter,
                     sourceName, lineno, securityDomain, compilerEnvironsProcessor);
         }
 
         @Override
         protected Function compileFunction(final VarScope scope, String source,
                 final Evaluator compiler, final ErrorReporter compilationErrorReporter,
                 final String sourceName, final int lineno, final Object securityDomain) {
 
             if (deminifyFunctionCode_) {
                 final Function f = super.compileFunction(scope, source, compiler,
                         compilationErrorReporter, sourceName, lineno, securityDomain);
                 source = decompileFunction(f, 4).trim().replace("\n    ", "\n");
             }
             return super.compileFunction(scope, source, compiler,
                     compilationErrorReporter, sourceName, lineno, securityDomain);
         }
     }
 
     /**
      * Pre process the specified source code in the context of the given page using the processor specified
      * in the {@link WebClient}. This method delegates to the pre processor handler specified in the
      * <code>WebClient</code>. If no pre processor handler is defined, the original source code is returned
      * unchanged.
      * @param htmlPage the page
      * @param sourceCode the code to process
      * @param sourceName a name for the chunk of code (used in error messages)
      * @param lineNumber the line number of the source code
      * @param htmlElement the HTML element that will act as the context
      * @return the source code after being pre processed
      * @see org.htmlunit.ScriptPreProcessor
      */
     protected String preProcess(
         final HtmlPage htmlPage, final String sourceCode, final String sourceName, final int lineNumber,
         final HtmlElement htmlElement) {
 
         String newSourceCode = sourceCode;
         final ScriptPreProcessor preProcessor = webClient_.getScriptPreProcessor();
         if (preProcessor != null) {
             newSourceCode = preProcessor.preProcess(htmlPage, sourceCode, sourceName, lineNumber, htmlElement);
             if (newSourceCode == null) {
                 newSourceCode = "";
             }
         }
         return newSourceCode;
     }
 
     /**
      * {@inheritDoc}
      */
     @Override
     protected Context makeContext() {
         final TimeoutContext cx = new TimeoutContext(this);
         cx.setLanguageVersion(Context.VERSION_ES6);
         cx.setLocale(browserVersion_.getBrowserLocale());
         cx.setTimeZone(browserVersion_.getSystemTimezone());
 
         // make sure no java classes are usable from js
         cx.setClassShutter(fullClassName -> false);
 
         // Use pure interpreter mode to get observeInstructionCount() callbacks.
         cx.setInterpretedMode(true);
 
         // Set threshold on how often we want to receive the callbacks
         cx.setInstructionObserverThreshold(INSTRUCTION_COUNT_THRESHOLD);
 
         cx.setErrorReporter(new HtmlUnitErrorReporter(webClient_.getJavaScriptErrorListener()));
         // We don't want to wrap String & Co.
         cx.getWrapFactory().setJavaPrimitiveWrap(false);
 
         if (debugger_ != null) {
             cx.setDebugger(debugger_, null);
         }
 
         cx.setMaximumInterpreterStackDepth(5_000);
 
         return cx;
     }
 
     /**
      * Run-time calls this when instruction counting is enabled and the counter
      * reaches limit set by setInstructionObserverThreshold(). A script can be
      * terminated by throwing an Error instance here.
      *
      * @param cx the context calling us
      * @param instructionCount amount of script instruction executed since last call to observeInstructionCount
      */
     @Override
     protected void observeInstructionCount(final Context cx, final int instructionCount) {
         final TimeoutContext tcx = (TimeoutContext) cx;
         tcx.terminateScriptIfNecessary();
     }
 
     /**
      * {@inheritDoc}
      */
     @Override
     protected Object doTopCall(final Callable callable,
             final Context cx, final VarScope scope,
             final Object thisObj, final Object[] args) {
 
         final TimeoutContext tcx = (TimeoutContext) cx;
         tcx.startClock();
         return super.doTopCall(callable, cx, scope, thisObj, args);
     }
 
     /**
      * {@inheritDoc}
      */
     @Override
     protected Object doTopCall(final Script script,
             final Context cx, final VarScope scope,
             final Object thisObj) {
 
         final TimeoutContext tcx = (TimeoutContext) cx;
         tcx.startClock();
         return super.doTopCall(script, cx, scope, thisObj);
     }
 
     /**
      * Same as {@link ContextFactory}{@link #call(ContextAction)} but with handling
      * of some exceptions.
      *
      * @param <T> return type of the action
      * @param action the contextAction
      * @param page the page
      * @return the result of the call
      */
     public final <T> T callSecured(final ContextAction<T> action, final HtmlPage page) {
         try {
             return call(action);
         }
         catch (final StackOverflowError e) {
             webClient_.getJavaScriptErrorListener().scriptException(page, new ScriptException(page, e));
             return null;
         }
     }
 
     /**
      * {@inheritDoc}
      */
     @Override
     protected boolean hasFeature(final Context cx, final int featureIndex) {
         return switch (featureIndex) {
             case Context.FEATURE_RESERVED_KEYWORD_AS_IDENTIFIER,
                  Context.FEATURE_OLD_UNDEF_NULL_THIS,
                  Context.FEATURE_LITTLE_ENDIAN,
                  Context.FEATURE_LOCATION_INFORMATION_IN_ERROR,
                  Context.FEATURE_INTL_402,
                  Context.FEATURE_HTMLUNIT_FN_ARGUMENTS_IS_RO_VIEW -> true;
             case Context.FEATURE_E4X -> false;
             case Context.FEATURE_HTMLUNIT_MEMBERBOX_NAME -> browserVersion_.hasFeature(JS_PROPERTY_DESCRIPTOR_NAME);
             case Context.FEATURE_HTMLUNIT_ARRAY_SORT_COMPERATOR_ACCEPTS_BOOL ->
                 browserVersion_.hasFeature(JS_ARRAY_SORT_ACCEPTS_INCONSISTENT_COMPERATOR);
             default -> super.hasFeature(cx, featureIndex);
         };
     }
 
     private static final class HtmlUnitErrorReporter implements ErrorReporter, Serializable {
 
         private final JavaScriptErrorListener javaScriptErrorListener_;
 
         /**
          * Ctor.
          *
          * @param javaScriptErrorListener the listener to be used
          */
         HtmlUnitErrorReporter(final JavaScriptErrorListener javaScriptErrorListener) {
             javaScriptErrorListener_ = javaScriptErrorListener;
         }
 
         /**
          * Logs a warning.
          *
          * @param message the message to be displayed
          * @param sourceName the name of the source file
          * @param line the line number
          * @param lineSource the source code that failed
          * @param lineOffset the line offset
          */
         @Override
         public void warning(
                 final String message, final String sourceName, final int line,
                 final String lineSource, final int lineOffset) {
             javaScriptErrorListener_.warn(message, sourceName, line, lineSource, lineOffset);
         }
 
         /**
          * Logs an error.
          *
          * @param message the message to be displayed
          * @param sourceName the name of the source file
          * @param line the line number
          * @param lineSource the source code that failed
          * @param lineOffset the line offset
          */
         @Override
         public void error(final String message, final String sourceName, final int line,
                 final String lineSource, final int lineOffset) {
             // no need to log here, this is only used to create the exception
             // gets logged if not catched later on
             throw new EvaluatorException(message, sourceName, line, lineSource, lineOffset);
         }
 
         /**
          * Logs a runtime error.
          *
          * @param message the message to be displayed
          * @param sourceName the name of the source file
          * @param line the line number
          * @param lineSource the source code that failed
          * @param lineOffset the line offset
          * @return an evaluator exception
          */
         @Override
         public EvaluatorException runtimeError(
                 final String message, final String sourceName, final int line,
                 final String lineSource, final int lineOffset) {
             // no need to log here, this is only used to create the exception
             // gets logged if not catched later on
             return new EvaluatorException(message, sourceName, line, lineSource, lineOffset);
         }
     }
 }