/*
    * Licensed to the Apache Software Foundation (ASF) under one
    * or more contributor license agreements.  See the NOTICE file
    * distributed with this work for additional information
    * regarding copyright ownership.  The ASF licenses this file
    * to you 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 org.apache.maven.shared.scriptinterpreter;
  
  import java.io.Closeable;
  import java.io.File;
  import java.io.IOException;
  import java.io.PrintStream;
  import java.nio.file.Files;
  import java.util.HashMap;
  import java.util.LinkedHashMap;
  import java.util.List;
  import java.util.Locale;
  import java.util.Map;
  
  import org.apache.commons.io.FilenameUtils;
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  
  /**
   * Runs pre-/post-build hook scripts.
   *
   * @author Benjamin Bentmann
   */
  public class ScriptRunner implements Closeable {
  
      private static final Object LOCK = new Object();
  
      private static final Logger LOG = LoggerFactory.getLogger(ScriptRunner.class);
  
      /**
       * The supported script interpreters, indexed by the lower-case file extension of their associated script files,
       * never <code>null</code>.
       */
      private final Map<String, ScriptInterpreter> scriptInterpreters;
  
      /**
       * The common set of global variables to pass into the script interpreter, never <code>null</code>.
       */
      private final Map<String, Object> globalVariables;
  
      /**
       * The file encoding of the hook scripts or <code>null</code> to use platform encoding.
       */
      private String encoding;
  
      /**
       * Creates a new script runner with BSH and Groovy interpreters.
       */
      public ScriptRunner() {
          scriptInterpreters = new LinkedHashMap<>();
          scriptInterpreters.put("bsh", new BeanShellScriptInterpreter());
          scriptInterpreters.put("groovy", new GroovyScriptInterpreter());
          globalVariables = new HashMap<>();
      }
  
      /**
       * Add new script Interpreter
       *
       * @param id The Id of interpreter
       * @param scriptInterpreter the Script Interpreter implementation
       */
      public void addScriptInterpreter(String id, ScriptInterpreter scriptInterpreter) {
          scriptInterpreters.put(id, scriptInterpreter);
      }
  
      /**
       * Sets a global variable for the script interpreter.
       *
       * @param name The name of the variable, must not be <code>null</code>.
       * @param value The value of the variable, may be <code>null</code>.
       */
      public void setGlobalVariable(String name, Object value) {
          this.globalVariables.put(name, value);
      }
  
      /**
       * Sets the additional class path for the hook scripts. Note that the provided list is copied, so any later changes
       * will not affect the scripts.
       *
       * @param classPath The additional class path for the script interpreter, may be <code>null</code> or empty if only
       * the plugin realm should be used for the script evaluation. If specified, this class path will precede the
       * artifacts from the plugin class path.
      */
     public void setClassPath(List<String> classPath) {
         if (classPath != null && !classPath.isEmpty()) {
             scriptInterpreters.values().forEach(scriptInterpreter -> scriptInterpreter.setClassPath(classPath));
         }
     }
 
     /**
      * Sets the file encoding of the hook scripts.
      *
      * @param encoding The file encoding of the hook scripts, may be <code>null</code> or empty to use the platform's
      *                 default encoding.
      */
     public void setScriptEncoding(String encoding) {
         this.encoding = encoding != null && !encoding.isEmpty() ? encoding : null;
     }
 
     /**
      * Runs the specified hook script (after resolution).
      *
      * @param scriptDescription The description of the script to use for logging, must not be <code>null</code>.
      * @param basedir The base directory of the project, must not be <code>null</code>.
      * @param relativeScriptPath The path to the script relative to the project base directory, may be <code>null</code>
      *            to skip the script execution and may not have extensions (resolution will search).
      * @param context The key-value storage used to share information between hook scripts, may be <code>null</code>.
      * @param logger The logger to redirect the script output to, may be <code>null</code> to use stdout/stderr.
      * @throws IOException If an I/O error occurred while reading the script file.
      * @throws ScriptException If the script did not return <code>true</code> of threw an exception.
      */
     public void run(
             final String scriptDescription,
             final File basedir,
             final String relativeScriptPath,
             final Map<String, ?> context,
             final ExecutionLogger logger)
             throws IOException, ScriptException {
         if (relativeScriptPath == null) {
             LOG.debug("{}: relativeScriptPath is null, not executing script", scriptDescription);
             return;
         }
 
         final File scriptFile = resolveScript(new File(basedir, relativeScriptPath));
 
         if (!scriptFile.exists()) {
             LOG.debug(
                     "{} : no script '{}' found in directory {}",
                     scriptDescription,
                     relativeScriptPath,
                     basedir.getAbsolutePath());
             return;
         }
 
         executeRun(scriptDescription, scriptFile, context, logger);
     }
 
     /**
      * Runs the specified hook script.
      *
      * @param scriptDescription The description of the script to use for logging, must not be <code>null</code>.
      * @param scriptFile The path to the script, may be <code>null</code> to skip the script execution.
      * @param context The key-value storage used to share information between hook scripts, may be <code>null</code>.
      * @param logger The logger to redirect the script output to, may be <code>null</code> to use stdout/stderr.
      * @throws IOException         If an I/O error occurred while reading the script file.
      * @throws ScriptException If the script did not return <code>true</code> of threw an exception.
      */
     public void run(
             final String scriptDescription, File scriptFile, final Map<String, ?> context, final ExecutionLogger logger)
             throws IOException, ScriptException {
 
         if (!scriptFile.exists()) {
             LOG.debug("{} : script file not found in directory {}", scriptDescription, scriptFile.getAbsolutePath());
             return;
         }
 
         executeRun(scriptDescription, scriptFile, context, logger);
     }
 
     private void executeRun(
             final String scriptDescription, File scriptFile, final Map<String, ?> context, final ExecutionLogger logger)
             throws IOException, ScriptException {
         ScriptInterpreter interpreter = getInterpreter(scriptFile);
         if (LOG.isDebugEnabled()) {
             String name = interpreter.getClass().getName();
             name = name.substring(name.lastIndexOf('.') + 1);
             LOG.debug("Running script with {} :{}", name, scriptFile);
         }
 
         String script;
         try {
             byte[] bytes = Files.readAllBytes(scriptFile.toPath());
             if (encoding != null) {
                 script = new String(bytes, encoding);
             } else {
                 script = new String(bytes);
             }
         } catch (IOException e) {
             String errorMessage =
                     "error reading " + scriptDescription + " " + scriptFile.getPath() + ", " + e.getMessage();
             throw new IOException(errorMessage, e);
         }
 
         Object result;
         try {
             if (logger != null) {
                 logger.consumeLine("Running " + scriptDescription + ": " + scriptFile);
             }
 
             PrintStream out = (logger != null) ? logger.getPrintStream() : null;
 
             Map<String, Object> scriptVariables = new HashMap<>(this.globalVariables);
             scriptVariables.put("basedir", scriptFile.getParentFile());
             scriptVariables.put("context", context);
 
             synchronized (LOCK) {
                 result = interpreter.evaluateScript(script, scriptVariables, out);
             }
             if (logger != null) {
                 logger.consumeLine("Finished " + scriptDescription + ": " + scriptFile);
             }
         } catch (ScriptEvaluationException e) {
             Throwable t = (e.getCause() != null) ? e.getCause() : e;
             if (logger != null) {
                 t.printStackTrace(logger.getPrintStream());
             }
             throw e;
         }
 
         if (!(result == null || Boolean.parseBoolean(String.valueOf(result)))) {
             throw new ScriptReturnException("The " + scriptDescription + " returned " + result + ".", result);
         }
     }
 
     /**
      * Gets the effective path to the specified script. For convenience, we allow to specify a script path as "verify"
      * and have the plugin auto-append the file extension to search for "verify.bsh" and "verify.groovy".
      *
      * @param scriptFile The script file to resolve, may be <code>null</code>.
      * @return The effective path to the script file or <code>null</code> if the input was <code>null</code>.
      */
     private File resolveScript(File scriptFile) {
         if (scriptFile != null && !scriptFile.exists()) {
             for (String ext : this.scriptInterpreters.keySet()) {
                 File candidateFile = new File(scriptFile.getPath() + '.' + ext);
                 if (candidateFile.exists()) {
                     scriptFile = candidateFile;
                     break;
                 }
             }
         }
         return scriptFile;
     }
 
     /**
      * Determines the script interpreter for the specified script file by looking at its file extension. In this
      * context, file extensions are considered case-insensitive. For backward compatibility with plugin versions 1.2-,
      * the BeanShell interpreter will be used for any unrecognized extension.
      *
      * @param scriptFile The script file for which to determine an interpreter, must not be <code>null</code>.
      * @return The script interpreter for the file, never <code>null</code>.
      */
     private ScriptInterpreter getInterpreter(File scriptFile) {
         String ext = FilenameUtils.getExtension(scriptFile.getName()).toLowerCase(Locale.ENGLISH);
         ScriptInterpreter interpreter = scriptInterpreters.get(ext);
         if (interpreter == null) {
             interpreter = scriptInterpreters.get("bsh");
         }
         return interpreter;
     }
 
     /**
      * Closes this script interpreter and releases any system resources associated with it.
      *
      * @throws IOException if an I/O error occurs.
      */
     @Override
     public void close() throws IOException {
         for (ScriptInterpreter scriptInterpreter : scriptInterpreters.values()) {
             scriptInterpreter.close();
         }
         scriptInterpreters.clear();
     }
 }