/*
 * 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.jmeter.functions.gui;

import java.awt.BorderLayout;
import java.awt.FlowLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.io.IOException;
import java.io.Reader;
import java.io.StringReader;
import java.lang.reflect.InvocationTargetException;
import java.util.Arrays;
import java.util.List;
import java.util.stream.Collectors;

import javax.swing.AbstractAction;
import javax.swing.Action;
import javax.swing.InputMap;
import javax.swing.JButton;
import javax.swing.JComponent;
import javax.swing.JDialog;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JRootPane;
import javax.swing.event.ChangeEvent;
import javax.swing.event.ChangeListener;

import org.apache.commons.lang3.exception.ExceptionUtils;
import org.apache.jmeter.config.Argument;
import org.apache.jmeter.config.Arguments;
import org.apache.jmeter.config.gui.ArgumentsPanel;
import org.apache.jmeter.engine.util.CompoundVariable;
import org.apache.jmeter.functions.Function;
import org.apache.jmeter.gui.action.ActionNames;
import org.apache.jmeter.gui.action.ActionRouter;
import org.apache.jmeter.gui.action.Help;
import org.apache.jmeter.gui.action.KeyStrokes;
import org.apache.jmeter.gui.util.JSyntaxTextArea;
import org.apache.jmeter.gui.util.JTextScrollPane;
import org.apache.jmeter.testelement.property.PropertyIterator;
import org.apache.jmeter.threads.JMeterContext;
import org.apache.jmeter.threads.JMeterContextService;
import org.apache.jmeter.threads.JMeterThread;
import org.apache.jmeter.threads.JMeterVariables;
import org.apache.jmeter.threads.ThreadGroup;
import org.apache.jmeter.util.JMeterUtils;
import org.apache.jmeter.util.LocaleChangeEvent;
import org.apache.jmeter.util.LocaleChangeListener;
import org.apache.jorphan.documentation.VisibleForTesting;
import org.apache.jorphan.gui.ComponentUtil;
import org.apache.jorphan.gui.GuiUtils;
import org.apache.jorphan.gui.JLabeledChoice;
import org.apache.jorphan.gui.JLabeledTextField;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import net.miginfocom.swing.MigLayout;

public class FunctionHelper extends JDialog implements ActionListener, ChangeListener, LocaleChangeListener {
    private static final long serialVersionUID = 240L;

    private static final Logger log = LoggerFactory.getLogger(FunctionHelper.class);

    private static final String GENERATE = "GENERATE";

    private static final String RESET_VARS = "RESET_VARS";

    private static final String FUNCTION_PREFIX = "__";

    private JLabeledChoice functionList;

    private ArgumentsPanel parameterPanel;

    private JLabeledTextField cutPasteFunction;

    private JSyntaxTextArea resultTextArea;

    private JSyntaxTextArea variablesTextArea;

    private JMeterVariables jMeterVariables = new JMeterVariables();

    @VisibleForTesting
    public FunctionHelper() {
        super();
    }

    public FunctionHelper(JFrame parent) {
        super(parent, JMeterUtils.getResString("function_helper_title"), false); //$NON-NLS-1$
        init();
        JMeterUtils.addLocaleChangeListener(this);
    }

    /**
     * Allow Dialog to be closed by ESC key
     */
    @Override
    protected JRootPane createRootPane() {
        JRootPane rootPane = new JRootPane();
        javax.swing.Action escapeAction = new AbstractAction("ESCAPE") {

            private static final long serialVersionUID = -4036804004190858925L;

            @Override
            public void actionPerformed(ActionEvent actionEvent) {
                setVisible(false);
            }
        };
        rootPane.getActionMap().put(escapeAction.getValue(Action.NAME), escapeAction);
        InputMap inputMap = rootPane.getInputMap(JComponent.WHEN_IN_FOCUSED_WINDOW);
        inputMap.put(KeyStrokes.ESC, escapeAction.getValue(Action.NAME));
        return rootPane;
    }

    private void init() { // WARNING: called from ctor so must not be overridden (i.e. must be private or final)
        parameterPanel = new ArgumentsPanel(true,JMeterUtils.getResString("function_params")); //$NON-NLS-1$
        initializeFunctionList();
        this.getContentPane().setLayout(new BorderLayout(10, 10));
        JPanel comboPanel = new JPanel(new FlowLayout(FlowLayout.CENTER));
        comboPanel.add(functionList);
        JButton helpButton = new JButton(JMeterUtils.getResString("help")); //$NON-NLS-1$
        helpButton.addActionListener(new HelpListener());
        comboPanel.add(helpButton);
        this.getContentPane().add(comboPanel, BorderLayout.NORTH);
        this.getContentPane().add(parameterPanel, BorderLayout.CENTER);
        JPanel resultsPanel = new JPanel(new MigLayout("fillx, wrap 2", "[][fill,grow]"));
        JPanel generatePanel = new JPanel(new FlowLayout(FlowLayout.CENTER));
        cutPasteFunction = new JLabeledTextField(JMeterUtils.getResString("cut_paste_function"), 35, null, false); //$NON-NLS-1$
        cutPasteFunction.setEnabled(false);
        generatePanel.add(cutPasteFunction);
        JButton generateButton = new JButton(JMeterUtils.getResString("generate")); //$NON-NLS-1$
        generateButton.setActionCommand(GENERATE);
        generateButton.addActionListener(this);
        generatePanel.add(generateButton);

        JButton resetVarsButton = new JButton(JMeterUtils.getResString("function_helper_reset_vars")); //$NON-NLS-1$
        resetVarsButton.setActionCommand(RESET_VARS);
        resetVarsButton.addActionListener(this);
        generatePanel.add(resetVarsButton);

        resultTextArea = JSyntaxTextArea.getInstance(5,60);
        resultTextArea.setEditable(false);
        resultTextArea.setToolTipText(JMeterUtils.getResString("function_helper_dialog_result_warn"));

        variablesTextArea = JSyntaxTextArea.getInstance(10,60);
        variablesTextArea.setEditable(false);

        resultsPanel.add(generatePanel, "span 2");
        JTextScrollPane resultTextAreaJSP = JTextScrollPane.getInstance(resultTextArea);
        resultsPanel.add(JMeterUtils.labelFor(resultTextAreaJSP, "result_function"));
        resultsPanel.add(resultTextAreaJSP);
        JTextScrollPane variablesTextAreaJSP = JTextScrollPane.getInstance(variablesTextArea);
        resultsPanel.add(JMeterUtils.labelFor(variablesTextAreaJSP, "function_helper_dialog_variables"));
        resultsPanel.add(variablesTextAreaJSP);

        this.getContentPane().add(resultsPanel, BorderLayout.SOUTH);
        this.pack();
        ComponentUtil.centerComponentInWindow(this);
    }

    private void initializeFunctionList() {
        String[] functionNames = CompoundVariable.getFunctionNames();
        Arrays.sort(functionNames, String::compareToIgnoreCase);
        functionList = new JLabeledChoice(JMeterUtils.getResString("choose_function"), //$NON-NLS-1$
                Arrays.stream(functionNames).map(
                        e -> e.substring(FUNCTION_PREFIX.length())).collect(Collectors.toList()).toArray(new String[0]));
        functionList.addChangeListener(this);
    }

    @Override
    public void stateChanged(ChangeEvent event) {
        try {
            initParameterPanel();
            getContentPane().remove(parameterPanel);
            this.pack();
            getContentPane().add(parameterPanel, BorderLayout.CENTER);
            this.pack();
            this.validate();
            resultTextArea.setText("");
            this.repaint();
        } catch (InstantiationException | IllegalAccessException ex) {
            log.info("Exception during stateChanged", ex);
        }
    }

    /**
     * @throws InstantiationException if function instantiation fails
     * @throws IllegalAccessException if function instantiation fails
     */
    protected void initParameterPanel() throws InstantiationException, IllegalAccessException {
        Arguments args = new Arguments();
        Function function;
        String functionName = getFunctionName(functionList.getText());
        try {
            function = CompoundVariable.getFunctionClass(functionName)
                    .getDeclaredConstructor()
                    .newInstance();
        } catch (InvocationTargetException | NoSuchMethodException e) {
            InstantiationException ex = new InstantiationException("Unable to instantiate " + functionName);
            ex.initCause(e instanceof InvocationTargetException ? e.getCause() : e);
            throw ex;
        }
        List<String> argumentDesc = function.getArgumentDesc();
        for (String help : argumentDesc) {
            args.addArgument(help, ""); //$NON-NLS-1$
        }
        parameterPanel.configure(args);
        parameterPanel.revalidate();
    }

    /**
     * @param text Function name without __ prefix
     * @return String function name with __ prefix
     */
    private static final String getFunctionName(String text) {
        return FUNCTION_PREFIX+text;
    }

    @Override
    public void actionPerformed(ActionEvent e) {
        String actionCommand = e.getActionCommand();
        if(GENERATE.equals(actionCommand)) {
            String functionName = getFunctionName(functionList.getText());
            Arguments args = (Arguments) parameterPanel.createTestElement();
            String functionCall = buildFunctionCallString(functionName, args);
            cutPasteFunction.setText(functionCall);
            cutPasteFunction.setEnabled(true);
            GuiUtils.copyTextToClipboard(cutPasteFunction.getText());
            CompoundVariable function = new CompoundVariable(functionCall);
            JMeterContext threadContext = JMeterContextService.getContext();
            threadContext.setVariables(jMeterVariables);
            threadContext.setThreadNum(1);
            threadContext.getVariables().put(JMeterThread.LAST_SAMPLE_OK, "true");
            ThreadGroup threadGroup = new ThreadGroup();
            threadGroup.setName("FunctionHelper-Dialog-ThreadGroup");
            threadContext.setThreadGroup(threadGroup);

            try {
                resultTextArea.setText(function.execute().trim());
            } catch(Exception ex) {
                log.error("Error calling function {}", functionCall, ex);
                resultTextArea.setText(ex.getMessage() + ", \nstacktrace:\n "+
                        ExceptionUtils.getStackTrace(ex));
                resultTextArea.setCaretPosition(0);
            }

            variablesTextArea.setText(variablesToString(jMeterVariables));
        } else {
            jMeterVariables = new JMeterVariables();
            variablesTextArea.setText(variablesToString(jMeterVariables));
        }
    }

    private static String variablesToString(JMeterVariables jMeterVariables) {
        StringBuilder sb = new StringBuilder();
        jMeterVariables.entrySet().forEach(e->sb.append(e.getKey()).append("=").append(e.getValue()).append("\r\n"));
        return sb.toString();
    }

    @VisibleForTesting
    static String buildFunctionCallString(String functionName, Arguments args) {
        StringBuilder functionCall = new StringBuilder("${");
        functionCall.append(functionName);
        if (args.getArguments().size() > 0) {
            functionCall.append("(");
            PropertyIterator iter = args.iterator();
            boolean first = true;
            while (iter.hasNext()) {
                Argument arg = (Argument) iter.next().getObjectValue();
                if (!first) {
                    functionCall.append(",");
                }
                functionCall.append(escapeCommata(arg.getValue()));
                first = false;
            }
            functionCall.append(")");
        }
        functionCall.append("}");
        return functionCall.toString();
    }

    private static final char ANY_NORMAL_CHAR = ' ';

    /**
     * Escape commata that are in the argument but "outside" of variable replacement structures.
     *
     * @param arg string that should be escaped
     * @return escaped string
     */
    private static String escapeCommata(String arg) {
        int level = 0;
        StringBuilder result = new StringBuilder(arg.length());
        try (Reader r = new StringReader(arg)) {
            int c;
            char lastChar = ANY_NORMAL_CHAR;
            while ((c = r.read()) != -1) {
                char nextChar = (char) c;
                if (lastChar == '\\') {
                    lastChar = ANY_NORMAL_CHAR;
                } else if (lastChar == '$' && nextChar == '{') {
                    level++;
                    lastChar = ANY_NORMAL_CHAR;
                } else if (nextChar == '}') {
                    level--;
                    lastChar = ANY_NORMAL_CHAR;
                } else if (nextChar == ',' && level == 0) {
                    result.append('\\');
                    lastChar = ANY_NORMAL_CHAR;
                } else {
                    lastChar = nextChar;
                }
                result.append(nextChar);
            }
        } catch (IOException e) {
            log.warn("Can't escape commata in input string: {}", arg, e);
            return arg;
        }
        return result.toString();
    }

    private class HelpListener implements ActionListener {
        @Override
        public void actionPerformed(ActionEvent e) {
            String[] source = new String[] { Help.HELP_FUNCTIONS, getFunctionName(functionList.getText()) };
            ActionRouter.getInstance().doActionNow(
                    new ActionEvent(source, e.getID(), ActionNames.HELP));

        }
    }

    @Override
    public void localeChanged(LocaleChangeEvent event) {
        setTitle(JMeterUtils.getResString("function_helper_title")); //$NON-NLS-1$
        this.getContentPane().removeAll(); // so we can add them again in init
        init();
    }

    @Override
    public void setVisible(boolean visible) {
        super.setVisible(visible);
        if (visible) {
            try {
                initParameterPanel();
            } catch (InstantiationException | IllegalAccessException ex) {
                log.error("Error initializing parameter panel", ex);
            }
        }
    }
}
