/*
 * Copyright (c) 2014, Oracle and/or its affiliates. All rights reserved.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This code is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 only, as
 * published by the Free Software Foundation.
 *
 * This code is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
 * or visit www.oracle.com if you need additional information or have any
 * questions.
 */
package org.graalvm.compiler.options;

import java.io.PrintStream;
import java.util.ArrayList;
import java.util.Collections;
import java.util.Formatter;
import java.util.List;
import java.util.Map;
import java.util.ServiceLoader;
import java.util.Set;
import java.util.SortedMap;
import java.util.TreeMap;

/**
 * This class contains methods for parsing Graal options and matching them against a set of
 * {@link OptionDescriptors}. The {@link OptionDescriptors} are loaded via a {@link ServiceLoader}.
 */
public class OptionsParser {

    public interface OptionConsumer {
        void set(OptionDescriptor desc, Object value);
    }

    /**
     * Parses a map representing assignments of values to options.
     *
     * @param optionSettings option settings (i.e., assignments of values to options)
     * @param setter the object to notify of the parsed option and value
     * @param loader the loader for {@linkplain #lookup(ServiceLoader, String) looking} up
     *            {@link OptionDescriptor}s
     * @throws IllegalArgumentException if there's a problem parsing {@code option}
     */
    public static void parseOptions(Map<String, String> optionSettings, OptionConsumer setter, ServiceLoader<OptionDescriptors> loader) {
        if (optionSettings != null && !optionSettings.isEmpty()) {

            for (Map.Entry<String, String> e : optionSettings.entrySet()) {
                parseOption(e.getKey(), e.getValue(), setter, loader);
            }
        }
    }

    /**
     * Parses a given option setting string to a map of settings.
     *
     * @param optionSetting a string matching the pattern {@code <name>=<value>}
     */
    public static void parseOptionSettingTo(String optionSetting, Map<String, String> dst) {
        int eqIndex = optionSetting.indexOf('=');
        if (eqIndex == -1) {
            throw new InternalError("Option setting has does not match the pattern <name>=<value>: " + optionSetting);
        }
        dst.put(optionSetting.substring(0, eqIndex), optionSetting.substring(eqIndex + 1));
    }

    /**
     * Looks up an {@link OptionDescriptor} based on a given name.
     *
     * @param loader provides the available {@link OptionDescriptor}s
     * @param name the name of the option to look up
     * @return the {@link OptionDescriptor} whose name equals {@code name} or null if not such
     *         descriptor is available
     */
    private static OptionDescriptor lookup(ServiceLoader<OptionDescriptors> loader, String name) {
        for (OptionDescriptors optionDescriptors : loader) {
            OptionDescriptor desc = optionDescriptors.get(name);
            if (desc != null) {
                return desc;
            }
        }
        return null;
    }

    /**
     * Parses a given option name and value.
     *
     * @param name the option name
     * @param valueString the option value as a string
     * @param setter the object to notify of the parsed option and value
     * @param loader the loader for {@linkplain #lookup(ServiceLoader, String) looking} up
     *            {@link OptionDescriptor}s
     * @throws IllegalArgumentException if there's a problem parsing {@code option}
     */
    private static void parseOption(String name, String valueString, OptionConsumer setter, ServiceLoader<OptionDescriptors> loader) {

        OptionDescriptor desc = lookup(loader, name);
        if (desc == null) {
            List<OptionDescriptor> matches = fuzzyMatch(loader, name);
            Formatter msg = new Formatter();
            msg.format("Could not find option %s", name);
            if (!matches.isEmpty()) {
                msg.format("%nDid you mean one of the following?");
                for (OptionDescriptor match : matches) {
                    msg.format("%n    %s=<value>", match.getName());
                }
            }
            throw new IllegalArgumentException(msg.toString());
        }

        Class<?> optionType = desc.getType();
        Object value;
        if (optionType == Boolean.class) {
            if ("true".equals(valueString)) {
                value = Boolean.TRUE;
            } else if ("false".equals(valueString)) {
                value = Boolean.FALSE;
            } else {
                throw new IllegalArgumentException("Boolean option '" + name + "' must have value \"true\" or \"false\", not \"" + valueString + "\"");
            }
        } else if (optionType == String.class || Enum.class.isAssignableFrom(optionType)) {
            value = valueString;
        } else {
            if (valueString.isEmpty()) {
                throw new IllegalArgumentException("Non empty value required for option '" + name + "'");
            }
            try {
                if (optionType == Float.class) {
                    value = Float.parseFloat(valueString);
                } else if (optionType == Double.class) {
                    value = Double.parseDouble(valueString);
                } else if (optionType == Integer.class) {
                    value = Integer.valueOf((int) parseLong(valueString));
                } else if (optionType == Long.class) {
                    value = Long.valueOf(parseLong(valueString));
                } else {
                    throw new IllegalArgumentException("Wrong value for option '" + name + "'");
                }
            } catch (NumberFormatException nfe) {
                throw new IllegalArgumentException("Value for option '" + name + "' has invalid number format: " + valueString);
            }
        }
        if (setter == null) {
            desc.getOptionValue().setValue(value);
        } else {
            setter.set(desc, value);
        }
    }

    private static long parseLong(String v) {
        String valueString = v.toLowerCase();
        long scale = 1;
        if (valueString.endsWith("k")) {
            scale = 1024L;
        } else if (valueString.endsWith("m")) {
            scale = 1024L * 1024L;
        } else if (valueString.endsWith("g")) {
            scale = 1024L * 1024L * 1024L;
        } else if (valueString.endsWith("t")) {
            scale = 1024L * 1024L * 1024L * 1024L;
        }

        if (scale != 1) {
            /* Remove trailing scale character. */
            valueString = valueString.substring(0, valueString.length() - 1);
        }

        return Long.parseLong(valueString) * scale;
    }

    /**
     * Wraps some given text to one or more lines of a given maximum width.
     *
     * @param text text to wrap
     * @param width maximum width of an output line, exception for words in {@code text} longer than
     *            this value
     * @return {@code text} broken into lines
     */
    private static List<String> wrap(String text, int width) {
        List<String> lines = Collections.singletonList(text);
        if (text.length() > width) {
            String[] chunks = text.split("\\s+");
            lines = new ArrayList<>();
            StringBuilder line = new StringBuilder();
            for (String chunk : chunks) {
                if (line.length() + chunk.length() > width) {
                    lines.add(line.toString());
                    line.setLength(0);
                }
                if (line.length() != 0) {
                    line.append(' ');
                }
                String[] embeddedLines = chunk.split("%n", -2);
                if (embeddedLines.length == 1) {
                    line.append(chunk);
                } else {
                    for (int i = 0; i < embeddedLines.length; i++) {
                        line.append(embeddedLines[i]);
                        if (i < embeddedLines.length - 1) {
                            lines.add(line.toString());
                            line.setLength(0);
                        }
                    }
                }
            }
            if (line.length() != 0) {
                lines.add(line.toString());
            }
        }
        return lines;
    }

    private static final int PROPERTY_LINE_WIDTH = 80;
    private static final int PROPERTY_HELP_INDENT = 10;

    public static void printFlags(ServiceLoader<OptionDescriptors> loader, PrintStream out, Set<String> explicitlyAssigned, String namePrefix) {
        SortedMap<String, OptionDescriptor> sortedOptions = new TreeMap<>();
        for (OptionDescriptors opts : loader) {
            for (OptionDescriptor desc : opts) {
                String name = desc.getName();
                OptionDescriptor existing = sortedOptions.put(name, desc);
                assert existing == null : "Option named \"" + name + "\" has multiple definitions: " + existing.getLocation() + " and " + desc.getLocation();
            }
        }
        for (Map.Entry<String, OptionDescriptor> e : sortedOptions.entrySet()) {
            OptionDescriptor desc = e.getValue();
            Object value = desc.getOptionValue().getValue();
            if (value instanceof String) {
                value = '"' + String.valueOf(value) + '"';
            }
            String help = desc.getHelp();
            if (desc.getOptionValue() instanceof EnumOptionValue) {
                EnumOptionValue<?> eoption = (EnumOptionValue<?>) desc.getOptionValue();
                String evalues = eoption.getOptionValues().toString();
                if (help.length() > 0 && !help.endsWith(".")) {
                    help += ".";
                }
                help += " Valid values are: " + evalues.substring(1, evalues.length() - 1);
            }
            String name = namePrefix + e.getKey();
            String assign = explicitlyAssigned.contains(name) ? ":=" : "=";
            String typeName = desc.getOptionValue() instanceof EnumOptionValue ? "String" : desc.getType().getSimpleName();
            String linePrefix = String.format("%s %s %s ", name, assign, value);
            int typeStartPos = PROPERTY_LINE_WIDTH - typeName.length();
            int linePad = typeStartPos - linePrefix.length();
            if (linePad > 0) {
                out.printf("%s%-" + linePad + "s[%s]%n", linePrefix, "", typeName);
            } else {
                out.printf("%s[%s]%n", linePrefix, typeName);
            }

            if (help.length() != 0) {
                List<String> helpLines = wrap(help, PROPERTY_LINE_WIDTH - PROPERTY_HELP_INDENT);
                for (int i = 0; i < helpLines.size(); i++) {
                    out.printf("%" + PROPERTY_HELP_INDENT + "s%s%n", "", helpLines.get(i));
                }
            }
        }
    }

    /**
     * Compute string similarity based on Dice's coefficient.
     *
     * Ported from str_similar() in globals.cpp.
     */
    static float stringSimiliarity(String str1, String str2) {
        int hit = 0;
        for (int i = 0; i < str1.length() - 1; ++i) {
            for (int j = 0; j < str2.length() - 1; ++j) {
                if ((str1.charAt(i) == str2.charAt(j)) && (str1.charAt(i + 1) == str2.charAt(j + 1))) {
                    ++hit;
                    break;
                }
            }
        }
        return 2.0f * hit / (str1.length() + str2.length());
    }

    private static final float FUZZY_MATCH_THRESHOLD = 0.7F;

    /**
     * Returns the set of options that fuzzy match a given option name.
     */
    private static List<OptionDescriptor> fuzzyMatch(ServiceLoader<OptionDescriptors> loader, String optionName) {
        List<OptionDescriptor> matches = new ArrayList<>();
        for (OptionDescriptors options : loader) {
            for (OptionDescriptor option : options) {
                float score = stringSimiliarity(option.getName(), optionName);
                if (score >= FUZZY_MATCH_THRESHOLD) {
                    matches.add(option);
                }
            }
        }
        return matches;
    }
}