/*
 *  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.ivy.plugins.latest;

import java.util.Comparator;
import java.util.HashMap;
import java.util.Locale;
import java.util.Map;

import org.apache.ivy.core.IvyContext;
import org.apache.ivy.core.module.id.ModuleRevisionId;
import org.apache.ivy.plugins.version.VersionMatcher;

public class LatestRevisionStrategy extends ComparatorLatestStrategy {
    /**
     * Compares two ModuleRevisionId by their revision. Revisions are compared using an algorithm
     * inspired by PHP version_compare one.
     */
    final class MridComparator implements Comparator {
        public int compare(Object o1, Object o2) {
            String rev1 = ((ModuleRevisionId) o1).getRevision();
            String rev2 = ((ModuleRevisionId) o2).getRevision();
        
            rev1 = rev1.replaceAll("([a-zA-Z])(\\d)", "$1.$2");
            rev1 = rev1.replaceAll("(\\d)([a-zA-Z])", "$1.$2");
            rev2 = rev2.replaceAll("([a-zA-Z])(\\d)", "$1.$2");
            rev2 = rev2.replaceAll("(\\d)([a-zA-Z])", "$1.$2");
        
            String[] parts1 = rev1.split("[\\._\\-\\+]");
            String[] parts2 = rev2.split("[\\._\\-\\+]");
        
            int i = 0;
            for (; i < parts1.length && i < parts2.length; i++) {
                if (parts1[i].equals(parts2[i])) {
                    continue;
                }
                boolean is1Number = isNumber(parts1[i]);
                boolean is2Number = isNumber(parts2[i]);
                if (is1Number && !is2Number) {
                    return 1;
                }
                if (is2Number && !is1Number) {
                    return -1;
                }
                if (is1Number && is2Number) {
                    return Long.valueOf(parts1[i]).compareTo(Long.valueOf(parts2[i]));
                }
                // both are strings, we compare them taking into account special meaning
                Map specialMeanings = getSpecialMeanings();
                Integer sm1 = (Integer) specialMeanings.get(parts1[i].toLowerCase(Locale.US));
                Integer sm2 = (Integer) specialMeanings.get(parts2[i].toLowerCase(Locale.US));
                if (sm1 != null) {
                    sm2 = sm2 == null ? new Integer(0) : sm2;
                    return sm1.compareTo(sm2);
                }
                if (sm2 != null) {
                    return new Integer(0).compareTo(sm2);
                }
                return parts1[i].compareTo(parts2[i]);
            }
            if (i < parts1.length) {
                return isNumber(parts1[i]) ? 1 : -1;
            }
            if (i < parts2.length) {
                return isNumber(parts2[i]) ? -1 : 1;
            }
            return 0;
        }

        private boolean isNumber(String str) {
            return str.matches("\\d+");
        }
    }

    /**
     * Compares two ArtifactInfo by their revision. Revisions are compared using an algorithm
     * inspired by PHP version_compare one, unless a dynamic revision is given, in which case the
     * version matcher is used to perform the comparison.
     */
    final class ArtifactInfoComparator implements Comparator {
        public int compare(Object o1, Object o2) {
            String rev1 = ((ArtifactInfo) o1).getRevision();
            String rev2 = ((ArtifactInfo) o2).getRevision();
        
            /*
             * The revisions can still be not resolved, so we use the current version matcher to
             * know if one revision is dynamic, and in this case if it should be considered greater
             * or lower than the other one. Note that if the version matcher compare method returns
             * 0, it's because it's not possible to know which revision is greater. In this case we
             * consider the dynamic one to be greater, because most of the time it will then be
             * actually resolved and a real comparison will occur.
             */
            VersionMatcher vmatcher = IvyContext.getContext().getSettings().getVersionMatcher();
            ModuleRevisionId mrid1 = ModuleRevisionId.newInstance("", "", rev1);
            ModuleRevisionId mrid2 = ModuleRevisionId.newInstance("", "", rev2);

            if (vmatcher.isDynamic(mrid1)) {
                int c = vmatcher.compare(mrid1, mrid2, mridComparator);
                return c >= 0 ? 1 : -1;
            } else if (vmatcher.isDynamic(mrid2)) {
                int c = vmatcher.compare(mrid2, mrid1, mridComparator);
                return c >= 0 ? -1 : 1;
            }
        
            return mridComparator.compare(mrid1, mrid2);
        }
    }

    public static class SpecialMeaning {
        private String name;

        private Integer value;

        public String getName() {
            return name;
        }

        public void setName(String name) {
            this.name = name;
        }

        public Integer getValue() {
            return value;
        }

        public void setValue(Integer value) {
            this.value = value;
        }

        public void validate() {
            if (name == null) {
                throw new IllegalStateException("a special meaning should have a name");
            }
            if (value == null) {
                throw new IllegalStateException("a special meaning should have a value");
            }
        }
    }

    private static final Map DEFAULT_SPECIAL_MEANINGS;
    static {
        DEFAULT_SPECIAL_MEANINGS = new HashMap();
        DEFAULT_SPECIAL_MEANINGS.put("dev", new Integer(-1));
        DEFAULT_SPECIAL_MEANINGS.put("rc", new Integer(1));
        DEFAULT_SPECIAL_MEANINGS.put("final", new Integer(2));
    }

    private final Comparator mridComparator = new MridComparator();

    private final Comparator artifactInfoComparator = new ArtifactInfoComparator();

    private Map specialMeanings = null;

    private boolean usedefaultspecialmeanings = true;

    public LatestRevisionStrategy() {
        setComparator(artifactInfoComparator);
        setName("latest-revision");
    }

    public void addConfiguredSpecialMeaning(SpecialMeaning meaning) {
        meaning.validate();
        getSpecialMeanings().put(meaning.getName().toLowerCase(Locale.US), meaning.getValue());
    }

    public synchronized Map getSpecialMeanings() {
        if (specialMeanings == null) {
            specialMeanings = new HashMap();
            if (isUsedefaultspecialmeanings()) {
                specialMeanings.putAll(DEFAULT_SPECIAL_MEANINGS);
            }
        }
        return specialMeanings;
    }

    public boolean isUsedefaultspecialmeanings() {
        return usedefaultspecialmeanings;
    }

    public void setUsedefaultspecialmeanings(boolean usedefaultspecialmeanings) {
        this.usedefaultspecialmeanings = usedefaultspecialmeanings;
    }
}
