/*
 * 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.catalina.util;


import java.util.StringTokenizer;


/**
 * Utility class that represents either an available "Optional Package" (formerly known as "Standard Extension") as
 * described in the manifest of a JAR file, or the requirement for such an optional package. It is used to support the
 * requirements of the Servlet Specification, version 2.3, related to providing shared extensions to all webapps.
 * <p>
 * In addition, static utility methods are available to scan a manifest and return an array of either available or
 * required optional modules documented in that manifest.
 * <p>
 * For more information about optional packages, see the document <em>Optional Package Versioning</em> in the
 * documentation bundle for your Java2 Standard Edition package, in file <code>guide/extensions/versioning.html</code>.
 *
 * @author Craig McClanahan
 * @author Justyna Horwat
 * @author Greg Murray
 */
public final class Extension {


    // ------------------------------------------------------------- Properties


    /**
     * The name of the optional package being made available, or required.
     */
    private String extensionName = null;


    public String getExtensionName() {
        return this.extensionName;
    }

    public void setExtensionName(String extensionName) {
        this.extensionName = extensionName;
    }

    /**
     * The URL from which the most recent version of this optional package can be obtained if it is not already
     * installed.
     */
    private String implementationURL = null;

    public String getImplementationURL() {
        return this.implementationURL;
    }

    public void setImplementationURL(String implementationURL) {
        this.implementationURL = implementationURL;
    }


    /**
     * The name of the company or organization that produced this implementation of this optional package.
     */
    private String implementationVendor = null;

    public String getImplementationVendor() {
        return this.implementationVendor;
    }

    public void setImplementationVendor(String implementationVendor) {
        this.implementationVendor = implementationVendor;
    }


    /**
     * The unique identifier of the company that produced the optional package contained in this JAR file.
     */
    private String implementationVendorId = null;

    public String getImplementationVendorId() {
        return this.implementationVendorId;
    }

    public void setImplementationVendorId(String implementationVendorId) {
        this.implementationVendorId = implementationVendorId;
    }


    /**
     * The version number (dotted decimal notation) for this implementation of the optional package.
     */
    private String implementationVersion = null;

    public String getImplementationVersion() {
        return this.implementationVersion;
    }

    public void setImplementationVersion(String implementationVersion) {
        this.implementationVersion = implementationVersion;
    }


    /**
     * The name of the company or organization that originated the specification to which this optional package
     * conforms.
     */
    private String specificationVendor = null;

    public String getSpecificationVendor() {
        return this.specificationVendor;
    }

    public void setSpecificationVendor(String specificationVendor) {
        this.specificationVendor = specificationVendor;
    }


    /**
     * The version number (dotted decimal notation) of the specification to which this optional package conforms.
     */
    private String specificationVersion = null;

    public String getSpecificationVersion() {
        return this.specificationVersion;
    }

    public void setSpecificationVersion(String specificationVersion) {
        this.specificationVersion = specificationVersion;
    }


    /**
     * fulfilled is true if all the required extension dependencies have been satisfied
     */
    private boolean fulfilled = false;

    public void setFulfilled(boolean fulfilled) {
        this.fulfilled = fulfilled;
    }

    public boolean isFulfilled() {
        return fulfilled;
    }

    // --------------------------------------------------------- Public Methods

    /**
     * Return <code>true</code> if the specified <code>Extension</code> (which represents an optional package required
     * by this application) is satisfied by this <code>Extension</code> (which represents an optional package that is
     * already installed. Otherwise, return <code>false</code>.
     *
     * @param required Extension of the required optional package
     *
     * @return <code>true</code> if the extension is satisfied
     */
    public boolean isCompatibleWith(Extension required) {

        // Extension Name must match
        if (extensionName == null) {
            return false;
        }
        if (!extensionName.equals(required.getExtensionName())) {
            return false;
        }

        // If specified, available specification version must be >= required
        if (required.getSpecificationVersion() != null) {
            if (!isNewer(specificationVersion, required.getSpecificationVersion())) {
                return false;
            }
        }

        // If specified, Implementation Vendor ID must match
        if (required.getImplementationVendorId() != null) {
            if (implementationVendorId == null) {
                return false;
            }
            if (!implementationVendorId.equals(required.getImplementationVendorId())) {
                return false;
            }
        }

        // If specified, Implementation version must be >= required
        if (required.getImplementationVersion() != null) {
            if (!isNewer(implementationVersion, required.getImplementationVersion())) {
                return false;
            }
        }

        // This available optional package satisfies the requirements
        return true;

    }

    @Override
    public String toString() {
        StringBuilder sb = new StringBuilder("Extension[");
        sb.append(extensionName);
        if (implementationURL != null) {
            sb.append(", implementationURL=");
            sb.append(implementationURL);
        }
        if (implementationVendor != null) {
            sb.append(", implementationVendor=");
            sb.append(implementationVendor);
        }
        if (implementationVendorId != null) {
            sb.append(", implementationVendorId=");
            sb.append(implementationVendorId);
        }
        if (implementationVersion != null) {
            sb.append(", implementationVersion=");
            sb.append(implementationVersion);
        }
        if (specificationVendor != null) {
            sb.append(", specificationVendor=");
            sb.append(specificationVendor);
        }
        if (specificationVersion != null) {
            sb.append(", specificationVersion=");
            sb.append(specificationVersion);
        }
        sb.append(']');
        return sb.toString();
    }


    // -------------------------------------------------------- Private Methods


    /**
     * Return <code>true</code> if the first version number is greater than or equal to the second; otherwise return
     * <code>false</code>.
     *
     * @param first  First version number (dotted decimal)
     * @param second Second version number (dotted decimal)
     *
     * @exception NumberFormatException on a malformed version number
     */
    private boolean isNewer(String first, String second) throws NumberFormatException {

        if ((first == null) || (second == null)) {
            return false;
        }
        if (first.equals(second)) {
            return true;
        }

        StringTokenizer fTok = new StringTokenizer(first, ".", true);
        StringTokenizer sTok = new StringTokenizer(second, ".", true);
        int fVersion = 0;
        int sVersion = 0;
        while (fTok.hasMoreTokens() || sTok.hasMoreTokens()) {
            if (fTok.hasMoreTokens()) {
                fVersion = Integer.parseInt(fTok.nextToken());
            } else {
                fVersion = 0;
            }
            if (sTok.hasMoreTokens()) {
                sVersion = Integer.parseInt(sTok.nextToken());
            } else {
                sVersion = 0;
            }
            if (fVersion < sVersion) {
                return false;
            } else if (fVersion > sVersion) {
                return true;
            }
            if (fTok.hasMoreTokens()) {
                fTok.nextToken();
            }
            if (sTok.hasMoreTokens()) {
                sTok.nextToken();
            }
        }

        return true; // Exact match

    }


}
