/*
 * Copyright (c) 2015 Brocade Communications Systems, Inc. and others.  All rights reserved.
 *
 * This program and the accompanying materials are made available under the
 * terms of the Eclipse Public License v1.0 which accompanies this distribution,
 * and is available at http://www.eclipse.org/legal/epl-v10.html
 */

package org.opendaylight.aaa.shiro.web.env;

import java.io.File;
import java.io.FileNotFoundException;
import java.util.Collection;
import org.apache.shiro.config.Ini;
import org.apache.shiro.config.Ini.Section;
import org.apache.shiro.web.env.IniWebEnvironment;
import org.opendaylight.aaa.shiro.accounting.Accounter;
import org.opendaylight.aaa.shiro.authorization.DefaultRBACRules;
import org.opendaylight.aaa.shiro.authorization.RBACRule;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

/**
 * Identical to <code>IniWebEnvironment</code> except the Ini is loaded from
 * <code>$KARAF_HOME/etc/shiro.ini</code>.
 *
 * @author Ryan Goulding (ryandgoulding@gmail.com)
 *
 */
public class KarafIniWebEnvironment extends IniWebEnvironment {

    private static final Logger LOG = LoggerFactory.getLogger(KarafIniWebEnvironment.class);
    public static final String DEFAULT_SHIRO_INI_FILE = "etc/shiro.ini";
    public static final String SHIRO_FILE_PREFIX = "file:/";

    public KarafIniWebEnvironment() {
    }

    @Override
    public void init() {
        // Initialize the Shiro environment from etc/shiro.ini then delegate to
        // the parent class
        Ini ini;
        try {
            ini = createDefaultShiroIni();
            // appendCustomIniRules(ini);
            setIni(ini);
        } catch (FileNotFoundException e) {
            final String ERROR_MESSAGE = "Could not find etc/shiro.ini";
            LOG.error(ERROR_MESSAGE, e);
        }
        super.init();
    }

    /**
     * A hook for installing custom default RBAC rules for security purposes.
     *
     * @param ini
     */
    private void appendCustomIniRules(final Ini ini) {
        final String INSTALL_MESSAGE = "Installing the RBAC rule: %s";
        Section urlSection = getOrCreateUrlSection(ini);
        Collection<RBACRule> rbacRules = DefaultRBACRules.getInstance().getRBACRules();
        for (RBACRule rbacRule : rbacRules) {
            urlSection.put(rbacRule.getUrlPattern(), rbacRule.getRolesInShiroFormat());
            Accounter.output(String.format(INSTALL_MESSAGE, rbacRule));
        }
    }

    /**
     * Extracts the url section of the Ini file, or creates one if it doesn't
     * already exist
     *
     * @param ini
     * @return
     */
    private Section getOrCreateUrlSection(final Ini ini) {
        final String URL_SECTION_TITLE = "urls";
        Section urlSection = ini.getSection(URL_SECTION_TITLE);
        if (urlSection == null) {
            LOG.debug("shiro.ini does not contain a [urls] section; creating one");
            urlSection = ini.addSection(URL_SECTION_TITLE);
        } else {
            LOG.debug("shiro.ini contains a [urls] section; appending rules to existing");
        }
        return urlSection;
    }

    /**
     *
     * @return Ini associated with <code>$KARAF_HOME/etc/shiro.ini</code>
     * @throws FileNotFoundException
     */
    static Ini createDefaultShiroIni() throws FileNotFoundException {
        return createShiroIni(DEFAULT_SHIRO_INI_FILE);
    }

    /**
     *
     * @param path
     *            the file path, which is either absolute or relative to
     *            <code>$KARAF_HOME</code>
     * @return Ini loaded from <code>path</code>
     */
    static Ini createShiroIni(final String path) throws FileNotFoundException {
        File f = new File(path);
        Ini ini = new Ini();
        final String fileBasedIniPath = createFileBasedIniPath(f.getAbsolutePath());
        ini.loadFromPath(fileBasedIniPath);
        return ini;
    }

    /**
     *
     * @param path
     *            the file path, which is either absolute or relative to
     *            <code>$KARAF_HOME</code>
     * @return <code>file:/$KARAF_HOME/etc/shiro.ini</code>
     */
    static String createFileBasedIniPath(final String path) {
        String fileBasedIniPath = SHIRO_FILE_PREFIX + path;
        LOG.debug(fileBasedIniPath);
        return fileBasedIniPath;
    }
}