/*
 * JBoss, Home of Professional Open Source.
 * Copyright 2013, Red Hat, Inc., and individual contributors
 * as indicated by the @author tags. See the copyright.txt file in the
 * distribution for a full listing of individual contributors.
 *
 * This is free software; you can redistribute it and/or modify it
 * under the terms of the GNU Lesser General Public License as
 * published by the Free Software Foundation; either version 2.1 of
 * the License, or (at your option) any later version.
 *
 * This software 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
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this software; if not, write to the Free
 * Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
 * 02110-1301 USA, or see the FSF site: http://www.fsf.org.
 */

package org.jboss.as.domain.management.security;

import static org.jboss.as.domain.management.DomainManagementMessages.MESSAGES;

import java.io.Closeable;
import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.security.KeyStore;
import java.security.KeyStoreException;
import java.security.NoSuchAlgorithmException;
import java.security.UnrecoverableEntryException;
import java.security.cert.CertificateException;
import java.util.Enumeration;

import org.jboss.msc.service.StartException;

/**
 * Store the keystore and last modification date. Able to reload the keystore incase
 * the file has changed
 *
 * @author <a href="mailto:flemming.harms@gmail.com">Flemming Harms</a>
 *
 */
final class FileKeystore {

    private KeyStore keyStore;
    private final String provider;
    private final String path;
    private long lastModificationTime;
    private final char[] keystorePassword;
    /** If not a KeyStore it is being used as a trust store. */
    private final boolean isKeyStore;

    private final char[] keyPassword;
    private final String alias;

    private FileKeystore(final String provider, final String path, final char[] keystorePassword) {
        this.provider = provider;
        this.path = path;
        this.keystorePassword = keystorePassword;
        this.keyPassword = null;
        this.alias = null;
        this.lastModificationTime = 0;
        this.isKeyStore = false;
    }

    private FileKeystore(final String provider, final String path, final char[] keystorePassword, final char[] keyPassword, final String alias) {
        this.provider = provider;
        this.path = path;
        this.keystorePassword = keystorePassword;
        this.keyPassword = keyPassword;
        this.alias = alias;
        this.lastModificationTime = 0;
        this.isKeyStore = true;
    }

    static FileKeystore newKeyStore(final String provider, final String path, final char[] keystorePassword, final char[] keyPassword, final String alias) {
        return new FileKeystore(provider, path, keystorePassword, keyPassword, alias);
    }

    static FileKeystore newTrustStore(final String provider, final String path, final char[] keystorePassword) {
        return new FileKeystore(provider, path, keystorePassword);
    }

    /**
     * @return true if the keystore file is modified since it was loaded the first time
     */
    boolean isModified() {
        long lastModified = new File(path).lastModified();
        if (lastModified > this.lastModificationTime) {
            return true;
        } else if (lastModified == 0) {
            return true;
        }
        return false;
    }

    /**
     * Load the keystore file and cache the keystore. if the keystore file has changed
     * call load() again for updating the keystore
     * @throws StartException
     */
    void load() throws StartException {
        FileInputStream fis = null;
        try {
            KeyStore loadedKeystore = KeyStore.getInstance(provider);

            if (new File(path).exists()) {
                fis = new FileInputStream(path);
                loadedKeystore.load(fis, keystorePassword);
            } else if (isKeyStore) {
                throw MESSAGES.keyStoreNotFound(path);
            } else {
                loadedKeystore.load(null);
            }

            if (isKeyStore) {
                assertContainsKey(loadedKeystore);
            }

            if (alias == null) {
                this.setKeyStore(loadedKeystore);
            } else {
                KeyStore newKeystore = KeyStore.getInstance("JKS");
                newKeystore.load(null);

                KeyStore.ProtectionParameter passParam = new KeyStore.PasswordProtection(keyPassword == null ? keystorePassword
                        : keyPassword);

                if (loadedKeystore.containsAlias(alias)) {
                    if (loadedKeystore.isKeyEntry(alias)) {
                        KeyStore.Entry entry = loadedKeystore.getEntry(this.alias, passParam);
                        newKeystore.setEntry(alias, entry, passParam);
                    } else {
                        throw MESSAGES.aliasNotKey(alias, validAliasList(loadedKeystore));
                    }
                } else {
                    throw MESSAGES.aliasNotFound(alias, validAliasList(loadedKeystore));
                }

                this.setKeyStore(newKeystore);
            }
            this.lastModificationTime = new File(path).lastModified();
        } catch (KeyStoreException e) {
            throw MESSAGES.unableToStart(e);
        } catch (NoSuchAlgorithmException e) {
            throw MESSAGES.unableToStart(e);
        } catch (CertificateException e) {
            throw MESSAGES.unableToStart(e);
        } catch (IOException e) {
            throw MESSAGES.unableToStart(e);
        } catch (UnrecoverableEntryException e) {
            throw MESSAGES.unableToStart(e);
        } finally {
            safeClose(fis);
        }
    }

    private void assertContainsKey(final KeyStore keyStore) throws StartException, KeyStoreException {
        Enumeration<String> aliases = keyStore.aliases();
        while (aliases.hasMoreElements()) {
            if (keyStore.isKeyEntry(aliases.nextElement())) {
                return;
            }
        }

        throw MESSAGES.noKey(path);
    }

    private String validAliasList(final KeyStore keyStore) throws KeyStoreException {
        Enumeration<String> aliases = keyStore.aliases();
        StringBuilder sb = new StringBuilder("{");
        while (aliases.hasMoreElements()) {
            String current = aliases.nextElement();
            if (keyStore.isKeyEntry(current)) {
                if (sb.length() > 1) {
                    sb.append(", ");
                }
                sb.append(current);
            }

        }

        return sb.append("}").toString();
    }

    /**
     * @return the current cached keystore.
     */
    KeyStore getKeyStore() {
        return keyStore;
    }

    private void setKeyStore(KeyStore keyStore) {
        this.keyStore = keyStore;
    }

    private void safeClose(Closeable c) {
        if (c != null) {
            try {
                c.close();
            } catch (IOException ignored) {
            }
        }
    }

}
