/*
 * 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.shindig.gadgets.oauth;

import org.apache.commons.io.IOUtils;
import org.apache.commons.lang.StringUtils;
import org.apache.shindig.common.crypto.BasicBlobCrypter;
import org.apache.shindig.common.crypto.BlobCrypter;
import org.apache.shindig.common.crypto.Crypto;
import org.apache.shindig.common.util.ResourceLoader;
import org.apache.shindig.gadgets.oauth.BasicOAuthStoreConsumerKeyAndSecret.KeyType;

import java.io.File;
import java.io.IOException;
import java.util.logging.Level;
import java.util.logging.Logger;

import com.google.inject.AbstractModule;
import com.google.inject.Inject;
import com.google.inject.Provider;
import com.google.inject.name.Named;
import com.google.inject.name.Names;

/**
 * Loads pre-reqs for OAuth.
 */
public class OAuthModule extends AbstractModule {

  private static final Logger logger = Logger.getLogger(OAuthModule.class.getName());

  private static final String OAUTH_CONFIG = "config/oauth.json";
  private static final String OAUTH_SIGNING_KEY_FILE = "shindig.signing.key-file";
  private static final String OAUTH_SIGNING_KEY_NAME = "shindig.signing.key-name";

  @Override
  protected void configure() {
    // Used for encrypting client-side OAuth state.
    bind(BlobCrypter.class).annotatedWith(Names.named(OAuthFetcherConfig.OAUTH_STATE_CRYPTER))
        .toProvider(OAuthCrypterProvider.class);
    
    // Used for persistent storage of OAuth access tokens.
    bind(OAuthStore.class).toProvider(OAuthStoreProvider.class);
  }

  public static class OAuthCrypterProvider implements Provider<BlobCrypter> {

    private final BlobCrypter crypter;

    @Inject
    public OAuthCrypterProvider(@Named("shindig.oauth.state-key") String stateCrypterPath)
        throws IOException {
      if (StringUtils.isBlank(stateCrypterPath)) {
        logger.info("Using random key for OAuth client-side state encryption");
        crypter = new BasicBlobCrypter(Crypto.getRandomBytes(BasicBlobCrypter.MASTER_KEY_MIN_LEN));
      } else {
        logger.info("Using file " + stateCrypterPath + " for OAuth client-side state encryption");
        crypter = new BasicBlobCrypter(new File(stateCrypterPath));
      }
    }

    public BlobCrypter get() {
      return crypter;
    }
  }

  public static class OAuthStoreProvider implements Provider<OAuthStore> {

    private BasicOAuthStore store;

    @Inject
    public OAuthStoreProvider(
        @Named(OAUTH_SIGNING_KEY_FILE) String signingKeyFile,
        @Named(OAUTH_SIGNING_KEY_NAME) String signingKeyName) {
      store = new BasicOAuthStore();
      loadDefaultKey(signingKeyFile, signingKeyName);
      loadConsumers();
    }

    private void loadDefaultKey(String signingKeyFile, String signingKeyName) {
      BasicOAuthStoreConsumerKeyAndSecret key = null;
      if (!StringUtils.isBlank(signingKeyFile)) {
        try {
          logger.info("Loading OAuth signing key from " + signingKeyFile);
          String privateKey = IOUtils.toString(ResourceLoader.open(signingKeyFile), "UTF-8");
          privateKey = BasicOAuthStore.convertFromOpenSsl(privateKey);
          key = new BasicOAuthStoreConsumerKeyAndSecret(null, privateKey, KeyType.RSA_PRIVATE,
              signingKeyName);
        } catch (Throwable t) {
          logger.log(Level.WARNING, "Couldn't load key file " + signingKeyFile, t);
        }
      }
      if (key != null) {
        store.setDefaultKey(key);
      } else {
        logger.log(Level.WARNING, "Couldn't load OAuth signing key.  To create a key, run:\n" +
            "  openssl req -newkey rsa:1024 -days 365 -nodes -x509 -keyout testkey.pem \\\n" +
            "     -out testkey.pem -subj '/CN=mytestkey'\n" +
            "  openssl pkcs8 -in testkey.pem -out oauthkey.pem -topk8 -nocrypt -outform PEM\n" +
            "\n" +
            "Then edit gadgets.properties and add these lines:\n" +
            OAUTH_SIGNING_KEY_FILE + "=<path-to-oauthkey.pem>\n" +
            OAUTH_SIGNING_KEY_NAME + "=mykey\n");    
      }
    }

    private void loadConsumers() {
      try {
        String oauthConfigString = ResourceLoader.getContent(OAUTH_CONFIG);
        store.initFromConfigString(oauthConfigString);
      } catch (Throwable t) {
        logger.log(Level.WARNING, "Failed to initialize OAuth consumers from " + OAUTH_CONFIG, t);
      }
    }

    public OAuthStore get() {
      return store;
    }
  }
}