/*
 * Copyright 2008 Web Cohesion
 * 
 * Licensed 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.maxkey.authz.oauth2.provider.token;

import java.util.Date;
import java.util.Set;
import java.util.UUID;

import org.maxkey.authz.oauth2.common.DefaultExpiringOAuth2RefreshToken;
import org.maxkey.authz.oauth2.common.DefaultOAuth2AccessToken;
import org.maxkey.authz.oauth2.common.DefaultOAuth2RefreshToken;
import org.maxkey.authz.oauth2.common.ExpiringOAuth2RefreshToken;
import org.maxkey.authz.oauth2.common.OAuth2AccessToken;
import org.maxkey.authz.oauth2.common.OAuth2RefreshToken;
import org.maxkey.authz.oauth2.common.exceptions.InvalidGrantException;
import org.maxkey.authz.oauth2.common.exceptions.InvalidScopeException;
import org.maxkey.authz.oauth2.common.exceptions.InvalidTokenException;
import org.maxkey.authz.oauth2.provider.ClientDetailsService;
import org.maxkey.authz.oauth2.provider.ClientRegistrationException;
import org.maxkey.authz.oauth2.provider.OAuth2Authentication;
import org.maxkey.authz.oauth2.provider.OAuth2Request;
import org.maxkey.authz.oauth2.provider.TokenRequest;
import org.maxkey.domain.apps.oauth2.provider.ClientDetails;
import org.springframework.beans.factory.InitializingBean;
import org.springframework.security.authentication.AuthenticationManager;
import org.springframework.security.core.Authentication;
import org.springframework.security.core.AuthenticationException;
import org.springframework.security.web.authentication.preauth.PreAuthenticatedAuthenticationToken;
import org.springframework.transaction.annotation.Transactional;
import org.springframework.util.Assert;

/**
 * Base implementation for token services using random UUID values for the access token and refresh token values. The
 * main extension point for customizations is the {@link TokenEnhancer} which will be called after the access and
 * refresh tokens have been generated but before they are stored.
 * <p>
 * Persistence is delegated to a {@code TokenStore} implementation and customization of the access token to a
 * {@link TokenEnhancer}.
 * 
 * @author Ryan Heaton
 * @author Luke Taylor
 * @author Dave Syer
 */
public class DefaultTokenServices implements AuthorizationServerTokenServices, ResourceServerTokenServices,
		ConsumerTokenServices, InitializingBean {

	private int refreshTokenValiditySeconds = 60 * 60 * 24 * 30; // default 30 days.

	private int accessTokenValiditySeconds = 60 * 60 * 12; // default 12 hours.

	private boolean supportRefreshToken = false;

	private boolean reuseRefreshToken = true;

	private TokenStore tokenStore;

	private ClientDetailsService clientDetailsService;

	private TokenEnhancer accessTokenEnhancer;

	private AuthenticationManager authenticationManager;

	/**
	 * Initialize these token services. If no random generator is set, one will be created.
	 */
	public void afterPropertiesSet() throws Exception {
		Assert.notNull(tokenStore, "tokenStore must be set");
	}

	@Transactional
	public OAuth2AccessToken createAccessToken(OAuth2Authentication authentication) throws AuthenticationException {

		OAuth2AccessToken existingAccessToken = tokenStore.getAccessToken(authentication);
		OAuth2RefreshToken refreshToken = null;
		if (existingAccessToken != null) {
			if (existingAccessToken.isExpired()) {
				if (existingAccessToken.getRefreshToken() != null) {
					refreshToken = existingAccessToken.getRefreshToken();
					// The token store could remove the refresh token when the
					// access token is removed, but we want to
					// be sure...
					tokenStore.removeRefreshToken(refreshToken);
				}
				tokenStore.removeAccessToken(existingAccessToken);
			}
			else {
				// Re-store the access token in case the authentication has changed
				tokenStore.storeAccessToken(existingAccessToken, authentication);
				return existingAccessToken;
			}
		}

		// Only create a new refresh token if there wasn't an existing one
		// associated with an expired access token.
		// Clients might be holding existing refresh tokens, so we re-use it in
		// the case that the old access token
		// expired.
		if (refreshToken == null) {
			refreshToken = createRefreshToken(authentication);
		}
		// But the refresh token itself might need to be re-issued if it has
		// expired.
		else if (refreshToken instanceof ExpiringOAuth2RefreshToken) {
			ExpiringOAuth2RefreshToken expiring = (ExpiringOAuth2RefreshToken) refreshToken;
			if (System.currentTimeMillis() > expiring.getExpiration().getTime()) {
				refreshToken = createRefreshToken(authentication);
			}
		}

		OAuth2AccessToken accessToken = createAccessToken(authentication, refreshToken);
		tokenStore.storeAccessToken(accessToken, authentication);
		// In case it was modified
		refreshToken = accessToken.getRefreshToken();
		if (refreshToken != null) {
			tokenStore.storeRefreshToken(refreshToken, authentication);
		}
		return accessToken;

	}

	@Transactional(noRollbackFor={InvalidTokenException.class, InvalidGrantException.class})
	public OAuth2AccessToken refreshAccessToken(String refreshTokenValue, TokenRequest tokenRequest)
			throws AuthenticationException {

		if (!supportRefreshToken) {
			throw new InvalidGrantException("Invalid refresh token: " + refreshTokenValue);
		}

		OAuth2RefreshToken refreshToken = tokenStore.readRefreshToken(refreshTokenValue);
		if (refreshToken == null) {
			throw new InvalidGrantException("Invalid refresh token: " + refreshTokenValue);
		}

		OAuth2Authentication authentication = tokenStore.readAuthenticationForRefreshToken(refreshToken);
		if (this.authenticationManager != null && !authentication.isClientOnly()) {
			// The client has already been authenticated, but the user authentication might be old now, so give it a
			// chance to re-authenticate.
			Authentication user = new PreAuthenticatedAuthenticationToken(authentication.getUserAuthentication(), "", authentication.getAuthorities());
			user = authenticationManager.authenticate(user);
			Object details = authentication.getDetails();
			authentication = new OAuth2Authentication(authentication.getOAuth2Request(), user);
			authentication.setDetails(details);
		}
		String clientId = authentication.getOAuth2Request().getClientId();
		if (clientId == null || !clientId.equals(tokenRequest.getClientId())) {
			throw new InvalidGrantException("Wrong client for this refresh token: " + refreshTokenValue);
		}

		// clear out any access tokens already associated with the refresh
		// token.
		tokenStore.removeAccessTokenUsingRefreshToken(refreshToken);

		if (isExpired(refreshToken)) {
			tokenStore.removeRefreshToken(refreshToken);
			throw new InvalidTokenException("Invalid refresh token (expired): " + refreshToken);
		}

		authentication = createRefreshedAuthentication(authentication, tokenRequest);

		if (!reuseRefreshToken) {
			tokenStore.removeRefreshToken(refreshToken);
			refreshToken = createRefreshToken(authentication);
		}

		OAuth2AccessToken accessToken = createAccessToken(authentication, refreshToken);
		tokenStore.storeAccessToken(accessToken, authentication);
		if (!reuseRefreshToken) {
			tokenStore.storeRefreshToken(refreshToken, authentication);
		}
		return accessToken;
	}

	public OAuth2AccessToken getAccessToken(OAuth2Authentication authentication) {
		return tokenStore.getAccessToken(authentication);
	}

	/**
	 * Create a refreshed authentication.
	 * 
	 * @param authentication The authentication.
	 * @param scope The scope for the refreshed token.
	 * @return The refreshed authentication.
	 * @throws InvalidScopeException If the scope requested is invalid or wider than the original scope.
	 */
	private OAuth2Authentication createRefreshedAuthentication(OAuth2Authentication authentication, TokenRequest request) {
		OAuth2Authentication narrowed = authentication;
		Set<String> scope = request.getScope();
		OAuth2Request clientAuth = authentication.getOAuth2Request().refresh(request);
		if (scope != null && !scope.isEmpty()) {
			Set<String> originalScope = clientAuth.getScope();
			if (originalScope == null || !originalScope.containsAll(scope)) {
				throw new InvalidScopeException("Unable to narrow the scope of the client authentication to " + scope
						+ ".", originalScope);
			}
			else {
				clientAuth = clientAuth.narrowScope(scope);
			}
		}
		narrowed = new OAuth2Authentication(clientAuth, authentication.getUserAuthentication());
		return narrowed;
	}

	protected boolean isExpired(OAuth2RefreshToken refreshToken) {
		if (refreshToken instanceof ExpiringOAuth2RefreshToken) {
			ExpiringOAuth2RefreshToken expiringToken = (ExpiringOAuth2RefreshToken) refreshToken;
			return expiringToken.getExpiration() == null
					|| System.currentTimeMillis() > expiringToken.getExpiration().getTime();
		}
		return false;
	}

	public OAuth2AccessToken readAccessToken(String accessToken) {
		return tokenStore.readAccessToken(accessToken);
	}

	public OAuth2Authentication loadAuthentication(String accessTokenValue) throws AuthenticationException,
			InvalidTokenException {
		OAuth2AccessToken accessToken = tokenStore.readAccessToken(accessTokenValue);
		if (accessToken == null) {
			throw new InvalidTokenException("Invalid access token: " + accessTokenValue);
		}
		else if (accessToken.isExpired()) {
			tokenStore.removeAccessToken(accessToken);
			throw new InvalidTokenException("Access token expired: " + accessTokenValue);
		}

		OAuth2Authentication result = tokenStore.readAuthentication(accessToken);
		if (result == null) {
			// in case of race condition
			throw new InvalidTokenException("Invalid access token: " + accessTokenValue);
		}
		
		if (clientDetailsService != null) {
			String clientId = result.getOAuth2Request().getClientId();
			try {
				clientDetailsService.loadClientByClientId(clientId);
			}
			catch (ClientRegistrationException e) {
				throw new InvalidTokenException("Client not valid: " + clientId, e);
			}
		}
		return result;
	}

	public String getClientId(String tokenValue) {
		OAuth2Authentication authentication = tokenStore.readAuthentication(tokenValue);
		if (authentication == null) {
			throw new InvalidTokenException("Invalid access token: " + tokenValue);
		}
		OAuth2Request clientAuth = authentication.getOAuth2Request();
		if (clientAuth == null) {
			throw new InvalidTokenException("Invalid access token (no client id): " + tokenValue);
		}
		return clientAuth.getClientId();
	}

	public boolean revokeToken(String tokenValue) {
		OAuth2AccessToken accessToken = tokenStore.readAccessToken(tokenValue);
		if (accessToken == null) {
			return false;
		}
		if (accessToken.getRefreshToken() != null) {
			tokenStore.removeRefreshToken(accessToken.getRefreshToken());
		}
		tokenStore.removeAccessToken(accessToken);
		return true;
	}

	private OAuth2RefreshToken createRefreshToken(OAuth2Authentication authentication) {
		if (!isSupportRefreshToken(authentication.getOAuth2Request())) {
			return null;
		}
		int validitySeconds = getRefreshTokenValiditySeconds(authentication.getOAuth2Request());
		String value = UUID.randomUUID().toString();
		if (validitySeconds > 0) {
			return new DefaultExpiringOAuth2RefreshToken(value, new Date(System.currentTimeMillis()
					+ (validitySeconds * 1000L)));
		}
		return new DefaultOAuth2RefreshToken(value);
	}

	private OAuth2AccessToken createAccessToken(OAuth2Authentication authentication, OAuth2RefreshToken refreshToken) {
		DefaultOAuth2AccessToken token = new DefaultOAuth2AccessToken(UUID.randomUUID().toString());
		int validitySeconds = getAccessTokenValiditySeconds(authentication.getOAuth2Request());
		if (validitySeconds > 0) {
			token.setExpiration(new Date(System.currentTimeMillis() + (validitySeconds * 1000L)));
		}
		token.setRefreshToken(refreshToken);
		token.setScope(authentication.getOAuth2Request().getScope());

		return accessTokenEnhancer != null ? accessTokenEnhancer.enhance(token, authentication) : token;
	}

	/**
	 * The access token validity period in seconds
	 * 
	 * @param authorizationRequest the current authorization request
	 * @return the access token validity period in seconds
	 */
	protected int getAccessTokenValiditySeconds(OAuth2Request clientAuth) {
		if (clientDetailsService != null) {
			ClientDetails client = clientDetailsService.loadClientByClientId(clientAuth.getClientId());
			Integer validity = client.getAccessTokenValiditySeconds();
			if (validity != null) {
				return validity;
			}
		}
		return accessTokenValiditySeconds;
	}

	/**
	 * The refresh token validity period in seconds
	 * 
	 * @param authorizationRequest the current authorization request
	 * @return the refresh token validity period in seconds
	 */
	protected int getRefreshTokenValiditySeconds(OAuth2Request clientAuth) {
		if (clientDetailsService != null) {
			ClientDetails client = clientDetailsService.loadClientByClientId(clientAuth.getClientId());
			Integer validity = client.getRefreshTokenValiditySeconds();
			if (validity != null) {
				return validity;
			}
		}
		return refreshTokenValiditySeconds;
	}

	/**
	 * Is a refresh token supported for this client (or the global setting if
	 * {@link #setClientDetailsService(ClientDetailsService) clientDetailsService} is not set.
	 * 
	 * @param authorizationRequest the current authorization request
	 * @return boolean to indicate if refresh token is supported
	 */
	protected boolean isSupportRefreshToken(OAuth2Request clientAuth) {
		if (clientDetailsService != null) {
			ClientDetails client = clientDetailsService.loadClientByClientId(clientAuth.getClientId());
			return client.getAuthorizedGrantTypes().contains("refresh_token");
		}
		return this.supportRefreshToken;
	}

	/**
	 * An access token enhancer that will be applied to a new token before it is saved in the token store.
	 * 
	 * @param accessTokenEnhancer the access token enhancer to set
	 */
	public void setTokenEnhancer(TokenEnhancer accessTokenEnhancer) {
		this.accessTokenEnhancer = accessTokenEnhancer;
	}

	/**
	 * The validity (in seconds) of the refresh token. If less than or equal to zero then the tokens will be
	 * non-expiring.
	 * 
	 * @param refreshTokenValiditySeconds The validity (in seconds) of the refresh token.
	 */
	public void setRefreshTokenValiditySeconds(int refreshTokenValiditySeconds) {
		this.refreshTokenValiditySeconds = refreshTokenValiditySeconds;
	}

	/**
	 * The default validity (in seconds) of the access token. Zero or negative for non-expiring tokens. If a client
	 * details service is set the validity period will be read from he client, defaulting to this value if not defined
	 * by the client.
	 * 
	 * @param accessTokenValiditySeconds The validity (in seconds) of the access token.
	 */
	public void setAccessTokenValiditySeconds(int accessTokenValiditySeconds) {
		this.accessTokenValiditySeconds = accessTokenValiditySeconds;
	}

	/**
	 * Whether to support the refresh token.
	 * 
	 * @param supportRefreshToken Whether to support the refresh token.
	 */
	public void setSupportRefreshToken(boolean supportRefreshToken) {
		this.supportRefreshToken = supportRefreshToken;
	}

	/**
	 * Whether to reuse refresh tokens (until expired).
	 * 
	 * @param reuseRefreshToken Whether to reuse refresh tokens (until expired).
	 */
	public void setReuseRefreshToken(boolean reuseRefreshToken) {
		this.reuseRefreshToken = reuseRefreshToken;
	}

	/**
	 * The persistence strategy for token storage.
	 * 
	 * @param tokenStore the store for access and refresh tokens.
	 */
	public void setTokenStore(TokenStore tokenStore) {
		this.tokenStore = tokenStore;
	}

	/**
	 * An authentication manager that will be used (if provided) to check the user authentication when a token is
	 * refreshed.
	 * 
	 * @param authenticationManager the authenticationManager to set
	 */
	public void setAuthenticationManager(AuthenticationManager authenticationManager) {
		this.authenticationManager = authenticationManager;
	}

	/**
	 * The client details service to use for looking up clients (if necessary). Optional if the access token expiry is
	 * set globally via {@link #setAccessTokenValiditySeconds(int)}.
	 * 
	 * @param clientDetailsService the client details service
	 */
	public void setClientDetailsService(ClientDetailsService clientDetailsService) {
		this.clientDetailsService = clientDetailsService;
	}

}