/*
 * Copyright 1999-2018 Alibaba Group Holding Ltd.
 *
 * 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 com.alibaba.nacos.utils;

import io.jsonwebtoken.Claims;
import io.jsonwebtoken.ExpiredJwtException;
import io.jsonwebtoken.Jwts;
import io.jsonwebtoken.MalformedJwtException;
import io.jsonwebtoken.SignatureAlgorithm;
import io.jsonwebtoken.SignatureException;
import io.jsonwebtoken.UnsupportedJwtException;
import io.jsonwebtoken.security.Keys;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.security.authentication.UsernamePasswordAuthenticationToken;
import org.springframework.security.core.Authentication;
import org.springframework.security.core.GrantedAuthority;
import org.springframework.security.core.authority.AuthorityUtils;
import org.springframework.security.core.userdetails.User;
import org.springframework.stereotype.Component;

import javax.annotation.PostConstruct;
import javax.crypto.SecretKey;
import java.util.Date;
import java.util.List;

/**
 * Jwt token tool.
 *
 * @author wfnuser
 */
@Component
public class JwtTokenUtils {

	private final Logger log = LoggerFactory.getLogger(JwtTokenUtils.class);

	private static final String AUTHORITIES_KEY = "auth";

	/**
	 * minimum SHA_256 secretKey string length.
	 */
	private static final int SHA_256_SECRET_CHAR_SIZE = 256 / 8;

	/**
	 * default SHA_256 secretKey flag.
	 */
	private static final String DEFAULT_SECRET_FLAG = "default";

	/**
	 * custom SHA_256 secretKey from config property.
	 */
	@Value("${nacos.security.token.secret-key:default}")
	private String customSecretKeyStr;

	/**
	 * secret key.
	 */
	private SecretKey secretKey;

	/**
	 * Token validity time(ms).
	 */
	private long tokenValidityInMilliseconds;

	/**
	 * Init.
	 */
	@PostConstruct
	public void init() {
		// use default secretKey for SHA-256
		if (customSecretKeyStr == null || DEFAULT_SECRET_FLAG.equals(customSecretKeyStr)) {
			this.secretKey = Keys.secretKeyFor(SignatureAlgorithm.HS256);
		}
		else {
			// use custom secretKey
			int size = customSecretKeyStr.length();
			int left = SHA_256_SECRET_CHAR_SIZE - size;
			if (left > 0) {
				// character for padding
				StringBuilder stringBuilder = new StringBuilder(customSecretKeyStr);
				for (int i = 0; i < left; i++) {
					stringBuilder.append(i % 10);
				}
				this.secretKey = Keys.hmacShaKeyFor(stringBuilder.toString().getBytes());
			}
			else {
				this.secretKey = Keys.hmacShaKeyFor(customSecretKeyStr.getBytes());
			}
		}
		this.tokenValidityInMilliseconds = 1000 * 60 * 30L;
	}

	/**
	 * Create token.
	 * @param authentication auth info
	 * @return token
	 */
	public String createToken(Authentication authentication) {

		long now = System.currentTimeMillis();

		Date validity = new Date(now + this.tokenValidityInMilliseconds);

		return Jwts.builder().setSubject(authentication.getName()).claim(AUTHORITIES_KEY, "").setExpiration(validity)
				.signWith(secretKey, SignatureAlgorithm.HS256).compact();
	}

	/**
	 * Get auth Info.
	 * @param token token
	 * @return auth info
	 */
	public Authentication getAuthentication(String token) {

		Claims claims = Jwts.parser().setSigningKey(secretKey).parseClaimsJws(token).getBody();

		List<GrantedAuthority> authorities = AuthorityUtils
				.commaSeparatedStringToAuthorityList((String) claims.get(AUTHORITIES_KEY));

		User principal = new User(claims.getSubject(), "", authorities);
		return new UsernamePasswordAuthenticationToken(principal, "", authorities);
	}

	/**
	 * validate token.
	 * @param token token
	 * @return whether valid
	 */
	public boolean validateToken(String token) {
		try {
			Jwts.parser().setSigningKey(secretKey).parseClaimsJws(token);
			return true;
		}
		catch (SignatureException e) {
			log.info("Invalid JWT signature.");
			log.trace("Invalid JWT signature trace: {}", e);
		}
		catch (MalformedJwtException e) {
			log.info("Invalid JWT token.");
			log.trace("Invalid JWT token trace: {}", e);
		}
		catch (ExpiredJwtException e) {
			log.info("Expired JWT token.");
			log.trace("Expired JWT token trace: {}", e);
		}
		catch (UnsupportedJwtException e) {
			log.info("Unsupported JWT token.");
			log.trace("Unsupported JWT token trace: {}", e);
		}
		catch (IllegalArgumentException e) {
			log.info("JWT token compact of handler are invalid.");
			log.trace("JWT token compact of handler are invalid trace: {}", e);
		}
		return false;
	}

}