import jakarta.annotation.Resource;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.context.annotation.Configuration;
import org.springframework.security.config.annotation.authentication.builders.AuthenticationManagerBuilder;
import org.springframework.security.config.annotation.method.configuration.EnableMethodSecurity;
import org.springframework.security.config.annotation.web.configuration.EnableWebSecurity;
import org.springframework.security.core.userdetails.UserDetailsService;
import org.springframework.security.crypto.bcrypt.BCryptPasswordEncoder;
import org.springframework.security.crypto.password.PasswordEncoder;
import org.springframework.security.web.SecurityFilterChain;

@Configuration
@EnableWebSecurity
@EnableMethodSecurity()
public class WebSecurityConfig implements SecurityFilterChain {
	@Resource
	private UserDetailsService userDetailsService;
	
	@Autowired
	public void configureAuthentication(AuthenticationManagerBuilder authenticationManagerBuilder) throws Exception {
		authenticationManagerBuilder
			.userDetailsService(this.userDetailsService)
			.passwordEncoder(passwordEncoder());
	}
	
	@Bean
	public PasswordEncoder passwordEncoder() {
		return new BCryptPasswordEncoder();
	}
}

public interface PasswordEncoder {
	// 用來對明文密碼進(jìn)行加密
	String encode(CharSequence rawPassword);
	// 用來進(jìn)行密碼比對
	boolean matches(CharSequence rawPassword, String encodedPassword);
	// 用來判斷當(dāng)前密碼是否需要升級，默認(rèn)返回false表示不需要升級
	default boolean upgradeEncoding(String encodedPassword) {
		return false;
	}
}

public String encode(CharSequence rawPassword) {
	if (rawPassword == null) {
		throw new IllegalArgumentException("rawPassword cannot be null");
	}
	String salt = getSalt();
	return BCrypt.hashpw(rawPassword.toString(), salt);
}

private String getSalt() {
	if (this.random != null) {
		return BCrypt.gensalt(this.version.getVersion(), this.strength, this.random);
	}
	return BCrypt.gensalt(this.version.getVersion(), this.strength);
}

public BCryptPasswordEncoder(BCryptVersion version, int strength, SecureRandom random) {
	if (strength != -1 && (strength < BCrypt.MIN_LOG_ROUNDS || strength > BCrypt.MAX_LOG_ROUNDS)) {
		throw new IllegalArgumentException("Bad strength");
	}
	this.version = version;
	this.strength = (strength == -1) ? 10 : strength;
	this.random = random;
}

public static PasswordEncoder createDelegatingPasswordEncoder() {
	String encodingId = "bcrypt";
	Map<String, PasswordEncoder> encoders = new HashMap();
	encoders.put(encodingId, new BCryptPasswordEncoder());
	encoders.put("ldap", new LdapShaPasswordEncoder());
	encoders.put("MD4", new Md4PasswordEncoder());
	encoders.put("MD5", new MessageDigestPasswordEncoder("MD5"));
	encoders.put("noop", NoOpPasswordEncoder.getInstance());
	encoders.put("pbkdf2", Pbkdf2PasswordEncoder.defaultsForSpringSecurity_v5_5());
	encoders.put("pbkdf2@SpringSecurity_v5_8", Pbkdf2PasswordEncoder.defaultsForSpringSecurity_v5_8());
	encoders.put("scrypt", SCryptPasswordEncoder.defaultsForSpringSecurity_v4_1());
	encoders.put("scrypt@SpringSecurity_v5_8", SCryptPasswordEncoder.defaultsForSpringSecurity_v5_8());
	encoders.put("SHA-1", new MessageDigestPasswordEncoder("SHA-1"));
	encoders.put("SHA-256", new MessageDigestPasswordEncoder("SHA-256"));
	encoders.put("sha256", new StandardPasswordEncoder());
	encoders.put("argon2", Argon2PasswordEncoder.defaultsForSpringSecurity_v5_2());
	encoders.put("argon2@SpringSecurity_v5_8", Argon2PasswordEncoder.defaultsForSpringSecurity_v5_8());
	return new DelegatingPasswordEncoder(encodingId, encoders);
}

// 默認(rèn)的前綴和后綴，用于包裹將來生成的加密方案的id
private static final String DEFAULT_ID_PREFIX = "{";
private static final String DEFAULT_ID_SUFFIX = "}";
// 構(gòu)造方法里支持傳入用戶自定義的前綴和后綴
private final String idPrefix;
private final String idSuffix;
// 默認(rèn)的加密方案id
private final String idForEncode;
// 根據(jù)idForEncode從idToPasswordEncoder map中提取出來的
private final PasswordEncoder passwordEncoderForEncode;
// 保存id和加密方案之間的映射
private final Map<String, PasswordEncoder> idToPasswordEncoder;
// 默認(rèn)的密碼比對器，當(dāng)根據(jù)密碼加密方案的id無法找到對應(yīng)的加密方案時，就會使用默認(rèn)的密碼比對器。默認(rèn)類型是UnmappedIdPasswordEncoder
private PasswordEncoder defaultPasswordEncoderForMatches = new UnmappedIdPasswordEncoder();

private class UnmappedIdPasswordEncoder implements PasswordEncoder {
	@Override
	public String encode(CharSequence rawPassword) {
		// 直接拋出異常
		throw new UnsupportedOperationException("encode is not supported");
	}

	@Override
	public boolean matches(CharSequence rawPassword, String prefixEncodedPassword) {
		// 并不會做任何密碼比對操作，直接拋出異常
		String id = extractId(prefixEncodedPassword);
		throw new IllegalArgumentException("There is no PasswordEncoder mapped for the id \"" + id + "\"");
	}
}

public String encode(CharSequence rawPassword) {
	return this.idPrefix + this.idForEncode + this.idSuffix + this.passwordEncoderForEncode.encode(rawPassword);
}

public boolean matches(CharSequence rawPassword, String prefixEncodedPassword) {
	if (rawPassword == null && prefixEncodedPassword == null) {
		return true;
	}
	String id = extractId(prefixEncodedPassword);
	PasswordEncoder delegate = this.idToPasswordEncoder.get(id);
	if (delegate == null) {
		return this.defaultPasswordEncoderForMatches.matches(rawPassword, prefixEncodedPassword);
	}
	String encodedPassword = extractEncodedPassword(prefixEncodedPassword);
	return delegate.matches(rawPassword, encodedPassword);
}

public boolean upgradeEncoding(String prefixEncodedPassword) {
	String id = extractId(prefixEncodedPassword);
	if (!this.idForEncode.equalsIgnoreCase(id)) {
		return true;
	} else {
		String encodedPassword = extractEncodedPassword(prefixEncodedPassword);
		return this.idToPasswordEncoder.get(id).upgradeEncoding(encodedPassword);
	}
}

public class Sha512PasswordEncoder implements PasswordEncoder {
	@Override
	public String encode(CharSequence rawPassword) {
		return hashWithSha512(rawPassword.toString());
	}
	
	@Override
	public boolean matches(CharSequence rawPassword, String encodedPassword) {
		String hashedPassword = encode(rawPassword);
		return encodedPassword.equals(hashedPassword);
	}

	@Override
	public boolean upgradeEncoding(String prefixEncodedPassword) {
		// 不需要升級
		return false;
	}
	
	private String hashWithSha512(String input) {
		StringBuilder result = new StringBuilder();
		try {
			MessageDigest md = MessageDigest.getInstance("SHA-512");
			byte [] digested = md.digest(input.getBytes());
			for (int i = 0; i < digested.length; i++) {
				result.append(Integer.toHexString(0xFF & digested[i]));
			}
		} catch (NoSuchAlgorithmException e) {
			throw new RuntimeException("Bad algorithm");
		}
		return result.toString();
	}
}