package kr.co.gt1000.security;

import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;

/**
 * Spring 을 사용하지 않는 시스템을 위한 스프링 코드 포팅
 * @author CheonJeongDae
 *
 */
public class SpringSecurityShaPasswordEncoder {
	
	private final String algorithm;
	private boolean encodeHashAsBase64 = false;
	private int iterations = 1;
	
	
	public SpringSecurityShaPasswordEncoder() {
		this(1);
	}
	
	public SpringSecurityShaPasswordEncoder(int strength) {
		if(strength != 1 && strength != 224 && strength != 256 && strength != 384 && strength != 512) {
			throw new IllegalArgumentException("No such algorithm [" + strength + "]");
		}
		
		algorithm = "SHA-" + strength;
		getMessageDigest();
	}
	
	/**
	 * 비밀번호 암호화
	 * @param rawPass
	 * @param salt
	 * @return
	 */
	public String encodePassword(String rawPass, Object salt) {
		String saltedPass = mergePasswordAndSalt(rawPass, salt, false);
		MessageDigest messageDigest = getMessageDigest();
		byte[] digest = messageDigest.digest(SpringSecurityUtf8.encode(saltedPass));

		for (int i = 1; i < this.iterations; ++i) {
			digest = messageDigest.digest(digest);
		}

		if (encodeHashAsBase64) {
			return SpringSecurityUtf8.decode(SpringSecurityBase64.encode(digest));
		}

		return new String(SpringSecurityHex.encode(digest));
	}
	
	protected final MessageDigest getMessageDigest() throws IllegalArgumentException {
		try {
			return MessageDigest.getInstance(this.algorithm);
		} catch (NoSuchAlgorithmException e) {
			throw new IllegalArgumentException("No such algorithm [" + this.algorithm + "]");
		}
	}

	/**
	 * 비밀번호 비교
	 * @param encPass
	 * @param rawPass
	 * @param salt
	 * @return
	 */
	public boolean isPasswordValid(String encPass, String rawPass, Object salt) {
		String pass1 = "" + encPass;
		String pass2 = encodePassword(rawPass, salt);

		return SpringSecurityPasswordEncoderUtils.equals(pass1, pass2);
	}

	public String getAlgorithm() {
		return this.algorithm;
	}

	public void setIterations(int iterations) {
		if (!(iterations > 0)) throw new IllegalArgumentException("Iterations value must be greater than zero");
		this.iterations = iterations;
	}
	
	public void setEncodeHashAsBase64(boolean encodeHashAsBase64) {
		this.encodeHashAsBase64 = encodeHashAsBase64;
	}

	protected String[] demergePasswordAndSalt(String mergedPasswordSalt) {
		if ((mergedPasswordSalt == null) || ("".equals(mergedPasswordSalt))) {
			throw new IllegalArgumentException("Cannot pass a null or empty String");
		}

		String password = mergedPasswordSalt;
		String salt = "";

		int saltBegins = mergedPasswordSalt.lastIndexOf("{");

		if ((saltBegins != -1) && (saltBegins + 1 < mergedPasswordSalt.length())) {
			salt = mergedPasswordSalt.substring(saltBegins + 1, mergedPasswordSalt.length() - 1);
			password = mergedPasswordSalt.substring(0, saltBegins);
		}

		return new String[] { password, salt };
	}

	/**
	 * 비밀번호와 salt를 merge
	 * @param password
	 * @param salt
	 * @param strict
	 * @return
	 */
	protected String mergePasswordAndSalt(String password, Object salt, boolean strict) {
		if (password == null) {
			password = "";
		}

		if ((strict) && (salt != null)
				&& (((salt.toString().lastIndexOf("{") != -1) || (salt.toString().lastIndexOf("}") != -1)))) {
			throw new IllegalArgumentException("Cannot use { or } in salt.toString()");
		}

		if ((salt == null) || ("".equals(salt))) {
			return password;
		}

		return password + "{" + salt.toString() + "}";
	}
}