package org.springframework.security.config.authentication;

import java.util.HashMap;
import java.util.Map;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.springframework.beans.BeanMetadataElement;
import org.springframework.beans.factory.config.BeanDefinition;
import org.springframework.beans.factory.config.RuntimeBeanReference;
import org.springframework.beans.factory.support.BeanDefinitionBuilder;
import org.springframework.beans.factory.support.RootBeanDefinition;
import org.springframework.beans.factory.xml.ParserContext;
import org.springframework.security.authentication.encoding.BaseDigestPasswordEncoder;
import org.springframework.security.authentication.encoding.LdapShaPasswordEncoder;
import org.springframework.security.authentication.encoding.Md4PasswordEncoder;
import org.springframework.security.authentication.encoding.Md5PasswordEncoder;
import org.springframework.security.authentication.encoding.PasswordEncoder;
import org.springframework.security.authentication.encoding.PlaintextPasswordEncoder;
import org.springframework.security.authentication.encoding.ShaPasswordEncoder;
import org.springframework.security.config.Elements;
import org.springframework.util.StringUtils;
import org.springframework.util.xml.DomUtils;
import org.w3c.dom.Element;

/**
 * Stateful parser for the <password-encoder> element.
 *
 * Will produce a PasswordEncoder and (optionally) a SaltSource.
 *
 * @author Luke Taylor
 */
public class PasswordEncoderParser {
    static final String ATT_REF = "ref";
    public static final String ATT_HASH = "hash";
    static final String ATT_BASE_64 = "base64";
    static final String OPT_HASH_PLAINTEXT = "plaintext";
    static final String OPT_HASH_SHA = "sha";
    static final String OPT_HASH_SHA256 = "sha-256";
    static final String OPT_HASH_MD4 = "md4";
    static final String OPT_HASH_MD5 = "md5";
    static final String OPT_HASH_LDAP_SHA = "{sha}";
    static final String OPT_HASH_LDAP_SSHA = "{ssha}";

    private static final Map<String, Class<? extends PasswordEncoder>> ENCODER_CLASSES;

    static {
        ENCODER_CLASSES = new HashMap<String, Class<? extends PasswordEncoder>>();
        ENCODER_CLASSES.put(OPT_HASH_PLAINTEXT, PlaintextPasswordEncoder.class);
        ENCODER_CLASSES.put(OPT_HASH_SHA, ShaPasswordEncoder.class);
        ENCODER_CLASSES.put(OPT_HASH_SHA256, ShaPasswordEncoder.class);
        ENCODER_CLASSES.put(OPT_HASH_MD4, Md4PasswordEncoder.class);
        ENCODER_CLASSES.put(OPT_HASH_MD5, Md5PasswordEncoder.class);
        ENCODER_CLASSES.put(OPT_HASH_LDAP_SHA, LdapShaPasswordEncoder.class);
        ENCODER_CLASSES.put(OPT_HASH_LDAP_SSHA, LdapShaPasswordEncoder.class);
    }

    private static final Log logger = LogFactory.getLog(PasswordEncoderParser.class);

    private BeanMetadataElement passwordEncoder;
    private BeanMetadataElement saltSource;

    public PasswordEncoderParser(Element element, ParserContext parserContext) {
        parse(element, parserContext);
    }

    private void parse(Element element, ParserContext parserContext) {
        String hash = element.getAttribute(ATT_HASH);
        boolean useBase64 = false;

        if (StringUtils.hasText(element.getAttribute(ATT_BASE_64))) {
            useBase64 = Boolean.valueOf(element.getAttribute(ATT_BASE_64)).booleanValue();
        }

        String ref = element.getAttribute(ATT_REF);

        if (StringUtils.hasText(ref)) {
            passwordEncoder = new RuntimeBeanReference(ref);
        } else {
            passwordEncoder = createPasswordEncoderBeanDefinition(hash, useBase64);
            ((RootBeanDefinition)passwordEncoder).setSource(parserContext.extractSource(element));
        }

        Element saltSourceElt = DomUtils.getChildElementByTagName(element, Elements.SALT_SOURCE);

        if (saltSourceElt != null) {
            saltSource = new SaltSourceBeanDefinitionParser().parse(saltSourceElt, parserContext);
        }
    }

    public static BeanDefinition createPasswordEncoderBeanDefinition(String hash, boolean useBase64) {
        Class<? extends PasswordEncoder> beanClass = ENCODER_CLASSES.get(hash);
        BeanDefinitionBuilder beanBldr = BeanDefinitionBuilder.rootBeanDefinition(beanClass);

        if (OPT_HASH_SHA256.equals(hash)) {
            beanBldr.addConstructorArgValue(new Integer(256));
        }

        if (useBase64) {
            if (BaseDigestPasswordEncoder.class.isAssignableFrom(beanClass)) {
                beanBldr.addPropertyValue("encodeHashAsBase64", "true");
            } else {
                logger.warn(ATT_BASE_64 + " isn't compatible with " + hash + " and will be ignored");
            }
        }
        return beanBldr.getBeanDefinition();
    }

    public BeanMetadataElement getPasswordEncoder() {
        return passwordEncoder;
    }

    public BeanMetadataElement getSaltSource() {
        return saltSource;
    }
}
