package org.springframework.security.provisioning;

import java.util.Collection;
import java.util.Enumeration;
import java.util.HashMap;
import java.util.Map;
import java.util.Properties;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.springframework.security.access.AccessDeniedException;
import org.springframework.security.authentication.AuthenticationManager;
import org.springframework.security.authentication.UsernamePasswordAuthenticationToken;
import org.springframework.security.core.Authentication;
import org.springframework.security.core.context.SecurityContextHolder;
import org.springframework.security.core.userdetails.User;
import org.springframework.security.core.userdetails.UserDetails;
import org.springframework.security.core.userdetails.UsernameNotFoundException;
import org.springframework.security.core.userdetails.memory.UserAttribute;
import org.springframework.security.core.userdetails.memory.UserAttributeEditor;
import org.springframework.util.Assert;

/**
 * Non-persistent implementation of {@code UserDetailsManager} which is backed by an in-memory map.
 * <p>
 * Mainly intended for testing and demonstration purposes, where a full blown persistent system isn't required.
 *
 * @author Luke Taylor
 * @since 3.1
 */
public class InMemoryUserDetailsManager implements UserDetailsManager {
    protected final Log logger = LogFactory.getLog(getClass());

    private final Map<String, MutableUserDetails> users = new HashMap<String,MutableUserDetails>();

    private AuthenticationManager authenticationManager;

    public InMemoryUserDetailsManager(Collection<UserDetails> users) {
        for (UserDetails user : users) {
            createUser(user);
        }
    }

    public InMemoryUserDetailsManager(Properties users) {
        Enumeration<?> names = users.propertyNames();
        UserAttributeEditor editor = new UserAttributeEditor();

        while(names.hasMoreElements()) {
            String name = (String) names.nextElement();
            editor.setAsText(users.getProperty(name));
            UserAttribute attr = (UserAttribute) editor.getValue();
            UserDetails user = new User(name, attr.getPassword(), attr.isEnabled(), true, true, true,
                    attr.getAuthorities());
            createUser(user);
        }
    }

    public void createUser(UserDetails user) {
        Assert.isTrue(!userExists(user.getUsername()));

        users.put(user.getUsername().toLowerCase(), new MutableUser(user));
    }

    public void deleteUser(String username) {
        users.remove(username.toLowerCase());
    }

    public void updateUser(UserDetails user) {
        Assert.isTrue(userExists(user.getUsername()));

        users.put(user.getUsername().toLowerCase(), new MutableUser(user));
    }

    public boolean userExists(String username) {
        return users.containsKey(username.toLowerCase());
    }

    public void changePassword(String oldPassword, String newPassword) {
        Authentication currentUser = SecurityContextHolder.getContext().getAuthentication();

        if (currentUser == null) {
            // This would indicate bad coding somewhere
            throw new AccessDeniedException("Can't change password as no Authentication object found in context " +
                    "for current user.");
        }

        String username = currentUser.getName();

        logger.debug("Changing password for user '"+ username + "'");

        // If an authentication manager has been set, re-authenticate the user with the supplied password.
        if (authenticationManager != null) {
            logger.debug("Reauthenticating user '"+ username + "' for password change request.");

            authenticationManager.authenticate(new UsernamePasswordAuthenticationToken(username, oldPassword));
        } else {
            logger.debug("No authentication manager set. Password won't be re-checked.");
        }

        MutableUserDetails user = users.get(username);

        if (user == null) {
            throw new IllegalStateException("Current user doesn't exist in database.");
        }

        user.setPassword(newPassword);
    }

    public UserDetails loadUserByUsername(String username) throws UsernameNotFoundException {
        UserDetails user = users.get(username.toLowerCase());

        if (user == null) {
            throw new UsernameNotFoundException(username);
        }

        return new User(user.getUsername(), user.getPassword(), user.isEnabled(), user.isAccountNonExpired(),
                user.isCredentialsNonExpired(), user.isAccountNonLocked(), user.getAuthorities());
    }

}
