/*
 * Copyright (c) 2018 ETH Zürich, Educational Development and Technology (LET)
 *
 * This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/.
 */

package ch.ethz.seb.sebserver;

import java.io.IOException;

import javax.servlet.http.HttpServletResponse;

import org.springframework.beans.factory.annotation.Value;
import org.springframework.boot.web.servlet.FilterRegistrationBean;
import org.springframework.boot.web.servlet.error.ErrorController;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.core.annotation.Order;
import org.springframework.http.HttpHeaders;
import org.springframework.security.config.annotation.web.builders.WebSecurity;
import org.springframework.security.config.annotation.web.configuration.WebSecurityConfigurerAdapter;
import org.springframework.security.crypto.bcrypt.BCryptPasswordEncoder;
import org.springframework.security.crypto.password.PasswordEncoder;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;
import org.springframework.web.filter.CharacterEncodingFilter;

import ch.ethz.seb.sebserver.gbl.api.API;
import ch.ethz.seb.sebserver.gbl.profile.GuiProfile;
import ch.ethz.seb.sebserver.gbl.profile.WebServiceProfile;

/** This is the overall seb-server Spring web-configuration that is loaded for all profiles.
 * Defines some overall web-security beans needed on both -- web-service and web-gui -- profiles */
@Configuration
@WebServiceProfile
@GuiProfile
@RestController
@Order(7)
public class WebSecurityConfig extends WebSecurityConfigurerAdapter implements ErrorController {

    private static final String ERROR_PATH = "/sebserver/error";
    private static final String CHECK_PATH = "/sebserver/check";

    @Value("${sebserver.webservice.http.redirect.gui}")
    private String guiRedirect;
    @Value("${sebserver.webservice.api.exam.endpoint.discovery}")
    private String examAPIDiscoveryEndpoint;
    @Value("${sebserver.webservice.api.admin.endpoint}")
    private String adminAPIEndpoint;

    /** Spring bean name of user password encoder */
    public static final String USER_PASSWORD_ENCODER_BEAN_NAME = "userPasswordEncoder";
    /** Spring bean name of client (application) password encoder */
    public static final String CLIENT_PASSWORD_ENCODER_BEAN_NAME = "clientPasswordEncoder";

    @Bean
    public FilterRegistrationBean<CharacterEncodingFilter> filterRegistrationBean() {
        final FilterRegistrationBean<CharacterEncodingFilter> registrationBean = new FilterRegistrationBean<>();
        final CharacterEncodingFilter characterEncodingFilter = new CharacterEncodingFilter();
        characterEncodingFilter.setForceEncoding(true);
        characterEncodingFilter.setEncoding("UTF-8");
        registrationBean.setFilter(characterEncodingFilter);
        return registrationBean;
    }

    /** Password encoder used for user passwords (stronger protection) */
    @Bean(USER_PASSWORD_ENCODER_BEAN_NAME)
    public PasswordEncoder userPasswordEncoder() {
        return new BCryptPasswordEncoder(8);
    }

    /** Password encode used for client (application) passwords */
    @Bean(CLIENT_PASSWORD_ENCODER_BEAN_NAME)
    public PasswordEncoder clientPasswordEncoder() {
        return new BCryptPasswordEncoder(4);
    }

    @Override
    public void configure(final WebSecurity web) {
        web
                .ignoring()
                .antMatchers(ERROR_PATH)
                .antMatchers(CHECK_PATH)
                .antMatchers(this.examAPIDiscoveryEndpoint)
                .antMatchers(this.adminAPIEndpoint + API.INFO_ENDPOINT + API.LOGO_PATH_SEGMENT + "/**")
                .antMatchers(this.adminAPIEndpoint + API.INFO_ENDPOINT + API.INFO_INST_PATH_SEGMENT + "/**")
                .antMatchers(this.adminAPIEndpoint + API.REGISTER_ENDPOINT);
    }

    @RequestMapping(CHECK_PATH)
    public void check() throws IOException {
    }

    @RequestMapping(ERROR_PATH)
    public void handleError(final HttpServletResponse response) throws IOException {
        response.getOutputStream().print(response.getStatus());
        response.setHeader(HttpHeaders.LOCATION, this.guiRedirect);
        response.flushBuffer();
    }

}