/**
 * Security Configuration
 * 
 * Spring Security configuration for JWT-based authentication.
 * 
 * @author David Valera Melendez <david@valera-melendez.de>
 * @since February  2025
 */
package com.company.auth.config;

import com.company.auth.security.JwtAuthenticationEntryPoint;
import com.company.auth.security.JwtAuthenticationFilter;
import com.company.auth.service.UserService;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.security.authentication.AuthenticationManager;
import org.springframework.security.authentication.AuthenticationProvider;
import org.springframework.security.authentication.dao.DaoAuthenticationProvider;
import org.springframework.security.config.annotation.authentication.configuration.AuthenticationConfiguration;
import org.springframework.security.config.annotation.method.configuration.EnableMethodSecurity;
import org.springframework.security.config.annotation.web.builders.HttpSecurity;
import org.springframework.security.config.annotation.web.configuration.EnableWebSecurity;
import org.springframework.security.config.annotation.web.configurers.AbstractHttpConfigurer;
import org.springframework.security.config.http.SessionCreationPolicy;
import org.springframework.security.crypto.bcrypt.BCryptPasswordEncoder;
import org.springframework.security.crypto.password.PasswordEncoder;
import org.springframework.security.web.SecurityFilterChain;
import org.springframework.security.web.authentication.UsernamePasswordAuthenticationFilter;
import org.springframework.web.cors.CorsConfiguration;
import org.springframework.web.cors.CorsConfigurationSource;
import org.springframework.web.cors.UrlBasedCorsConfigurationSource;

import java.util.Arrays;
import java.util.List;

/**
 * Security Configuration
 * 
 * Configures Spring Security for:
 * - JWT-based authentication
 * - Stateless session management
 * - CORS configuration
 * - Security filters and providers
 */
@Configuration
@EnableWebSecurity
@EnableMethodSecurity(prePostEnabled = true)
public class SecurityConfig {

    @Autowired
    private JwtAuthenticationEntryPoint jwtAuthenticationEntryPoint;

    @Autowired
    private JwtAuthenticationFilter jwtAuthenticationFilter;

    @Autowired
    private UserService userService;

    @Autowired
    private PasswordEncoder passwordEncoder;

    /**
     * Authentication provider bean
     * 
     * @return DAO authentication provider
     */
    @Bean
    public AuthenticationProvider authenticationProvider() {
        DaoAuthenticationProvider authProvider = new DaoAuthenticationProvider();
        authProvider.setUserDetailsService(userService);
        authProvider.setPasswordEncoder(passwordEncoder);
        return authProvider;
    }

    /**
     * Authentication manager bean
     * 
     * @param config Authentication configuration
     * @return Authentication manager
     * @throws Exception if configuration fails
     */
    @Bean
    public AuthenticationManager authenticationManager(AuthenticationConfiguration config) throws Exception {
        return config.getAuthenticationManager();
    }

    /**
     * CORS configuration source
     * 
     * @return CORS configuration source
     */
    @Bean
    public CorsConfigurationSource corsConfigurationSource() {
        CorsConfiguration configuration = new CorsConfiguration();
        
        // Allow specific origins in production, * for development
        configuration.setAllowedOriginPatterns(Arrays.asList(
            "http://localhost:3000",     // React development
            "http://localhost:4200",     // Angular development
            "http://localhost:8080",     // Local backend
            "https://*.company.com",     // Production domains
            "https://company.com"
        ));
        
        configuration.setAllowedMethods(Arrays.asList(
            "GET", "POST", "PUT", "DELETE", "PATCH", "OPTIONS"
        ));
        
        configuration.setAllowedHeaders(Arrays.asList(
            "Authorization",
            "Content-Type",
            "X-Requested-With",
            "Accept",
            "Origin",
            "Access-Control-Request-Method",
            "Access-Control-Request-Headers",
            // Custom headers for device fingerprinting
            "User-Agent",
            "Accept-Language",
            "Timezone",
            "Screen-Resolution",
            "Color-Depth",
            "Hardware-Concurrency",
            "Device-Memory",
            "Platform",
            "Cookie-Enabled",
            "DNT",
            "Webdriver",
            "Device-Fingerprint"
        ));
        
        configuration.setExposedHeaders(Arrays.asList(
            "Authorization",
            "Content-Disposition"
        ));
        
        configuration.setAllowCredentials(true);
        configuration.setMaxAge(3600L); // 1 hour preflight cache
        
        UrlBasedCorsConfigurationSource source = new UrlBasedCorsConfigurationSource();
        source.registerCorsConfiguration("/**", configuration);
        
        return source;
    }

    /**
     * Security filter chain configuration
     * 
     * @param http HTTP security configuration
     * @return Security filter chain
     * @throws Exception if configuration fails
     */
    @Bean
    public SecurityFilterChain filterChain(HttpSecurity http) throws Exception {
        http
            // Disable CSRF for stateless REST APIs
            .csrf(AbstractHttpConfigurer::disable)
            
            // Configure CORS
            .cors(cors -> cors.configurationSource(corsConfigurationSource()))
            
            // Configure authorization rules
            .authorizeHttpRequests(authz -> authz
                // Public endpoints
                .requestMatchers(
                    "/api/auth/register",
                    "/api/auth/login",
                    "/api/auth/verify-device",
                    "/api/auth/verify-2fa",
                    "/api/auth/refresh",
                    "/api/auth/resend-device-verification",
                    "/api/auth/resend-2fa"
                ).permitAll()
                
                // Health check and monitoring endpoints
                .requestMatchers(
                    "/actuator/health",
                    "/actuator/health/**",
                    "/actuator/info"
                ).permitAll()
                
                // API documentation endpoints
                .requestMatchers(
                    "/v3/api-docs/**",
                    "/swagger-ui/**",
                    "/swagger-ui.html",
                    "/swagger-resources/**",
                    "/webjars/**"
                ).permitAll()
                
                // Static resources
                .requestMatchers(
                    "/favicon.ico",
                    "/error"
                ).permitAll()
                
                // All other endpoints require authentication
                .anyRequest().authenticated()
            )
            
            // Configure exception handling
            .exceptionHandling(ex -> ex
                .authenticationEntryPoint(jwtAuthenticationEntryPoint)
            )
            
            // Configure session management (stateless)
            .sessionManagement(session -> session
                .sessionCreationPolicy(SessionCreationPolicy.STATELESS)
            )
            
            // Configure authentication provider
            .authenticationProvider(authenticationProvider())
            
            // Add JWT authentication filter
            .addFilterBefore(jwtAuthenticationFilter, UsernamePasswordAuthenticationFilter.class);

        return http.build();
    }
}