src/main/java/com/dalab/policyengine/config/SecurityConfiguration.java

package com.dalab.policyengine.config;

import org.springframework.beans.factory.annotation.Value;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
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.http.SessionCreationPolicy;
import org.springframework.security.oauth2.jwt.JwtDecoder;
import org.springframework.security.oauth2.jwt.NimbusJwtDecoder;
import org.springframework.security.web.SecurityFilterChain;

@Configuration
@EnableWebSecurity
@EnableMethodSecurity(prePostEnabled = true, securedEnabled = true)
public class SecurityConfiguration {

    @Value("${spring.security.oauth2.resourceserver.jwt.issuer-uri}")
    private String issuerUri;

    @Bean
    public SecurityFilterChain filterChain(HttpSecurity http) throws Exception {
        http
            .csrf(csrf -> csrf.disable()) // Typically disable CSRF for stateless REST APIs
            .sessionManagement(session -> session.sessionCreationPolicy(SessionCreationPolicy.STATELESS))
            .authorizeHttpRequests(authz -> authz
                // Define public endpoints if any (e.g., actuator/health, swagger-ui)
                // .requestMatchers("/public/**").permitAll()
                .anyRequest().authenticated() // All other requests require authentication
            )
            .oauth2ResourceServer(oauth2 -> oauth2
                .jwt(jwt -> jwt.decoder(jwtDecoder()))
            );
        return http.build();
    }

    @Bean
    public JwtDecoder jwtDecoder() {
        // NimbusJwtDecoder automatically fetches the JWK Set URI from the issuer URI
        // (e.g., ISSUER_URI/.well-known/openid-configuration or ISSUER_URI/protocol/openid-connect/certs)
        return NimbusJwtDecoder.withIssuerLocation(issuerUri).build();
    }
}