s3 bucket integration for image storage

backend/src/main/java/com/aiteacher/config/FigureStorageConfig.java

@@ -1,25 +1,37 @@
 package com.aiteacher.config;
 
-import org.springframework.beans.factory.annotation.Value;
-import org.springframework.context.annotation.Configuration;
-import org.springframework.web.servlet.config.annotation.ResourceHandlerRegistry;
-import org.springframework.web.servlet.config.annotation.WebMvcConfigurer;
+import com.aiteacher.figure.FigureStorageService;
+import org.springframework.http.HttpStatus;
+import org.springframework.web.bind.annotation.*;
+import org.springframework.web.server.ResponseStatusException;
 
-import java.nio.file.Paths;
+import jakarta.servlet.http.HttpServletResponse;
+import java.io.IOException;
 
-@Configuration
-public class FigureStorageConfig implements WebMvcConfigurer {
+/**
+ * Serves figure images by redirecting to a presigned S3 URL.
+ * The key stored in DB is the full S3 object key, e.g. "figures/{bookId}/{figureId}.png".
+ */
+@RestController
+@RequestMapping("/api/v1/figures")
+public class FigureStorageConfig {
 
-    private final String basePath;
+    private final FigureStorageService figureStorageService;
 
-    public FigureStorageConfig(@Value("${app.figure-storage.base-path:./uploads}") String basePath) {
-        this.basePath = Paths.get(basePath).toAbsolutePath().normalize().toString();
+    public FigureStorageConfig(FigureStorageService figureStorageService) {
+        this.figureStorageService = figureStorageService;
     }
 
-    @Override
-    public void addResourceHandlers(ResourceHandlerRegistry registry) {
-        // Serve GET /api/v1/figures/** from the local file store
-        registry.addResourceHandler("/api/v1/figures/**")
-                .addResourceLocations("file:" + basePath + "/figures/");
+    @GetMapping("/{bookId}/{filename}")
+    public void serve(@PathVariable String bookId,
+                      @PathVariable String filename,
+                      HttpServletResponse response) throws IOException {
+        String key = "figures/" + bookId + "/" + filename;
+        try {
+            String url = figureStorageService.presignedUrl(key);
+            response.sendRedirect(url);
+        } catch (Exception ex) {
+            throw new ResponseStatusException(HttpStatus.NOT_FOUND, "Figure not found: " + key);
+        }
     }
 }

backend/src/main/java/com/aiteacher/config/SecurityConfig.java

@@ -20,7 +20,9 @@ public class SecurityConfig {
     @Bean
     public SecurityFilterChain filterChain(HttpSecurity http) throws Exception {
         http
-            .authorizeHttpRequests(auth -> auth.anyRequest().authenticated())
+            .authorizeHttpRequests(auth -> auth
+                .requestMatchers("/api/v1/figures/**").permitAll()
+                .anyRequest().authenticated())
             .httpBasic(Customizer.withDefaults())
             .csrf(AbstractHttpConfigurer::disable);
         return http.build();