Basic blog generation

src/main/java/com/homelabpulse/Application.java

@@ -3,9 +3,11 @@ package com.homelabpulse;
 import org.springframework.boot.SpringApplication;
 import org.springframework.boot.autoconfigure.SpringBootApplication;
 import org.springframework.data.jpa.repository.config.EnableJpaAuditing;
+import org.springframework.scheduling.annotation.EnableAsync;
 
 @SpringBootApplication
 @EnableJpaAuditing
+@EnableAsync
 public class Application {
     public static void main(String[] args) {
         SpringApplication.run(Application.class, args);

src/main/java/com/homelabpulse/config/OllamaConfig.java

@@ -6,6 +6,7 @@ import org.springframework.ai.ollama.api.OllamaApi;
 import org.springframework.beans.factory.annotation.Value;
 import org.springframework.context.annotation.Bean;
 import org.springframework.context.annotation.Configuration;
+import org.springframework.scheduling.concurrent.ThreadPoolTaskExecutor;
 
 @Configuration
 public class OllamaConfig {
@@ -20,4 +21,15 @@ public class OllamaConfig {
                 .build();
     }
 
+    @Bean(name = "ollamaExecutor")
+    public ThreadPoolTaskExecutor ollamaExecutor() {
+        ThreadPoolTaskExecutor executor = new ThreadPoolTaskExecutor();
+        executor.setCorePoolSize(10); // Set your core pool size
+        executor.setMaxPoolSize(25);  // Set your maximum pool size
+        executor.setQueueCapacity(250); // Set your queue capacity
+        executor.setThreadNamePrefix("OllamaAsync-"); // Prefix for thread names
+        executor.initialize();
+        return executor;
+    }
+
 }

src/main/java/com/homelabpulse/controller/BlogController.java

@@ -2,6 +2,7 @@ package com.homelabpulse.controller;
 
 import com.homelabpulse.dto.BlogDTO;
 import com.homelabpulse.service.BlogService;
+import com.homelabpulse.service.BlogWriterService;
 import lombok.RequiredArgsConstructor;
 import org.springframework.http.HttpStatus;
 import org.springframework.http.ResponseEntity;
@@ -14,12 +15,18 @@ import java.util.List;
 @RequestMapping("/blogs")
 public class BlogController {
     private final BlogService blogService;
+    private final BlogWriterService blogWriterService;
 
     @PostMapping
     public ResponseEntity<BlogDTO> save(@RequestBody BlogDTO blogDTO) {
         return new ResponseEntity<>(blogService.save(blogDTO), HttpStatus.CREATED);
     }
 
+    @PostMapping("/{id}/write")
+    public ResponseEntity<BlogDTO> write(@PathVariable("id") Long id) {
+        return ResponseEntity.ok(blogWriterService.writeProductBlog(id));
+    }
+
     @GetMapping
     public ResponseEntity<List<BlogDTO>> getAll() {
         List<BlogDTO> blogs = blogService.getAll();

src/main/java/com/homelabpulse/dto/BlogDTO.java

@@ -12,5 +12,6 @@ import lombok.Setter;
 public class BlogDTO extends AuditableDTO {
     private Long id;
     private Long productId;
+    private String title;
     private String content;
 }

src/main/java/com/homelabpulse/entity/Blog.java

@@ -17,6 +17,9 @@ public class Blog extends AuditableEntity {
     @Column(name = "product_id")
     private Long productId;
 
+    @Column(name = "title")
+    private String title;
+
     @Column(name = "content")
     private String content;
 }

src/main/java/com/homelabpulse/service/BlogService.java

@@ -38,4 +38,5 @@ public class BlogService {
         blogOpt.ifPresent(blogRepository::delete);
         return blogDto;
     }
+
 }

src/main/java/com/homelabpulse/service/BlogWriterService.java

@@ -0,0 +1,112 @@
+package com.homelabpulse.service;
+
+import com.homelabpulse.dto.BlogDTO;
+import com.homelabpulse.entity.Blog;
+import com.homelabpulse.entity.Product;
+import com.homelabpulse.mapper.BlogMapper;
+import com.homelabpulse.repository.BlogRepository;
+import com.homelabpulse.repository.ProductRepository;
+import jakarta.persistence.EntityNotFoundException;
+import lombok.RequiredArgsConstructor;
+import lombok.extern.slf4j.Slf4j;
+import org.springframework.ai.chat.messages.SystemMessage;
+import org.springframework.ai.chat.messages.UserMessage;
+import org.springframework.stereotype.Service;
+
+@Service
+@RequiredArgsConstructor
+@Slf4j
+public class BlogWriterService {
+    private final OllamaService ollamaService;
+    private final BlogRepository blogRepository;
+    private final ProductRepository productRepository;
+    private final BlogMapper blogMapper;
+
+    private static final String SYSTEM_MESSAGE = """
+                        You are a blog writer for Homelab Pulse (https://homelabpulse.com), specializing in homelab tech.
+                        You review products in a subtle way, so your readers aren't turned off by blatant advertising.
+                        When possible, provide an example use case of a project for which the product can be used.
+                        The products you review are not made or supported by homelabpulse.com.
+            """;
+    private static final String PRODUCT_MESSAGE_SEGMENT = """
+                        Here is the product info:
+            
+                        ``` Product URL
+                        %1$s
+                        ```
+            
+                        ``` Product Title
+                        %2$s
+                        ```
+            
+                        ``` Product Description
+                        %3$s
+                        ```
+            """;
+
+    public BlogDTO writeProductBlog(Long blogId) {
+        log.info("Writing blogId={}", blogId);
+        Blog blog = blogRepository.findById(blogId).orElseThrow(() -> new EntityNotFoundException("Blog id=" + blogId + " not found"));
+        Product product = productRepository.findById(blog.getProductId()).orElseThrow(() -> new EntityNotFoundException("Product id=" + blog.getProductId() + " not found"));
+
+        boolean newTitle = false;
+        if (blog.getTitle() == null) {
+            newTitle = true;
+            String title = generateNewTitle(blog, product);
+            blog.setTitle(title);
+        }
+
+        if (blog.getContent() == null || newTitle) {
+            String content = generateNewContent(blog, product);
+            blog.setContent(content);
+        }
+
+        blogRepository.save(blog);
+        log.info("Finished writing blogId={}", blogId);
+        return blogMapper.toDTO(blog);
+    }
+
+    private String generateNewContent(Blog blog, Product product) {
+        UserMessage userMessage = new UserMessage(
+                """
+                        There exists an empty blog titled "%1$s".
+                        Write the blog post, in markdown format.
+                        
+                        %2$s
+                        """.formatted(blog.getTitle(), getProductSegment(product))
+        );
+        String content = ollamaService.call(
+                new SystemMessage(SYSTEM_MESSAGE),
+                userMessage
+        );
+        log.debug("Content for blog id={}:\n\n{}", blog.getId(), content);
+        return content;
+    }
+
+    private String generateNewTitle(Blog blog, Product product) {
+
+        UserMessage userMessage = new UserMessage(
+                """
+                        Write the title of a blog post about the following product.
+                        Only write the title of the post; do not add anything else to the response.
+                        Maximum characters is 200.
+                        
+                        %1$s
+                        """.formatted(getProductSegment(product))
+        );
+        String title = ollamaService.call(
+                new SystemMessage(SYSTEM_MESSAGE),
+                userMessage
+        );
+        if (title.startsWith("Title: ")) {
+            log.debug("Removing 'Title: '");
+            title = title.replace("Title: ", "").strip();
+        }
+        log.info("Title for blogId={}: {}", blog.getId(), title);
+        return title;
+    }
+
+    private String getProductSegment(Product product) {
+        return PRODUCT_MESSAGE_SEGMENT.formatted(product.getUrl(), product.getTitle(), product.getDescription());
+    }
+}

src/main/java/com/homelabpulse/service/OllamaService.java

@@ -0,0 +1,43 @@
+package com.homelabpulse.service;
+
+import lombok.RequiredArgsConstructor;
+import lombok.extern.slf4j.Slf4j;
+import org.springframework.ai.chat.messages.SystemMessage;
+import org.springframework.ai.chat.messages.UserMessage;
+import org.springframework.ai.chat.model.ChatModel;
+import org.springframework.ai.chat.model.ChatResponse;
+import org.springframework.ai.chat.prompt.Prompt;
+import org.springframework.ai.ollama.api.OllamaOptions;
+import org.springframework.stereotype.Service;
+
+import java.util.Arrays;
+
+@Service
+@RequiredArgsConstructor
+@Slf4j
+public class OllamaService {
+    private final ChatModel chatModel;
+    private static final String DEFAULT_MODEL = "hermes3";
+
+    public String call(SystemMessage systemMessage, UserMessage userMessage) {
+        return call(systemMessage, userMessage, DEFAULT_MODEL);
+    }
+
+    public String call(SystemMessage systemMessage, UserMessage userMessage, String model) {
+        log.debug("UserMessage:\n{}", userMessage.getText());
+        OllamaOptions ollamaOptions = OllamaOptions.builder()
+                .model(model)
+                .build();
+        Prompt prompt = new Prompt(Arrays.asList(systemMessage, userMessage), ollamaOptions);
+        ChatResponse chatResponse = chatModel.call(prompt);
+        String responseStr = chatResponse.getResult().getOutput().getText();
+        log.debug("Response: {}", responseStr);
+        responseStr = responseStr.strip();
+        if (responseStr.charAt(0) == '"' && responseStr.charAt(responseStr.length() - 1) == '"') {
+            log.debug("Stripping quotes: {}", responseStr);
+            responseStr = responseStr.substring(1, responseStr.length() - 1).strip();
+        }
+        log.debug("Trimmed response: {}", responseStr);
+        return responseStr;
+    }
+}

src/main/resources/db/migration/V3__Blog_Title.sql

@@ -0,0 +1,3 @@
+-- V3__Blog_Title.sql
+
+ALTER TABLE blog ADD COLUMN title VARCHAR(500);