package com.et.rag.controller;
import com.et.rag.service.SBotService;
import lombok.RequiredArgsConstructor;
import org.springframework.http.ResponseEntity;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PostMapping;
import org.springframework.web.bind.annotation.RequestBody;
@Controller
@RequiredArgsConstructor
public class SBotController {
    private final SBotService sBotService;
    @GetMapping
    public String home() {
        return "index";
    }
    @PostMapping("/ask")
    public ResponseEntity<String> ask(@RequestBody String question) {
        try {
            return ResponseEntity.ok(sBotService.askQuestion(question));
        } catch (Exception e) {
            return ResponseEntity.badRequest().body("Sorry, I can't process your question right now.");
        }
    }
}

package com.et.rag.service;
import dev.langchain4j.chain.ConversationalRetrievalChain;
import lombok.RequiredArgsConstructor;
import lombok.extern.slf4j.Slf4j;
import org.springframework.stereotype.Service;
@Service
@RequiredArgsConstructor
@Slf4j
public class SBotService {
    private final ConversationalRetrievalChain chain;
    public String askQuestion(String question) {
        log.debug("======================================================");
        log.debug("Question: " + question);
        String answer = chain.execute(question);
        log.debug("Answer: " + answer);
        log.debug("======================================================");
        return answer;
    }
}

package com.et.rag.retriever;
import dev.langchain4j.data.segment.TextSegment;
import dev.langchain4j.retriever.EmbeddingStoreRetriever;
import dev.langchain4j.retriever.Retriever;
import lombok.RequiredArgsConstructor;
import lombok.extern.slf4j.Slf4j;
import java.util.List;
/**
 * EmbeddingStoreLoggingRetriever is a logging-enhanced for an EmbeddingStoreRetriever.
 * <p>
 * This class logs the relevant TextSegments discovered by the supplied
 * EmbeddingStoreRetriever for improved transparency and debugging.
 * <p>
 * Logging happens at INFO level, printing each relevant TextSegment found
 * for a given input text once the findRelevant method is called.
 */
@RequiredArgsConstructor
@Slf4j
public class EmbeddingStoreLoggingRetriever implements Retriever<TextSegment> {
    private final EmbeddingStoreRetriever retriever;
    @Override
    public List<TextSegment> findRelevant(String text) {
        List<TextSegment> relevant = retriever.findRelevant(text);
        relevant.forEach(segment -> {
            log.debug("=======================================================");
            log.debug("Found relevant text segment: {}", segment);
        });
        return relevant;
    }
}

package com.et.rag.configuration;
import dev.langchain4j.data.document.Document;
import dev.langchain4j.data.document.UrlDocumentLoader;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import java.util.List;
import static com.et.rag.constant.Constants.SPRING_BOOT_RESOURCES_LIST;
@Configuration
public class DocumentConfiguration {
    @Bean
    public List<Document> documents() {
        return SPRING_BOOT_RESOURCES_LIST.stream()
                .map(url -> {
                    try {
                        return UrlDocumentLoader.load(url);
                    } catch (Exception e) {
                        throw new RuntimeException("Failed to load document from " + url, e);
                    }
                })
                .toList();
    }
}

package com.et.rag.configuration;
import com.et.rag.retriever.EmbeddingStoreLoggingRetriever;
import dev.langchain4j.chain.ConversationalRetrievalChain;
import dev.langchain4j.data.document.Document;
import dev.langchain4j.data.document.splitter.DocumentSplitters;
import dev.langchain4j.data.segment.TextSegment;
import dev.langchain4j.model.embedding.AllMiniLmL6V2EmbeddingModel;
import dev.langchain4j.model.embedding.EmbeddingModel;
import dev.langchain4j.model.input.PromptTemplate;
import dev.langchain4j.model.openai.OpenAiChatModel;
import dev.langchain4j.retriever.EmbeddingStoreRetriever;
import dev.langchain4j.store.embedding.EmbeddingStore;
import dev.langchain4j.store.embedding.EmbeddingStoreIngestor;
import dev.langchain4j.store.embedding.inmemory.InMemoryEmbeddingStore;
import lombok.RequiredArgsConstructor;
import lombok.extern.slf4j.Slf4j;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import java.time.Duration;
import java.util.List;
import static com.et.rag.constant.Constants.PROMPT_TEMPLATE_2;
@Configuration
@RequiredArgsConstructor
@Slf4j
public class LangChainConfiguration {
    @Value("${langchain.api.key}")
    private String apiKey;
    @Value("${langchain.timeout}")
    private Long timeout;
    private final List<Document> documents;
    @Bean
    public ConversationalRetrievalChain chain() {
        EmbeddingModel embeddingModel = new AllMiniLmL6V2EmbeddingModel();
        EmbeddingStore<TextSegment> embeddingStore = new InMemoryEmbeddingStore<>();
        EmbeddingStoreIngestor ingestor = EmbeddingStoreIngestor.builder()
                .documentSplitter(DocumentSplitters.recursive(500, 0))
                .embeddingModel(embeddingModel)
                .embeddingStore(embeddingStore)
                .build();
        log.info("Ingesting Spring Boot Resources ...");
        ingestor.ingest(documents);
        log.info("Ingested {} documents", documents.size());
        EmbeddingStoreRetriever retriever = EmbeddingStoreRetriever.from(embeddingStore, embeddingModel);
        EmbeddingStoreLoggingRetriever loggingRetriever = new EmbeddingStoreLoggingRetriever(retriever);
        /*MessageWindowChatMemory chatMemory = MessageWindowChatMemory.builder()
                .maxMessages(10)
                .build();*/
        log.info("Building ConversationalRetrievalChain ...");
        ConversationalRetrievalChain chain = ConversationalRetrievalChain.builder()
                .chatLanguageModel(OpenAiChatModel.builder()
                        .apiKey(apiKey)
                        .timeout(Duration.ofSeconds(timeout))
                        .build()
                )
                .promptTemplate(PromptTemplate.from(PROMPT_TEMPLATE_2))
                //.chatMemory(chatMemory)
                .retriever(loggingRetriever)
                .build();
        log.info("Spring Boot knowledge base is ready!");
        return chain;
    }
}

langchain:
  api:
    # "demo" is a free API key for testing purposes only. Please replace it with your own API key.
    key: demo
    # key: OPEN_API_KEY
  # API call to complete before it is timed out.
  timeout: 30

<!DOCTYPE html>
<html lang="en"
      xmlns="http://www.w3.org/1999/xhtml">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1">
    <title>Spring Boot Doc Bot</title>
    <link  rel="external nofollow"  rel="stylesheet">
    <link rel="stylesheet"  rel="external nofollow" >
</head>
<body>
<nav class="bg-dark text-white py-3">
    <div class="text-center d-flex justify-content-center align-items-center">
        <img src="/logo.png" alt="Logo" style="width:60px; margin-right: 10px;">
        <h2 style="margin: 0;">Welcome to Spring Boot Documentation Bot</h2>
    </div>
</nav>
<div class="container mt-5">
    <div class="row">
        <div class="col-md-8 offset-2">
            <h3 class="text-center mb-3">Ask your Spring related queries here!</h3>
            <form>
                <div class="mb-3">
                    <label for="questionInput" class="form-label">Question</label>
                    <input type="text" class="form-control" id="questionInput" name="question" placeholder="Enter your question" required>
                </div>
                <div class="mb-3 text-center">
                    <button id="submitBtn" type="button" class="btn btn-primary">Ask!</button>
                    <button id="clearBtn" type="button" class="btn btn-secondary">Clear</button>
                </div>
            </form>
        </div>
    </div>
    <div class="row my-5">
        <div class="col-md-8 offset-md-2">
            <label for="answerBox" class="form-label"><h5>Answer</h5></label>
            <div class="position-relative my-3">
                <textarea class="form-control" rows="10" id="answerBox" disabled></textarea>
                <a href="#" rel="external nofollow"  class="position-absolute top-0 end-0 m-2" id="copyBtn">
                    <i class="far fa-copy"></i>
                </a>
            </div>
        </div>
    </div>
</div>
<script src="https://code.jquery.com/jquery-3.7.1.min.js"></script>
<script>
    $(document).ready(function () {
        $("#submitBtn").click(function () {
            let questionValue = $("#questionInput").val();
            if (!questionValue) {
                alert('Please enter your question');
                return;
            }
            $("#answerBox").val('Please wait... fetching answer...');
            $.ajax({
                type: "POST",
                url: "/ask",
                data: JSON.stringify({ question: $("#questionInput").val() }),
                //contentType: "application/json; charset=utf-8",
                dataType: "text",
                success: function (data) {
                    //console.log(typeof data);
                    //console.log(data);
                    $("#answerBox").val(data);
                },
                error: function (errMsg) {
                    alert(errMsg);
                }
            });
        });
        $("#clearBtn").click(function () {
            $("#questionInput").val('');
            $("#answerBox").val('');
        });
        document.getElementById("copyBtn").addEventListener("click", function() {
            var copyText = document.getElementById("answerBox");
            copyText.select();
            copyText.setSelectionRange(0, 99999);
            document.execCommand("copy");
            alert("Copied: " + copyText.value);
        });
    });
</script>
</body>
</html>