Building a Chat Engine

package chatengine

import (
    "context"
    "fmt"

    "codesignal/llmconfig"

    "github.com/tmc/langchaingo/llms"
    "github.com/tmc/langchaingo/llms/openai"
)

type Message struct {
    Role    string
    Content string
}

type ChatEngine struct {
    LLM                 llms.Model
    SystemPrompt        string
    ConversationHistory []Message
}

func NewChatEngine(ctx context.Context) (*ChatEngine, error) {
    // Initialize OpenAI LLM for chat
    llm, err := openai.New(
        openai.WithModel("gpt-5.6-luna"),
        openai.WithHTTPClient(llmconfig.ReasoningNone()), // Answer directly, without a reasoning step
    )
    if err != nil {
        return nil, fmt.Errorf("failed to initialize OpenAI client: %w", err)
    }

    return &ChatEngine{
        LLM: llm,
        SystemPrompt: "You are a helpful assistant that ONLY answers questions based on the provided context. If no relevant context is provided, do NOT answer the question and politely inform the user that you don't have the necessary information to answer their question accurately.",
        ConversationHistory: []Message{},
    }, nil
}

import (
    "bytes"
    "text/template"
)

func (ce *ChatEngine) SendMessage(ctx context.Context, userMessage string, context string) (string, error) {
    // Create a prompt template that includes system instructions, context, and question
    const promptTemplate = `{{.SystemPrompt}}

{{if .Context}}Context:
{{.Context}}
{{end}}
Question: {{.Question}}`

    // Define template data structure
    type TemplateData struct {
        SystemPrompt string
        Context      string
        Question     string
    }

    // Parse and execute the template
    tmpl, err := template.New("prompt").Parse(promptTemplate)
    if err != nil {
        return "", fmt.Errorf("failed to parse template: %w", err)
    }

    data := TemplateData{
        SystemPrompt: ce.SystemPrompt,
        Context:      context,
        Question:     userMessage,
    }

    var formattedPrompt bytes.Buffer
    err = tmpl.Execute(&formattedPrompt, data)
    if err != nil {
        return "", fmt.Errorf("failed to execute template: %w", err)
    }

    // Get response from the language model
    response, err := llms.GenerateFromSinglePrompt(ctx, ce.LLM, formattedPrompt.String())
    if err != nil {
        return "", fmt.Errorf("failed to get response from chat model: %w", err)
    }

    // Add the interaction to conversation history
    ce.ConversationHistory = append(ce.ConversationHistory, Message{
        Role:    "user",
        Content: userMessage,
    })
    ce.ConversationHistory = append(ce.ConversationHistory, Message{
        Role:    "assistant",
        Content: response,
    })

    return response, nil
}

func (ce *ChatEngine) GetConversationHistory() []Message {
    return ce.ConversationHistory
}

func (ce *ChatEngine) ResetConversation() {
    ce.ConversationHistory = []Message{}
}

package main

import (
    "context"
    "fmt"
    "log"

    "codesignal/chatengine"
)

func main() {
    ctx := context.Background()

    // Initialize the chat engine
    engine, err := chatengine.NewChatEngine(ctx)
    if err != nil {
        log.Fatalf("failed to initialize chat engine: %v", err)
    }

    // Send a message without context (should politely decline)
    query := "What is the capital of France?"
    response, err := engine.SendMessage(ctx, query, "")
    if err != nil {
        log.Fatalf("error sending message: %v", err)
    }

    fmt.Printf("Question: %s\n", query)
    fmt.Printf("Answer: %s\n", response)

    // Print conversation history
    fmt.Println("\nConversation history:")
    history := engine.GetConversationHistory()
    for i, msg := range history {
        fmt.Printf("%d. [%s]: %s\n", i+1, msg.Role, msg.Content)
    }
}

Question: What is the capital of France?
Answer: I'm sorry, but I don't have any context provided to answer your question. Without relevant information about France's capital in the context, I cannot provide an accurate answer. If you could provide additional context, I'd be happy to help.

Conversation history:
1. [user]: What is the capital of France?
2. [assistant]: I'm sorry, but I don't have any context provided to answer your question. Without relevant information about France's capital in the context, I cannot provide an accurate answer. If you could provide additional context, I'd be happy to help.

package main

import (
    "context"
    "fmt"
    "log"

    "codesignal/chatengine"
)

func main() {
    ctx := context.Background()

    // Initialize the chat engine
    engine, err := chatengine.NewChatEngine(ctx)
    if err != nil {
        log.Fatalf("failed to initialize chat engine: %v", err)
    }

    // First, send a message without context
    query1 := "What is the capital of France?"
    response1, err := engine.SendMessage(ctx, query1, "")
    if err != nil {
        log.Fatalf("error sending message: %v", err)
    }

    fmt.Printf("Question: %s\n", query1)
    fmt.Printf("Answer: %s\n\n", response1)

    // Now send a message WITH context
    context := `Paris is the capital and most populous city of France. 
The Eiffel Tower, the Louvre Museum, and Notre-Dame Cathedral are among its most famous landmarks.`
    query2 := "Tell me about the landmarks mentioned in the context."

    response2, err := engine.SendMessage(ctx, query2, context)
    if err != nil {
        log.Fatalf("error sending message: %v", err)
    }

    fmt.Printf("Question: %s\n", query2)
    fmt.Printf("Answer: %s\n", response2)

    // Print updated conversation history
    fmt.Println("\nFull conversation history:")
    history := engine.GetConversationHistory()
    for i, msg := range history {
        fmt.Printf("%d. [%s]: %s\n", i+1, msg.Role, msg.Content)
    }
}

Question: What is the capital of France?
Answer: I'm sorry, but I don't have any context provided to answer your question. Without relevant information about France's capital in the context, I cannot provide an accurate answer. If you could provide additional context, I'd be happy to help.

Question: Tell me about the landmarks mentioned in the context.
Answer: Based on the provided context, Paris has three famous landmarks mentioned:

1. The Eiffel Tower - one of the most iconic symbols of Paris and France
2. The Louvre Museum - a world-renowned art museum
3. Notre-Dame Cathedral - a historic cathedral and architectural masterpiece

These landmarks are among the most famous attractions in Paris, which is the capital and most populous city of France.

Full conversation history:
1. [user]: What is the capital of France?
2. [assistant]: I'm sorry, but I don't have any context provided to answer your question. Without relevant information about France's capital in the context, I cannot provide an accurate answer. If you could provide additional context, I'd be happy to help.
3. [user]: Tell me about the landmarks mentioned in the context.
4. [assistant]: Based on the provided context, Paris has three famous landmarks mentioned:

1. The Eiffel Tower - one of the most iconic symbols of Paris and France
2. The Louvre Museum - a world-renowned art museum
3. Notre-Dame Cathedral - a historic cathedral and architectural masterpiece

These landmarks are among the most famous attractions in Paris, which is the capital and most populous city of France.

package main

import (
    "context"
    "fmt"
    "log"

    "codesignal/chatengine"
)

func main() {
    ctx := context.Background()

    // Initialize the chat engine
    engine, err := chatengine.NewChatEngine(ctx)
    if err != nil {
        log.Fatalf("failed to initialize chat engine: %v", err)
    }

    // Simulate some conversation
    engine.SendMessage(ctx, "What is the capital of France?", "")
    engine.SendMessage(ctx, "Tell me about landmarks.", "Paris has the Eiffel Tower and Louvre Museum.")

    fmt.Printf("Conversation history before reset: %d messages\n", len(engine.GetConversationHistory()))

    // Reset the conversation history
    engine.ResetConversation()
    fmt.Println("Conversation history has been reset.")

    // Print conversation history after reset
    fmt.Printf("Conversation history after reset: %d messages\n", len(engine.GetConversationHistory()))
    
    history := engine.GetConversationHistory()
    for i, msg := range history {
        fmt.Printf("%d. [%s]: %s\n", i+1, msg.Role, msg.Content)
    }
}

Conversation history before reset: 4 messages
Conversation history has been reset.
Conversation history after reset: 0 messages