feat: implement chat and conversation history management with database schema and API endpoints

internal/services/chatbotService.go

@@ -4,25 +4,34 @@ import (
 	"context"
 	"errors"
 	"fmt"
+	"history-api/internal/dtos/request"
+	"history-api/internal/gen/sqlc"
+	"history-api/internal/models"
 	"history-api/internal/repositories"
 	"history-api/pkg/ai"
 	"history-api/pkg/constants"
+	"history-api/pkg/convert"
+
+	"github.com/jackc/pgx/v5/pgtype"
 )
 
 type ChatbotService interface {
 	Chat(ctx context.Context, userID string, projectID *string, question string) (string, error)
+	GetHistory(ctx context.Context, userID string, dto *request.GetChatbotHistoryDto) ([]*models.ChatbotHistoryEntity, error)
 }
 
 type chatbotService struct {
 	repo      repositories.RagRepository
 	usageRepo repositories.UsageRepository
+	chatRepo  repositories.ChatRepository
 	ragUtils  *ai.RagUtils
 }
 
-func NewChatbotService(repo repositories.RagRepository, usageRepo repositories.UsageRepository, ragUtils *ai.RagUtils) ChatbotService {
+func NewChatbotService(repo repositories.RagRepository, usageRepo repositories.UsageRepository, chatRepo repositories.ChatRepository, ragUtils *ai.RagUtils) ChatbotService {
 	return &chatbotService{
 		repo:      repo,
 		usageRepo: usageRepo,
+		chatRepo:  chatRepo,
 		ragUtils:  ragUtils,
 	}
 }
@@ -51,15 +60,38 @@ func (s *chatbotService) Chat(ctx context.Context, userID string, projectID *str
 		contextStr += fmt.Sprintf("[Document %d]: %s\n", i+1, res.Content)
 	}
 
+	pgUserID, err := convert.StringToUUID(userID)
+	if err != nil {
+		return "", fmt.Errorf("invalid user id: %w", err)
+	}
+
+	histories, err := s.chatRepo.GetChatbotHistory(ctx, sqlc.GetChatbotHistoryParams{
+		UserID: pgUserID,
+		Limit:  10,
+	})
+	if err != nil {
+		fmt.Printf("Warning: failed to get chatbot history: %v\n", err)
+	}
+
+	historyStr := ""
+	for _, h := range histories {
+		historyStr += fmt.Sprintf("User: %s\nAssistant: %s\n\n", h.Question, h.Answer)
+	}
+
 	var prompt string
 	if contextStr == "" {
-		prompt = fmt.Sprintf(`You are a friendly history assistant chatbot. The user said: "%s"
+		prompt = fmt.Sprintf(`You are a friendly history assistant chatbot.
+
+Recent Chat History:
+%s
+
+The user said: "%s"
 
 Rules:
 - If it is a greeting (like "hello", "hi", "xin chào"), respond with a friendly greeting and briefly introduce yourself.
 - If it is a history question, say that you don't have relevant documents to answer.
 - You MUST wrap your final response inside <answer> tags. Example: <answer>Hello!</answer>
-- Do NOT show your reasoning outside or inside the tags if possible, but the final answer MUST be in <answer> tags.`, question)
+- Do NOT show your reasoning outside or inside the tags if possible, but the final answer MUST be in <answer> tags.`, historyStr, question)
 	} else {
 		prompt = fmt.Sprintf(`You are a helpful history assistant. Answer the question using ONLY the provided context.
 
@@ -71,7 +103,10 @@ Rules:
 Context:
 %s
 
-Question: %s`, contextStr, question)
+Recent Chat History:
+%s
+
+Question: %s`, contextStr, historyStr, question)
 	}
 
 	response, err := s.ragUtils.GenerateResponse(ctx, prompt)
@@ -80,5 +115,40 @@ Question: %s`, contextStr, question)
 	}
 	_, _ = s.usageRepo.IncrementAIUsage(ctx, userID)
 
+	_, err = s.chatRepo.CreateChatbotHistory(ctx, sqlc.CreateChatbotHistoryParams{
+		UserID:   pgUserID,
+		Question: question,
+		Answer:   response,
+	})
+	if err != nil {
+		fmt.Printf("Warning: failed to save chatbot history: %v\n", err)
+	}
+
 	return response, nil
 }
+
+func (s *chatbotService) GetHistory(ctx context.Context, userID string, dto *request.GetChatbotHistoryDto) ([]*models.ChatbotHistoryEntity, error) {
+	pgUserID, err := convert.StringToUUID(userID)
+	if err != nil {
+		return nil, fmt.Errorf("invalid user id: %w", err)
+	}
+
+	var pgCursorID pgtype.UUID
+	if dto.Cursor != nil {
+		if err := pgCursorID.Scan(*dto.Cursor); err != nil {
+			return nil, fmt.Errorf("invalid cursor id: %w", err)
+		}
+	} else {
+		pgCursorID.Valid = false
+	}
+
+	if dto.Limit <= 0 {
+		dto.Limit = 10
+	}
+
+	return s.chatRepo.GetChatbotHistory(ctx, sqlc.GetChatbotHistoryParams{
+		UserID:   pgUserID,
+		CursorID: pgCursorID,
+		Limit:    int32(dto.Limit),
+	})
+}