feat: implement ChatbotService for RAG-based AI interactions and history management

internal/services/chatbotService.go

@@ -2,7 +2,6 @@ package services
 
 import (
 	"context"
-	"errors"
 	"fmt"
 	"history-api/internal/dtos/request"
 	"history-api/internal/gen/sqlc"
@@ -11,8 +10,10 @@ import (
 	"history-api/pkg/ai"
 	"history-api/pkg/constants"
 	"history-api/pkg/convert"
+	"strings"
 
 	"github.com/jackc/pgx/v5/pgtype"
+	"github.com/rs/zerolog/log"
 )
 
 type ChatbotService interface {
@@ -43,23 +44,32 @@ func (s *chatbotService) Chat(ctx context.Context, userID string, projectID *str
 	}
 
 	if usage >= constants.MaxDailyAIUsage {
-		return "", errors.New("you have reached your daily limit of 10 questions. Please come back tomorrow")
+		return "", fmt.Errorf("you have reached your daily limit of %d questions. Please come back tomorrow", constants.MaxDailyAIUsage)
 	}
 
 	qVector, err := s.ragUtils.EmbedQuery(ctx, question)
 	if err != nil {
 		return "", fmt.Errorf("failed to embed question: %w", err)
 	}
-	results, err := s.repo.SearchSimilar(ctx, projectID, qVector, 5, 0.65)
+
+	results, err := s.repo.SearchSimilar(ctx, projectID, qVector, 8, 0.50)
 	if err != nil {
 		return "", fmt.Errorf("failed to search similar content: %w", err)
 	}
 
-	contextStr := ""
+	if len(results) < 3 {
-	for i, res := range results {
+		broadResults, err := s.repo.SearchSimilar(ctx, projectID, qVector, 8, 0.35)
-		contextStr += fmt.Sprintf("[Document %d]: %s\n", i+1, res.Content)
+		if err == nil && len(broadResults) > len(results) {
+			results = broadResults
+		}
 	}
 
+	var contextBuilder strings.Builder
+	for i, res := range results {
+		contextBuilder.WriteString(fmt.Sprintf("[Document %d (score: %.2f)]: %s\n", i+1, res.Similarity, res.Content))
+	}
+	contextStr := contextBuilder.String()
+
 	pgUserID, err := convert.StringToUUID(userID)
 	if err != nil {
 		return "", fmt.Errorf("invalid user id: %w", err)
@@ -70,13 +80,14 @@ func (s *chatbotService) Chat(ctx context.Context, userID string, projectID *str
 		Limit:  10,
 	})
 	if err != nil {
-		fmt.Printf("Warning: failed to get chatbot history: %v\n", err)
+		log.Warn().Err(err).Msg("failed to get chatbot history")
 	}
 
-	historyStr := ""
+	var historyBuilder strings.Builder
 	for _, h := range histories {
-		historyStr += fmt.Sprintf("User: %s\nAssistant: %s\n\n", h.Question, h.Answer)
+		historyBuilder.WriteString(fmt.Sprintf("User: %s\nAssistant: %s\n\n", h.Question, h.Answer))
 	}
+	historyStr := historyBuilder.String()
 
 	var prompt string
 	if contextStr == "" {
@@ -115,7 +126,9 @@ Question: %s`, contextStr, historyStr, question)
 	if err != nil {
 		return "", err
 	}
-	_, _ = s.usageRepo.IncrementAIUsage(ctx, userID)
+	if _, err := s.usageRepo.IncrementAIUsage(ctx, userID); err != nil {
+		log.Warn().Err(err).Str("userID", userID).Msg("failed to increment AI usage")
+	}
 
 	_, err = s.chatRepo.CreateChatbotHistory(ctx, sqlc.CreateChatbotHistoryParams{
 		UserID:   pgUserID,
@@ -123,7 +136,7 @@ Question: %s`, contextStr, historyStr, question)
 		Answer:   response,
 	})
 	if err != nil {
-		fmt.Printf("Warning: failed to save chatbot history: %v\n", err)
+		log.Warn().Err(err).Msg("failed to save chatbot history")
 	}
 
 	return response, nil