package chat

import (
	"context"
	"fmt"
	"resume-platform/internal/model"
	"resume-platform/internal/prompt"
	"resume-platform/internal/repository"
	"resume-platform/internal/service/ai"

	"github.com/google/uuid"
)

type ChatService interface {
	Chat(ctx context.Context, userID string, question string) (string, error)
	GetChatHistory(ctx context.Context, userID string) ([]*model.ChatHistory, error)
	DeleteChatHistory(ctx context.Context, userID string) error
}

type chatService struct {
	repo repository.ResumeRepository
	ai   *ai.AIService
}

func NewChatService(repo repository.ResumeRepository, ai *ai.AIService) ChatService {
	return &chatService{repo: repo, ai: ai}
}

func (s *chatService) Chat(ctx context.Context, userID string, question string) (string, error) {
	chunks, err := s.repo.GetDocumentChunksByUserID(userID)
	if err != nil {
		return "", err
	}

	if len(chunks) == 0 {
		return s.ai.Generate(ctx, question)
	}

	var chunkList []model.ChunkWithScore
	for _, chunk := range chunks {
		chunkList = append(chunkList, model.ChunkWithScore{
			Content:  chunk.Content,
			Metadata: chunk.Embedding,
		})
	}

	var contextStr string
	for i, chunk := range chunkList[:min(5, len(chunkList))] {
		contextStr += fmt.Sprintf("[文档片段%d]\n%s\n\n", i+1, chunk.Content)
	}

	promptText := prompt.BuildDocumentAnalysisPrompt(contextStr, question)

	answer, err := s.ai.Generate(ctx, promptText)
	if err != nil {
		return "", err
	}

	history := &model.ChatHistory{
		ID:       uuid.New().String(),
		UserID:   userID,
		Question: question,
		Answer:   answer,
		Context:  contextStr,
	}
	s.repo.CreateChatHistory(history)

	return answer, nil
}

func (s *chatService) GetChatHistory(ctx context.Context, userID string) ([]*model.ChatHistory, error) {
	return s.repo.GetChatHistoryByUserID(userID)
}

func (s *chatService) DeleteChatHistory(ctx context.Context, userID string) error {
	return nil
}