package service

import (
	"context"
	"strings"

	"github.com/topfans/backend/services/aiChatService/model"
)

// AIProvider 流式对话接口（实现类：LLMService、DifyAdapter）
type AIProvider interface {
	StreamChat(ctx context.Context, messages []model.Message) (StreamReader, error)
}

// ChatService 对话服务
type ChatService struct {
	aiProvider     AIProvider
	personaService *PersonaService
	memoryService  *MemoryService
	auditService   *AuditService
}

// NewChatService 创建对话服务
func NewChatService(
	aiProvider AIProvider,
	personaService *PersonaService,
	memoryService *MemoryService,
	auditService *AuditService,
) *ChatService {
	return &ChatService{
		aiProvider:     aiProvider,
		personaService: personaService,
		memoryService:  memoryService,
		auditService:   auditService,
	}
}

// GetHistory 获取对话历史
func (s *ChatService) GetHistory(ctx context.Context, sessionID string) ([]model.Message, error) {
	return s.memoryService.GetContext(ctx, sessionID)
}

// SaveContext 保存对话上下文
func (s *ChatService) SaveContext(ctx context.Context, sessionID string, messages []model.Message, personaID string) error {
	return s.memoryService.SaveContext(ctx, sessionID, messages, personaID)
}

// GetWelcomeMessage 获取欢迎消息
func (s *ChatService) GetWelcomeMessage(sessionID string, userID int64, starID int64) string {
	// 默认欢迎消息
	return "亲爱的你来辣 ~~"
}

// StreamChat 流式对话（委托给 aiProvider）
func (s *ChatService) StreamChat(ctx context.Context, messages []model.Message) (StreamReader, error) {
	return s.aiProvider.StreamChat(ctx, messages)
}

// Chat 非流式对话，收集所有流式 chunk 拼接为完整响应
func (s *ChatService) Chat(ctx context.Context, messages []model.Message) (string, error) {
	reader, err := s.aiProvider.StreamChat(ctx, messages)
	if err != nil {
		return "", err
	}
	defer reader.Close()

	var sb strings.Builder
	for {
		content, done, err := reader.Next()
		if err != nil {
			return sb.String(), err
		}
		sb.WriteString(content)
		if done {
			break
		}
	}
	return sb.String(), nil
}