package chat

import (
	"context"
	"fmt"
	"log/slog"
	"strings"

	"engimind/internal/config"
	"engimind/internal/project"
	"engimind/internal/vector"

	"github.com/wailsapp/wails/v3/pkg/application"
)

// ChatService handles chat interactions and chapter generation (A+C→B).
type ChatService struct {
	llm        *LLMClient
	rag        *vector.RAGService
	configSvc  *config.ConfigService
	projectSvc *project.ProjectService
}

// NewChatService creates a chat service.
func NewChatService(
	configSvc *config.ConfigService,
	projectSvc *project.ProjectService,
	rag *vector.RAGService,
) *ChatService {
	return &ChatService{
		llm:        NewLLMClient(),
		rag:        rag,
		configSvc:  configSvc,
		projectSvc: projectSvc,
	}
}

// SendMessage handles a user chat message with RAG context.
func (s *ChatService) SendMessage(content string, selectedFileIDs []string, modelID string) (string, error) {
	providers, _ := s.configSvc.GetAllProviders()
	var provider *struct{ URL, Key, Model, ProviderType string }
	for _, p := range providers {
		if p.ID == modelID && p.Enabled {
			provider = &struct{ URL, Key, Model, ProviderType string }{p.BaseURL, p.APIKey, p.ModelID, p.Provider}
			break
		}
	}
	if provider == nil {
		return "", fmt.Errorf("model %s not found or disabled", modelID)
	}

	// RAG: search context
	projectID := s.projectSvc.GetCurrentProjectID()
	var contextText string
	if projectID != "" && len(selectedFileIDs) > 0 {
		embCfg := s.getEmbeddingConfig()
		chunks, err := s.rag.SearchContext(context.Background(), projectID, content, 5, embCfg)
		if err != nil {
			slog.Warn("RAG search failed, proceeding without context", "err", err)
		} else {
			var parts []string
			for _, c := range chunks {
				parts = append(parts, c.Text)
			}
			contextText = strings.Join(parts, "\n\n---\n\n")
		}
	}

	messages := []Message{
		{Role: "system", Content: "你是一位专业的工程技术助手。基于提供的工程素材回答问题，引用来源时使用 [N] 标注。"},
	}
	if contextText != "" {
		messages = append(messages, Message{
			Role:    "user",
			Content: fmt.Sprintf("参考以下工程素材：\n\n%s\n\n---\n\n用户提问：%s", contextText, content),
		})
	} else {
		messages = append(messages, Message{Role: "user", Content: content})
	}

	resp, err := s.llm.Complete(provider.URL, provider.Key, provider.Model, messages)
	if err != nil {
		return "", err
	}
	if len(resp.Choices) == 0 {
		return "", fmt.Errorf("no response from model")
	}
	return resp.Choices[0].Message.Content, nil
}

// StreamMessage handles a user chat message and streams the response via Wails events.
func (s *ChatService) StreamMessage(content string, selectedFileIDs []string, modelID string, messageID string) (string, error) {
	providers, _ := s.configSvc.GetAllProviders()
	var provider *struct{ URL, Key, Model, ProviderType string }
	for _, p := range providers {
		if p.ID == modelID && p.Enabled {
			provider = &struct{ URL, Key, Model, ProviderType string }{p.BaseURL, p.APIKey, p.ModelID, p.Provider}
			break
		}
	}
	if provider == nil {
		return "", fmt.Errorf("model %s not found or disabled", modelID)
	}

	projectID := s.projectSvc.GetCurrentProjectID()
	var contextText string
	if projectID != "" && len(selectedFileIDs) > 0 {
		embCfg := s.getEmbeddingConfig()
		chunks, err := s.rag.SearchContext(context.Background(), projectID, content, 5, embCfg)
		if err == nil {
			var parts []string
			for _, c := range chunks {
				parts = append(parts, c.Text)
			}
			contextText = strings.Join(parts, "\n\n---\n\n")
		}
	}

	messages := []Message{
		{Role: "system", Content: "你是一位专业的工程技术助手。基于提供的工程素材回答问题，引用来源时使用 [N] 标注。"},
	}
	if contextText != "" {
		messages = append(messages, Message{
			Role:    "user",
			Content: fmt.Sprintf("参考以下工程素材：\n\n%s\n\n---\n\n用户提问：%s", contextText, content),
		})
	} else {
		messages = append(messages, Message{Role: "user", Content: content})
	}

	var fullText string
	err := s.llm.StreamComplete(provider.URL, provider.Key, provider.Model, messages, func(chunk string) {
		fullText += chunk
		application.Get().Event.Emit("chat_stream_"+messageID, fullText)
	})
	return fullText, err
}

// GenerateChapter implements the A+C→B logic for a single chapter.
func (s *ChatService) GenerateChapter(chapterTitle string, selectedFileIDs []string, modelID string) (string, error) {
	providers, _ := s.configSvc.GetAllProviders()
	var provider *struct{ URL, Key, Model string }
	for _, p := range providers {
		if p.ID == modelID && p.Enabled {
			provider = &struct{ URL, Key, Model string }{p.BaseURL, p.APIKey, p.ModelID}
			break
		}
	}
	if provider == nil {
		return "", fmt.Errorf("model %s not found or disabled", modelID)
	}

	// RAG: search context for chapter topic
	projectID := s.projectSvc.GetCurrentProjectID()
	embCfg := s.getEmbeddingConfig()
	chunks, err := s.rag.SearchContext(context.Background(), projectID, chapterTitle, 8, embCfg)
	if err != nil {
		slog.Warn("RAG search failed for chapter generation", "err", err)
	}

	var contextParts []string
	for _, c := range chunks {
		contextParts = append(contextParts, c.Text)
	}
	contextText := strings.Join(contextParts, "\n\n---\n\n")

	prompt := fmt.Sprintf(
		"你是工程报告撰写专家。请根据以下工程素材，按照章节要求撰写报告内容。\n\n"+
			"## 章节要求\n%s\n\n"+
			"## 参考素材\n%s\n\n"+
			"## 输出要求\n"+
			"1. 使用 Markdown 格式\n"+
			"2. 引用素材时使用 [N] 标注\n"+
			"3. 内容专业、结构清晰\n"+
			"4. 包含具体数据和分析结论",
		chapterTitle, contextText,
	)

	messages := []Message{
		{Role: "system", Content: "你是一位资深工程报告撰写专家，擅长根据工程素材生成结构化的技术报告章节。"},
		{Role: "user", Content: prompt},
	}

	resp, err := s.llm.Complete(provider.URL, provider.Key, provider.Model, messages)
	if err != nil {
		return "", err
	}
	if len(resp.Choices) == 0 {
		return "", fmt.Errorf("no response from model")
	}
	return resp.Choices[0].Message.Content, nil
}

// StreamTemplateDirectory uses the active LLM to extract a structured chapter outline from delivery standard text, streaming to frontend.
func (s *ChatService) StreamTemplateDirectory(content string, modelID string, messageID string) (string, error) {
	providers, _ := s.configSvc.GetAllProviders()
	var provider *struct{ URL, Key, Model, ProviderType string }
	for _, p := range providers {
		if p.ID == modelID && p.Enabled {
			provider = &struct{ URL, Key, Model, ProviderType string }{p.BaseURL, p.APIKey, p.ModelID, p.Provider}
			break
		}
	}
	if provider == nil {
		return "", fmt.Errorf("model %s not found or disabled", modelID)
	}

	prompt := fmt.Sprintf(
		"你是一个工程标准的目录解析助手。请从下面提供的交付标准文本中提取工程的主干章节，并以 JSON 数组的格式返回。\n\n"+
			"### 要求：\n"+
			"1. 只返回 JSON 数组，不包含其他废话或者回答前缀。\n"+
			"2. 输出格式必须严格符合：[{ \"id\": \"chapter-1\", \"title\": \"1. 原材料进场检验\", \"content\": \"...如果标准里有简要描述可附上\" }]\n\n"+
			"### 交付标准内容：\n%s",
		content,
	)

	messages := []Message{
		{Role: "system", Content: "你是一个专业的结构化数据抽取工具。你只输出合法的 JSON，不要使用 Markdown 代码块包裹，也不要给出任何其他解释。"},
		{Role: "user", Content: prompt},
	}

	var fullText string
	err := s.llm.StreamComplete(provider.URL, provider.Key, provider.Model, messages, func(chunk string) {
		fullText += chunk
		application.Get().Event.Emit("chat_stream_"+messageID, fullText)
	})

	return fullText, err
}

func (s *ChatService) getEmbeddingConfig() vector.EmbeddingConfig {
	// Use bge-m3 via Ollama as default embedding model
	return vector.EmbeddingConfig{
		BaseURL:  "http://localhost:11434",
		Model:    "bge-m3",
		APIKey:   "",
		Provider: "Ollama",
	}
}