package llm

import (
	"context"
	"encoding/json"
	"fmt"
	"strings"
	"time"

	openai "github.com/sashabaranov/go-openai"

	"spider/internal/extractor"
)

// Client is an OpenAI-compatible LLM client.
// Used only for TG message merchant extraction (fallback when regex fails).
type Client struct {
	client  *openai.Client
	model   string
	timeout time.Duration
}

// New creates a client. baseURL empty = OpenAI official endpoint.
func New(baseURL, apiKey, model string, timeout time.Duration) *Client {
	cfg := openai.DefaultConfig(apiKey)
	if baseURL != "" {
		cfg.BaseURL = baseURL
	}
	return &Client{
		client:  openai.NewClientWithConfig(cfg),
		model:   model,
		timeout: timeout,
	}
}

func (c *Client) chat(ctx context.Context, system, user string) (string, error) {
	ctx, cancel := context.WithTimeout(ctx, c.timeout)
	defer cancel()

	resp, err := c.client.CreateChatCompletion(ctx, openai.ChatCompletionRequest{
		Model: c.model,
		Messages: []openai.ChatCompletionMessage{
			{Role: openai.ChatMessageRoleSystem, Content: system},
			{Role: openai.ChatMessageRoleUser, Content: user},
		},
	})
	if err != nil {
		return "", fmt.Errorf("llm chat: %w", err)
	}
	if len(resp.Choices) == 0 {
		return "", fmt.Errorf("llm chat: empty response")
	}
	return strings.TrimSpace(resp.Choices[0].Message.Content), nil
}

// ParseMerchant extracts merchant info from text.
// Used as fallback when regex extraction fails on non-standard formats like "加V：xxx".
func (c *Client) ParseMerchant(ctx context.Context, message string) (*extractor.MerchantInfo, error) {
	const system = `你是信息提取专家。从以下文本中提取商户联系信息，返回 JSON 格式。
字段：merchant_name, tg_username(不含@), website, email, phone, industry, description
如果某字段没有信息则为空字符串。只返回 JSON，不要 markdown 代码块。`

	text, err := c.chat(ctx, system, message)
	if err != nil {
		return &extractor.MerchantInfo{}, err
	}

	text = stripMarkdownCode(text)

	info := &extractor.MerchantInfo{}
	if jsonErr := json.Unmarshal([]byte(text), info); jsonErr != nil {
		return &extractor.MerchantInfo{}, fmt.Errorf("llm parse merchant: json unmarshal: %w (raw: %s)", jsonErr, text)
	}
	return info, nil
}

func stripMarkdownCode(s string) string {
	s = strings.TrimSpace(s)
	if strings.HasPrefix(s, "```") {
		lines := strings.SplitN(s, "\n", 2)
		if len(lines) == 2 {
			s = lines[1]
		}
		if idx := strings.LastIndex(s, "```"); idx >= 0 {
			s = s[:idx]
		}
		s = strings.TrimSpace(s)
	}
	return s
}