package main

// autotitle.go — LLM-generated session titles. When the first user message
// of an unnamed session persists, the daemon makes one cheap chat-completion
// call (the default provider, ZAI-compatible endpoint) asking for a 3-6 word
// title, then stores it via the normal rename path so session_list, the web
// sidebar and the tab title pick it up.

import (
	"bytes"
	"context"
	"encoding/json"
	"fmt"
	"log"
	"net/http"
	"os"
	"strings"
	"sync"
	"time"
)

const (
	autoTitleMaxChars   int           = 400 // prompt excerpt cap
	autoTitleTimeout    time.Duration = 20 * time.Second
	autoTitlePromptTail string        = "\n\nReply with ONLY a 3-6 word title for this request. No quotes, no punctuation at the end, no explanation."
)

var autoTitleTried = struct {
	mu sync.Mutex
	m  map[string]bool
}{m: map[string]bool{}}

// needsAutoTitle reports whether frame f is a persisted user message_end of
// a session that has no name yet and no prior attempt.
func (h *Hub) needsAutoTitle(f frame) bool {
	if f.typ != evMessageEnd {
		return false
	}
	var probe struct {
		Message struct {
			Role string `json:"role"`
		} `json:"message"`
	}
	if err := json.Unmarshal(f.raw, &probe); err != nil || probe.Message.Role != "user" {
		return false
	}
	autoTitleTried.mu.Lock()
	defer autoTitleTried.mu.Unlock()
	if autoTitleTried.m[f.sessionID] {
		return false
	}
	if rows, err := h.store.Sessions(); err == nil {
		for _, row := range rows {
			if row.Info.ID == f.sessionID {
				if row.Info.Name != nil && *row.Info.Name != "" {
					autoTitleTried.m[f.sessionID] = true
					return false
				}
				break
			}
		}
	}
	autoTitleTried.m[f.sessionID] = true
	return true
}

// firstUserText extracts the message text from a message_end frame payload.
func firstUserText(raw []byte) string {
	var probe struct {
		Message struct {
			Text string `json:"text"`
		} `json:"message"`
	}
	if err := json.Unmarshal(raw, &probe); err != nil {
		return ""
	}
	return probe.Message.Text
}

// autoTitle asks the provider API for a title and applies it on success.
func (h *Hub) autoTitle(sessionID, userText string) {
	title, err := requestTitle(userText)
	if err != nil {
		log.Printf("autotitle %s: %v", sessionID, err)
		return
	}
	if title == "" {
		return
	}
	if _, err := h.store.SetSessionName(sessionID, title); err != nil {
		log.Printf("autotitle %s: set name: %v", sessionID, err)
		return
	}
	// live conns see it via session_list; an open chat also refreshes on it.
	h.BroadcastSessionList()
}

// requestTitle performs the one-shot completion against the ZAI-compatible
// endpoint configured for the default provider.
func requestTitle(userText string) (string, error) {
	key := os.Getenv(envProviderAPIKey)
	if key == "" {
		return "", fmt.Errorf("no %s configured", envProviderAPIKey)
	}
	if len(userText) > autoTitleMaxChars {
		userText = userText[:autoTitleMaxChars]
	}
	body, err := json.Marshal(map[string]any{
		"model": envOr("LVMH_AUTOTITLE_MODEL", "glm-5.3"),
		"messages": []map[string]string{
			{"role": "user", "content": userText + autoTitlePromptTail},
		},
		"max_tokens": 24,
	})
	if err != nil {
		return "", err
	}
	ctx, cancel := context.WithTimeout(context.Background(), autoTitleTimeout)
	defer cancel()
	endpoint := envOr("LVMH_AUTOTITLE_URL", "https://api.z.ai/api/coding/paas/v4/chat/completions")
	req, err := http.NewRequestWithContext(ctx, http.MethodPost, endpoint, bytes.NewReader(body))
	if err != nil {
		return "", err
	}
	req.Header.Set("Authorization", "Bearer "+key)
	req.Header.Set("Content-Type", "application/json")
	resp, err := http.DefaultClient.Do(req)
	if err != nil {
		return "", err
	}
	defer resp.Body.Close()
	if resp.StatusCode != http.StatusOK {
		return "", fmt.Errorf("title api: %s", resp.Status)
	}
	var out struct {
		Choices []struct {
			Message struct {
				Content string `json:"content"`
			} `json:"message"`
		} `json:"choices"`
	}
	if err := json.NewDecoder(resp.Body).Decode(&out); err != nil {
		return "", err
	}
	if len(out.Choices) == 0 {
		return "", fmt.Errorf("empty choices")
	}
	title := strings.TrimSpace(out.Choices[0].Message.Content)
	title = strings.Trim(title, "\"'`*. ")
	if idx := strings.IndexAny(title, "\n"); idx >= 0 {
		title = strings.TrimSpace(title[:idx])
	}
	if len(title) > 60 {
		title = title[:60]
	}
	if title == "" {
		return "", fmt.Errorf("empty title")
	}
	return title, nil
}