package main

import (
	"bytes"
	"context"
	"database/sql"
	"encoding/json"
	"errors"
	"fmt"
	"io"
	"log/slog"
	"net/http"
	"net/url"
	"os"
	"os/signal"
	"path/filepath"
	"strconv"
	"strings"
	"syscall"
	"time"

	"github.com/jackc/pgx/v5"
	"github.com/jackc/pgx/v5/pgxpool"
)

const (
	verticalHR = "hr"
)

type config struct {
	APIHost             string
	APIPort             int
	PublicBasePath      string
	PythonBaseURL       string
	MediaDir            string
	PostgresUser        string
	PostgresPassword    string
	PostgresDB          string
	PostgresHost        string
	PostgresPort        int
	PollIntervalSeconds int
	LLMEnabled          bool
	LLMBaseURL          string
	LLMAPIKey           string
	LLMModel            string
	LLMTimeout          time.Duration
}

type app struct {
	cfg    config
	db     *pgxpool.Pool
	http   *http.Client
	python *http.Client
}

type accessScope struct {
	IsAdmin   bool
	CanManage bool
	CanAuth   bool
	DeptID    string
}

type sectionOut struct {
	ID             int64     `json:"id"`
	Vertical       string    `json:"vertical"`
	DepartmentID   *string   `json:"department_id,omitempty"`
	Slug           string    `json:"slug"`
	Title          string    `json:"title"`
	Emoji          *string   `json:"emoji,omitempty"`
	Description    *string   `json:"description,omitempty"`
	CreatedAt      time.Time `json:"created_at"`
	ChannelsTotal  int64     `json:"channels_total"`
	ChannelsActive int64     `json:"channels_active"`
	MessagesTotal  int64     `json:"messages_total"`
	LeadsTotal     int64     `json:"leads_total"`
}

type channelOut struct {
	ID            int64      `json:"id"`
	TGID          *int64     `json:"tg_id,omitempty"`
	Identifier    string     `json:"identifier"`
	Title         *string    `json:"title,omitempty"`
	Vertical      string     `json:"vertical"`
	SectionID     int64      `json:"section_id"`
	SectionSlug   *string    `json:"section_slug,omitempty"`
	IsActive      bool       `json:"is_active"`
	LastMessageID *int64     `json:"last_message_id,omitempty"`
	LastPolledAt  *time.Time `json:"last_polled_at,omitempty"`
	CreatedAt     time.Time  `json:"created_at"`
}

type messageOut struct {
	ID                 int64            `json:"id"`
	ChannelID          int64            `json:"channel_id"`
	ChannelVertical    *string          `json:"channel_vertical,omitempty"`
	ChannelSectionSlug *string          `json:"channel_section_slug,omitempty"`
	TGMessageID        int64            `json:"tg_message_id"`
	GroupedID          *int64           `json:"grouped_id,omitempty"`
	GroupSize          int              `json:"group_size"`
	Date               time.Time        `json:"date"`
	Text               *string          `json:"text,omitempty"`
	SenderID           *int64           `json:"sender_id,omitempty"`
	SenderUsername     *string          `json:"sender_username,omitempty"`
	SenderName         *string          `json:"sender_name,omitempty"`
	PostURL            *string          `json:"post_url,omitempty"`
	HasMedia           bool             `json:"has_media"`
	MediaFiles         []map[string]any `json:"media_files,omitempty"`
	Extracted          json.RawMessage  `json:"extracted,omitempty"`
	Views              *int64           `json:"views,omitempty"`
	Forwards           *int64           `json:"forwards,omitempty"`
	FetchedAt          time.Time        `json:"fetched_at"`
}

func main() {
	cfg := loadConfig()
	logger := slog.New(slog.NewJSONHandler(os.Stdout, nil))
	slog.SetDefault(logger)

	ctx, stop := signal.NotifyContext(context.Background(), syscall.SIGINT, syscall.SIGTERM)
	defer stop()

	pool, err := pgxpool.New(ctx, cfg.databaseURL())
	if err != nil {
		slog.Error("db_connect_failed", "error", err)
		os.Exit(1)
	}
	defer pool.Close()

	srvApp := &app{
		cfg:    cfg,
		db:     pool,
		http:   &http.Client{Timeout: cfg.LLMTimeout},
		python: &http.Client{Timeout: 15 * time.Minute},
	}

	server := &http.Server{
		Addr:              fmt.Sprintf("%s:%d", cfg.APIHost, cfg.APIPort),
		Handler:           http.HandlerFunc(srvApp.serveHTTP),
		ReadHeaderTimeout: 10 * time.Second,
	}

	go func() {
		<-ctx.Done()
		shutdownCtx, cancel := context.WithTimeout(context.Background(), 10*time.Second)
		defer cancel()
		_ = server.Shutdown(shutdownCtx)
	}()

	slog.Info("go_api_started", "addr", server.Addr, "python_base_url", cfg.PythonBaseURL)
	if err := server.ListenAndServe(); err != nil && !errors.Is(err, http.ErrServerClosed) {
		slog.Error("server_failed", "error", err)
		os.Exit(1)
	}
}

func (a *app) serveHTTP(w http.ResponseWriter, r *http.Request) {
	path := a.apiPath(r.URL.Path)
	if path == "/healthz" {
		writeJSON(w, http.StatusOK, map[string]string{"status": "ok"})
		return
	}
	if path == "/" {
		writeJSON(w, http.StatusOK, map[string]string{"service": "monitoring-tg", "ui": "portal", "api": "go"})
		return
	}
	if !strings.HasPrefix(path, "/api/v1") {
		writeError(w, http.StatusNotFound, "not found")
		return
	}

	ctx := r.Context()
	switch {
	case r.Method == http.MethodGet && path == "/api/v1/access/me":
		a.handleAccessMe(w, r)
	case path == "/api/v1/auth/status" || strings.HasPrefix(path, "/api/v1/auth/"):
		a.proxyPython(w, r, path)
	case path == "/api/v1/sections":
		a.handleSections(w, r)
	case strings.HasPrefix(path, "/api/v1/sections/"):
		a.handleSectionItem(w, r, path)
	case path == "/api/v1/channels":
		a.handleChannels(w, r)
	case strings.HasPrefix(path, "/api/v1/channels/"):
		a.handleChannelItem(ctx, w, r, path)
	case strings.HasPrefix(path, "/api/v1/media/"):
		a.handleMedia(w, r, path)
	case path == "/api/v1/messages":
		a.handleMessages(ctx, w, r)
	case strings.HasPrefix(path, "/api/v1/messages/"):
		a.handleMessageItem(ctx, w, r, path)
	case path == "/api/v1/stats":
		a.handleStats(ctx, w, r)
	case path == "/api/v1/llm/status":
		a.handleLLMStatus(ctx, w)
	case path == "/api/v1/llm/queue":
		a.handleLLMQueue(ctx, w, r)
	case path == "/api/v1/llm/prompt":
		a.handlePrompt(ctx, w, r)
	case r.Method == http.MethodPost && path == "/api/v1/poll":
		a.proxyPython(w, r, path)
	default:
		writeError(w, http.StatusNotFound, "not found")
	}
}

func (a *app) apiPath(path string) string {
	base := strings.TrimRight(a.cfg.PublicBasePath, "/")
	if base != "" && strings.HasPrefix(path, base+"/") {
		return strings.TrimPrefix(path, base)
	}
	if base != "" && path == base {
		return "/"
	}
	return path
}

func (a *app) handleAccessMe(w http.ResponseWriter, r *http.Request) {
	scope := readAccess(r)
	writeJSON(w, http.StatusOK, map[string]any{
		"is_admin":              scope.IsAdmin,
		"can_manage_department": scope.CanManage,
		"can_auth_telegram":     scope.CanAuth,
		"department_id":         nullableString(scope.DeptID),
	})
}

func (a *app) handleSections(w http.ResponseWriter, r *http.Request) {
	switch r.Method {
	case http.MethodGet:
		a.listSections(r.Context(), w, r)
	case http.MethodPost:
		a.createSection(r.Context(), w, r)
	default:
		writeError(w, http.StatusMethodNotAllowed, "method not allowed")
	}
}

func (a *app) listSections(ctx context.Context, w http.ResponseWriter, r *http.Request) {
	scope, ok := a.readScope(w, r, false)
	if !ok {
		return
	}
	vertical := queryRequired(w, r, "vertical")
	if vertical == "" {
		return
	}

	args := []any{vertical}
	deptFilter := ""
	if !scope.IsAdmin {
		args = append(args, scope.DeptID)
		deptFilter = fmt.Sprintf(" AND s.department_id = $%d", len(args))
	}

	rows, err := a.db.Query(ctx, `
		SELECT
		  s.id,
		  s.vertical,
		  COALESCE(s.department_id, ''),
		  s.slug,
		  s.title,
		  COALESCE(s.emoji, ''),
		  COALESCE(s.description, ''),
		  s.created_at,
		  (SELECT count(*) FROM channels c WHERE c.section_id = s.id),
		  (SELECT count(*) FROM channels c WHERE c.section_id = s.id AND c.is_active = true),
		  (SELECT count(*)
		     FROM messages m
		     JOIN channels c ON c.id = m.channel_id
		    WHERE c.section_id = s.id),
		  (SELECT count(*)
		     FROM messages m
		     JOIN channels c ON c.id = m.channel_id
		    WHERE c.section_id = s.id
		      AND (
		        (s.vertical = 'hr' AND m.extracted->'hr_lead'->>'is_lead' = 'true')
		        OR (s.vertical <> 'hr' AND m.extracted->'lead'->>'is_listing' = 'true')
		      ))
		FROM sections s
		WHERE s.vertical = $1`+deptFilter+`
		ORDER BY s.created_at ASC, s.id ASC
	`, args...)
	if err != nil {
		writeDBError(w, err)
		return
	}
	defer rows.Close()

	out := []sectionOut{}
	for rows.Next() {
		item, err := scanSection(rows)
		if err != nil {
			writeDBError(w, err)
			return
		}
		out = append(out, item)
	}
	if err := rows.Err(); err != nil {
		writeDBError(w, err)
		return
	}
	writeJSON(w, http.StatusOK, out)
}

func (a *app) createSection(ctx context.Context, w http.ResponseWriter, r *http.Request) {
	scope, ok := a.readScope(w, r, true)
	if !ok {
		return
	}
	var payload struct {
		Vertical    string  `json:"vertical"`
		Slug        string  `json:"slug"`
		Title       string  `json:"title"`
		Emoji       *string `json:"emoji"`
		Description *string `json:"description"`
	}
	if !readBody(w, r, &payload) {
		return
	}
	payload.Vertical = strings.TrimSpace(payload.Vertical)
	payload.Slug = normalizeSlug(payload.Slug)
	payload.Title = strings.TrimSpace(payload.Title)
	if payload.Vertical == "" || payload.Slug == "" || payload.Title == "" {
		writeError(w, http.StatusBadRequest, "vertical, slug and title are required")
		return
	}
	dept := nullableString(scope.DeptID)
	row := a.db.QueryRow(ctx, `
		INSERT INTO sections (vertical, department_id, slug, title, emoji, description)
		VALUES ($1, $2, $3, $4, $5, $6)
		RETURNING id, vertical, COALESCE(department_id, ''), slug, title, COALESCE(emoji, ''), COALESCE(description, ''), created_at,
		          0::bigint, 0::bigint, 0::bigint, 0::bigint
	`, payload.Vertical, dept, payload.Slug, payload.Title, payload.Emoji, payload.Description)
	item, err := scanSectionRow(row)
	if err != nil {
		writeDBError(w, err)
		return
	}
	writeJSON(w, http.StatusCreated, item)
}

func (a *app) handleSectionItem(w http.ResponseWriter, r *http.Request, path string) {
	rest := strings.TrimPrefix(path, "/api/v1/sections/")
	parts := strings.SplitN(rest, "/", 2)
	if len(parts) != 2 {
		writeError(w, http.StatusNotFound, "not found")
		return
	}
	vertical, err := url.PathUnescape(parts[0])
	if err != nil {
		writeError(w, http.StatusBadRequest, "bad vertical")
		return
	}
	slug, err := url.PathUnescape(parts[1])
	if err != nil {
		writeError(w, http.StatusBadRequest, "bad slug")
		return
	}

	switch r.Method {
	case http.MethodGet:
		a.getSection(r.Context(), w, r, vertical, slug)
	case http.MethodPatch:
		a.updateSection(r.Context(), w, r, vertical, slug)
	case http.MethodDelete:
		a.deleteSection(r.Context(), w, r, vertical, slug)
	default:
		writeError(w, http.StatusMethodNotAllowed, "method not allowed")
	}
}

func (a *app) getSection(ctx context.Context, w http.ResponseWriter, r *http.Request, vertical, slug string) {
	scope, ok := a.readScope(w, r, false)
	if !ok {
		return
	}
	item, err := a.findSection(ctx, vertical, slug, scope)
	if err != nil {
		writeDBError(w, err)
		return
	}
	writeJSON(w, http.StatusOK, item)
}

func (a *app) updateSection(ctx context.Context, w http.ResponseWriter, r *http.Request, vertical, slug string) {
	scope, ok := a.readScope(w, r, true)
	if !ok {
		return
	}
	var payload struct {
		Title       *string `json:"title"`
		Emoji       *string `json:"emoji"`
		Description *string `json:"description"`
	}
	if !readBody(w, r, &payload) {
		return
	}
	set := []string{}
	args := []any{}
	if payload.Title != nil {
		args = append(args, strings.TrimSpace(*payload.Title))
		set = append(set, fmt.Sprintf("title = $%d", len(args)))
	}
	if payload.Emoji != nil {
		args = append(args, nullableString(strings.TrimSpace(*payload.Emoji)))
		set = append(set, fmt.Sprintf("emoji = $%d", len(args)))
	}
	if payload.Description != nil {
		args = append(args, nullableString(strings.TrimSpace(*payload.Description)))
		set = append(set, fmt.Sprintf("description = $%d", len(args)))
	}
	if len(set) == 0 {
		a.getSection(ctx, w, r, vertical, slug)
		return
	}
	args = append(args, vertical, slug)
	where := fmt.Sprintf("vertical = $%d AND slug = $%d", len(args)-1, len(args))
	if !scope.IsAdmin {
		args = append(args, scope.DeptID)
		where += fmt.Sprintf(" AND department_id = $%d", len(args))
	}
	row := a.db.QueryRow(ctx, `
		UPDATE sections
		SET `+strings.Join(set, ", ")+`
		WHERE `+where+`
		RETURNING id, vertical, COALESCE(department_id, ''), slug, title, COALESCE(emoji, ''), COALESCE(description, ''), created_at,
		          (SELECT count(*) FROM channels c WHERE c.section_id = sections.id),
		          (SELECT count(*) FROM channels c WHERE c.section_id = sections.id AND c.is_active = true),
		          (SELECT count(*) FROM messages m JOIN channels c ON c.id = m.channel_id WHERE c.section_id = sections.id),
		          0::bigint
	`, args...)
	item, err := scanSectionRow(row)
	if err != nil {
		writeDBError(w, err)
		return
	}
	writeJSON(w, http.StatusOK, item)
}

func (a *app) deleteSection(ctx context.Context, w http.ResponseWriter, r *http.Request, vertical, slug string) {
	scope, ok := a.readScope(w, r, true)
	if !ok {
		return
	}
	section, err := a.findSection(ctx, vertical, slug, scope)
	if err != nil {
		writeDBError(w, err)
		return
	}
	var count int64
	if err := a.db.QueryRow(ctx, `SELECT count(*) FROM channels WHERE section_id = $1`, section.ID).Scan(&count); err != nil {
		writeDBError(w, err)
		return
	}
	if count > 0 {
		writeError(w, http.StatusBadRequest, fmt.Sprintf("section has %d channels - move or delete them first", count))
		return
	}
	if _, err := a.db.Exec(ctx, `DELETE FROM sections WHERE id = $1`, section.ID); err != nil {
		writeDBError(w, err)
		return
	}
	w.WriteHeader(http.StatusNoContent)
}

func (a *app) findSection(ctx context.Context, vertical, slug string, scope accessScope) (sectionOut, error) {
	args := []any{vertical, slug}
	where := "s.vertical = $1 AND s.slug = $2"
	if !scope.IsAdmin {
		args = append(args, scope.DeptID)
		where += fmt.Sprintf(" AND s.department_id = $%d", len(args))
	}
	row := a.db.QueryRow(ctx, `
		SELECT s.id, s.vertical, COALESCE(s.department_id, ''), s.slug, s.title, COALESCE(s.emoji, ''), COALESCE(s.description, ''), s.created_at,
		       (SELECT count(*) FROM channels c WHERE c.section_id = s.id),
		       (SELECT count(*) FROM channels c WHERE c.section_id = s.id AND c.is_active = true),
		       (SELECT count(*) FROM messages m JOIN channels c ON c.id = m.channel_id WHERE c.section_id = s.id),
		       0::bigint
		FROM sections s
		WHERE `+where+`
	`, args...)
	return scanSectionRow(row)
}

func (a *app) handleChannels(w http.ResponseWriter, r *http.Request) {
	switch r.Method {
	case http.MethodGet:
		a.listChannels(r.Context(), w, r)
	case http.MethodPost:
		a.createChannel(r.Context(), w, r)
	default:
		writeError(w, http.StatusMethodNotAllowed, "method not allowed")
	}
}

func (a *app) listChannels(ctx context.Context, w http.ResponseWriter, r *http.Request) {
	scope, ok := a.readScope(w, r, false)
	if !ok {
		return
	}
	vertical := queryRequired(w, r, "vertical")
	if vertical == "" {
		return
	}
	section := strings.TrimSpace(r.URL.Query().Get("section"))
	args := []any{vertical}
	where := "c.vertical = $1"
	if section != "" {
		args = append(args, section)
		where += fmt.Sprintf(" AND s.slug = $%d", len(args))
	}
	if !scope.IsAdmin {
		args = append(args, scope.DeptID)
		where += fmt.Sprintf(" AND s.department_id = $%d", len(args))
	}
	rows, err := a.db.Query(ctx, `
		SELECT c.id, c.tg_id, c.identifier, c.title, c.vertical, c.section_id, s.slug,
		       c.is_active, c.last_message_id, c.last_polled_at, c.created_at
		FROM channels c
		JOIN sections s ON s.id = c.section_id
		WHERE `+where+`
		ORDER BY c.created_at DESC, c.id DESC
	`, args...)
	if err != nil {
		writeDBError(w, err)
		return
	}
	defer rows.Close()
	out := []channelOut{}
	for rows.Next() {
		item, err := scanChannel(rows)
		if err != nil {
			writeDBError(w, err)
			return
		}
		out = append(out, item)
	}
	if err := rows.Err(); err != nil {
		writeDBError(w, err)
		return
	}
	writeJSON(w, http.StatusOK, out)
}

func (a *app) createChannel(ctx context.Context, w http.ResponseWriter, r *http.Request) {
	scope, ok := a.readScope(w, r, true)
	if !ok {
		return
	}
	var payload struct {
		Identifier string `json:"identifier"`
		Vertical   string `json:"vertical"`
		Section    string `json:"section"`
	}
	if !readBody(w, r, &payload) {
		return
	}
	payload.Identifier = strings.TrimSpace(payload.Identifier)
	payload.Vertical = strings.TrimSpace(payload.Vertical)
	payload.Section = strings.TrimSpace(payload.Section)
	if payload.Identifier == "" || payload.Vertical == "" || payload.Section == "" {
		writeError(w, http.StatusBadRequest, "identifier, vertical and section are required")
		return
	}
	section, err := a.findSection(ctx, payload.Vertical, payload.Section, scope)
	if err != nil {
		writeDBError(w, err)
		return
	}
	row := a.db.QueryRow(ctx, `
		INSERT INTO channels (identifier, vertical, section_id, is_active)
		VALUES ($1, $2, $3, true)
		RETURNING id, tg_id, identifier, title, vertical, section_id, $4::text, is_active, last_message_id, last_polled_at, created_at
	`, payload.Identifier, payload.Vertical, section.ID, section.Slug)
	item, err := scanChannelRow(row)
	if err != nil {
		writeDBError(w, err)
		return
	}
	writeJSON(w, http.StatusCreated, item)
}

func (a *app) handleChannelItem(ctx context.Context, w http.ResponseWriter, r *http.Request, path string) {
	rest := strings.TrimPrefix(path, "/api/v1/channels/")
	parts := strings.Split(rest, "/")
	if len(parts) == 0 {
		writeError(w, http.StatusNotFound, "not found")
		return
	}
	id, err := strconv.ParseInt(parts[0], 10, 64)
	if err != nil {
		writeError(w, http.StatusBadRequest, "bad channel id")
		return
	}
	if len(parts) == 2 {
		switch parts[1] {
		case "poll", "backfill-media":
			a.proxyPython(w, r, path)
		case "reanalyze":
			a.reanalyzeChannel(ctx, w, r, id)
		case "stats":
			a.channelStats(ctx, w, r, id)
		default:
			writeError(w, http.StatusNotFound, "not found")
		}
		return
	}

	switch r.Method {
	case http.MethodGet:
		a.getChannel(ctx, w, r, id)
	case http.MethodPatch:
		a.updateChannel(ctx, w, r, id)
	case http.MethodDelete:
		a.deleteChannel(ctx, w, r, id)
	default:
		writeError(w, http.StatusMethodNotAllowed, "method not allowed")
	}
}

func (a *app) getChannel(ctx context.Context, w http.ResponseWriter, r *http.Request, id int64) {
	scope, ok := a.readScope(w, r, false)
	if !ok {
		return
	}
	channel, err := a.findChannel(ctx, id, scope, r.URL.Query().Get("vertical"), r.URL.Query().Get("section"))
	if err != nil {
		writeDBError(w, err)
		return
	}
	writeJSON(w, http.StatusOK, channel)
}

func (a *app) updateChannel(ctx context.Context, w http.ResponseWriter, r *http.Request, id int64) {
	scope, ok := a.readScope(w, r, true)
	if !ok {
		return
	}
	if _, err := a.findChannel(ctx, id, scope, r.URL.Query().Get("vertical"), r.URL.Query().Get("section")); err != nil {
		writeDBError(w, err)
		return
	}
	var payload struct {
		IsActive *bool   `json:"is_active"`
		Vertical *string `json:"vertical"`
		Section  *string `json:"section"`
	}
	if !readBody(w, r, &payload) {
		return
	}
	set := []string{}
	args := []any{}
	if payload.IsActive != nil {
		args = append(args, *payload.IsActive)
		set = append(set, fmt.Sprintf("is_active = $%d", len(args)))
	}
	if payload.Vertical != nil {
		args = append(args, strings.TrimSpace(*payload.Vertical))
		set = append(set, fmt.Sprintf("vertical = $%d", len(args)))
	}
	if payload.Section != nil && strings.TrimSpace(*payload.Section) != "" {
		vertical := r.URL.Query().Get("vertical")
		if payload.Vertical != nil && strings.TrimSpace(*payload.Vertical) != "" {
			vertical = strings.TrimSpace(*payload.Vertical)
		}
		section, err := a.findSection(ctx, vertical, strings.TrimSpace(*payload.Section), scope)
		if err != nil {
			writeDBError(w, err)
			return
		}
		args = append(args, section.ID)
		set = append(set, fmt.Sprintf("section_id = $%d", len(args)))
	}
	if len(set) == 0 {
		a.getChannel(ctx, w, r, id)
		return
	}
	args = append(args, id)
	row := a.db.QueryRow(ctx, `
		UPDATE channels
		SET `+strings.Join(set, ", ")+`
		WHERE id = $`+strconv.Itoa(len(args))+`
		RETURNING id, tg_id, identifier, title, vertical, section_id,
		          (SELECT slug FROM sections WHERE id = channels.section_id),
		          is_active, last_message_id, last_polled_at, created_at
	`, args...)
	item, err := scanChannelRow(row)
	if err != nil {
		writeDBError(w, err)
		return
	}
	writeJSON(w, http.StatusOK, item)
}

func (a *app) deleteChannel(ctx context.Context, w http.ResponseWriter, r *http.Request, id int64) {
	scope, ok := a.readScope(w, r, true)
	if !ok {
		return
	}
	if _, err := a.findChannel(ctx, id, scope, r.URL.Query().Get("vertical"), r.URL.Query().Get("section")); err != nil {
		writeDBError(w, err)
		return
	}
	if _, err := a.db.Exec(ctx, `DELETE FROM channels WHERE id = $1`, id); err != nil {
		writeDBError(w, err)
		return
	}
	w.WriteHeader(http.StatusNoContent)
}

func (a *app) findChannel(ctx context.Context, id int64, scope accessScope, vertical, section string) (channelOut, error) {
	args := []any{id}
	where := "c.id = $1"
	if strings.TrimSpace(vertical) != "" {
		args = append(args, strings.TrimSpace(vertical))
		where += fmt.Sprintf(" AND c.vertical = $%d", len(args))
	}
	if strings.TrimSpace(section) != "" {
		args = append(args, strings.TrimSpace(section))
		where += fmt.Sprintf(" AND s.slug = $%d", len(args))
	}
	if !scope.IsAdmin {
		args = append(args, scope.DeptID)
		where += fmt.Sprintf(" AND s.department_id = $%d", len(args))
	}
	row := a.db.QueryRow(ctx, `
		SELECT c.id, c.tg_id, c.identifier, c.title, c.vertical, c.section_id, s.slug,
		       c.is_active, c.last_message_id, c.last_polled_at, c.created_at
		FROM channels c
		JOIN sections s ON s.id = c.section_id
		WHERE `+where+`
	`, args...)
	return scanChannelRow(row)
}

func (a *app) channelStats(ctx context.Context, w http.ResponseWriter, r *http.Request, id int64) {
	scope, ok := a.readScope(w, r, false)
	if !ok {
		return
	}
	ch, err := a.findChannel(ctx, id, scope, r.URL.Query().Get("vertical"), r.URL.Query().Get("section"))
	if err != nil {
		writeDBError(w, err)
		return
	}
	var messages, leads int64
	key := "lead"
	field := "is_listing"
	if ch.Vertical == verticalHR {
		key = "hr_lead"
		field = "is_lead"
	}
	if err := a.db.QueryRow(ctx, `SELECT count(*) FROM messages WHERE channel_id = $1`, id).Scan(&messages); err != nil {
		writeDBError(w, err)
		return
	}
	if err := a.db.QueryRow(ctx, `SELECT count(*) FROM messages WHERE channel_id = $1 AND extracted -> $2 ->> $3 = 'true'`, id, key, field).Scan(&leads); err != nil {
		writeDBError(w, err)
		return
	}
	writeJSON(w, http.StatusOK, map[string]any{
		"channel_id":      id,
		"messages_total":  messages,
		"leads_total":     leads,
		"last_polled_at":  ch.LastPolledAt,
		"last_message_id": ch.LastMessageID,
	})
}

func (a *app) reanalyzeChannel(ctx context.Context, w http.ResponseWriter, r *http.Request, id int64) {
	scope, ok := a.readScope(w, r, true)
	if !ok {
		return
	}
	ch, err := a.findChannel(ctx, id, scope, r.URL.Query().Get("vertical"), r.URL.Query().Get("section"))
	if err != nil {
		writeDBError(w, err)
		return
	}
	key := verdictKey(ch.Vertical)
	tag, err := a.db.Exec(ctx, `
		UPDATE messages
		SET extracted = (
			CASE WHEN jsonb_typeof(extracted) = 'object' THEN extracted ELSE '{}'::jsonb END
		) - $1
		WHERE channel_id = $2
	`, key, id)
	if err != nil {
		writeDBError(w, err)
		return
	}
	pending, err := a.pendingLLM(ctx, scope, ch.Vertical, valueOrEmpty(ch.SectionSlug))
	if err != nil {
		writeDBError(w, err)
		return
	}
	writeJSON(w, http.StatusOK, map[string]int64{"updated": tag.RowsAffected(), "pending": pending})
}

func (a *app) handleMessages(ctx context.Context, w http.ResponseWriter, r *http.Request) {
	if r.Method != http.MethodGet {
		writeError(w, http.StatusMethodNotAllowed, "method not allowed")
		return
	}
	scope, ok := a.readScope(w, r, false)
	if !ok {
		return
	}
	vertical := queryRequired(w, r, "vertical")
	if vertical == "" {
		return
	}
	q := r.URL.Query()
	limit := clampInt(queryInt(q.Get("limit"), 50), 1, 500)
	offset := maxInt(queryInt(q.Get("offset"), 0), 0)
	args := []any{vertical}
	where := "c.vertical = $1"
	if section := strings.TrimSpace(q.Get("section")); section != "" {
		args = append(args, section)
		where += fmt.Sprintf(" AND s.slug = $%d", len(args))
	}
	if channelID := strings.TrimSpace(q.Get("channel_id")); channelID != "" {
		id, err := strconv.ParseInt(channelID, 10, 64)
		if err != nil {
			writeError(w, http.StatusBadRequest, "bad channel_id")
			return
		}
		args = append(args, id)
		where += fmt.Sprintf(" AND m.channel_id = $%d", len(args))
	}
	if text := strings.TrimSpace(q.Get("q")); text != "" {
		args = append(args, "%"+text+"%")
		where += fmt.Sprintf(" AND m.text ILIKE $%d", len(args))
	}
	if q.Get("leads_only") == "true" || q.Get("leads_only") == "1" {
		key := "lead"
		field := "is_listing"
		if vertical == verticalHR {
			key = "hr_lead"
			field = "is_lead"
		}
		args = append(args, key, field)
		where += fmt.Sprintf(" AND m.extracted -> $%d ->> $%d = 'true'", len(args)-1, len(args))
	}
	if !scope.IsAdmin {
		args = append(args, scope.DeptID)
		where += fmt.Sprintf(" AND s.department_id = $%d", len(args))
	}
	fetchLimit := clampInt(limit*5, limit, 1000)
	args = append(args, fetchLimit, offset)
	rows, err := a.db.Query(ctx, `
		SELECT m.id, m.channel_id, c.vertical, s.slug, m.tg_message_id, m.grouped_id, 1::int,
		       m.date, m.text, m.sender_id, m.sender_username, m.sender_name,
		       c.identifier, c.tg_id, m.has_media, COALESCE(m.extracted, 'null'::jsonb)::text,
		       COALESCE(m.media_files, '[]'::jsonb)::text, m.views, m.forwards, m.fetched_at
		FROM messages m
		JOIN channels c ON c.id = m.channel_id
		JOIN sections s ON s.id = c.section_id
		WHERE `+where+`
		ORDER BY m.date DESC, m.id DESC
		LIMIT $`+strconv.Itoa(len(args)-1)+` OFFSET $`+strconv.Itoa(len(args))+`
	`, args...)
	if err != nil {
		writeDBError(w, err)
		return
	}
	defer rows.Close()
	out := []messageOut{}
	for rows.Next() {
		item, err := scanMessage(rows)
		if err != nil {
			writeDBError(w, err)
			return
		}
		a.normalizeMessageMedia(&item)
		out = append(out, item)
	}
	if err := rows.Err(); err != nil {
		writeDBError(w, err)
		return
	}
	out = aggregateMessages(out, limit)
	writeJSON(w, http.StatusOK, out)
}

func (a *app) handleMessageItem(ctx context.Context, w http.ResponseWriter, r *http.Request, path string) {
	if r.Method != http.MethodGet {
		writeError(w, http.StatusMethodNotAllowed, "method not allowed")
		return
	}
	scope, ok := a.readScope(w, r, false)
	if !ok {
		return
	}
	idRaw := strings.TrimPrefix(path, "/api/v1/messages/")
	id, err := strconv.ParseInt(idRaw, 10, 64)
	if err != nil {
		writeError(w, http.StatusBadRequest, "bad message id")
		return
	}
	args := []any{id}
	where := "m.id = $1"
	if !scope.IsAdmin {
		args = append(args, scope.DeptID)
		where += fmt.Sprintf(" AND s.department_id = $%d", len(args))
	}
	row := a.db.QueryRow(ctx, `
		SELECT m.id, m.channel_id, c.vertical, s.slug, m.tg_message_id, m.grouped_id, 1::int,
		       m.date, m.text, m.sender_id, m.sender_username, m.sender_name,
		       c.identifier, c.tg_id, m.has_media, COALESCE(m.extracted, 'null'::jsonb)::text,
		       COALESCE(m.media_files, '[]'::jsonb)::text, m.views, m.forwards, m.fetched_at
		FROM messages m
		JOIN channels c ON c.id = m.channel_id
		JOIN sections s ON s.id = c.section_id
		WHERE `+where+`
	`, args...)
	item, err := scanMessageRow(row)
	if err != nil {
		writeDBError(w, err)
		return
	}
	a.normalizeMessageMedia(&item)
	writeJSON(w, http.StatusOK, item)
}

func (a *app) handleMedia(w http.ResponseWriter, r *http.Request, path string) {
	if r.Method != http.MethodGet {
		writeError(w, http.StatusMethodNotAllowed, "method not allowed")
		return
	}
	scope, ok := a.readScope(w, r, false)
	if !ok {
		return
	}
	rel, err := url.PathUnescape(strings.TrimPrefix(path, "/api/v1/media/"))
	if err != nil {
		writeError(w, http.StatusBadRequest, "bad media path")
		return
	}
	clean := strings.TrimPrefix(filepath.Clean("/"+rel), "/")
	if clean == "." || clean == "" || strings.HasPrefix(clean, "../") {
		writeError(w, http.StatusBadRequest, "bad media path")
		return
	}
	parts := strings.SplitN(clean, string(os.PathSeparator), 2)
	channelID, err := strconv.ParseInt(parts[0], 10, 64)
	if err != nil || channelID <= 0 {
		writeError(w, http.StatusBadRequest, "bad media path")
		return
	}
	allowed, err := a.canReadChannelMedia(r.Context(), scope, channelID)
	if err != nil {
		writeDBError(w, err)
		return
	}
	if !allowed {
		writeError(w, http.StatusNotFound, "not found")
		return
	}
	base, err := filepath.Abs(a.cfg.MediaDir)
	if err != nil {
		writeError(w, http.StatusInternalServerError, "media directory unavailable")
		return
	}
	full, err := filepath.Abs(filepath.Join(base, clean))
	if err != nil || (full != base && !strings.HasPrefix(full, base+string(os.PathSeparator))) {
		writeError(w, http.StatusBadRequest, "bad media path")
		return
	}
	http.ServeFile(w, r, full)
}

func (a *app) canReadChannelMedia(ctx context.Context, scope accessScope, channelID int64) (bool, error) {
	var dept sql.NullString
	err := a.db.QueryRow(ctx, `
		SELECT s.department_id
		FROM channels c
		JOIN sections s ON s.id = c.section_id
		WHERE c.id = $1
	`, channelID).Scan(&dept)
	if errors.Is(err, pgx.ErrNoRows) {
		return false, nil
	}
	if err != nil {
		return false, err
	}
	if scope.IsAdmin {
		return true, nil
	}
	return dept.Valid && dept.String == scope.DeptID, nil
}

func (a *app) handleStats(ctx context.Context, w http.ResponseWriter, r *http.Request) {
	if r.Method != http.MethodGet {
		writeError(w, http.StatusMethodNotAllowed, "method not allowed")
		return
	}
	scope, ok := a.readScope(w, r, false)
	if !ok {
		return
	}
	vertical := queryRequired(w, r, "vertical")
	if vertical == "" {
		return
	}
	section := strings.TrimSpace(r.URL.Query().Get("section"))
	args := []any{vertical}
	where := "c.vertical = $1"
	if section != "" {
		args = append(args, section)
		where += fmt.Sprintf(" AND s.slug = $%d", len(args))
	}
	if !scope.IsAdmin {
		args = append(args, scope.DeptID)
		where += fmt.Sprintf(" AND s.department_id = $%d", len(args))
	}

	var channelsTotal, channelsActive, messagesTotal, messages24h, leadsTotal, leads24h int64
	var lastPoll sql.NullTime
	countQuery := `FROM channels c JOIN sections s ON s.id = c.section_id WHERE ` + where
	if err := a.db.QueryRow(ctx, `SELECT count(*) `+countQuery, args...).Scan(&channelsTotal); err != nil {
		writeDBError(w, err)
		return
	}
	if err := a.db.QueryRow(ctx, `SELECT count(*) `+countQuery+` AND c.is_active = true`, args...).Scan(&channelsActive); err != nil {
		writeDBError(w, err)
		return
	}
	if err := a.db.QueryRow(ctx, `SELECT max(c.last_polled_at) `+countQuery, args...).Scan(&lastPoll); err != nil {
		writeDBError(w, err)
		return
	}
	messageFrom := `FROM messages m JOIN channels c ON c.id = m.channel_id JOIN sections s ON s.id = c.section_id WHERE ` + where
	if err := a.db.QueryRow(ctx, `SELECT count(*) `+messageFrom, args...).Scan(&messagesTotal); err != nil {
		writeDBError(w, err)
		return
	}
	if err := a.db.QueryRow(ctx, `SELECT count(*) `+messageFrom+` AND m.fetched_at >= now() - interval '24 hours'`, args...).Scan(&messages24h); err != nil {
		writeDBError(w, err)
		return
	}
	key := "lead"
	field := "is_listing"
	if vertical == verticalHR {
		key = "hr_lead"
		field = "is_lead"
	}
	leadArgs := append(append([]any{}, args...), key, field)
	leadClause := fmt.Sprintf(" AND m.extracted -> $%d ->> $%d = 'true'", len(leadArgs)-1, len(leadArgs))
	if err := a.db.QueryRow(ctx, `SELECT count(*) `+messageFrom+leadClause, leadArgs...).Scan(&leadsTotal); err != nil {
		writeDBError(w, err)
		return
	}
	if err := a.db.QueryRow(ctx, `SELECT count(*) `+messageFrom+leadClause+` AND m.fetched_at >= now() - interval '24 hours'`, leadArgs...).Scan(&leads24h); err != nil {
		writeDBError(w, err)
		return
	}
	writeJSON(w, http.StatusOK, map[string]any{
		"vertical":              vertical,
		"section_slug":          nullableString(section),
		"channels_total":        channelsTotal,
		"channels_active":       channelsActive,
		"messages_total":        messagesTotal,
		"messages_last_24h":     messages24h,
		"leads_total":           leadsTotal,
		"leads_last_24h":        leads24h,
		"poll_interval_seconds": a.cfg.PollIntervalSeconds,
		"last_poll_at":          nullTime(lastPoll),
	})
}

func (a *app) handleLLMStatus(ctx context.Context, w http.ResponseWriter) {
	ready := false
	if a.cfg.LLMEnabled {
		req, err := http.NewRequestWithContext(ctx, http.MethodGet, strings.TrimRight(a.cfg.LLMBaseURL, "/")+"/v1/models", nil)
		if err == nil {
			if a.cfg.LLMAPIKey != "" {
				req.Header.Set("Authorization", "Bearer "+a.cfg.LLMAPIKey)
			}
			resp, err := a.http.Do(req)
			if err == nil {
				ready = resp.StatusCode >= 200 && resp.StatusCode < 300
				_ = resp.Body.Close()
			}
		}
	}
	writeJSON(w, http.StatusOK, map[string]any{
		"enabled":  a.cfg.LLMEnabled,
		"ready":    ready,
		"base_url": a.cfg.LLMBaseURL,
		"model":    a.cfg.LLMModel,
	})
}

func (a *app) handleLLMQueue(ctx context.Context, w http.ResponseWriter, r *http.Request) {
	if r.Method != http.MethodGet {
		writeError(w, http.StatusMethodNotAllowed, "method not allowed")
		return
	}
	scope, ok := a.readScope(w, r, false)
	if !ok {
		return
	}
	vertical := queryRequired(w, r, "vertical")
	if vertical == "" {
		return
	}
	pending, err := a.pendingLLM(ctx, scope, vertical, strings.TrimSpace(r.URL.Query().Get("section")))
	if err != nil {
		writeDBError(w, err)
		return
	}
	writeJSON(w, http.StatusOK, map[string]int64{"pending": pending})
}

func (a *app) pendingLLM(ctx context.Context, scope accessScope, vertical, section string) (int64, error) {
	args := []any{vertical}
	where := `c.vertical = $1 AND m.text IS NOT NULL AND ((c.vertical = 'hr' AND (m.extracted IS NULL OR m.extracted->'hr_lead' IS NULL)) OR (c.vertical <> 'hr' AND (m.extracted IS NULL OR m.extracted->'lead' IS NULL)))`
	if section != "" {
		args = append(args, section)
		where += fmt.Sprintf(" AND s.slug = $%d", len(args))
	}
	if !scope.IsAdmin {
		args = append(args, scope.DeptID)
		where += fmt.Sprintf(" AND s.department_id = $%d", len(args))
	}
	var pending int64
	err := a.db.QueryRow(ctx, `
		SELECT count(*)
		FROM messages m
		JOIN channels c ON c.id = m.channel_id
		JOIN sections s ON s.id = c.section_id
		WHERE `+where, args...).Scan(&pending)
	return pending, err
}

func (a *app) handlePrompt(ctx context.Context, w http.ResponseWriter, r *http.Request) {
	switch r.Method {
	case http.MethodGet:
		a.getPrompt(ctx, w, r)
	case http.MethodPut:
		a.savePrompt(ctx, w, r)
	case http.MethodDelete:
		a.resetPrompt(ctx, w, r)
	default:
		writeError(w, http.StatusMethodNotAllowed, "method not allowed")
	}
}

func (a *app) getPrompt(ctx context.Context, w http.ResponseWriter, r *http.Request) {
	scope, ok := a.readScope(w, r, false)
	if !ok {
		return
	}
	vertical := queryRequired(w, r, "vertical")
	if vertical == "" {
		return
	}
	section := strings.TrimSpace(r.URL.Query().Get("section"))
	if section != "" {
		if _, err := a.findSection(ctx, vertical, section, scope); err != nil {
			writeDBError(w, err)
			return
		}
	}
	prompt, source, err := a.resolvePrompt(ctx, scope.DeptID, vertical, section)
	if err != nil {
		writeDBError(w, err)
		return
	}
	overridden, err := a.promptExists(ctx, scope.DeptID, vertical, section)
	if err != nil {
		writeDBError(w, err)
		return
	}
	writeJSON(w, http.StatusOK, map[string]any{
		"vertical":           vertical,
		"department_id":      nullableString(scope.DeptID),
		"section":            nullableString(section),
		"prompt":             prompt,
		"default":            defaultPrompt(vertical),
		"source":             source,
		"is_overridden_here": overridden,
	})
}

func (a *app) savePrompt(ctx context.Context, w http.ResponseWriter, r *http.Request) {
	scope, ok := a.readScope(w, r, true)
	if !ok {
		return
	}
	vertical := queryRequired(w, r, "vertical")
	if vertical == "" {
		return
	}
	section := strings.TrimSpace(r.URL.Query().Get("section"))
	var payload struct {
		Prompt string `json:"prompt"`
	}
	if !readBody(w, r, &payload) {
		return
	}
	text := strings.TrimSpace(payload.Prompt)
	if text == "" {
		writeError(w, http.StatusBadRequest, "prompt must be a non-empty string")
		return
	}
	if len(text) > 30000 {
		writeError(w, http.StatusBadRequest, "prompt is too long (max 30000 chars)")
		return
	}
	key := promptKey(scope.DeptID, vertical, section)
	value, _ := json.Marshal(text)
	if _, err := a.db.Exec(ctx, `
		INSERT INTO app_settings (key, value, updated_at)
		VALUES ($1, $2::jsonb, now())
		ON CONFLICT (key) DO UPDATE SET value = EXCLUDED.value, updated_at = now()
	`, key, string(value)); err != nil {
		writeDBError(w, err)
		return
	}
	writeJSON(w, http.StatusOK, map[string]any{"saved": true, "vertical": vertical, "department_id": nullableString(scope.DeptID), "section": nullableString(section), "length": len(text)})
}

func (a *app) resetPrompt(ctx context.Context, w http.ResponseWriter, r *http.Request) {
	scope, ok := a.readScope(w, r, true)
	if !ok {
		return
	}
	vertical := queryRequired(w, r, "vertical")
	if vertical == "" {
		return
	}
	section := strings.TrimSpace(r.URL.Query().Get("section"))
	if _, err := a.db.Exec(ctx, `DELETE FROM app_settings WHERE key = $1`, promptKey(scope.DeptID, vertical, section)); err != nil {
		writeDBError(w, err)
		return
	}
	w.WriteHeader(http.StatusNoContent)
}

func (a *app) resolvePrompt(ctx context.Context, deptID, vertical, section string) (string, string, error) {
	keys := []struct {
		key    string
		source string
	}{}
	if section != "" {
		keys = append(keys, struct {
			key    string
			source string
		}{promptKey(deptID, vertical, section), "section"})
	}
	keys = append(keys, struct {
		key    string
		source string
	}{promptKey(deptID, vertical, ""), "vertical"})

	for _, candidate := range keys {
		var text string
		err := a.db.QueryRow(ctx, `SELECT value #>> '{}' FROM app_settings WHERE key = $1`, candidate.key).Scan(&text)
		if err == nil && strings.TrimSpace(text) != "" {
			return text, candidate.source, nil
		}
		if err != nil && !errors.Is(err, pgx.ErrNoRows) {
			return "", "", err
		}
	}
	return defaultPrompt(vertical), "default", nil
}

func (a *app) promptExists(ctx context.Context, deptID, vertical, section string) (bool, error) {
	var exists bool
	err := a.db.QueryRow(ctx, `SELECT EXISTS(SELECT 1 FROM app_settings WHERE key = $1)`, promptKey(deptID, vertical, section)).Scan(&exists)
	return exists, err
}

func (a *app) proxyPython(w http.ResponseWriter, r *http.Request, path string) {
	scope := readAccess(r)
	if strings.Contains(path, "/auth/") && !scope.CanAuth {
		writeError(w, http.StatusNotFound, "not found")
		return
	}
	if (strings.Contains(path, "/poll") || strings.Contains(path, "/backfill-media")) && !scope.CanManage {
		writeError(w, http.StatusNotFound, "not found")
		return
	}
	target := strings.TrimRight(a.cfg.PythonBaseURL, "/") + path
	if r.URL.RawQuery != "" {
		target += "?" + r.URL.RawQuery
	}
	body, err := io.ReadAll(r.Body)
	if err != nil {
		writeError(w, http.StatusBadRequest, "bad body")
		return
	}
	req, err := http.NewRequestWithContext(r.Context(), r.Method, target, bytes.NewReader(body))
	if err != nil {
		writeError(w, http.StatusBadGateway, err.Error())
		return
	}
	req.Header = r.Header.Clone()
	resp, err := a.python.Do(req)
	if err != nil {
		writeError(w, http.StatusBadGateway, err.Error())
		return
	}
	defer resp.Body.Close()
	for k, values := range resp.Header {
		for _, v := range values {
			w.Header().Add(k, v)
		}
	}
	w.WriteHeader(resp.StatusCode)
	_, _ = io.Copy(w, resp.Body)
}

func (a *app) readScope(w http.ResponseWriter, r *http.Request, manage bool) (accessScope, bool) {
	scope := readAccess(r)
	if manage {
		if !scope.CanManage {
			writeError(w, http.StatusNotFound, "not found")
			return scope, false
		}
	} else if !scope.IsAdmin && scope.DeptID == "" {
		writeError(w, http.StatusForbidden, "department is required")
		return scope, false
	}
	if manage && !scope.IsAdmin && scope.DeptID == "" {
		writeError(w, http.StatusForbidden, "department is required")
		return scope, false
	}
	return scope, true
}

func readAccess(r *http.Request) accessScope {
	admin := r.Header.Get("X-User-Is-Admin") == "1"
	deptHead := r.Header.Get("X-User-Is-Department-Head") == "1"
	canManage := r.Header.Get("X-Monitoring-TG-Can-Manage") == "1"
	canAuth := r.Header.Get("X-Monitoring-TG-Can-Auth") == "1"
	return accessScope{
		IsAdmin:   admin,
		CanManage: admin || deptHead || canManage,
		CanAuth:   admin || canAuth,
		DeptID:    strings.TrimSpace(r.Header.Get("X-User-Department-Id")),
	}
}

type rowScanner interface {
	Scan(dest ...any) error
}

func scanSection(rows rowScanner) (sectionOut, error) {
	var item sectionOut
	var dept, emoji, description string
	err := rows.Scan(
		&item.ID,
		&item.Vertical,
		&dept,
		&item.Slug,
		&item.Title,
		&emoji,
		&description,
		&item.CreatedAt,
		&item.ChannelsTotal,
		&item.ChannelsActive,
		&item.MessagesTotal,
		&item.LeadsTotal,
	)
	item.DepartmentID = nullableString(dept)
	item.Emoji = nullableString(emoji)
	item.Description = nullableString(description)
	return item, err
}

func scanSectionRow(row pgx.Row) (sectionOut, error) {
	return scanSection(row)
}

func scanChannel(rows rowScanner) (channelOut, error) {
	var item channelOut
	var tgID, lastMsg sql.NullInt64
	var title, slug sql.NullString
	var lastPoll sql.NullTime
	err := rows.Scan(
		&item.ID,
		&tgID,
		&item.Identifier,
		&title,
		&item.Vertical,
		&item.SectionID,
		&slug,
		&item.IsActive,
		&lastMsg,
		&lastPoll,
		&item.CreatedAt,
	)
	item.TGID = nullInt(tgID)
	item.Title = nullString(title)
	item.SectionSlug = nullString(slug)
	item.LastMessageID = nullInt(lastMsg)
	item.LastPolledAt = nullTimePtr(lastPoll)
	return item, err
}

func scanChannelRow(row pgx.Row) (channelOut, error) {
	return scanChannel(row)
}

func scanMessage(rows rowScanner) (messageOut, error) {
	var item messageOut
	var vertical, slug string
	var grouped, senderID, tgID, views, forwards sql.NullInt64
	var text, senderUsername, senderName, identifier sql.NullString
	var extractedText, mediaText string
	err := rows.Scan(
		&item.ID,
		&item.ChannelID,
		&vertical,
		&slug,
		&item.TGMessageID,
		&grouped,
		&item.GroupSize,
		&item.Date,
		&text,
		&senderID,
		&senderUsername,
		&senderName,
		&identifier,
		&tgID,
		&item.HasMedia,
		&extractedText,
		&mediaText,
		&views,
		&forwards,
		&item.FetchedAt,
	)
	item.ChannelVertical = nullableString(vertical)
	item.ChannelSectionSlug = nullableString(slug)
	item.GroupedID = nullInt(grouped)
	item.Text = nullString(text)
	item.SenderID = nullInt(senderID)
	item.SenderUsername = nullString(senderUsername)
	item.SenderName = nullString(senderName)
	item.Views = nullInt(views)
	item.Forwards = nullInt(forwards)
	if extractedText != "" && extractedText != "null" {
		item.Extracted = json.RawMessage(extractedText)
	}
	if mediaText != "" && mediaText != "null" {
		_ = json.Unmarshal([]byte(mediaText), &item.MediaFiles)
	}
	item.PostURL = buildPostURL(identifier.String, tgID, item.TGMessageID)
	return item, err
}

func scanMessageRow(row pgx.Row) (messageOut, error) {
	return scanMessage(row)
}

func (a *app) normalizeMessageMedia(item *messageOut) {
	if len(item.MediaFiles) == 0 {
		return
	}
	for _, file := range item.MediaFiles {
		rawURL, _ := file["url"].(string)
		rel := mediaRelativePath(rawURL)
		if rel == "" {
			continue
		}
		file["url"] = a.mediaURL(rel)
		if _, ok := file["name"].(string); !ok {
			file["name"] = filepath.Base(rel)
		}
	}
}

func mediaRelativePath(raw string) string {
	raw = strings.TrimSpace(raw)
	if raw == "" {
		return ""
	}
	if idx := strings.Index(raw, "/media/"); idx >= 0 {
		raw = raw[idx+len("/media/"):]
	}
	raw = strings.TrimPrefix(raw, "/")
	raw = strings.TrimPrefix(raw, "media/")
	clean := strings.TrimPrefix(filepath.Clean("/"+raw), "/")
	if clean == "." || clean == "" || strings.HasPrefix(clean, "../") {
		return ""
	}
	return clean
}

func (a *app) mediaURL(rel string) string {
	base := strings.TrimRight(a.cfg.PublicBasePath, "/")
	return base + "/api/v1/media/" + strings.TrimPrefix(rel, "/")
}

func aggregateMessages(items []messageOut, limit int) []messageOut {
	out := make([]messageOut, 0, len(items))
	index := map[string]int{}
	for _, item := range items {
		key := messageGroupKey(item)
		if pos, ok := index[key]; ok {
			group := &out[pos]
			group.GroupSize++
			group.HasMedia = group.HasMedia || item.HasMedia
			group.MediaFiles = append(group.MediaFiles, item.MediaFiles...)
			if group.Text == nil && item.Text != nil {
				group.Text = item.Text
			}
			if len(group.Extracted) == 0 && len(item.Extracted) > 0 {
				group.Extracted = item.Extracted
			}
			continue
		}
		if item.GroupSize < 1 {
			item.GroupSize = 1
		}
		index[key] = len(out)
		out = append(out, item)
	}
	if len(out) > limit {
		return out[:limit]
	}
	return out
}

func messageGroupKey(item messageOut) string {
	if item.GroupedID != nil {
		return fmt.Sprintf("channel:%d:group:%d", item.ChannelID, *item.GroupedID)
	}
	return fmt.Sprintf("message:%d", item.ID)
}

func buildPostURL(identifier string, tgID sql.NullInt64, msgID int64) *string {
	identifier = strings.TrimSpace(identifier)
	if identifier == "" || msgID == 0 {
		return nil
	}
	if strings.HasPrefix(identifier, "https://t.me/") {
		base := strings.TrimRight(identifier, "/")
		v := base + "/" + strconv.FormatInt(msgID, 10)
		return &v
	}
	if strings.HasPrefix(identifier, "@") {
		v := "https://t.me/" + strings.TrimPrefix(identifier, "@") + "/" + strconv.FormatInt(msgID, 10)
		return &v
	}
	if !strings.Contains(identifier, "/") && !strings.Contains(identifier, "+") {
		v := "https://t.me/" + identifier + "/" + strconv.FormatInt(msgID, 10)
		return &v
	}
	return nil
}

func readBody(w http.ResponseWriter, r *http.Request, out any) bool {
	defer r.Body.Close()
	if err := json.NewDecoder(r.Body).Decode(out); err != nil {
		writeError(w, http.StatusBadRequest, "invalid json")
		return false
	}
	return true
}

func writeJSON(w http.ResponseWriter, status int, payload any) {
	w.Header().Set("Content-Type", "application/json; charset=utf-8")
	w.WriteHeader(status)
	_ = json.NewEncoder(w).Encode(payload)
}

func writeError(w http.ResponseWriter, status int, detail string) {
	writeJSON(w, status, map[string]string{"detail": detail})
}

func writeDBError(w http.ResponseWriter, err error) {
	if errors.Is(err, pgx.ErrNoRows) {
		writeError(w, http.StatusNotFound, "not found")
		return
	}
	slog.Error("api_db_error", "error", err)
	writeError(w, http.StatusInternalServerError, "database error")
}

func queryRequired(w http.ResponseWriter, r *http.Request, name string) string {
	value := strings.TrimSpace(r.URL.Query().Get(name))
	if value == "" {
		writeError(w, http.StatusBadRequest, name+" is required")
	}
	return value
}

func promptKey(deptID, vertical, section string) string {
	if deptID == "" {
		deptID = "global"
	}
	if section != "" {
		return fmt.Sprintf("llm_system_prompt:%s:%s:%s", deptID, vertical, section)
	}
	return fmt.Sprintf("llm_system_prompt:%s:%s", deptID, vertical)
}

func verdictKey(vertical string) string {
	if vertical == verticalHR {
		return "hr_lead"
	}
	return "lead"
}

func defaultPrompt(vertical string) string {
	if vertical == verticalHR {
		return defaultHRPrompt
	}
	return defaultREPrompt
}

func normalizeSlug(raw string) string {
	raw = strings.ToLower(strings.TrimSpace(raw))
	raw = strings.ReplaceAll(raw, " ", "-")
	var b strings.Builder
	for _, r := range raw {
		if (r >= 'a' && r <= 'z') || (r >= '0' && r <= '9') || r == '_' || r == '-' {
			b.WriteRune(r)
		}
	}
	return b.String()
}

func nullableString(v string) *string {
	v = strings.TrimSpace(v)
	if v == "" {
		return nil
	}
	return &v
}

func nullString(v sql.NullString) *string {
	if !v.Valid || strings.TrimSpace(v.String) == "" {
		return nil
	}
	return &v.String
}

func nullInt(v sql.NullInt64) *int64 {
	if !v.Valid {
		return nil
	}
	return &v.Int64
}

func nullTime(v sql.NullTime) any {
	if !v.Valid {
		return nil
	}
	return v.Time
}

func nullTimePtr(v sql.NullTime) *time.Time {
	if !v.Valid {
		return nil
	}
	return &v.Time
}

func valueOrEmpty(v *string) string {
	if v == nil {
		return ""
	}
	return *v
}

func queryInt(raw string, fallback int) int {
	if raw == "" {
		return fallback
	}
	n, err := strconv.Atoi(raw)
	if err != nil {
		return fallback
	}
	return n
}

func clampInt(n, min, max int) int {
	if n < min {
		return min
	}
	if n > max {
		return max
	}
	return n
}

func maxInt(n, min int) int {
	if n < min {
		return min
	}
	return n
}

func loadConfig() config {
	return config{
		APIHost:             env("API_HOST", "0.0.0.0"),
		APIPort:             envInt("API_PORT", 8000),
		PublicBasePath:      env("PUBLIC_BASE_PATH", ""),
		PythonBaseURL:       env("PYTHON_BASE_URL", "http://127.0.0.1:8001"),
		MediaDir:            env("MEDIA_DIR", "/data/media"),
		PostgresUser:        env("POSTGRES_USER", "parser"),
		PostgresPassword:    env("POSTGRES_PASSWORD", "parser"),
		PostgresDB:          env("POSTGRES_DB", "parser"),
		PostgresHost:        env("POSTGRES_HOST", "db"),
		PostgresPort:        envInt("POSTGRES_PORT", 5432),
		PollIntervalSeconds: envInt("POLL_INTERVAL_SECONDS", 60),
		LLMEnabled:          envBool("LLM_ENABLED", true),
		LLMBaseURL:          env("LLM_BASE_URL", "http://10.2.3.5:8002"),
		LLMAPIKey:           env("LLM_API_KEY", ""),
		LLMModel:            env("LLM_MODEL", "qwen2.5-14b"),
		LLMTimeout:          time.Duration(envInt("LLM_TIMEOUT_SECONDS", 120)) * time.Second,
	}
}

func (c config) databaseURL() string {
	return fmt.Sprintf(
		"postgres://%s:%s@%s:%d/%s",
		url.QueryEscape(c.PostgresUser),
		url.QueryEscape(c.PostgresPassword),
		c.PostgresHost,
		c.PostgresPort,
		url.QueryEscape(c.PostgresDB),
	)
}

func env(key, fallback string) string {
	if v := strings.TrimSpace(os.Getenv(key)); v != "" {
		return v
	}
	return fallback
}

func envInt(key string, fallback int) int {
	if raw := strings.TrimSpace(os.Getenv(key)); raw != "" {
		if n, err := strconv.Atoi(raw); err == nil {
			return n
		}
	}
	return fallback
}

func envBool(key string, fallback bool) bool {
	if raw := strings.TrimSpace(os.Getenv(key)); raw != "" {
		if b, err := strconv.ParseBool(raw); err == nil {
			return b
		}
		if raw == "1" {
			return true
		}
		if raw == "0" {
			return false
		}
	}
	return fallback
}

const defaultREPrompt = `Ты — аналитик объявлений о недвижимости. Тебе дают текст из Telegram-канала.
Определи, является ли сообщение реальным объявлением о покупке, продаже или аренде недвижимости.
Отвечай строго валидным JSON без markdown:
{
  "is_listing": boolean,
  "kind": "sale" | "rent" | "purchase" | null,
  "property_type": string | null,
  "rooms": string | null,
  "area_m2": number | null,
  "price_text": string | null,
  "price_value": number | null,
  "currency": "RUB" | "USD" | "EUR" | "AED" | "GBP" | "CNY" | "TRY" | "KZT" | "BYN" | "UAH" | null,
  "location": string | null,
  "contact_phone": string | null,
  "contact_name": string | null,
  "summary": string,
  "confidence": number
}
summary всегда по-русски, confidence в диапазоне 0..1.`

const defaultHRPrompt = `Ты — аналитик HR-объявлений. Тебе дают текст из Telegram-канала.
Определи, относится ли сообщение к рынку труда: вакансия, резюме или короткий HR-контакт.
Отвечай строго валидным JSON без markdown:
{
  "is_lead": boolean,
  "kind": "vacancy" | "resume" | "contact" | null,
  "title": string | null,
  "company": string | null,
  "candidate_name": string | null,
  "experience_years": number | null,
  "skills": string[],
  "location": string | null,
  "remote": boolean | null,
  "employment_type": "full-time" | "part-time" | "contract" | "internship" | null,
  "salary_text": string | null,
  "salary_value": number | null,
  "currency": "RUB" | "USD" | "EUR" | "AED" | "GBP" | "CNY" | "TRY" | "KZT" | "BYN" | "UAH" | null,
  "contact_phone": string | null,
  "contact_name": string | null,
  "summary": string,
  "confidence": number
}
summary всегда по-русски, confidence в диапазоне 0..1.`