// Package web is the HTTP surface of the Compass/NHS service: /health, the
// service's own session login, the server-rendered HTMX dashboard, the Send
// panel and the machine endpoint the 6:00am n8n schedule calls (AGENTS.md §5,
// §9, §11 Phase 7).
package web

import (
	"context"
	"crypto/subtle"
	"embed"
	"encoding/json"
	"fmt"
	"html/template"
	"io/fs"
	"log/slog"
	"net/http"
	"net/url"
	"strconv"
	"strings"
	"time"

	"gitea.lab.audasmedia.com.au/sam/compass_teams_nhs/internal/apprise"
	"gitea.lab.audasmedia.com.au/sam/compass_teams_nhs/internal/auth"
	"gitea.lab.audasmedia.com.au/sam/compass_teams_nhs/internal/brief"
	"gitea.lab.audasmedia.com.au/sam/compass_teams_nhs/internal/calendar"
	"gitea.lab.audasmedia.com.au/sam/compass_teams_nhs/internal/config"
	"gitea.lab.audasmedia.com.au/sam/compass_teams_nhs/internal/dashboard"
	"gitea.lab.audasmedia.com.au/sam/compass_teams_nhs/internal/store"
)

//go:embed templates/*.html templates/partials/*.html
var templateFS embed.FS

//go:embed static
var staticFS embed.FS

// Server holds the dependencies for the HTTP handlers.
type Server struct {
	cfg   *config.Config
	store *store.Store
	auth  *auth.Manager
	tmpl  *template.Template
	log   *slog.Logger
	brief *brief.Service
}

// New builds a Server and parses the embedded templates.
func New(cfg *config.Config, st *store.Store, am *auth.Manager, log *slog.Logger) (*Server, error) {
	funcs := template.FuncMap{
		"year":  func() int { return time.Now().Year() },
		"clock": func() string { return time.Now().Format("15:04:05 MST") },
	}
	tmpl, err := template.New("").Funcs(funcs).ParseFS(templateFS,
		"templates/*.html", "templates/partials/*.html")
	if err != nil {
		return nil, fmt.Errorf("parse templates: %w", err)
	}
	client := apprise.New(cfg.Apprise.BaseURL, cfg.Apprise.Key, cfg.Apprise.Token, cfg.Apprise.Timeout)
	svc := brief.New(st, client, cfg.Apprise, cfg.Location, log)
	return &Server{cfg: cfg, store: st, auth: am, tmpl: tmpl, log: log, brief: svc}, nil
}

// Handler returns the fully wrapped HTTP handler.
func (s *Server) Handler() http.Handler {
	mux := http.NewServeMux()

	mux.HandleFunc("GET /health", s.handleHealth)
	mux.HandleFunc("GET /login", s.handleLoginPage)
	mux.HandleFunc("POST /login", s.handleLoginSubmit)
	mux.HandleFunc("POST /logout", s.handleLogout)

	mux.HandleFunc("GET /{$}", s.requireAuth(s.handleDashboard))
	mux.HandleFunc("GET /items/{id}", s.requireAuth(s.handleItemDetail))
	mux.HandleFunc("POST /items/{id}/delete", s.requireAuth(s.handleItemDelete))
	mux.HandleFunc("POST /items/{id}/calendar", s.requireAuth(s.handleItemCalendarPush))
	mux.HandleFunc("POST /summaries/build", s.requireAuth(s.handleSummaryBuild))
	mux.HandleFunc("POST /summaries/send", s.requireAuth(s.handleSendBrief))
	mux.HandleFunc("POST /summaries/{id}/send", s.requireAuth(s.handleSummarySend))
	mux.HandleFunc("POST /summaries/{id}/delete", s.requireAuth(s.handleSummaryDelete))
	mux.HandleFunc("GET /partials/scan-status", s.requireAuth(s.handleScanStatusPartial))

	// The endpoint the 6:00am n8n schedule calls (AGENTS.md §11 Phase 7). It is
	// machine-to-machine: a bearer token, not the dashboard session.
	mux.HandleFunc("POST /notify/morning", s.handleMorningNotify)

	staticSub, err := fs.Sub(staticFS, "static")
	if err != nil {
		panic("web: embedded static dir missing: " + err.Error())
	}
	mux.Handle("GET /static/", http.StripPrefix("/static/", http.FileServer(http.FS(staticSub))))

	return s.recoverer(s.securityHeaders(s.requestLogger(mux)))
}

// ---------- middleware ----------

type statusRecorder struct {
	http.ResponseWriter
	status int
}

func (r *statusRecorder) WriteHeader(code int) {
	r.status = code
	r.ResponseWriter.WriteHeader(code)
}

func (s *Server) requestLogger(next http.Handler) http.Handler {
	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		start := time.Now()
		rec := &statusRecorder{ResponseWriter: w, status: http.StatusOK}
		next.ServeHTTP(rec, r)
		s.log.Info("http",
			"method", r.Method,
			"path", r.URL.Path,
			"status", rec.status,
			"remote", r.RemoteAddr,
			"duration", time.Since(start).String(),
		)
	})
}

func (s *Server) securityHeaders(next http.Handler) http.Handler {
	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		h := w.Header()
		h.Set("X-Content-Type-Options", "nosniff")
		h.Set("X-Frame-Options", "DENY")
		h.Set("Referrer-Policy", "same-origin")
		h.Set("Content-Security-Policy",
			"default-src 'self'; img-src 'self' data:; style-src 'self'; script-src 'self'; form-action 'self'; frame-ancestors 'none'")
		next.ServeHTTP(w, r)
	})
}

func (s *Server) recoverer(next http.Handler) http.Handler {
	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		defer func() {
			if rec := recover(); rec != nil {
				s.log.Error("panic", "err", rec, "path", r.URL.Path)
				http.Error(w, "internal server error", http.StatusInternalServerError)
			}
		}()
		next.ServeHTTP(w, r)
	})
}

func (s *Server) requireAuth(next http.HandlerFunc) http.HandlerFunc {
	return func(w http.ResponseWriter, r *http.Request) {
		if !s.auth.Authenticated(r) {
			http.Redirect(w, r, "/login", http.StatusSeeOther)
			return
		}
		next(w, r)
	}
}

// ---------- health ----------

type healthResponse struct {
	Status   string           `json:"status"`
	Service  string           `json:"service"`
	Version  string           `json:"version"`
	Database string           `json:"database"`
	Scans    store.ScanStatus `json:"scans"`
	Time     string           `json:"time"`
}

func (s *Server) handleHealth(w http.ResponseWriter, r *http.Request) {
	resp := healthResponse{
		Status:   "ok",
		Service:  "compass-teams-nhs",
		Version:  s.cfg.Version,
		Database: "ok",
		Time:     time.Now().UTC().Format(time.RFC3339),
	}
	code := http.StatusOK
	if err := s.store.Ping(r.Context()); err != nil {
		resp.Status = "error"
		resp.Database = "error"
		code = http.StatusServiceUnavailable
	}
	if st, err := s.store.ScanSummary(r.Context()); err == nil {
		resp.Scans = st
	}

	w.Header().Set("Content-Type", "application/json; charset=utf-8")
	w.WriteHeader(code)
	_ = json.NewEncoder(w).Encode(resp)
}

// ---------- login ----------

type loginData struct {
	CSRF     string
	Error    string
	Username string
}

func (s *Server) handleLoginPage(w http.ResponseWriter, r *http.Request) {
	if s.auth.Authenticated(r) {
		http.Redirect(w, r, "/", http.StatusSeeOther)
		return
	}
	s.render(w, r, "login.html", loginData{CSRF: s.auth.EnsureCSRF(w, r)})
}

func (s *Server) handleLoginSubmit(w http.ResponseWriter, r *http.Request) {
	if err := r.ParseForm(); err != nil {
		http.Error(w, "bad request", http.StatusBadRequest)
		return
	}
	username := strings.TrimSpace(r.PostFormValue("username"))

	if !s.auth.CheckCSRF(r) {
		s.log.Warn("login rejected: bad csrf token", "remote", r.RemoteAddr)
		s.render(w, r, "login.html", loginData{
			CSRF:     s.auth.EnsureCSRF(w, r),
			Error:    "Session expired. Please try again.",
			Username: username,
		})
		return
	}

	if !s.auth.CheckCredentials(username, r.PostFormValue("password")) {
		s.log.Warn("login failed", "user", username, "remote", r.RemoteAddr)
		w.WriteHeader(http.StatusUnauthorized)
		s.render(w, r, "login.html", loginData{
			CSRF:     s.auth.EnsureCSRF(w, r),
			Error:    "Incorrect username or password.",
			Username: username,
		})
		return
	}

	s.auth.Issue(w)
	s.log.Info("login success", "user", username, "remote", r.RemoteAddr)
	http.Redirect(w, r, "/", http.StatusSeeOther)
}

func (s *Server) handleLogout(w http.ResponseWriter, r *http.Request) {
	if err := r.ParseForm(); err != nil {
		http.Error(w, "bad request", http.StatusBadRequest)
		return
	}
	s.auth.Clear(w)
	http.Redirect(w, r, "/login", http.StatusSeeOther)
}

// ---------- fail-loudly scan banner (FR-12) ----------

// scanStatusView is the fail-loudly view of scan health. It is shared by the
// dashboard, the item detail page and the HTMX partial. The template never
// renders an empty day as "nothing due".
type scanStatusView struct {
	store.ScanStatus
	// Level is "none", "error", "ok" or "warn".
	Level   string
	Message string
	LastAt  string
}

// scanStatusFor builds the banner from a scan summary. The caller supplies the
// summary so the dashboard can show the global view and the per-child view.
func (s *Server) scanStatusFor(st store.ScanStatus, err error) scanStatusView {
	if err != nil {
		s.log.Error("scan summary", "err", err)
		return scanStatusView{Level: "error", Message: "Could not read the scan log: " + err.Error()}
	}
	v := scanStatusView{ScanStatus: st}
	if !st.EverRun {
		v.Level = "warn"
		v.Message = "NO SCAN HAS RUN YET — do not read this as “nothing due”."
		return v
	}
	if st.Last != nil && !st.Last.OK {
		v.Level = "error"
		v.Message = "SCAN FAILED — the last scan did not complete, so due work is UNKNOWN."
		if st.Last.Error != "" {
			v.Message += " " + st.Last.Error
		}
		v.LastAt = st.Last.StartedAt.Format("Mon 02 Jan 2006 15:04")
		return v
	}
	v.Level = "ok"
	v.Message = "Last scan completed."
	if st.Last != nil {
		v.LastAt = st.Last.StartedAt.Format("Mon 02 Jan 2006 15:04")
	}
	return v
}

func (s *Server) scanStatus(ctx context.Context) scanStatusView {
	st, err := s.store.ScanSummary(ctx)
	return s.scanStatusFor(st, err)
}

// scanOK reports whether the banner is healthy, so an empty section may say
// "nothing due" instead of "unknown".
func (v scanStatusView) OK() bool { return v.Level == "ok" }

// ---------- fail-loudly calendar banner (FR-8, FR-12) ----------

// calendarBannerView is the fail-loudly view of the Home Assistant calendar
// target. A missing target or a failed write is shown explicitly, so the
// family never assumes an event was written when it was not.
type calendarBannerView struct {
	// Level is "off", "warn", "error" or "ok".
	Level   string
	Message string
	Entity  string
	LastAt  string
	Written int
	Failed  int
}

// OK reports whether the calendar target is healthy.
func (v calendarBannerView) OK() bool { return v.Level == "ok" }

func (s *Server) calendarBanner(ctx context.Context) calendarBannerView {
	cc := s.cfg.Calendar
	if !cc.Enabled() {
		return calendarBannerView{
			Level:   "warn",
			Message: "CALENDAR NOT CONFIGURED — important school events are not being written. Set " + strings.Join(cc.Missing(), ", ") + ".",
		}
	}
	v := calendarBannerView{Entity: cc.EntityID}
	st, err := s.store.CalendarPushSummary(ctx)
	if err != nil {
		s.log.Error("calendar push summary", "err", err)
		v.Level = "error"
		v.Message = "Could not read the calendar log: " + err.Error()
		return v
	}
	v.Written = st.Total - st.Failed
	v.Failed = st.Failed
	if st.Last != nil {
		v.LastAt = st.Last.CreatedAt.In(s.cfg.Location).Format("Mon 02 Jan 2006 15:04")
	}
	if st.Last != nil && !st.Last.OK {
		v.Level = "error"
		v.Message = "CALENDAR WRITE FAILED — the last write to " + cc.EntityID + " did not complete."
		if st.Last.Error != "" {
			v.Message += " " + st.Last.Error
		}
		return v
	}
	if !st.EverRun {
		v.Level = "warn"
		v.Message = "No calendar write has run yet for " + cc.EntityID + "."
		return v
	}
	v.Level = "ok"
	v.Message = "Last calendar write completed."
	return v
}

// ---------- dashboard (FR-6, FR-7) ----------

type itemView struct {
	store.Item
	DueLabel    string
	StatusLabel string
	TypeLabel   string
	BodyLines   []string
}

type sectionView struct {
	Key   string
	Title string
	Tone  string
	Empty string
	Items []itemView
}

type childPanel struct {
	ID         int64
	Name       string
	Year       string
	Headline   string
	Overdue    int
	Scan       scanStatusView
	LaterCount int
	DoneCount  int
	Sections   []sectionView
}

type childTab struct {
	ID      int64
	Name    string
	Overdue int
	Active  bool
}

type summaryView struct {
	ID        int64
	Scope     string
	Recipient string
	Channel   string
	Tag       string
	Created   string
	Sent      string
	Draft     bool
	Failed    bool
	Error     string
	Text      string
}

// notifyBannerView is the fail-loudly view of the Apprise gateway (FR-12).
type notifyBannerView struct {
	// Level is "off", "warn", "error" or "ok".
	Level   string
	Message string
	Sent    int
	Failed  int
	LastAt  string
}

// OK reports whether the last delivery attempt succeeded.
func (v notifyBannerView) OK() bool { return v.Level == "ok" }

// channelOption is one tick box in the Send panel.
type channelOption struct {
	Name    string
	Label   string
	Checked bool
}

// recipientOption is one recipient tick box in the Send panel.
type recipientOption struct {
	Name    string
	Tag     string
	Checked bool
}

// sendScopeView is one brief the Send panel can build, preview and send:
// a child's own brief, or the combined brief to Jo and Sam.
type sendScopeView struct {
	Key        string
	Label      string
	Preview    string
	Warning    string
	Recipients []recipientOption
}

// sendPanelView is the Send panel (AGENTS.md §5 screen 4): choose recipients,
// preview the brief, send.
type sendPanelView struct {
	Enabled  bool
	Missing  []string
	Channels []channelOption
	Scopes   []sendScopeView
}

type dashboardData struct {
	Title      string
	Username   string
	CSRF       string
	Version    string
	AppEnv     string
	Scan       scanStatusView
	Calendar   calendarBannerView
	Notify     notifyBannerView
	Tabs       []childTab
	Child      childPanel
	HasChild   bool
	Summaries  []summaryView
	Send       sendPanelView
	ServerUp   string
	ErrMsg     string
	Flash      string
	FlashLevel string
}

var serverStarted = time.Now()

func (s *Server) handleDashboard(w http.ResponseWriter, r *http.Request) {
	ctx, cancel := context.WithTimeout(r.Context(), 5*time.Second)
	defer cancel()

	loc := s.cfg.Location
	data := dashboardData{
		Title:    "What is due",
		Username: s.cfg.AdminUsername,
		CSRF:     s.auth.EnsureCSRF(w, r),
		Version:  s.cfg.Version,
		AppEnv:   s.cfg.AppEnv,
		Scan:     s.scanStatus(ctx),
		Calendar: s.calendarBanner(ctx),
		Notify:   s.notifyBanner(ctx),
		ServerUp: time.Since(serverStarted).Round(time.Second).String(),
		ErrMsg:   strings.TrimSpace(r.URL.Query().Get("err")),
	}
	// A send reports back on the dashboard: what went out, or what failed.
	if msg := strings.TrimSpace(r.URL.Query().Get("msg")); msg != "" {
		data.Flash = msg
		data.FlashLevel = "ok"
	}
	if level := strings.TrimSpace(r.URL.Query().Get("level")); level == "error" {
		data.FlashLevel = "error"
		data.ErrMsg = ""
	}

	children, err := s.store.ListChildren(ctx)
	if err != nil {
		s.log.Error("list children", "err", err)
		data.ErrMsg = "Could not read the children: " + err.Error()
	}

	// Which tab? ?child=ID, else the first child.
	selected := int64(0)
	if v, err := strconv.ParseInt(r.URL.Query().Get("child"), 10, 64); err == nil {
		selected = v
	}
	found := false
	for _, c := range children {
		if selected == 0 || c.ID == selected {
			if !found {
				selected = c.ID
				found = true
			}
		}
	}
	if !found && len(children) > 0 {
		selected = children[0].ID
		found = true
	}

	overdueByChild := map[int64]int{}
	for _, c := range children {
		items, err := s.store.ItemsForChild(ctx, c.ID)
		if err != nil {
			s.log.Error("items for child", "child", c.Name, "err", err)
			continue
		}
		overdueByChild[c.ID] = len(dashboard.Classify(items, time.Now(), loc).Overdue)
	}

	for _, c := range children {
		tab := childTab{ID: c.ID, Name: c.Name, Overdue: overdueByChild[c.ID], Active: c.ID == selected}
		data.Tabs = append(data.Tabs, tab)
		if c.ID == selected {
			data.Child = s.buildChildPanel(ctx, c, loc)
			data.HasChild = true
		}
	}

	data.Send = s.sendPanel(ctx, children)

	notifications, err := s.store.RecentNotifications(ctx, 12)
	if err != nil {
		s.log.Error("list notifications", "err", err)
	}
	for _, n := range notifications {
		v := summaryView{
			ID:        n.ID,
			Scope:     n.Scope,
			Recipient: n.Recipient,
			Channel:   n.Channel,
			Tag:       n.Tag,
			Created:   n.CreatedAt.In(loc).Format("Mon 02 Jan 15:04"),
			Text:      n.Text,
			Draft:     n.Channel == "",
			Failed:    n.Channel != "" && !n.OK,
			Error:     n.Error,
		}
		switch {
		case n.Channel == "":
			v.Sent = "draft"
		case n.SentAt != nil:
			v.Sent = n.SentAt.In(loc).Format("Mon 02 Jan 15:04")
		default:
			v.Sent = "failed"
		}
		data.Summaries = append(data.Summaries, v)
	}

	s.render(w, r, "dashboard.html", data)
}

// notifyBanner is the fail-loudly banner for the Apprise gateway (FR-12).
func (s *Server) notifyBanner(ctx context.Context) notifyBannerView {
	ac := s.cfg.Apprise
	if !ac.Enabled() {
		return notifyBannerView{
			Level:   "warn",
			Message: "NOTIFICATIONS NOT CONFIGURED — the morning briefs cannot be sent. Set " + strings.Join(ac.Missing(), ", ") + ".",
		}
	}
	st, err := s.store.NotificationSummary(ctx)
	if err != nil {
		s.log.Error("notification summary", "err", err)
		return notifyBannerView{Level: "error", Message: "Could not read the delivery log: " + err.Error()}
	}
	v := notifyBannerView{Sent: st.Sent, Failed: st.Failed}
	if st.Last != nil {
		v.LastAt = st.Last.CreatedAt.In(s.cfg.Location).Format("Mon 02 Jan 2006 15:04")
	}
	if st.Failed > 0 && st.Last != nil && !st.Last.OK {
		v.Level = "error"
		v.Message = fmt.Sprintf("SEND FAILED — the last brief delivery did not complete (%s/%s). It was NOT delivered.",
			st.Last.Recipient, channelLabel(st.Last.Channel))
		if st.Last.Error != "" {
			v.Message += " " + st.Last.Error
		}
		return v
	}
	if !st.EverRun() || st.Sent == 0 {
		v.Level = "warn"
		v.Message = "No brief has been sent yet."
		return v
	}
	v.Level = "ok"
	v.Message = fmt.Sprintf("%d delivery attempt(s) delivered, %d failed.", st.Sent, st.Failed)
	return v
}

// sendPanel builds the Send panel (AGENTS.md §5 screen 4): one card per brief
// that can go out, each with a preview, the recipients and the channels.
func (s *Server) sendPanel(ctx context.Context, children []store.Child) sendPanelView {
	ac := s.cfg.Apprise
	p := sendPanelView{Enabled: ac.Enabled(), Missing: ac.Missing()}
	for _, ch := range ac.Channels {
		p.Channels = append(p.Channels, channelOption{Name: ch, Label: channelLabel(ch), Checked: true})
	}

	parents := ac.ParentRecipients()
	for _, c := range children {
		scope := sendScopeView{Key: strconv.FormatInt(c.ID, 10), Label: c.Name}
		text, scanOK, err := s.brief.ChildrenText(ctx, c)
		if err != nil {
			s.log.Error("brief preview", "child", c.Name, "err", err)
			scope.Warning = "Could not build the brief: " + err.Error()
		}
		scope.Preview = text
		if !scanOK {
			scope.Warning = "The last scan for " + c.Name + " did not complete. The brief says so and must not be read as “nothing due” (FR-12)."
		}
		if r, ok := ac.RecipientByName(c.Name); ok {
			scope.Recipients = append(scope.Recipients, recipientOption{Name: r.Name, Tag: ac.ChannelTag(r, config.ChannelEmail), Checked: true})
		}
		for _, r := range parents {
			scope.Recipients = append(scope.Recipients, recipientOption{Name: r.Name, Tag: ac.ChannelTag(r, config.ChannelEmail)})
		}
		p.Scopes = append(p.Scopes, scope)
	}

	combined := sendScopeView{Key: brief.ScopeCombined, Label: brief.CombinedNames(children) + " (combined)"}
	text, failed, err := s.brief.CombinedText(ctx, children)
	if err != nil {
		s.log.Error("combined brief preview", "err", err)
		combined.Warning = "Could not build the combined brief: " + err.Error()
	}
	combined.Preview = text
	if len(failed) > 0 {
		combined.Warning = "The last scan did not complete for " + strings.Join(failed, ", ") + ". The brief says so (FR-12)."
	}
	for _, r := range parents {
		combined.Recipients = append(combined.Recipients, recipientOption{Name: r.Name, Tag: ac.ChannelTag(r, config.ChannelEmail), Checked: true})
	}
	p.Scopes = append(p.Scopes, combined)
	return p
}

func channelLabel(ch string) string {
	switch ch {
	case config.ChannelEmail:
		return "Email"
	case config.ChannelWhatsApp:
		return "WhatsApp"
	case "":
		return "draft"
	default:
		return ch
	}
}

// buildChildPanel classifies one child's items and prepares the sections.
func (s *Server) buildChildPanel(ctx context.Context, c store.Child, loc *time.Location) childPanel {
	items, err := s.store.ItemsForChild(ctx, c.ID)
	if err != nil {
		s.log.Error("items for child", "child", c.Name, "err", err)
	}
	b := dashboard.Classify(items, time.Now(), loc)

	sc, scErr := s.store.ScanSummaryForChild(ctx, c.ID)
	scan := s.scanStatusFor(sc, scErr)

	p := childPanel{
		ID:         c.ID,
		Name:       c.Name,
		Year:       c.Year,
		Headline:   b.Headline(),
		Overdue:    len(b.Overdue),
		Scan:       scan,
		LaterCount: len(b.Later),
		DoneCount:  len(b.Done),
	}

	known := scan.OK()
	p.Sections = []sectionView{
		{Key: "overdue", Title: "Overdue", Tone: "danger", Items: itemViews(b.Overdue, loc),
			Empty: emptyText(known, "Nothing overdue.")},
		{Key: "today", Title: "Due today", Items: itemViews(b.DueToday, loc),
			Empty: emptyText(known, "Nothing due today.")},
		{Key: "week", Title: "Due this week", Items: itemViews(b.DueWeek, loc),
			Empty: emptyText(known, "Nothing else due this week.")},
	}
	if len(b.NoDue) > 0 {
		p.Sections = append(p.Sections, sectionView{Key: "nodue", Title: "No due date",
			Items: itemViews(b.NoDue, loc)})
	}
	p.Sections = append(p.Sections, sectionView{Key: "messages", Title: "Messages",
		Items: itemViews(b.Messages, loc), Empty: emptyText(known, "No messages.")})
	return p
}

// emptyText never turns a failed or missing scan into "nothing due" (FR-12).
func emptyText(scanKnown bool, ok string) string {
	if scanKnown {
		return ok
	}
	return "Unknown — the last scan did not complete."
}

func itemViews(items []store.Item, loc *time.Location) []itemView {
	out := make([]itemView, 0, len(items))
	for _, it := range items {
		v := itemView{Item: it, TypeLabel: typeLabel(it.Type)}
		if it.DueAt != nil {
			v.DueLabel = it.DueAt.In(loc).Format("Mon 02 Jan 15:04")
		}
		if st := dashboard.Status(it.Body); st != "" && st != "pending" {
			v.StatusLabel = strings.ToUpper(st[:1]) + st[1:]
		}
		if strings.TrimSpace(it.Body) != "" {
			v.BodyLines = strings.Split(strings.TrimSpace(it.Body), "\n")
		}
		out = append(out, v)
	}
	return out
}

func typeLabel(t string) string {
	switch t {
	case "task":
		return "Task"
	case "event":
		return "Event"
	case "message":
		return "Message"
	default:
		return t
	}
}

// ---------- item detail + delete (FR-10, §5 screen 3) ----------

type itemData struct {
	Title      string
	Username   string
	CSRF       string
	Version    string
	AppEnv     string
	Item       itemView
	Child      store.Child
	Scan       scanStatusView
	Calendar   calendarItemView
	Flash      string
	FlashLevel string
	ServerUp   string
}

// calendarItemView is the calendar state of one item on the item screen.
type calendarItemView struct {
	Configured bool
	Entity     string
	Eligible   bool
	InCalendar bool
	UID        string
	PushedAt   string
}

// itemCalendarView describes whether one item can go to the calendar and
// whether it is already there. An important, future Compass event is eligible.
func (s *Server) itemCalendarView(it store.CalendarItem, now time.Time) calendarItemView {
	v := calendarItemView{
		Configured: s.cfg.Calendar.Enabled(),
		Entity:     s.cfg.Calendar.EntityID,
		InCalendar: it.HAEventUID != "",
		UID:        it.HAEventUID,
	}
	v.Eligible = it.Type == "event" && it.Source == "compass" && it.Importance == "high" &&
		it.DueAt != nil && !it.DueAt.Before(calendar.StartOfDay(now))
	if it.HAPushedAt != nil {
		v.PushedAt = it.HAPushedAt.In(s.cfg.Location).Format("Mon 02 Jan 2006 15:04")
	}
	return v
}

func (s *Server) handleItemDetail(w http.ResponseWriter, r *http.Request) {
	id, ok := pathID(r, "id")
	if !ok {
		http.NotFound(w, r)
		return
	}
	s.renderItemDetail(w, r, id, "", "")
}

// renderItemDetail renders the item screen, optionally with a calendar flash.
func (s *Server) renderItemDetail(w http.ResponseWriter, r *http.Request, id int64, flash, flashLevel string) {
	ctx, cancel := context.WithTimeout(r.Context(), 5*time.Second)
	defer cancel()

	ci, err := s.store.CalendarItemByID(ctx, id)
	if err != nil {
		s.log.Error("item", "id", id, "err", err)
		http.Error(w, "could not read the item", http.StatusInternalServerError)
		return
	}
	if ci == nil {
		http.NotFound(w, r)
		return
	}
	child, err := s.store.ChildByID(ctx, ci.ChildID)
	if err != nil || child == nil {
		child = &store.Child{ID: ci.ChildID, Name: ci.Child}
	}

	s.render(w, r, "item.html", itemData{
		Title:      ci.Title,
		Username:   s.cfg.AdminUsername,
		CSRF:       s.auth.EnsureCSRF(w, r),
		Version:    s.cfg.Version,
		AppEnv:     s.cfg.AppEnv,
		Item:       itemViews([]store.Item{ci.Item}, s.cfg.Location)[0],
		Child:      *child,
		Scan:       s.scanStatus(ctx),
		Calendar:   s.itemCalendarView(*ci, time.Now()),
		Flash:      flash,
		FlashLevel: flashLevel,
		ServerUp:   time.Since(serverStarted).Round(time.Second).String(),
	})
}

// handleItemCalendarPush writes one item to Sam's Home Assistant calendar. The
// school stays read-only: the only write is to the calendar (AGENTS.md §10
// rule 1). A failure is shown on the page and recorded in calendar_pushes.
func (s *Server) handleItemCalendarPush(w http.ResponseWriter, r *http.Request) {
	ctx, cancel := context.WithTimeout(r.Context(), 60*time.Second)
	defer cancel()

	if err := r.ParseForm(); err != nil {
		http.Error(w, "bad request", http.StatusBadRequest)
		return
	}
	if !s.auth.CheckCSRF(r) {
		s.log.Warn("calendar push rejected: bad csrf token", "path", r.URL.Path)
		http.Error(w, "session expired", http.StatusForbidden)
		return
	}
	id, ok := pathID(r, "id")
	if !ok {
		http.NotFound(w, r)
		return
	}

	ci, err := s.store.CalendarItemByID(ctx, id)
	if err != nil {
		s.log.Error("item", "id", id, "err", err)
		http.Error(w, "could not read the item", http.StatusInternalServerError)
		return
	}
	if ci == nil {
		http.NotFound(w, r)
		return
	}

	if missing := s.cfg.Calendar.Missing(); len(missing) > 0 {
		s.renderItemDetail(w, r, id,
			"Calendar is not configured. Set "+strings.Join(missing, ", ")+".", "error")
		return
	}
	client, err := calendar.New(s.cfg.Calendar, s.log)
	if err != nil {
		s.log.Error("calendar client", "err", err)
		s.renderItemDetail(w, r, id, "Calendar is not usable: "+err.Error(), "error")
		return
	}

	res, err := calendar.Sync(ctx, s.store, client,
		calendar.Options{ItemID: &id, Now: time.Now().In(s.cfg.Location)}, s.log)
	if err != nil {
		s.log.Error("calendar push", "item", id, "err", err)
		s.renderItemDetail(w, r, id, "Calendar write failed: "+err.Error(), "error")
		return
	}
	switch {
	case res.Failed > 0:
		msg := "Calendar write failed."
		if len(res.Errors) > 0 {
			msg = "Calendar write failed: " + strings.Join(res.Errors, "; ")
		}
		s.log.Error("calendar push failed", "item", id, "child", ci.Child, "errors", res.Errors)
		s.renderItemDetail(w, r, id, msg, "error")
	case res.Created == 0 && res.Skipped > 0:
		s.renderItemDetail(w, r, id, "Already in the calendar ("+s.cfg.Calendar.EntityID+").", "ok")
	case res.Created == 0:
		s.renderItemDetail(w, r, id,
			"Nothing to write: only important, future school events go to the calendar.", "error")
	default:
		s.log.Info("calendar event written", "item", id, "child", ci.Child, "title", ci.Title, "entity", s.cfg.Calendar.EntityID)
		s.renderItemDetail(w, r, id, "Added to "+s.cfg.Calendar.EntityID+" on Sam's Home Assistant calendar.", "ok")
	}
}

func (s *Server) handleItemDelete(w http.ResponseWriter, r *http.Request) {
	ctx, cancel := context.WithTimeout(r.Context(), 5*time.Second)
	defer cancel()

	if err := r.ParseForm(); err != nil {
		http.Error(w, "bad request", http.StatusBadRequest)
		return
	}
	if !s.auth.CheckCSRF(r) {
		s.log.Warn("delete rejected: bad csrf token", "path", r.URL.Path)
		http.Error(w, "session expired", http.StatusForbidden)
		return
	}
	id, ok := pathID(r, "id")
	if !ok {
		http.NotFound(w, r)
		return
	}
	it, err := s.store.ItemByID(ctx, id)
	if err != nil {
		s.log.Error("item", "id", id, "err", err)
		http.Error(w, "could not read the item", http.StatusInternalServerError)
		return
	}
	if it == nil {
		http.NotFound(w, r)
		return
	}
	if _, err := s.store.DeleteItemByID(ctx, id); err != nil {
		s.log.Error("delete item", "id", id, "err", err)
		http.Error(w, "could not delete the item", http.StatusInternalServerError)
		return
	}
	s.log.Info("item deleted", "id", id, "child", it.Child, "title", it.Title)
	s.redirectAfterWrite(w, r, "/?child="+strconv.FormatInt(it.ChildID, 10))
}

func (s *Server) handleSummaryBuild(w http.ResponseWriter, r *http.Request) {
	ctx, cancel := context.WithTimeout(r.Context(), 5*time.Second)
	defer cancel()

	if err := r.ParseForm(); err != nil {
		http.Error(w, "bad request", http.StatusBadRequest)
		return
	}
	if !s.auth.CheckCSRF(r) {
		http.Error(w, "session expired", http.StatusForbidden)
		return
	}

	// The combined brief is built from both children (FR-14); a child brief is
	// built from that child's items only.
	if scope := strings.TrimSpace(r.PostFormValue("scope")); strings.EqualFold(scope, brief.ScopeCombined) {
		children, err := s.store.ListChildren(ctx)
		if err != nil {
			s.log.Error("list children", "err", err)
			http.Error(w, "could not read the children", http.StatusInternalServerError)
			return
		}
		text, _, err := s.brief.CombinedText(ctx, children)
		if err != nil {
			s.log.Error("combined brief", "err", err)
			http.Error(w, "could not build the combined brief", http.StatusInternalServerError)
			return
		}
		id, err := s.store.CreateDraft(ctx, brief.ScopeCombined, brief.CombinedNames(children), text)
		if err != nil {
			s.log.Error("create combined draft", "err", err)
			http.Error(w, "could not store the summary", http.StatusInternalServerError)
			return
		}
		s.log.Info("combined summary built", "id", id)
		s.redirectAfterWrite(w, r, "/?msg="+url.QueryEscape("Combined brief built as a draft."))
		return
	}

	childID, err := strconv.ParseInt(r.PostFormValue("child"), 10, 64)
	if err != nil {
		http.Error(w, "bad request", http.StatusBadRequest)
		return
	}
	child, err := s.store.ChildByID(ctx, childID)
	if err != nil || child == nil {
		http.NotFound(w, r)
		return
	}
	text, _, err := s.brief.ChildrenText(ctx, *child)
	if err != nil {
		s.log.Error("build brief", "child", child.Name, "err", err)
		http.Error(w, "could not read the items", http.StatusInternalServerError)
		return
	}
	id, err := s.store.CreateSummary(ctx, child.Name, text)
	if err != nil {
		s.log.Error("create summary", "child", child.Name, "err", err)
		http.Error(w, "could not store the summary", http.StatusInternalServerError)
		return
	}
	s.log.Info("summary built", "id", id, "recipient", child.Name)
	s.redirectAfterWrite(w, r, "/?child="+strconv.FormatInt(childID, 10))
}

// ---------- Send panel (FR-9, FR-10, §5 screen 4) ----------

// handleSendBrief builds the brief for the chosen scope and delivers it to the
// chosen recipients on the chosen channels. Every attempt is recorded, so a
// failure is visible on the page and in `notifications` (FR-12).
func (s *Server) handleSendBrief(w http.ResponseWriter, r *http.Request) {
	// Sending waits on SMTP and the WhatsApp gateway, so it is allowed longer
	// than a page render but is still bounded.
	ctx, cancel := context.WithTimeout(r.Context(), 90*time.Second)
	defer cancel()

	if err := r.ParseForm(); err != nil {
		http.Error(w, "bad request", http.StatusBadRequest)
		return
	}
	if !s.auth.CheckCSRF(r) {
		http.Error(w, "session expired", http.StatusForbidden)
		return
	}

	scope := strings.TrimSpace(r.PostFormValue("scope"))
	if scope == "" {
		http.Error(w, "choose a brief to send", http.StatusBadRequest)
		return
	}

	channels := r.PostForm["channel"]
	if len(channels) == 0 {
		channels = s.cfg.Apprise.Channels
	}

	text, childID, label, err := s.briefText(ctx, scope)
	if err != nil {
		s.redirectSendError(w, r, err.Error())
		return
	}
	recipients, err := s.recipientsForScope(ctx, label, childID, r.PostForm["recipient"])
	if err != nil {
		s.redirectSendError(w, r, err.Error())
		return
	}

	title := "School brief — " + label
	send, err := s.brief.Deliver(ctx, label, title, text, recipients, channels)
	if err != nil {
		s.redirectSendError(w, r, err.Error())
		return
	}

	s.log.Info("brief sent from the Send panel", "scope", label, "delivered", send.Delivered(), "failed", send.Failed())
	msg := describeSend(send)
	if send.Failed() > 0 || len(send.ScanFailed) > 0 {
		s.redirectSendError(w, r, msg)
		return
	}
	s.redirectAfterWrite(w, r, "/?msg="+url.QueryEscape(msg))
}

// handleSummarySend sends one stored brief (a draft) as it is. It is the Send
// action on a summary (FR-10).
func (s *Server) handleSummarySend(w http.ResponseWriter, r *http.Request) {
	ctx, cancel := context.WithTimeout(r.Context(), 90*time.Second)
	defer cancel()

	if err := r.ParseForm(); err != nil {
		http.Error(w, "bad request", http.StatusBadRequest)
		return
	}
	if !s.auth.CheckCSRF(r) {
		http.Error(w, "session expired", http.StatusForbidden)
		return
	}
	id, ok := pathID(r, "id")
	if !ok {
		http.NotFound(w, r)
		return
	}
	n, err := s.store.NotificationByID(ctx, id)
	if err != nil || n == nil {
		http.NotFound(w, r)
		return
	}

	scope := n.Scope
	if scope == "" {
		scope = n.Recipient
	}
	var childID int64
	if !strings.EqualFold(scope, brief.ScopeCombined) {
		if c, err := s.store.ChildByName(ctx, scope); err == nil && c != nil {
			childID = c.ID
		}
	}

	channels := r.PostForm["channel"]
	if len(channels) == 0 {
		channels = s.cfg.Apprise.Channels
	}
	recipients, err := s.recipientsForScope(ctx, scope, childID, r.PostForm["recipient"])
	if err != nil {
		s.redirectSendError(w, r, err.Error())
		return
	}

	send, err := s.brief.Deliver(ctx, scope, "School brief — "+scope, n.Text, recipients, channels)
	if err != nil {
		s.redirectSendError(w, r, err.Error())
		return
	}
	// The stored brief is stamped only when every channel delivered, so a row is
	// never marked sent after a failure (FR-12).
	tag, channel := "", ""
	if len(send.Deliveries) > 0 {
		tag, channel = send.Deliveries[0].Tag, send.Deliveries[0].Channel
	}
	if err := s.store.MarkSummarySent(ctx, n.ID, channel, tag, send.SentOK(), send.FirstError(), s.brief.Now()); err != nil {
		s.log.Error("mark summary sent", "id", n.ID, "err", err)
	}

	msg := describeSend(send)
	if !send.SentOK() {
		s.redirectSendError(w, r, msg)
		return
	}
	s.redirectAfterWrite(w, r, "/?msg="+url.QueryEscape(msg))
}

// briefText builds the brief text for a scope. The scope is either
// "combined" or a child id; the returned label is the stored scope name
// ("combined" or the child's name), so the delivery log never shows a bare id.
func (s *Server) briefText(ctx context.Context, scope string) (string, int64, string, error) {
	if strings.EqualFold(scope, brief.ScopeCombined) {
		children, err := s.store.ListChildren(ctx)
		if err != nil {
			return "", 0, "", err
		}
		text, _, err := s.brief.CombinedText(ctx, children)
		return text, 0, brief.ScopeCombined, err
	}
	id, err := strconv.ParseInt(scope, 10, 64)
	if err != nil {
		return "", 0, "", fmt.Errorf("unknown brief %q", scope)
	}
	child, err := s.store.ChildByID(ctx, id)
	if err != nil || child == nil {
		return "", 0, "", fmt.Errorf("unknown child %d", id)
	}
	text, _, err := s.brief.ChildrenText(ctx, *child)
	return text, child.ID, child.Name, err
}

// recipientsForScope resolves the tick boxes: the explicit list when given,
// otherwise the child, otherwise the parents (FR-14).
func (s *Server) recipientsForScope(ctx context.Context, scope string, childID int64, names []string) ([]config.Recipient, error) {
	if len(names) > 0 {
		return s.brief.RecipientsFor(names)
	}
	if strings.EqualFold(scope, brief.ScopeCombined) || childID == 0 {
		parents, _, err := s.brief.ParentRecipients()
		return parents, err
	}
	child, err := s.store.ChildByID(ctx, childID)
	if err != nil || child == nil {
		return nil, fmt.Errorf("unknown child %d", childID)
	}
	return s.brief.ChildRecipients(*child)
}

// describeSend is the one-line result shown on the dashboard.
func describeSend(send brief.Send) string {
	parts := make([]string, 0, len(send.Deliveries))
	for _, d := range send.Deliveries {
		if d.OK {
			parts = append(parts, fmt.Sprintf("%s %s: sent", d.Recipient, channelLabel(d.Channel)))
			continue
		}
		parts = append(parts, fmt.Sprintf("%s %s: FAILED (%s)", d.Recipient, channelLabel(d.Channel), apprise.Truncate(d.Error, 140)))
	}
	msg := fmt.Sprintf("%s: %d delivered, %d failed", scopeDisplay(send.Scope), send.Delivered(), send.Failed())
	if len(parts) > 0 {
		msg += " — " + strings.Join(parts, "; ")
	}
	if len(send.ScanFailed) > 0 {
		msg += fmt.Sprintf(" — scan failed for %s, so due work is UNKNOWN", strings.Join(send.ScanFailed, ", "))
	}
	return msg
}

func scopeDisplay(scope string) string {
	if strings.EqualFold(scope, brief.ScopeCombined) {
		return "combined"
	}
	return scope
}

// redirectSendError sends the send result back to the dashboard as an error, so
// a failed delivery is never a silent success.
func (s *Server) redirectSendError(w http.ResponseWriter, r *http.Request, msg string) {
	s.log.Error("brief send reported a failure", "err", msg)
	s.redirectAfterWrite(w, r, "/?level=error&err="+url.QueryEscape(msg))
}

// ---------- the 6:00am endpoint n8n calls (§11 Phase 7) ----------

// morningResponse is the machine-readable result of POST /notify/morning.
type morningResponse struct {
	OK          bool          `json:"ok"`
	At          string        `json:"at"`
	DryRun      bool          `json:"dry_run,omitempty"`
	Channels    []string      `json:"channels"`
	ScansFailed []string      `json:"scans_failed,omitempty"`
	Sends       []morningSend `json:"sends"`
	Error       string        `json:"error,omitempty"`
}

type morningSend struct {
	Scope      string            `json:"scope"`
	Title      string            `json:"title,omitempty"`
	Recipients []string          `json:"recipients"`
	Delivered  int               `json:"delivered"`
	Failed     int               `json:"failed"`
	Deliveries []morningDelivery `json:"deliveries"`
	// Text is the brief itself; it is filled in only by a dry run, so the n8n
	// wiring can be checked without messaging the family.
	Text string `json:"text,omitempty"`
}

type morningDelivery struct {
	Recipient string `json:"recipient"`
	Channel   string `json:"channel"`
	Tag       string `json:"tag"`
	OK        bool   `json:"ok"`
	Status    int    `json:"status"`
	Error     string `json:"error,omitempty"`
}

// handleMorningNotify builds and sends every morning brief. n8n calls it at
// 6:00am with the shared bearer token (SCHOOL_NOTIFY_TOKEN). It never needs the
// dashboard session, and it fails loudly: a delivery failure returns 207 with
// the failure in the body, an internal error returns 500.
func (s *Server) handleMorningNotify(w http.ResponseWriter, r *http.Request) {
	token := strings.TrimSpace(s.cfg.Apprise.NotifyToken)
	if token == "" {
		s.writeJSON(w, http.StatusServiceUnavailable, morningResponse{
			Error: "the morning endpoint is disabled: set SCHOOL_NOTIFY_TOKEN",
		})
		return
	}
	provided := strings.TrimSpace(strings.TrimPrefix(r.Header.Get("Authorization"), "Bearer "))
	if subtle.ConstantTimeCompare([]byte(provided), []byte(token)) != 1 {
		s.writeJSON(w, http.StatusUnauthorized, morningResponse{Error: "missing or bad bearer token"})
		return
	}

	dryRun := strings.TrimSpace(r.URL.Query().Get("dry_run")) != ""

	channels := s.cfg.Apprise.Channels
	if v := strings.TrimSpace(r.URL.Query().Get("channels")); v != "" {
		channels = nil
		for _, ch := range strings.Split(v, ",") {
			if ch = strings.TrimSpace(ch); ch != "" {
				channels = append(channels, ch)
			}
		}
	}

	// A brief of many recipients on two channels needs longer than one send.
	ctx, cancel := context.WithTimeout(r.Context(), 180*time.Second)
	defer cancel()

	if dryRun {
		plans, err := s.brief.Plan(ctx)
		if err != nil {
			s.log.Error("morning dry run", "err", err)
			s.writeJSON(w, http.StatusInternalServerError, morningResponse{Error: err.Error()})
			return
		}
		resp := morningResponse{OK: true, DryRun: true, Channels: channels,
			At: time.Now().In(s.cfg.Location).Format(time.RFC3339)}
		for _, p := range plans {
			resp.Sends = append(resp.Sends, morningSend{
				Scope: p.Scope, Title: p.Title, Recipients: p.Recipients, Text: p.Text,
			})
			resp.ScansFailed = append(resp.ScansFailed, p.ScanFailed...)
		}
		resp.ScansFailed = dedupe(resp.ScansFailed)
		if len(resp.ScansFailed) > 0 {
			resp.OK = false
		}
		s.log.Info("morning dry run", "sends", len(resp.Sends), "scans_failed", strings.Join(resp.ScansFailed, ","))
		s.writeJSON(w, http.StatusOK, resp)
		return
	}

	sends, err := s.brief.Morning(ctx, channels)
	if err != nil {
		s.log.Error("morning brief", "err", err)
		s.writeJSON(w, http.StatusInternalServerError, morningResponse{Error: err.Error()})
		return
	}

	resp := morningResponse{
		OK:       true,
		At:       time.Now().In(s.cfg.Location).Format(time.RFC3339),
		Channels: channels,
	}
	status := http.StatusOK
	for _, send := range sends {
		ms := morningSend{Scope: send.Scope, Recipients: send.Recipients, Delivered: send.Delivered(), Failed: send.Failed()}
		for _, d := range send.Deliveries {
			ms.Deliveries = append(ms.Deliveries, morningDelivery{
				Recipient: d.Recipient, Channel: d.Channel, Tag: d.Tag, OK: d.OK, Status: d.Status, Error: d.Error,
			})
		}
		resp.Sends = append(resp.Sends, ms)
		resp.ScansFailed = append(resp.ScansFailed, send.ScanFailed...)
		if send.Failed() > 0 {
			status = http.StatusMultiStatus
		}
	}
	if len(resp.ScansFailed) > 0 {
		// A child can appear in both its own brief and the combined brief, so
		// the summary list is deduplicated.
		resp.ScansFailed = dedupe(resp.ScansFailed)
		status = http.StatusMultiStatus
	}
	if status != http.StatusOK {
		resp.OK = false
		resp.Error = "one or more briefs did not deliver, or a scan did not complete"
	}
	s.log.Info("morning run", "status", status, "sends", len(resp.Sends), "scans_failed", strings.Join(resp.ScansFailed, ","))
	s.writeJSON(w, status, resp)
}

func (s *Server) writeJSON(w http.ResponseWriter, status int, body any) {
	w.Header().Set("Content-Type", "application/json; charset=utf-8")
	w.WriteHeader(status)
	if err := json.NewEncoder(w).Encode(body); err != nil {
		s.log.Error("write json", "err", err)
	}
}

func (s *Server) handleSummaryDelete(w http.ResponseWriter, r *http.Request) {
	ctx, cancel := context.WithTimeout(r.Context(), 5*time.Second)
	defer cancel()

	if err := r.ParseForm(); err != nil {
		http.Error(w, "bad request", http.StatusBadRequest)
		return
	}
	if !s.auth.CheckCSRF(r) {
		http.Error(w, "session expired", http.StatusForbidden)
		return
	}
	id, ok := pathID(r, "id")
	if !ok {
		http.NotFound(w, r)
		return
	}
	if _, err := s.store.DeleteNotification(ctx, id); err != nil {
		s.log.Error("delete summary", "id", id, "err", err)
		http.Error(w, "could not delete the summary", http.StatusInternalServerError)
		return
	}
	s.log.Info("summary deleted", "id", id)
	s.redirectAfterWrite(w, r, "/")
}

// redirectAfterWrite answers an HTMX request with 204 so the element can be
// removed, and a plain form post with a redirect to the dashboard.
func (s *Server) redirectAfterWrite(w http.ResponseWriter, r *http.Request, to string) {
	if r.Header.Get("HX-Request") != "" {
		w.WriteHeader(http.StatusNoContent)
		return
	}
	http.Redirect(w, r, to, http.StatusSeeOther)
}

func pathID(r *http.Request, name string) (int64, bool) {
	v, err := strconv.ParseInt(r.PathValue(name), 10, 64)
	if err != nil || v <= 0 {
		return 0, false
	}
	return v, true
}

// ---------- partials ----------

func (s *Server) handleScanStatusPartial(w http.ResponseWriter, r *http.Request) {
	ctx, cancel := context.WithTimeout(r.Context(), 2*time.Second)
	defer cancel()
	s.renderFragment(w, r, "scan-status.html", s.scanStatus(ctx))
}

func (s *Server) render(w http.ResponseWriter, _ *http.Request, name string, data any) {
	w.Header().Set("Content-Type", "text/html; charset=utf-8")
	if err := s.tmpl.ExecuteTemplate(w, name, data); err != nil {
		s.log.Error("render", "template", name, "err", err)
		http.Error(w, "template error", http.StatusInternalServerError)
	}
}

func (s *Server) renderFragment(w http.ResponseWriter, _ *http.Request, name string, data any) {
	w.Header().Set("Content-Type", "text/html; charset=utf-8")
	if err := s.tmpl.ExecuteTemplate(w, name, data); err != nil {
		s.log.Error("render fragment", "template", name, "err", err)
		http.Error(w, "template error", http.StatusInternalServerError)
	}
}

// dedupe keeps the first occurrence of each name, in order.
func dedupe(names []string) []string {
	seen := map[string]bool{}
	out := make([]string, 0, len(names))
	for _, n := range names {
		if seen[n] {
			continue
		}
		seen[n] = true
		out = append(out, n)
	}
	return out
}