noema/internal/ui/ui.go

// Package ui serves the server-rendered administration interface. Every page
// is a Go handler plus an html/template; live updates reuse the same templates
// through SSE fragments (ADR-0007).
package ui

import (
	"bytes"
	"encoding/base64"
	"fmt"
	"html/template"
	"io/fs"
	"net/http"
	"net/url"
	"os"
	"strings"
	"time"

	"github.com/andydixon/noema/internal/api"
	"github.com/andydixon/noema/internal/app"
	"github.com/andydixon/noema/internal/auth"
	"github.com/andydixon/noema/internal/minds"
	"github.com/andydixon/noema/internal/version"
	"github.com/andydixon/noema/pkg/ids"
	"github.com/andydixon/noema/web"
)

// UI holds handlers and the parsed template set.
type UI struct {
	deps    app.Deps
	pages   map[string]*template.Template
	static  fs.FS
	statusF func(r *http.Request) any                                  // system status provider injected by api
	ctxF    func(r *http.Request, id ids.ID) (api.EventContext, error) // event forensic context, shared with api
}

// View is the data passed to every template.
type View struct {
	Title     string
	Path      string
	Principal *auth.Principal
	CSRF      string
	Flash     *Flash
	Version   string
	Data      any
}

// Flash is a one-shot message shown on the next page load.
type Flash struct{ Kind, Message string }

const flashCookie = "noema_flash"

// New parses templates. In development, when ./web exists on disk, templates
// and static files are read from disk so edits show without a rebuild.
func New(deps app.Deps, statusF func(r *http.Request) any, ctxF func(r *http.Request, id ids.ID) (api.EventContext, error)) (*UI, error) {
	tmplFS, staticFS := web.Templates(), web.Static()
	if !deps.Config.Production() {
		if st, err := os.Stat("web/templates"); err == nil && st.IsDir() {
			tmplFS, staticFS = os.DirFS("web/templates"), os.DirFS("web/static")
			deps.Log.Info("ui: serving templates and static files from ./web (development)")
		}
	}
	u := &UI{deps: deps, static: staticFS, statusF: statusF, ctxF: ctxF}
	if err := u.parse(tmplFS); err != nil {
		return nil, err
	}
	return u, nil
}

func (u *UI) parse(fsys fs.FS) error {
	funcs := template.FuncMap{
		"hasPrefix": strings.HasPrefix,
		"roles":     auth.AllRoles,
		"date":      func(t time.Time) string { return t.Local().Format("2006-01-02 15:04") },
		"ago":       ago,
		"duration":  func(s int64) string { return (time.Duration(s) * time.Second).Truncate(time.Second).String() },
		"bytes":     humanBytes,
		"pct":       func(f float64) string { return fmt.Sprintf("%.0f%%", f*100) },
		"conf":      func(f float64) string { return fmt.Sprintf("%.2f", f) },
		"inc":       func(i int) int { return i + 1 },
		"deref": func(f *float64) float64 {
			if f == nil {
				return 0
			}
			return *f
		},
		"title":     func(s string) string { s = strings.ReplaceAll(s, "_", " "); return strings.ToUpper(s[:1]) + s[1:] },
		"valueKeys": func() []string { return minds.ValueKeys },
		"traitKeys": func() []string { return minds.TraitKeys },
		"dict": func(kv ...any) map[string]any {
			m := map[string]any{}
			for i := 0; i+1 < len(kv); i += 2 {
				m[fmt.Sprint(kv[i])] = kv[i+1]
			}
			return m
		},
	}
	base, err := template.New("base").Funcs(funcs).ParseFS(fsys, "layout.html")
	if err != nil {
		return fmt.Errorf("ui: parse layout: %w", err)
	}
	if partials, _ := fs.Glob(fsys, "partials/*.html"); len(partials) > 0 {
		if _, err := base.ParseFS(fsys, partials...); err != nil {
			return fmt.Errorf("ui: parse partials: %w", err)
		}
	}
	pages, err := fs.Glob(fsys, "pages/*.html")
	if err != nil {
		return err
	}
	u.pages = map[string]*template.Template{}
	for _, p := range pages {
		t, err := base.Clone()
		if err != nil {
			return err
		}
		if _, err := t.ParseFS(fsys, p); err != nil {
			return fmt.Errorf("ui: parse %s: %w", p, err)
		}
		u.pages[strings.TrimPrefix(strings.TrimSuffix(p, ".html"), "pages/")] = t
	}
	return nil
}

// render executes a page template. Rendering into a buffer first means a
// template error yields a proper 500 instead of a half-written page.
func (u *UI) render(w http.ResponseWriter, r *http.Request, page, title string, data any) {
	t, ok := u.pages[page]
	if !ok {
		http.Error(w, "template not found: "+page, http.StatusInternalServerError)
		return
	}
	v := View{Title: title, Path: r.URL.Path, Version: version.Version, Data: data}
	if p, ok := auth.PrincipalFrom(r.Context()); ok {
		v.Principal = &p
		if tok, err := u.deps.Auth.CSRFToken(r.Context(), p.SessionID); err == nil {
			v.CSRF = tok
		}
	}
	if c, err := r.Cookie(flashCookie); err == nil && c.Value != "" {
		if raw, err := base64.RawURLEncoding.DecodeString(c.Value); err == nil {
			if kind, msg, ok := strings.Cut(string(raw), "|"); ok {
				v.Flash = &Flash{Kind: kind, Message: msg}
			}
		}
		http.SetCookie(w, &http.Cookie{Name: flashCookie, Path: "/", MaxAge: -1, HttpOnly: true, SameSite: http.SameSiteLaxMode})
	}
	var buf bytes.Buffer
	if err := t.ExecuteTemplate(&buf, "layout", v); err != nil {
		u.deps.Log.Error("template execution failed", "page", page, "err", err)
		http.Error(w, "template error", http.StatusInternalServerError)
		return
	}
	w.Header().Set("Content-Type", "text/html; charset=utf-8")
	w.Header().Set("Cache-Control", "no-store")
	buf.WriteTo(w) //nolint:errcheck
}

// flash stores a one-shot message and redirects.
func (u *UI) flash(w http.ResponseWriter, r *http.Request, kind, msg, to string) {
	val := base64.RawURLEncoding.EncodeToString([]byte(kind + "|" + msg))
	http.SetCookie(w, &http.Cookie{Name: flashCookie, Value: val, Path: "/", MaxAge: 60, HttpOnly: true, SameSite: http.SameSiteLaxMode, Secure: u.deps.Config.Production()})
	http.Redirect(w, r, to, http.StatusSeeOther)
}

func (u *UI) errorPage(w http.ResponseWriter, r *http.Request, status int, msg string) {
	w.WriteHeader(status)
	u.render(w, r, "error", http.StatusText(status), map[string]any{"Status": status, "Message": msg})
}

// uiAuthFail redirects anonymous users to login and shows 403 to others.
func (u *UI) uiAuthFail(w http.ResponseWriter, r *http.Request, authenticated bool) {
	if authenticated {
		u.errorPage(w, r, http.StatusForbidden, "Your role does not permit this page.")
		return
	}
	next := ""
	if r.Method == http.MethodGet && r.URL.Path != "/" {
		next = "?next=" + url.QueryEscape(r.URL.RequestURI())
	}
	http.Redirect(w, r, "/login"+next, http.StatusSeeOther)
}

func (u *UI) require(min auth.Role, h http.HandlerFunc) http.Handler {
	return auth.RequireRole(min, u.uiAuthFail)(h)
}

// Register mounts all UI routes.
func (u *UI) Register(m *http.ServeMux) {
	m.Handle("GET /static/", http.StripPrefix("/static/", cacheStatic(http.FileServerFS(u.static))))
	m.HandleFunc("GET /login", u.loginForm)
	m.HandleFunc("POST /login", u.loginSubmit)
	m.HandleFunc("POST /logout", u.logout)
	m.HandleFunc("GET /setup", u.setupForm)
	m.HandleFunc("POST /setup", u.setupSubmit)
	m.HandleFunc("GET /about", func(w http.ResponseWriter, r *http.Request) { u.render(w, r, "about", "Interpretation boundary", nil) })

	m.Handle("GET /{$}", u.require(auth.RoleObserver, u.dashboard))
	m.Handle("GET /system", u.require(auth.RoleObserver, u.system))
	m.Handle("GET /audit", u.require(auth.RoleOperator, u.audit))
	m.Handle("GET /account", u.require(auth.RoleObserver, u.account))
	m.Handle("POST /account/password", u.require(auth.RoleObserver, u.accountPassword))
	m.Handle("POST /account/sessions/{id}/revoke", u.require(auth.RoleObserver, u.accountSessionRevoke))
	m.Handle("POST /account/tokens", u.require(auth.RoleObserver, u.accountTokenCreate))
	m.Handle("POST /account/tokens/{id}/revoke", u.require(auth.RoleObserver, u.accountTokenRevoke))
	m.Handle("GET /admin/users", u.require(auth.RoleAdministrator, u.users))
	m.Handle("POST /admin/users", u.require(auth.RoleAdministrator, u.usersCreate))
	m.Handle("POST /admin/users/{id}", u.require(auth.RoleAdministrator, u.usersUpdate))

	u.mindRoutes(m)
	u.eventRoutes(m)

	for _, p := range []struct{ path, title, note string }{
		{"/approvals", "Approvals", "The approval centre arrives with the capability system."},
		{"/llm", "LLM", "Provider configuration arrives in phase 7."},
		{"/prompts", "Prompts", "The prompt manager arrives in phase 7."},
		{"/integrations", "Integrations", "Integrations arrive in phase 13."},
		{"/policies", "Policies", "The policy matrix arrives in phase 12."},
	} {
		m.Handle("GET "+p.path, u.require(auth.RoleObserver, func(w http.ResponseWriter, r *http.Request) { u.render(w, r, "placeholder", p.title, p.note) }))
	}
}

func cacheStatic(h http.Handler) http.Handler {
	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		w.Header().Set("Cache-Control", "public, max-age=300")
		h.ServeHTTP(w, r)
	})
}

func ago(t any) string {
	var tm time.Time
	switch v := t.(type) {
	case time.Time:
		tm = v
	case *time.Time:
		if v == nil {
			return "never"
		}
		tm = *v
	default:
		return ""
	}
	d := time.Since(tm)
	switch {
	case d < time.Minute:
		return "just now"
	case d < time.Hour:
		return fmt.Sprintf("%dm ago", int(d.Minutes()))
	case d < 48*time.Hour:
		return fmt.Sprintf("%dh ago", int(d.Hours()))
	default:
		return fmt.Sprintf("%dd ago", int(d.Hours()/24))
	}
}

func humanBytes(n uint64) string {
	const unit = 1024
	if n < unit {
		return fmt.Sprintf("%d B", n)
	}
	div, exp := uint64(unit), 0
	for m := n / unit; m >= unit; m /= unit {
		div *= unit
		exp++
	}
	return fmt.Sprintf("%.1f %ciB", float64(n)/float64(div), "KMGTPE"[exp])
}