package web

import (
	"crypto/hmac"
	"crypto/rand"
	"encoding/base64"
	"encoding/hex"
	"encoding/json"
	"errors"
	"net/http"
	"net/url"
	"strconv"
	"strings"
	"sync"
	"time"

	"gitea.dooplex.hu/admin/felhom-controller/internal/family"
)

// ── The family gate's answerer (v0.287.0, `09` §3 decisions 63 and 64; R-780) ─────────────────────────────
//
// traefik asks GET /__felhom_gate/family (forwardAuth) for every request to a family-gated app (except the anchored
// paths the template leaves to the app's own login — internal/stacks/family_gate.go writes that file). The answer:
//
//   - a valid FAMILY APP COOKIE (`felhom_famgate`, host-only on the app host) → 200;
//   - /__felhom_gate/fcb?t=<token> → the token (60 s, one use, bound to the host and to a family session) becomes the
//     app cookie, and the browser goes back where it was going;
//   - a browser GET without one → 302 to https://felhom.<domain>/__family/start?rd=<where it was going>;
//   - anything else → 401 JSON.
//
// On the DASHBOARD host, outside the dashboard's own auth (CatchAllMiddleware answers them first):
//
//   - /__family/start — with a valid FAMILY SESSION (`felhom_family`, Path=/__family, so the browser never even sends
//     it to a dashboard page) or the household's dashboard session: a token and a 302 to the app; without: the family
//     sign-in page;
//   - /__family/login — a member's OWN name and password; counted per VISITOR (clientIP, R-753) and per NAME, short
//     windows, never "everyone";
//   - /__family/logout — ends the family session, and with it every app cookie minted from it (the store is asked on
//     every request).
//
// THE RULE: a family cookie never opens the dashboard. RequireAuth reads only `felhom_session`; nothing here ever sets
// it. An app cookie names a store session, so a removed member, a reset password or a logout ends access at the next
// request on every app. Pinned by internal/web/family_gate_test.go.

const (
	familySessionCookie = "felhom_family"
	familyAppCookie     = "felhom_famgate"
	familyAuthPath      = "/__felhom_gate/family"
	familyCallbackURI   = "/__felhom_gate/fcb"
	familyStartPath     = "/__family/start"
	familyLoginPath     = "/__family/login"
	familyLogoutPath    = "/__family/logout"
	familyCookiePath    = "/__family"
	familyFormLife      = time.Hour

	familyVisitorMax    = 5
	familyVisitorWindow = time.Minute
	familyNameMax       = 10
	familyNameWindow    = 10 * time.Minute
)

type familyState struct {
	once  sync.Once
	store *family.Store

	mu      sync.Mutex
	visitor map[string][]time.Time
	name    map[string][]time.Time
}

// familyStore opens the family list once. An unreadable list is logged and answers "nobody" (fail closed — the gate
// stays shut; the household still passes with its dashboard session).
func (s *Server) familyStore() *family.Store {
	s.fam.once.Do(func() {
		s.fam.visitor = map[string][]time.Time{}
		s.fam.name = map[string][]time.Time{}
		if s.familyStoreOverride != nil {
			s.fam.store = s.familyStoreOverride
			return
		}
		if s.cfg == nil || s.cfg.Paths.DataDir == "" {
			return
		}
		st, err := family.Open(s.cfg.Paths.DataDir)
		if err != nil {
			s.logger.Printf("[ERROR] [web] family gate: the family list could not be read (%v) — only the household passes until it is fixed", err)
			return
		}
		s.fam.store = st
	})
	return s.fam.store
}

// familyLocked reports whether this visitor or this name is out of tries. Windows slide; a success clears both.
func (s *Server) familyLocked(visitor, name string) bool {
	s.familyStore()
	now := s.gateNow()
	s.fam.mu.Lock()
	defer s.fam.mu.Unlock()
	prune := func(m map[string][]time.Time, k string, win time.Duration) int {
		var keep []time.Time
		for _, t := range m[k] {
			if now.Sub(t) < win {
				keep = append(keep, t)
			}
		}
		if len(keep) == 0 {
			delete(m, k)
		} else {
			m[k] = keep
		}
		return len(keep)
	}
	v := prune(s.fam.visitor, visitor, familyVisitorWindow)
	n := 0
	if name != "" {
		n = prune(s.fam.name, name, familyNameWindow)
	}
	return v >= familyVisitorMax || n >= familyNameMax
}

func (s *Server) familyFailed(visitor, name string) {
	now := s.gateNow()
	s.fam.mu.Lock()
	defer s.fam.mu.Unlock()
	s.fam.visitor[visitor] = append(s.fam.visitor[visitor], now)
	if name != "" {
		s.fam.name[name] = append(s.fam.name[name], now)
	}
}

func (s *Server) familyCleared(visitor, name string) {
	s.fam.mu.Lock()
	defer s.fam.mu.Unlock()
	delete(s.fam.visitor, visitor)
	delete(s.fam.name, name)
}

// familyRDHost: the host of a return address that may be used — https, on this household's domain, a family-gated app.
func (s *Server) familyRDHost(rd string) (string, bool) {
	u, err := url.Parse(rd)
	if err != nil || u.Scheme != "https" || u.User != nil || u.Host == "" || s.stackMgr == nil || s.cfg == nil {
		return "", false
	}
	host := strings.ToLower(u.Hostname())
	if u.Port() != "" || !strings.HasSuffix(host, "."+strings.ToLower(s.cfg.Customer.Domain)) {
		return "", false
	}
	if _, found := s.stackMgr.FamilyGateHost(host); !found {
		return "", false
	}
	return host, true
}

type familyToken struct {
	Host  string `json:"h"`
	Sid   string `json:"s"`
	Exp   int64  `json:"e"`
	Nonce string `json:"n"`
	RD    string `json:"r"`
	MAC   string `json:"m"`
}

func (s *Server) mintFamilyToken(host, sid, rd string) string {
	nb := make([]byte, 12)
	_, _ = rand.Read(nb)
	t := familyToken{Host: host, Sid: sid, Exp: s.gateNow().Add(gateTokenLife).Unix(), Nonce: hex.EncodeToString(nb), RD: rd}
	t.MAC = s.gateMAC("ftoken", t.Host, t.Sid, strconv.FormatInt(t.Exp, 10), t.Nonce, t.RD)
	b, _ := json.Marshal(t)
	return base64.RawURLEncoding.EncodeToString(b)
}

// takeFamilyToken checks a token for host, uses it up, and returns the session and where the browser was going.
func (s *Server) takeFamilyToken(raw, host string) (sid, rd string, err error) {
	b, err := base64.RawURLEncoding.DecodeString(raw)
	if err != nil {
		return "", "", errors.New("malformed")
	}
	var t familyToken
	if json.Unmarshal(b, &t) != nil {
		return "", "", errors.New("malformed")
	}
	if !hmac.Equal([]byte(t.MAC), []byte(s.gateMAC("ftoken", t.Host, t.Sid, strconv.FormatInt(t.Exp, 10), t.Nonce, t.RD))) {
		return "", "", errors.New("bad signature")
	}
	if t.Host != host {
		return "", "", errors.New("for another app")
	}
	now := s.gateNow()
	if now.Unix() > t.Exp {
		return "", "", errors.New("expired")
	}
	s.gateKey()
	s.gate.mu.Lock()
	defer s.gate.mu.Unlock()
	for n, until := range s.gate.used {
		if now.After(until) {
			delete(s.gate.used, n)
		}
	}
	if _, seen := s.gate.used["f:"+t.Nonce]; seen {
		return "", "", errors.New("already used")
	}
	s.gate.used["f:"+t.Nonce] = time.Unix(t.Exp, 0).Add(time.Second)
	return t.Sid, t.RD, nil
}

// familyAppCookieSession: "<sid>.<unix expiry>.<mac over host+sid+expiry>" → the session, if the cookie is genuine for
// this host, unexpired, and the store still holds the session (a removed member / reset / logout fails here).
func (s *Server) familyAppCookieSession(r *http.Request, host string) (family.Session, bool) {
	c, err := r.Cookie(familyAppCookie)
	if err != nil {
		return family.Session{}, false
	}
	parts := strings.Split(c.Value, ".")
	if len(parts) != 3 {
		return family.Session{}, false
	}
	n, err := strconv.ParseInt(parts[1], 10, 64)
	if err != nil || s.gateNow().Unix() > n {
		return family.Session{}, false
	}
	if !hmac.Equal([]byte(parts[2]), []byte(s.gateMAC("famcookie", host, parts[0], parts[1]))) {
		return family.Session{}, false
	}
	return s.familyStore().Valid(parts[0])
}

func familyRefuse(w http.ResponseWriter, code int) {
	w.Header().Set("Content-Type", "application/json")
	w.Header().Set("Cache-Control", "no-store")
	w.WriteHeader(code)
	_, _ = w.Write([]byte(`{"error":"sign in with your family login"}`))
}

// ServeFamilyGateAuth is traefik's forwardAuth answer for a family-gated app. Like the setup gate it trusts only the
// X-Forwarded-Host/-Uri/-Method traefik writes from the request it forwards (forwardAuth's own, never the client's).
func (s *Server) ServeFamilyGateAuth(w http.ResponseWriter, r *http.Request) {
	host := strings.ToLower(r.Header.Get("X-Forwarded-Host"))
	if i := strings.LastIndex(host, ":"); i != -1 {
		host = host[:i]
	}
	uri := r.Header.Get("X-Forwarded-Uri")
	if uri == "" {
		uri = "/"
	}
	method := r.Header.Get("X-Forwarded-Method")
	if s.stackMgr == nil {
		familyRefuse(w, http.StatusForbidden)
		return
	}
	app, found := s.stackMgr.FamilyGateHost(host)
	if !found {
		s.logger.Printf("[WARN] [web] family gate: asked about %q, which no family app owns — refused", host)
		familyRefuse(w, http.StatusForbidden)
		return
	}
	if u, err := url.Parse(uri); err == nil && u.Path == familyCallbackURI {
		sid, rd, err := s.takeFamilyToken(u.Query().Get("t"), host)
		if err == nil {
			if _, ok := s.familyStore().Valid(sid); !ok {
				err = errors.New("the session ended")
			}
		}
		if err != nil {
			s.logger.Printf("[WARN] [web] family gate %s: a sign-in token was refused (%v) — visitor %s", app, err, clientIP(r))
			familyRefuse(w, http.StatusForbidden)
			return
		}
		exp := strconv.FormatInt(s.gateNow().Add(family.SessionLife).Unix(), 10)
		http.SetCookie(w, &http.Cookie{
			Name: familyAppCookie, Value: sid + "." + exp + "." + s.gateMAC("famcookie", host, sid, exp), Path: "/",
			MaxAge: int(family.SessionLife.Seconds()), HttpOnly: true, Secure: true, SameSite: http.SameSiteLaxMode,
		})
		s.logger.Printf("[INFO] [web] family gate %s: a signed-in browser passed — visitor %s", app, clientIP(r))
		w.Header().Set("Cache-Control", "no-store")
		http.Redirect(w, r, rd, http.StatusFound)
		return
	}
	if _, ok := s.familyAppCookieSession(r, host); ok {
		w.WriteHeader(http.StatusOK)
		return
	}
	if (method == "" || method == http.MethodGet) && strings.Contains(r.Header.Get("Accept"), "text/html") {
		w.Header().Set("Cache-Control", "no-store")
		http.Redirect(w, r, "https://felhom."+s.cfg.Customer.Domain+familyStartPath+"?"+url.Values{"rd": {"https://" + host + uri}}.Encode(), http.StatusFound)
		return
	}
	if s.isDebug() {
		s.logger.Printf("[DEBUG] [web] family gate %s: %s %s without a pass — 401 (visitor %s)", app, method, uri, clientIP(r))
	}
	familyRefuse(w, http.StatusUnauthorized)
}

// familySessionFromCookie: the family session this browser holds on the dashboard host.
func (s *Server) familySessionFromCookie(r *http.Request) (family.Session, bool) {
	c, err := r.Cookie(familySessionCookie)
	if err != nil {
		return family.Session{}, false
	}
	return s.familyStore().Valid(c.Value)
}

// ServeFamilyStart is /__family/start on the dashboard host.
func (s *Server) ServeFamilyStart(w http.ResponseWriter, r *http.Request) {
	rd := r.URL.Query().Get("rd")
	host, ok := s.familyRDHost(rd)
	if !ok {
		s.renderFamilyPage(w, r, "", "", http.StatusOK)
		return
	}
	w.Header().Set("Cache-Control", "no-store")
	se, ok := s.familySessionFromCookie(r)
	if !ok && s.hasSession(r) {
		// The household's own dashboard session vouches (decision 46's rule) — a household session in the family store,
		// never the dashboard session itself.
		if st := s.familyStore(); st != nil {
			if sid, err := st.NewSession(""); err == nil {
				se, ok = family.Session{ID: sid}, true
			}
		}
	}
	if ok {
		http.Redirect(w, r, "https://"+host+familyCallbackURI+"?"+url.Values{"t": {s.mintFamilyToken(host, se.ID, rd)}}.Encode(), http.StatusFound)
		return
	}
	s.renderFamilyPage(w, r, rd, "", http.StatusOK)
}

// familyFormToken is the sign-in form's own CSRF (the visitor has no session): an HMAC over its expiry.
func (s *Server) familyFormToken() string {
	exp := strconv.FormatInt(s.gateNow().Add(familyFormLife).Unix(), 10)
	return exp + "." + s.gateMAC("famform", exp)
}

func (s *Server) familyFormTokenValid(v string) bool {
	exp, mac, ok := strings.Cut(v, ".")
	n, err := strconv.ParseInt(exp, 10, 64)
	if !ok || err != nil || s.gateNow().Unix() > n {
		return false
	}
	return hmac.Equal([]byte(mac), []byte(s.gateMAC("famform", exp)))
}

// ServeFamilyLogin is /__family/login: GET = the page, POST = a member's own name and password.
func (s *Server) ServeFamilyLogin(w http.ResponseWriter, r *http.Request) {
	if r.Method != http.MethodPost {
		s.renderFamilyPage(w, r, r.URL.Query().Get("rd"), "", http.StatusOK)
		return
	}
	_ = r.ParseForm()
	rd := r.FormValue("rd")
	if !s.familyFormTokenValid(r.FormValue("_ft")) {
		s.renderFamilyPage(w, r, rd, s.msg(r, "family_gate.msg.form_expired"), http.StatusForbidden)
		return
	}
	name := strings.ToLower(strings.TrimSpace(r.FormValue("name")))
	visitor := rateKey(r)
	if s.familyLocked(visitor, name) {
		s.logger.Printf("[WARN] [web] family sign-in: too many wrong tries — visitor %s, name %q", visitor, name)
		s.renderFamilyPage(w, r, rd, s.msg(r, "family_gate.msg.locked"), http.StatusTooManyRequests)
		return
	}
	st := s.familyStore()
	if st == nil || !st.Verify(name, r.FormValue("password")) {
		s.familyFailed(visitor, name)
		s.logger.Printf("[WARN] [web] family sign-in failed — visitor %s", visitor)
		s.renderFamilyPage(w, r, rd, s.msg(r, "family_gate.msg.wrong"), http.StatusUnauthorized)
		return
	}
	sid, err := st.NewSession(name)
	if err != nil {
		s.logger.Printf("[ERROR] [web] family sign-in: the session could not be saved: %v", err)
		s.renderFamilyPage(w, r, rd, s.msg(r, "family_gate.msg.wrong"), http.StatusInternalServerError)
		return
	}
	s.familyCleared(visitor, name)
	http.SetCookie(w, &http.Cookie{Name: familySessionCookie, Value: sid, Path: familyCookiePath,
		MaxAge: int(family.SessionLife.Seconds()), HttpOnly: true, Secure: true, SameSite: http.SameSiteLaxMode})
	s.logger.Printf("[INFO] [web] family sign-in: %s — visitor %s", name, visitor)
	if _, ok := s.familyRDHost(rd); ok {
		http.Redirect(w, r, familyStartPath+"?"+url.Values{"rd": {rd}}.Encode(), http.StatusFound)
		return
	}
	s.renderFamilyPage(w, r, "", s.msg(r, "family_gate.msg.signed_in"), http.StatusOK)
}

// ServeFamilyLogout is /__family/logout: the family session ends, and every app cookie minted from it with it.
func (s *Server) ServeFamilyLogout(w http.ResponseWriter, r *http.Request) {
	if c, err := r.Cookie(familySessionCookie); err == nil {
		if err := s.familyStore().EndSession(c.Value); err != nil {
			s.logger.Printf("[ERROR] [web] family sign-out: %v", err)
		}
	}
	http.SetCookie(w, &http.Cookie{Name: familySessionCookie, Value: "", Path: familyCookiePath, MaxAge: -1, HttpOnly: true, Secure: true})
	s.renderFamilyPage(w, r, "", s.msg(r, "family_gate.msg.signed_out"), http.StatusOK)
}

func (s *Server) renderFamilyPage(w http.ResponseWriter, r *http.Request, rd, notice string, code int) {
	data := map[string]interface{}{"RD": rd, "Notice": notice, "FormToken": s.familyFormToken(), "Version": s.version}
	if host, ok := s.familyRDHost(rd); ok {
		data["Host"] = host
		if app, found := s.stackMgr.FamilyGateHost(host); found {
			if st, ok := s.stackMgr.GetStack(app); ok {
				data["AppName"] = st.Meta.DisplayName
			}
		}
	}
	if _, ok := s.familySessionFromCookie(r); ok {
		data["SignedIn"] = true
	}
	w.Header().Set("Content-Type", "text/html; charset=utf-8")
	w.Header().Set("Cache-Control", "no-store")
	w.WriteHeader(code)
	if err := s.executeTemplateLang(w, r, "familygate", data); err != nil {
		s.logger.Printf("[ERROR] [web] family page: %v", err)
	}
}

// ── the dashboard's „Család" card (authenticated, CSRF-protected) ───────────────────────────────────────────

func (s *Server) familyMembersHandler(w http.ResponseWriter, r *http.Request) {
	st := s.familyStore()
	if st == nil {
		escrowJSON(w, http.StatusServiceUnavailable, nil, s.msg(r, "family_gate.msg.store_unreadable"))
		return
	}
	escrowJSON(w, http.StatusOK, map[string]any{"members": st.Names()}, "")
}

// familyMemberActionHandler: POST /family/members/{add,reset,remove} with `name`. add/reset answer the new password
// ONCE (never logged, never in a page render).
func (s *Server) familyMemberActionHandler(w http.ResponseWriter, r *http.Request, action string) {
	st := s.familyStore()
	if st == nil {
		escrowJSON(w, http.StatusServiceUnavailable, nil, s.msg(r, "family_gate.msg.store_unreadable"))
		return
	}
	_ = r.ParseForm()
	name := strings.ToLower(strings.TrimSpace(r.FormValue("name")))
	w.Header().Set("Cache-Control", "no-store")
	var pw string
	var err error
	switch action {
	case "add":
		pw, err = st.Add(name)
	case "reset":
		pw, err = st.Reset(name)
	case "remove":
		err = st.Remove(name)
	default:
		escrowJSON(w, http.StatusNotFound, nil, "")
		return
	}
	switch {
	case errors.Is(err, family.ErrBadName):
		escrowJSON(w, http.StatusBadRequest, nil, s.msg(r, "family_gate.msg.bad_name"))
		return
	case errors.Is(err, family.ErrExists):
		escrowJSON(w, http.StatusConflict, nil, s.msg(r, "family_gate.msg.exists"))
		return
	case errors.Is(err, family.ErrNoMember):
		escrowJSON(w, http.StatusNotFound, nil, s.msg(r, "family_gate.msg.no_member"))
		return
	case err != nil:
		s.logger.Printf("[ERROR] [web] family %s %q: %v", action, name, err)
		escrowJSON(w, http.StatusInternalServerError, nil, s.msg(r, "family_gate.msg.store_unreadable"))
		return
	}
	s.logger.Printf("[INFO] [web] family: the household's %s of %q from %s (password never logged)", action, name, clientIP(r))
	out := map[string]any{"name": name, "members": st.Names()}
	if pw != "" {
		out["password"] = pw
	}
	escrowJSON(w, http.StatusOK, out, "")
}