package hub

import (
	"context"
	"errors"
)

// ErrNotFanout is a Fanout of a type that is targeted or server-raised.
var ErrNotFanout = errors.New("hub: not a fan-out type")

// Fanout is §4.3's chat and share: an admitted peer to every other
// admitted peer, the envelope rebuilt from the sender's participation so
// from and name can never be forged, nothing ringed or stored (§6).
// The sender's authority is §2.5's last row, exactly as Relay's: a
// member-kind participation re-derives standing first (§15.12), and one
// whose standing is gone is ended here with lost{standing} and answered
// ErrNotYours; a guest never consults standing at all (ruling 14).
func (h *Hub) Fanout(ctx context.Context, sqid, session string, from PeerID, m Message) error {
	if m.Type != TypeChat && m.Type != TypeShare {
		return ErrNotFanout
	}
	gone, err := h.memberStandingGone(ctx, sqid, session, from, true)
	if err != nil {
		return err
	}
	if gone {
		return ErrNotYours
	}
	h.mu.Lock()
	defer h.mu.Unlock()
	r, ok := h.rooms[sqid]
	if !ok {
		return ErrUnknownPeer
	}
	p, found := h.findLocked(sqid, session, from)
	if !found {
		return ErrUnknownPeer
	}
	if !p.Admitted {
		return ErrNotAdmitted
	}
	out := Message{Type: m.Type, From: p.Peer, Name: p.Name, Payload: m.Payload}
	h.broadcastLocked(r, out, func(q *Participation) bool { return q.Admitted && q.Peer != p.Peer })
	return nil
}