package buscompose

import (
	"slices"
	"strings"

	"git.novox.be/novox/mesh-sdk/go/keys"
	"git.novox.be/novox/mesh-sdk/go/seatdef"
)

// **A held call's end is heard by its caller alone** (design 47 G §677; lead answer A-264): a holder says the end of a call of
// a marked verb on its seat's event `gated-ended`, subject `mesh.seat.<seat>.event.gated-ended.<caller>.<call>`, `<caller>` the
// account the bus proved escaped as a key's name is, kept last per subject for a day in the stream SEAT_<seat>_gated-ended
// (KeptEventsOf, from the definition seatdef.Resolve gives). The caller is granted hearing `gated-ended.<caller>.>` and no other
// caller's, from its invokes of the marked verb by name; it reads the stream through an ordered consumer filtered to its own
// subjects (mesh-sdk process awaitGated), made for the read. A process that answers a marked verb says the event to any caller.

// gatedEndedGrants are the grants of the principal user from the marked verbs (`seat:<seat>.<verb>`) it invokes by name and
// those it answers.
func gatedEndedGrants(user string, marked, invokes, answers []string) (pub, sub []string) {
	caller := keys.EscapeName(user)
	if user == "" {
		return nil, nil
	}
	var heard, said []string
	for _, v := range marked {
		seat, _, ok := strings.Cut(strings.TrimPrefix(v, "seat:"), ".")
		if !ok || !safeSubject.MatchString(seat) {
			continue
		}
		if slices.Contains(invokes, v) {
			heard = append(heard, seat)
		}
		if slices.Contains(answers, v) {
			said = append(said, seat)
		}
	}
	for _, seat := range unique(heard) {
		stream := seatdef.KeptStream(seat, seatdef.Message{Name: seatdef.GatedEndedEvent})
		own := GatedEndedSubject(seat, caller) + ".>"
		sub = append(sub, own)
		pub = append(pub, "$JS.API.STREAM.INFO."+stream, "$JS.API.CONSUMER.CREATE."+stream+".*."+own,
			"$JS.API.CONSUMER.MSG.NEXT."+stream+".*", "$JS.API.CONSUMER.INFO."+stream+".*", "$JS.API.CONSUMER.DELETE."+stream+".*")
	}
	for _, seat := range unique(said) {
		pub = append(pub, GatedEndedSubject(seat, "*")+".*")
	}
	return pub, sub
}

// GatedEndedSubject is the subject of the seat's gated-ended for one caller, its escaped name (keys.EscapeName) or `*`.
func GatedEndedSubject(seat, caller string) string {
	return seatdef.EventSubject(seat, seatdef.GatedEndedEvent) + "." + caller
}