package buscompose

import (
	"fmt"

	"git.novox.be/novox/mesh-sdk/go/delivery"
)

// The compositions' buckets (novox/hq ADR 0539 clauses 2 and 4): one per node, `composed-<node>`, holding the
// compositions the ended controller made for that node, which only that node's node-engine reads. Nothing writes them
// since the controller ended (ADR 0590); a node composes its own modules (ADR 0547 §2).

// ComposedReads is what a node's node-engine publishes to follow its wants and compositions (ADR 0539 clauses 1, 2 and
// 9): every key of its own composition bucket, and its own wants (`want.<node>.<module>` and `want.<node>.node`) in the
// assigner's bucket; nothing of another node's, nor the bucket of digests.
func ComposedReads(node string) ([]string, error) {
	bucket, err := delivery.ComposedBucketFor(node)
	if err != nil {
		return nil, err
	}
	if !safeSubject.MatchString(node) {
		return nil, fmt.Errorf("%q cannot be part of a subject: a permission is a subject pattern, and this would widen it", node)
	}
	return append(readGrants(bucket, ""), readGrants(delivery.AssignerWantsBucket, "want."+node+".>")...), nil
}

// VerbsTheNodeAgentAsks are the seat verbs a node's node-engine calls of its own machine while it applies a want (ADR
// 0539 clause 16, ADR 0429 §14): its backup holder backs a data module up before it moves, and says when it was. Asked
// of its own machine only, `mesh.seat.<seat>.tool.<verb>.<node>`.
var VerbsTheNodeAgentAsks = []SeatVerb{{Seat: "node-backup", Verb: "now"}, {Seat: "node-backup", Verb: "backed-up"}}

// NodeAgentAsks are the subjects of VerbsTheNodeAgentAsks for one node.
func NodeAgentAsks(node string) ([]string, error) {
	if !safeSubject.MatchString(node) {
		return nil, fmt.Errorf("%q cannot be part of a subject: a permission is a subject pattern, and this would widen it", node)
	}
	var out []string
	for _, v := range VerbsTheNodeAgentAsks {
		out = append(out, "mesh.seat."+v.Seat+".tool."+v.Verb+"."+node)
	}
	return out, nil
}

// NodeAgentHears are the events a node's node-engine subscribes while it applies a want: the backup holder's word that a
// backup is taken (`backed-up`), from whichever module holds node-backup on its machine (restic today).
var NodeAgentHears = []string{"mesh.mod." + BackupHolderModule + ".event.backed-up"}

// BackupHolderModule is the module that holds node-backup on every node, restic: the one whose word a node-engine hears.
// A second holder of the seat is a change of this grant.
const BackupHolderModule = "restic"

// DeclarationsStream is the stream of each node's last declaration, `mesh.node.<node>.declare` (issue 107). Release 6
// sends none (ADR 0539 clauses 5 and 11): the stream is kept, with each node's consumer, only so a node away during the
// switch finds its last declaration and with it the new node-engine; the controller deletes it once every node's have
// names the new node-engine, and from then on neither asserts it nor any node's consumer on it; nor makes it again once
// it is gone from the bus for any reason, since a stream made anew would hold no node's last declaration (issue 1945).
const DeclarationsStream = "NODES"

// RaiseAfterDeclarations is Raise once the declarations' stream is retired: the mesh's streams and consumers but the
// declarations' stream, and no node's consumer of a declaration.
func RaiseAfterDeclarations(r Raiser) error {
	for _, s := range MeshStreams() {
		if s.Name == DeclarationsStream {
			continue
		}
		if err := r.EnsureStream(s); err != nil {
			return fmt.Errorf("asserting stream %s: %w", s.Name, err)
		}
	}
	return AssertMeshConsumers(r)
}