package link

import (
	"errors"
	"fmt"

	"github.com/nats-io/nats.go"
)

// FindingsBucket is the node-engine's state `findings`: the findings this engine writes in its own bucket, one key each,
// which the condition keeper raises as conditions and clears when the key goes (novox/hq ADR 0564 §2, ADR 0636 §1).
const FindingsBucket = "mesh-host_findings"

func (l *natsLink) findingsKV() (nats.KeyValue, error) {
	kv, err := l.js.KeyValue(FindingsBucket)
	if err != nil {
		return nil, fmt.Errorf("the node-engine's state %s cannot be bound (it is created from the node-engine's manifest; "+
			"written again once it is): %w", FindingsBucket, err)
	}
	return kv, nil
}

func (q *Session) findings() (nats.KeyValue, error) {
	q.init()
	q.mu.Lock()
	bus := q.bus
	q.mu.Unlock()
	l, ok := bus.(interface{ findingsKV() (nats.KeyValue, error) })
	if bus == nil || !ok {
		return nil, ErrNoLink
	}
	return l.findingsKV()
}

// PutFinding writes one finding of this engine over the link open now.
func (q *Session) PutFinding(key string, value []byte) error {
	kv, err := q.findings()
	if err != nil {
		return err
	}
	_, err = kv.Put(key, value)
	return err
}

// DeleteFinding clears one finding of this engine over the link open now; a finding already gone is cleared.
func (q *Session) DeleteFinding(key string) error {
	kv, err := q.findings()
	if err != nil {
		return err
	}
	if err = kv.Delete(key); err != nil && !errors.Is(err, nats.ErrKeyNotFound) {
		return err
	}
	return nil
}

func (o OverNATS) findingsKV() (nats.KeyValue, error) {
	kv, err := o.JS.KeyValue(FindingsBucket)
	if err != nil {
		return nil, fmt.Errorf("the node-engine's state %s cannot be bound: %w", FindingsBucket, err)
	}
	return kv, nil
}