package process

import (
	"context"
	"fmt"

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

// **A part does not stop for a bucket it can work without** (novox/hq issue 1945, met twice on 2026-10-25: the delivery
// builder exited on a refused read of the gate's source and crash-looped). A grant reaches the bus with a delivery, so a
// bucket, a watch or a consumer the bus refuses, or times out on, at start is often only not granted yet: exiting for it
// stops the part until a person's hand. A part opens what it cannot do its job at all without with EssentialBucket, which
// stops its start with an error naming the bucket and its grant, and everything else with OptionalBucket, which says what
// is not heard and goes on; a watch the bus refuses on an optional bucket is said with NotWatched. Here, beside State,
// because this is where a process opens what it keeps and reads on the bus; the parts that open buckets with their own
// JetStream (the delivery parts) take the same three.

// BucketOpener is the part of the bus a start opens buckets with: a jetstream.JetStream, or a test's fake.
type BucketOpener interface {
	KeyValue(ctx context.Context, bucket string) (jetstream.KeyValue, error)
}

// EssentialBucket opens a bucket part cannot work without (it cannot `does` without it); its error is EssentialErr's.
func EssentialBucket(ctx context.Context, js BucketOpener, part, name, does string) (jetstream.KeyValue, error) {
	kv, err := js.KeyValue(ctx, name)
	if err != nil {
		return nil, EssentialErr(part, name, does, err)
	}
	return kv, nil
}

// EssentialErr is the error of a bucket, consumer or stream named name that part cannot work without: it says what part
// cannot do, that it stops, and the grant to look at.
func EssentialErr(part, name, does string, err error) error {
	return fmt.Errorf("%s cannot be read (%v): the %s cannot %s without it, so it stops; where the bus refused it or did not "+
		"answer, this module's grant of %s (its manifest's reads, state or consumes, issued with its credential) has not "+
		"reached the bus yet", name, err, part, does, name)
}

// OptionalBucket opens a bucket the part works without: any error is said with what is not heard (without), and nil
// answered.
func OptionalBucket(ctx context.Context, js BucketOpener, name, without string, logf func(string, ...any)) jetstream.KeyValue {
	kv, err := js.KeyValue(ctx, name)
	if err != nil {
		logf("the bucket %s cannot be read (%v): %s", name, err, without)
		return nil
	}
	return kv
}

// NotWatched says that an optional bucket opened but its watch was refused or not answered: what is not heard.
func NotWatched(logf func(string, ...any), name string, err error, without string) {
	logf("the bucket %s cannot be watched (%v): %s", name, err, without)
}