package memory

import (
	"context"
	"encoding/json"
)

// Queue receives a one-line note about a memory change a tool just made, so the
// controller can fold it into the current turn — taking effect this session
// without touching the cache-stable system prefix. The remember/forget tools
// read it from their call context the same way background tools read the job
// manager.
type Queue interface{ QueueMemory(note string) }

type autoMemoryWriteClaimer interface {
	ClaimAutoMemoryWrite(args json.RawMessage) bool
}

type queueKey struct{}
type noQueue struct{}

// WithQueue stamps q onto ctx for the remember/forget tools to find.
func WithQueue(ctx context.Context, q Queue) context.Context {
	return context.WithValue(ctx, queueKey{}, q)
}

// WithoutQueue shadows an ancestor queue. Child agents may persist memory but
// must not inject turn-tail notes into the parent's live conversation.
func WithoutQueue(ctx context.Context) context.Context {
	return context.WithValue(ctx, queueKey{}, noQueue{})
}

// QueueFromContext returns the memory queue the agent stamped, if any.
func QueueFromContext(ctx context.Context) (Queue, bool) {
	q, ok := ctx.Value(queueKey{}).(Queue)
	return q, ok && q != nil
}

// ClaimAutoMemoryWriteFromContext consumes a host-issued create-only grant.
// Manual/approved writes have no claim and retain the legacy update behavior.
func ClaimAutoMemoryWriteFromContext(ctx context.Context, args json.RawMessage) bool {
	q, ok := QueueFromContext(ctx)
	if !ok {
		return false
	}
	claimer, ok := q.(autoMemoryWriteClaimer)
	return ok && claimer.ClaimAutoMemoryWrite(args)
}