// Package streamoffsetstub provides an in-process ports.StreamOffsetStore
// used by worker-level tests that do not need Redis. Production code
// never wires this stub.
package streamoffsetstub

import (
	"context"
	"errors"
	"sync"

	"galaxy/lobby/internal/ports"
)

// Store is a concurrency-safe in-memory ports.StreamOffsetStore.
type Store struct {
	mu      sync.Mutex
	offsets map[string]string
}

// NewStore constructs an empty Store.
func NewStore() *Store {
	return &Store{offsets: make(map[string]string)}
}

// Load returns the last saved entry id for streamLabel.
func (store *Store) Load(ctx context.Context, streamLabel string) (string, bool, error) {
	if ctx == nil {
		return "", false, errors.New("load offset: nil context")
	}
	store.mu.Lock()
	defer store.mu.Unlock()
	value, ok := store.offsets[streamLabel]
	return value, ok, nil
}

// Save records entryID as the offset for streamLabel.
func (store *Store) Save(ctx context.Context, streamLabel, entryID string) error {
	if ctx == nil {
		return errors.New("save offset: nil context")
	}
	store.mu.Lock()
	defer store.mu.Unlock()
	store.offsets[streamLabel] = entryID
	return nil
}

// Set forces the in-memory value for streamLabel; useful in tests to
// pre-populate state.
func (store *Store) Set(streamLabel, entryID string) {
	store.mu.Lock()
	defer store.mu.Unlock()
	store.offsets[streamLabel] = entryID
}

// Compile-time interface assertion.
var _ ports.StreamOffsetStore = (*Store)(nil)