feat(lib/store): add s3api storage backend (#1089)

* feat(lib/store): add s3api storage backend

Signed-off-by: Xe Iaso <me@xeiaso.net>

* docs(store/s3api): replace fake S3 API keys with the bee movie script

Signed-off-by: Xe Iaso <me@xeiaso.net>

* docs(store/s3api): fix spelling sin

Signed-off-by: Xe Iaso <me@xeiaso.net>

* fix(store/s3api): remove vestigal experiment

Signed-off-by: Xe Iaso <me@xeiaso.net>

* chore: spelling

Signed-off-by: Xe Iaso <me@xeiaso.net>

* chore: spelling

Signed-off-by: Xe Iaso <me@xeiaso.net>

* chore(store/s3api): support IsPersistent call

Ref #1088

Signed-off-by: Xe Iaso <me@xeiaso.net>

* chore: spelling

Signed-off-by: Xe Iaso <me@xeiaso.net>

* chore(test): go mod tidy

Signed-off-by: Xe Iaso <me@xeiaso.net>

---------

Signed-off-by: Xe Iaso <me@xeiaso.net>

lib/store/s3api/factory.go

@@ -0,0 +1,107 @@
+package s3api
+
+import (
+	"context"
+	"encoding/json"
+	"errors"
+	"fmt"
+
+	"github.com/TecharoHQ/anubis/lib/store"
+	awsConfig "github.com/aws/aws-sdk-go-v2/config"
+	"github.com/aws/aws-sdk-go-v2/service/s3"
+)
+
+var (
+	ErrNoRegion          = errors.New("s3api.Config: no region env var name defined")
+	ErrNoAccessKeyID     = errors.New("s3api.Config: no access key id env var name defined")
+	ErrNoSecretAccessKey = errors.New("s3api.Config: no secret access key env var name defined")
+	ErrNoBucketName      = errors.New("s3api.Config: no bucket name env var name defined")
+)
+
+func init() {
+	store.Register("s3api", Factory{})
+}
+
+// S3API is the subset of the AWS S3 client used by this store. It enables mocking in tests.
+type S3API interface {
+	PutObject(ctx context.Context, params *s3.PutObjectInput, optFns ...func(*s3.Options)) (*s3.PutObjectOutput, error)
+	GetObject(ctx context.Context, params *s3.GetObjectInput, optFns ...func(*s3.Options)) (*s3.GetObjectOutput, error)
+	DeleteObject(ctx context.Context, params *s3.DeleteObjectInput, optFns ...func(*s3.Options)) (*s3.DeleteObjectOutput, error)
+	HeadObject(ctx context.Context, params *s3.HeadObjectInput, optFns ...func(*s3.Options)) (*s3.HeadObjectOutput, error)
+}
+
+// Factory builds an S3-backed store. Tests can inject a Mock via Client.
+// Factory can optionally carry a preconstructed S3 client (e.g., a mock in tests).
+type Factory struct {
+	Client S3API
+}
+
+func (f Factory) Build(ctx context.Context, data json.RawMessage) (store.Interface, error) {
+	var config Config
+
+	if err := json.Unmarshal([]byte(data), &config); err != nil {
+		return nil, fmt.Errorf("%w: %w", store.ErrBadConfig, err)
+	}
+
+	if err := config.Valid(); err != nil {
+		return nil, fmt.Errorf("%w: %w", store.ErrBadConfig, err)
+	}
+
+	if config.BucketName == "" {
+		return nil, fmt.Errorf("%w: %s", store.ErrBadConfig, ErrNoBucketName)
+	}
+
+	// If a client was injected (e.g., tests), use it directly.
+	if f.Client != nil {
+		return &Store{
+			s3:     f.Client,
+			bucket: config.BucketName,
+		}, nil
+	}
+
+	cfg, err := awsConfig.LoadDefaultConfig(ctx)
+	if err != nil {
+		return nil, fmt.Errorf("can't load AWS config from environment: %w", err)
+	}
+
+	client := s3.NewFromConfig(cfg, func(o *s3.Options) {
+		o.UsePathStyle = config.PathStyle
+	})
+
+	return &Store{
+		s3:     client,
+		bucket: config.BucketName,
+	}, nil
+}
+
+func (Factory) Valid(data json.RawMessage) error {
+	var config Config
+	if err := json.Unmarshal([]byte(data), &config); err != nil {
+		return fmt.Errorf("%w: %w", store.ErrBadConfig, err)
+	}
+
+	if err := config.Valid(); err != nil {
+		return fmt.Errorf("%w: %w", store.ErrBadConfig, err)
+	}
+
+	return nil
+}
+
+type Config struct {
+	PathStyle  bool   `json:"pathStyle"`
+	BucketName string `json:"bucketName"`
+}
+
+func (c Config) Valid() error {
+	var errs []error
+
+	if c.BucketName == "" {
+		errs = append(errs, ErrNoBucketName)
+	}
+
+	if len(errs) != 0 {
+		return fmt.Errorf("s3api.Config: invalid config: %w", errors.Join(errs...))
+	}
+
+	return nil
+}