storage

type Attributes struct {
	// ContentType is the MIME type of the blob object. It will not be empty.
	ContentType string
	// Metadata holds key/value pairs associated with the blob.
	// Keys are guaranteed to be in lowercase, even if the backend provider
	// has case-sensitive keys (although note that Metadata written via
	// this package will always be lowercased). If there are duplicate
	// case-insensitive keys (e.g., "foo" and "FOO"), only one value
	// will be kept, and it is undefined which one.
	Metadata map[string]string
	// ModTime is the time the blob object was last modified.
	ModTime time.Time
	// CreationTime is the time the blob object was created.
	CreationTime time.Time
	// Size is the size of the object in bytes.
	Size int64
}

type CacheOptions struct {
	// MaxAge is the maximum time allowed since the underlying File's ModTime
	// This means that if the cache is older than MaxAge, the Cache will fetch from the src again.
	// If the expired File is still present on the src (i.e. not updated), it will be ignored.
	MaxAge time.Duration

	// DefaultExpired makes the cache treat a File as expired if its CreationTime cannot be checked.
	// By default, it is false, which means the cache will treat zero-CreationTime files as valid.
	// Only useful if MaxAge is set.
	DefaultExpired bool

	// NoData disables caching of the contents of the entries, it only stores the metadata.
	NoData bool
}

type FS interface {
	Walker

	// Open opens an existing file at path in the filesystem.  Callers must close the
	// File when done to release all underlying resources.
	Open(ctx context.Context, path string, options *ReaderOptions) (*File, error)

	// Attributes returns attributes about a path
	Attributes(ctx context.Context, path string, options *ReaderOptions) (*Attributes, error)

	// Create makes a new file at path in the filesystem.  Callers must close the
	// returned WriteCloser and check the error to be sure that the file
	// was successfully written.
	Create(ctx context.Context, path string, options *WriterOptions) (io.WriteCloser, error)

	// Delete removes a path from the filesystem.
	Delete(ctx context.Context, path string) error

	// URL resolves a path to an addressable URL
	URL(ctx context.Context, path string, options *SignedURLOptions) (string, error)
}

type File struct {
	io.ReadCloser // Underlying data.
	Attributes
}

type GetSetter interface {
	Get(key string) (string, error)
	Set(key string, value string) error
	Delete(key string) error
}

type Logger interface {
	Print(v ...interface{})
}

type ReaderOptions struct{}

type SignedURLOptions = blob.SignedURLOptions

type WalkFn func(path string) error

type Walker interface {
	// Walk traverses a path listing by prefix, calling fn with each path.
	Walk(ctx context.Context, path string, fn WalkFn) error
}

type WriterOptions struct {
	Attributes Attributes

	// BufferSize changes the default size in bytes of the chunks that
	// Writer will upload in a single request; larger blobs will be split into
	// multiple requests.
	//
	// This option may be ignored by some drivers.
	//
	// If 0, the driver will choose a reasonable default.
	//
	// If the Writer is used to do many small writes concurrently, using a
	// smaller BufferSize may reduce memory usage.
	BufferSize int
}