const (
	CACHE_CLEAR_ALL = "clear_all"
	CACHE_OTHER     = "other"
)

type ResourceCache struct {
	sync.RWMutex
	// contains filtered or unexported fields
}

type ResourceSourceDescriptor struct {
	// TargetPaths is a callback to fetch paths's relative to its owner.
	TargetPaths func() page.TargetPaths

	// Need one of these to load the resource content.
	SourceFile         source.File
	OpenReadSeekCloser resource.OpenReadSeekCloser

	FileInfo os.FileInfo

	// If OpenReadSeekerCloser is not set, we use this to open the file.
	SourceFilename string

	Fs afero.Fs

	// The relative target filename without any language code.
	RelTargetFilename string

	// Any base paths prepended to the target path. This will also typically be the
	// language code, but setting it here means that it should not have any effect on
	// the permalink.
	// This may be several values. In multihost mode we may publish the same resources to
	// multiple targets.
	TargetBasePaths []string

	// Delay publishing until either Permalink or RelPermalink is called. Maybe never.
	LazyPublish bool
}

type ResourceTransformation interface {
	Key() internal.ResourceTransformationKey
	Transform(ctx *ResourceTransformationCtx) error
}

type ResourceTransformationCtx struct {
	// The content to transform.
	From io.Reader

	// The target of content transformation.
	// The current implementation requires that r is written to w
	// even if no transformation is performed.
	To io.Writer

	// This is the relative path to the original source. Unix styled slashes.
	SourcePath string

	// This is the relative target path to the resource. Unix styled slashes.
	InPath string

	// The relative target path to the transformed resource. Unix styled slashes.
	OutPath string

	// The input media type
	InMediaType media.Type

	// The media type of the transformed resource.
	OutMediaType media.Type

	// Data data can be set on the transformed Resource. Not that this need
	// to be simple types, as it needs to be serialized to JSON and back.
	Data map[string]interface{}

	// This is used to publis additional artifacts, e.g. source maps.
	// We may improve this.
	OpenResourcePublisher func(relTargetPath string) (io.WriteCloser, error)
}

type ResourceTransformer interface {
	resource.Resource
	Transformer
}

type Spec struct {
	*helpers.PathSpec

	MediaTypes    media.Types
	OutputFormats output.Formats

	Logger      *loggers.Logger
	ErrorSender herrors.ErrorSender

	TextTemplates tpl.TemplateParseFinder

	Permalinks  page.PermalinkExpander
	BuildConfig config.Build

	ResourceCache *ResourceCache
	FileCaches    filecache.Caches

	PostProcessResources map[string]postpub.PostPublishedResource
	// contains filtered or unexported fields
}

type Transformer interface {
	Transform(...ResourceTransformation) (ResourceTransformer, error)
}