package videogen

import "context"

// VideoBackgroundRemovalRequest asks a video-matting backend (Robust Video
// Matting style) to separate the foreground subject from the background of a
// clip. Zero values mean "backend default" (ADR-0025).
type VideoBackgroundRemovalRequest struct {
	// Video is the encoded clip to matte. Required. Carried as bytes (never
	// a URL).
	Video []byte

	// MIME is the video MIME type (e.g. "video/mp4"); "" = let the backend
	// sniff it.
	MIME string

	// Filename is the multipart filename hint some backends key their format
	// detection on; "" derives one from MIME ("video.mp4") or falls back to
	// "video".
	Filename string

	// Output selects the delivery container: "greenscreen_mp4" (subject over
	// solid green, universally playable) or "alpha_webm" (true transparency,
	// VP9 alpha channel); "" = backend default.
	Output string
}

// VideoBackgroundRemovalOption mutates a VideoBackgroundRemovalRequest
// before it is sent.
type VideoBackgroundRemovalOption func(*VideoBackgroundRemovalRequest)

// WithVideoBackgroundOutput selects the delivery container
// ("greenscreen_mp4" or "alpha_webm").
func WithVideoBackgroundOutput(o string) VideoBackgroundRemovalOption {
	return func(r *VideoBackgroundRemovalRequest) { r.Output = o }
}

// Apply returns a copy of the request with all options applied.
func (r VideoBackgroundRemovalRequest) Apply(opts ...VideoBackgroundRemovalOption) VideoBackgroundRemovalRequest {
	for _, opt := range opts {
		opt(&r)
	}
	return r
}

// VideoBackgroundRemover mattes the subject out of video clips — the moving-
// picture sibling of imagegen.BackgroundRemover.
type VideoBackgroundRemover interface {
	// RemoveVideoBackground returns the matted clip. Matting is slow
	// (per-frame inference); bound the call with a context deadline.
	RemoveVideoBackground(ctx context.Context, req VideoBackgroundRemovalRequest, opts ...VideoBackgroundRemovalOption) (*Result, error)
}

// VideoBackgroundRemoverModelOption configures a VideoBackgroundRemover at
// construction time. Reserved for future per-model settings.
type VideoBackgroundRemoverModelOption func(*VideoBackgroundRemoverModelConfig)

// VideoBackgroundRemoverModelConfig carries per-model construction settings.
type VideoBackgroundRemoverModelConfig struct{}

// ApplyVideoBackgroundRemoverModelOptions folds options into a config.
func ApplyVideoBackgroundRemoverModelOptions(opts []VideoBackgroundRemoverModelOption) VideoBackgroundRemoverModelConfig {
	var cfg VideoBackgroundRemoverModelConfig
	for _, opt := range opts {
		opt(&cfg)
	}
	return cfg
}

// VideoBackgroundRemovalProvider mints VideoBackgroundRemovers bound to one
// backend.
type VideoBackgroundRemovalProvider interface {
	// Name is the registry identifier for the provider.
	Name() string

	// VideoBackgroundRemoverModel returns a VideoBackgroundRemover bound to
	// the given id (passed through to the backend verbatim; no catalog
	// validation).
	VideoBackgroundRemoverModel(id string, opts ...VideoBackgroundRemoverModelOption) (VideoBackgroundRemover, error)
}