package imagegen

import "context"

// SegmentationRequest asks a promptable-segmentation backend (GroundingDINO +
// SAM style) for the mask of a text-described region. Zero values mean
// "backend default" (ADR-0023).
type SegmentationRequest struct {
	// Image is the image to segment. Required.
	Image Image

	// Prompt is the text description of the region to segment (e.g. "the red
	// car"). Required — promptless segmentation is a different capability.
	Prompt string

	// Threshold is the detection confidence threshold in (0,1]; 0 = backend
	// default.
	Threshold float64
}

// SegmentationOption mutates a SegmentationRequest before it is sent.
type SegmentationOption func(*SegmentationRequest)

// WithSegmentationThreshold sets the detection confidence threshold.
func WithSegmentationThreshold(t float64) SegmentationOption {
	return func(r *SegmentationRequest) { r.Threshold = t }
}

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

// Segmenter extracts a prompted region's mask from an image. The result is a
// single grayscale mask image where WHITE marks the prompted region — the
// same polarity as EditRequest.Mask (white = repaint), so it feeds inpainting
// directly; derive a cutout client-side by applying the mask as alpha.
type Segmenter interface {
	// Segment returns the region mask as a one-image Result.
	Segment(ctx context.Context, req SegmentationRequest, opts ...SegmentationOption) (*Result, error)
}

// SegmentationModelOption configures a Segmenter at construction time.
// Reserved for future per-model settings (mirrors ModelOption).
type SegmentationModelOption func(*SegmentationModelConfig)

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

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

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

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