package crawl

import "context"

// Renderer renders a page of the site in a browser for the raw versus
// rendered comparison (D-70, P33-55): Render answers the page's DOM after
// JavaScript ran, Close releases the browser. A crawl without a Renderer
// records the comparison as skipped; a Render error records it as failed
// with the error and never fails the crawl.
type Renderer interface {
	Render(ctx context.Context, pageURL string) (string, error)
	Close() error
}

// DefaultRenderMax is the number of pages rendered per crawl when
// golem15.seo.crawl_render_max is unset.
const DefaultRenderMax = 200

// The render states of a crawl (models.RenderSkipped and the others).
const (
	renderStatusSkipped = "skipped"
	renderStatusDone    = "done"
	renderStatusFailed  = "failed"
)

type rendererKey struct{}

// WithRenderer returns a context whose crawls use r instead of the
// renderer built from config. It is the test seam of the comparison,
// settable only from Go code (like fetchguard.WithTransport): no config
// key, setting, request or MCP call reaches it.
func WithRenderer(ctx context.Context, r Renderer) context.Context {
	return context.WithValue(ctx, rendererKey{}, r)
}

// rendererFrom returns the renderer of ctx, nil when none.
func rendererFrom(ctx context.Context) Renderer {
	if ctx == nil {
		return nil
	}
	r, _ := ctx.Value(rendererKey{}).(Renderer)
	return r
}