import type { ResponseField } from '@velrim/sdk';

/** Scale a top-left anchor onto an uncropped page with matching orientation. */
export function sourceHighlight(field: ResponseField, page: number, width: number, height: number) {
	const anchor = field.anchor;
	if (
		field.state !== 'present' ||
		!anchor ||
		anchor.page !== page ||
		!Number.isInteger(page) ||
		page < 1 ||
		field.grounding === 'ungrounded' ||
		(field.grounding !== 'verified' && field.grounding !== 'cited')
	)
		return null;
	const { width: pw, height: ph } = anchor.page_dims;
	const [x0, y0, x1, y1] = anchor.bbox;
	if (
		![width, height, pw, ph, x0, y0, x1, y1].every(Number.isFinite) ||
		Math.min(width, height, pw, ph) <= 0 ||
		x0 < 0 ||
		y0 < 0 ||
		x1 <= x0 ||
		y1 <= y0 ||
		x1 > pw ||
		y1 > ph
	)
		return null;
	// A mismatch usually means letterboxing, a crop, or an orientation change.
	if (Math.abs(width / height / (pw / ph) - 1) > 0.01) return null;
	return {
		left: (x0 * width) / pw,
		top: (y0 * height) / ph,
		width: ((x1 - x0) * width) / pw,
		height: ((y1 - y0) * height) / ph,
		label:
			field.grounding === 'verified' ? 'Value located in source' : 'Citation; value unconfirmed',
	};
}