import { readFile, writeFile } from 'node:fs/promises';
import { pathToFileURL } from 'node:url';
import { z } from 'zod';
import { VelrimClient, type ExtractResponseBody } from '@velrim/sdk';

// Decimal strings retain printed precision; normalization belongs in business checks.
export const LineInvoice = z.object({
	invoice_number: z.string(),
	currency: z.string(),
	line_items: z.array(
		z.object({
			description: z.string(),
			quantity: z.string(),
			unit_price: z.string(),
			amount: z.string(),
		}),
	),
});

function cell(value: string): string {
	// Reject ambiguous spreadsheet input instead of silently changing source values.
	if (/^[=+\-@＝＋－＠]/u.test(value.normalize('NFKC').trimStart()) || /^[\t\r\n]/u.test(value)) {
		throw new Error('Spreadsheet formula-like text: inspect the JSON evidence before export.');
	}
	return `"${value.replaceAll('"', '""')}"`;
}

export function invoiceCsv(body: ExtractResponseBody) {
	const invoice = LineInvoice.parse(body.data);
	const reasons: string[] = [];
	if (!invoice.line_items.length) reasons.push('No line items returned; check the document.');
	const pointers = ['/invoice_number', '/currency'];
	invoice.line_items.forEach((_row, i) => {
		for (const key of ['description', 'quantity', 'unit_price', 'amount']) {
			pointers.push(`/line_items/${i}/${key}`);
		}
	});
	for (const pointer of pointers) {
		const field = body.fields[pointer];
		if (
			!field ||
			field.state !== 'present' ||
			field.conflict ||
			field.grounding !== 'verified' ||
			!field.anchor ||
			typeof field.confidence !== 'number' ||
			!Number.isFinite(field.confidence) ||
			field.confidence < 0 ||
			field.confidence > 1
		)
			reasons.push(pointer);
	}
	const rows = [
		['invoice_number', 'currency', 'line_index', 'description', 'quantity', 'unit_price', 'amount'],
		...invoice.line_items.map((row, i) => [
			invoice.invoice_number,
			invoice.currency,
			String(i),
			row.description,
			row.quantity,
			row.unit_price,
			row.amount,
		]),
	];
	return { csv: rows.map((row) => row.map(cell).join(',')).join('\r\n') + '\r\n', reasons };
}

if (process.argv[1] && import.meta.url === pathToFileURL(process.argv[1]).href) {
	const [mode, input, prefix] = process.argv.slice(2);
	if (!input || !prefix || (mode !== 'json' && mode !== 'pdf')) {
		throw new Error(
			'Usage: npx tsx line-items.ts json response.json output-prefix (or pdf invoice.pdf output-prefix)',
		);
	}
	let body: ExtractResponseBody;
	if (mode === 'pdf') {
		// Raw schema retains partial responses before strict application validation.
		const result = await new VelrimClient().extract(z.toJSONSchema(LineInvoice), {
			bytes: await readFile(input),
		});
		body = {
			data: result.data as Record<string, unknown>,
			fields: result.fields,
			meta: result.meta,
		};
	} else {
		body = JSON.parse(await readFile(input, 'utf8')) as ExtractResponseBody;
	}
	// Keep the envelope even if validation or spreadsheet checks reject the export.
	await writeFile(`${prefix}.evidence.json`, JSON.stringify(body, null, 2), {
		encoding: 'utf8',
		flag: 'wx',
	});
	const { csv, reasons } = invoiceCsv(body);
	await writeFile(`${prefix}.csv`, csv, { encoding: 'utf8', flag: 'wx' });
	console.log({
		request_id: body.meta.request_id,
		evidence_checks_flagged: reasons.length,
		next: 'review_and_business_checks',
	});
}