import { RequestHandler } from 'express';
import { PricingContext, Quote, quoteCall } from './pricing';
import { UsageRepo } from './usage';

export function meter(
  endpointId: string,
  repo: UsageRepo,
  pricing: PricingContext,
  onRecord?: (entry: { customerId: string; endpointId: string; cents: number }) => void,
): RequestHandler {
  return (req, res, next) => {
    const customer = req.customer;
    if (!customer) {
      res.status(401).json({ error: 'unauthenticated' });
      return;
    }
    const metadataBytes = Buffer.byteLength(
      JSON.stringify(req.body?.metadata ?? {}),
      'utf8',
    );
    const files = (req.files as Express.Multer.File[] | undefined) ?? [];
    const attachmentBytes = files.reduce((sum, f) => sum + f.size, 0);

    let quote: Quote;
    try {
      quote = quoteCall(
        pricing,
        customer.tierId,
        endpointId,
        { metadataBytes, attachmentBytes },
        customer.multiplierOverride,
      );
    } catch (err) {
      res.status(403).json({ error: (err as Error).message });
      return;
    }

    const entry = {
      customerId: customer.id,
      endpointId,
      cents: quote.totalCents,
      metadataBytes,
      attachmentBytes,
      timestamp: new Date(),
    };
    repo.record(entry);
    onRecord?.({ customerId: customer.id, endpointId, cents: quote.totalCents });
    res.locals.quote = quote;
    next();
  };
}