import type { ExportResult, ReportPayload } from '@/lib/reports/types';

/**
 * PDF export. Unlike CSV + Excel (which can serialise in the browser),
 * PDF generation runs server-side via `@react-pdf/renderer` so the
 * client posts the payload to `/api/v1/reports/export-pdf` and receives
 * the rendered bytes back.
 *
 * The server resolves the active port's branding (logo + primary
 * color + name) so per-port theming flows through automatically — the
 * client doesn't need to send branding fields.
 */

interface PdfExportOptions {
  /** Filename override mirroring the CSV / Excel exporters. */
  filenameOverride?: string;
}

export async function exportReportAsPdf(
  payload: ReportPayload,
  options: PdfExportOptions = {},
): Promise<ExportResult> {
  // Serialise dates to ISO so they survive the JSON trip.
  const wireBody = {
    title: payload.title,
    description: payload.description,
    filenameSlug: payload.filenameSlug,
    range: {
      from: payload.range.from.toISOString(),
      to: payload.range.to.toISOString(),
    },
    kpis: payload.kpis,
    sections: payload.sections.map((s) => ({
      title: s.title,
      columns: s.columns.map((c) => ({
        key: c.key,
        label: c.label,
        align: c.align,
        // `format` is a function and isn't serialisable; the server
        // falls back to plain stringification, which matches the CSV
        // exporter's default behaviour when no format is set.
      })),
      // Apply client-side format functions BEFORE serialising so the
      // server sees pre-formatted strings. This preserves money /
      // percentage / date formatting that the original ReportPayload
      // declared.
      rows: s.rows.map((row) => {
        const out: Record<string, unknown> = {};
        for (const col of s.columns) {
          out[col.key] = col.format ? col.format(row[col.key]) : row[col.key];
        }
        return out;
      }),
    })),
    filenameOverride: options.filenameOverride,
  };

  const res = await fetch('/api/v1/reports/export-pdf', {
    method: 'POST',
    headers: { 'Content-Type': 'application/json' },
    body: JSON.stringify(wireBody),
    credentials: 'include',
  });

  if (!res.ok) {
    const text = await res.text().catch(() => '');
    throw new Error(text || `PDF generation failed (${res.status})`);
  }

  const blob = await res.blob();
  const cdHeader = res.headers.get('content-disposition') ?? '';
  const match = cdHeader.match(/filename="([^"]+)"/);
  const filename = match?.[1] ?? options.filenameOverride ?? defaultPdfFilename(payload);

  return {
    filename,
    mimeType: 'application/pdf',
    body: blob,
  };
}

export function defaultPdfFilename(payload: ReportPayload): string {
  const fromIso = payload.range.from.toISOString().slice(0, 10);
  const toIso = payload.range.to.toISOString().slice(0, 10);
  return `${payload.filenameSlug}-${fromIso}_${toIso}.pdf`;
}