// POST /api/export
// Body (multi-size): { rows: [{ rowIndex: number, specs: BannerSpec[] }] }
// Body (legacy):     { specs: BannerSpec[] }
//
// Validates each spec via BannerSpecSchema. Invalid specs collect into the
// errors array rather than 400-ing the whole request — the producer should
// still get zips for the valid ones. Valid specs are rendered through
// renderMany() (single Chromium, concurrent contexts, capped at 3).
//
// Per-row body groups output by feed row:
//   exports/row-<N>/<artboard_id>.zip   (one zip per size, per row)
// Legacy specs body keeps the older layout:
//   exports/<campaign>/<version>.zip
//
// Synchronous: returns when every zip is on disk. The slice only produces
// a handful of banners per call so ~3-8 seconds blocking is acceptable.
// V1 will move to a queued + SSE-streamed flow.
//
// runtime: 'nodejs' — Playwright launches a subprocess and uses fs.
// dynamic: 'force-dynamic' — must run on every request; nothing about it
// is statically renderable.
//
// The render-worker is dynamic-imported for parity with /api/generate's
// pattern (heavy module, only loaded inside the request).

import { NextResponse } from 'next/server';
import type { BannerSpec } from '@banner-studio/types';

export const runtime = 'nodejs';
export const dynamic = 'force-dynamic';

interface ExportRequestBody {
  specs?: unknown;
  rows?: unknown;
}

interface RowInput {
  rowIndex: number;
  specs: BannerSpec[];
}

export async function POST(req: Request): Promise<NextResponse> {
  let body: ExportRequestBody;
  try {
    body = (await req.json()) as ExportRequestBody;
  } catch {
    return NextResponse.json(
      { error: 'Request body must be JSON' },
      { status: 400 }
    );
  }

  const path = await import('node:path');
  const { BannerSpecSchema } = await import('@banner-studio/types');
  const { renderMany } = await import('@banner-studio/render-worker');

  const errors: { version_id?: string; error: string }[] = [];

  // Per-row mode: validate every spec inside every row. Each spec carries
  // its row index forward so the renderer can emit exports/row-N/<size>.zip.
  let perRow: { spec: BannerSpec; rowIndex: number }[] | null = null;
  if (Array.isArray(body.rows)) {
    perRow = [];
    for (let r = 0; r < body.rows.length; r++) {
      const row = body.rows[r] as Partial<RowInput> | null;
      if (!row || typeof row !== 'object' || !Array.isArray(row.specs)) continue;
      const rowIndex = typeof row.rowIndex === 'number' ? row.rowIndex : r;
      for (let i = 0; i < row.specs.length; i++) {
        const parsed = BannerSpecSchema.safeParse(row.specs[i]);
        if (parsed.success) {
          perRow.push({ spec: parsed.data, rowIndex });
        } else {
          const raw = row.specs[i];
          const maybeVersionId =
            raw && typeof raw === 'object' && 'version_id' in raw
              ? String((raw as { version_id?: unknown }).version_id ?? '')
              : undefined;
          errors.push({
            version_id: maybeVersionId,
            error: `row[${r}].specs[${i}] failed validation: ${parsed.error.message}`
          });
        }
      }
    }
  }

  // Legacy specs mode: kept for any older caller. Flat array, default paths.
  let flat: BannerSpec[] | null = null;
  if (!perRow) {
    const rawSpecs = Array.isArray(body.specs) ? body.specs : null;
    if (!rawSpecs) {
      return NextResponse.json(
        { error: 'Request body must include either a "rows" or "specs" array' },
        { status: 400 }
      );
    }
    flat = [];
    for (let i = 0; i < rawSpecs.length; i++) {
      const parsed = BannerSpecSchema.safeParse(rawSpecs[i]);
      if (parsed.success) {
        flat.push(parsed.data);
      } else {
        const raw = rawSpecs[i];
        const maybeVersionId =
          raw && typeof raw === 'object' && 'version_id' in raw
            ? String((raw as { version_id?: unknown }).version_id ?? '')
            : undefined;
        errors.push({
          version_id: maybeVersionId,
          error: `spec[${i}] failed validation: ${parsed.error.message}`
        });
      }
    }
  }

  const repoRoot = path.resolve(process.cwd(), '..', '..');
  const outputDir = path.join(repoRoot, 'exports');

  let result;
  if (perRow) {
    const specsFlat = perRow.map((p) => p.spec);
    const rowIndexFor = perRow.map((p) => p.rowIndex);
    result = await renderMany({
      specs: specsFlat,
      outputDir,
      concurrency: 3,
      repoRoot,
      pathFor: (spec, idx) => ({
        subdir: `row-${(rowIndexFor[idx] ?? idx) + 1}`,
        filename: spec.artboards[0]!.artboard_id
      })
    });
  } else {
    result = await renderMany({
      specs: flat!,
      outputDir,
      concurrency: 3,
      repoRoot
    });
  }

  return NextResponse.json({
    exported: result.exported,
    errors: [...errors, ...result.errors]
  });
}

export async function GET() {
  return NextResponse.json({
    hint: 'POST { specs: BannerSpec[] } to render each into exports/<campaign>/<version>.zip'
  });
}