import { FastifyPluginAsync } from 'fastify';
import { eq } from 'drizzle-orm';
import { db } from '../config/database.js';
import { contentSections } from '../db/schema.js';
import { AssetService } from '../services/asset.service.js';
import { isManagedAsset, forgetManagedAsset } from '../services/managed-assets.service.js';
import { saveUploadedPdf } from '../services/upload.service.js';
import { env } from '../config/env.js';

const assets = new AssetService();

/**
 * Feste PDF-Plaetze. Die URL landet jeweils in einer Content-Section, damit
 * der Generator sie beim Publish in die Astro-Komponente schreiben kann.
 */
const PDF_SLOTS: Record<string, { section: string; field: string }> = {
  drinks: { section: 'drinks', field: 'pdfUrl' },
};

/** contentJson kommt je nach Treiber als Objekt oder als String zurueck. */
function asObject(value: any): Record<string, any> {
  if (!value) return {};
  if (typeof value === 'string') {
    try {
      const parsed = JSON.parse(value);
      return parsed && typeof parsed === 'object' ? parsed : {};
    } catch {
      return {};
    }
  }
  return typeof value === 'object' ? value : {};
}

const pdfRoute: FastifyPluginAsync = async (fastify) => {

  // PDF fuer einen festen Platz hochladen und verlinken
  fastify.post('/pdf/:slot', {
    preHandler: [fastify.authenticate],
  }, async (request, reply) => {
    const { slot } = request.params as { slot: string };
    const target = PDF_SLOTS[slot];

    if (!target) {
      return reply.code(404).send({ error: `Unknown PDF slot "${slot}"` });
    }

    try {
      const file = await (request as any).file({ limits: { fileSize: env.MAX_PDF_SIZE } });
      if (!file) {
        return reply.code(400).send({ error: 'No file uploaded' });
      }

      const mime = file.mimetype as string | undefined;
      const originalName = (file.filename as string | undefined) || '';
      if (mime !== 'application/pdf' && !originalName.toLowerCase().endsWith('.pdf')) {
        return reply.code(400).send({ error: 'Only PDF uploads are allowed' });
      }

      const chunks: Buffer[] = [];
      for await (const chunk of file.file) {
        chunks.push(Buffer.isBuffer(chunk) ? chunk : Buffer.from(chunk));
      }
      const buffer = Buffer.concat(chunks);

      if ((file.file as any)?.truncated) {
        const limit = Math.round(env.MAX_PDF_SIZE / 1024 / 1024);
        return reply.code(413).send({ error: `PDF too large. Maximum is ${limit} MB` });
      }

      // Inhalt gegenpruefen, damit nicht irgendetwas mit .pdf-Endung landet
      if (buffer.subarray(0, 5).toString('latin1') !== '%PDF-') {
        return reply.code(400).send({ error: 'File is not a valid PDF' });
      }

      const pdfUrl = await saveUploadedPdf(file, buffer);

      // URL in der Content-Section hinterlegen
      const [existing] = await db
        .select()
        .from(contentSections)
        .where(eq(contentSections.sectionName, target.section))
        .limit(1);

      const previousContent = asObject((existing as any)?.contentJson);
      const previousUrl = previousContent[target.field];
      const content = { ...previousContent, [target.field]: pdfUrl };

      if (existing) {
        await db
          .update(contentSections)
          .set({ contentJson: content, updatedAt: new Date() })
          .where(eq(contentSections.sectionName, target.section));
      } else {
        await db
          .insert(contentSections)
          .values({ sectionName: target.section, contentJson: content });
      }

      // Vorgaenger wegraeumen - greift nur bei frueher hochgeladenen PDFs,
      // die mitgelieferte Getraenkekarte aus dem Repo bleibt liegen
      if (previousUrl && previousUrl !== pdfUrl && (await isManagedAsset(previousUrl))) {
        try {
          if (assets.deletePdf(previousUrl)) {
            fastify.log.info(`Removed replaced PDF ${previousUrl}`);
          }
          await forgetManagedAsset(previousUrl);
        } catch (err) {
          fastify.log.warn({ err }, 'Could not remove replaced PDF');
        }
      }

      return reply.code(201).send({ pdfUrl, section: target.section });

    } catch (err: any) {
      if (err?.code === 'FST_REQ_FILE_TOO_LARGE') {
        const limit = Math.round(env.MAX_PDF_SIZE / 1024 / 1024);
        return reply.code(413).send({ error: `PDF too large. Maximum is ${limit} MB` });
      }
      fastify.log.error({ err }, 'PDF upload failed');
      return reply.code(500).send({ error: 'Failed to upload PDF' });
    }
  });
};

export default pdfRoute;