import { File, Paths } from 'expo-file-system';
import * as Sharing from 'expo-sharing';

import type { ProjectFile } from '@/src/lib/api';
import { getApiBaseUrlSync } from '@/src/lib/server-config';

export function getOpenableFileUrl(rawUrl: string): string {
  if (/^https?:\/\//i.test(rawUrl)) return rawUrl;

  const apiBaseUrl = getApiBaseUrlSync().replace(/\/+$/, '');
  const path = rawUrl.startsWith('/') ? rawUrl : `/${rawUrl}`;
  return `${apiBaseUrl}${path}`;
}

function safeFilename(file: ProjectFile): string {
  const fallback = `dokument-${file.id}`;
  const rawName = String(file.name || file.path?.split('/').pop() || fallback);
  return rawName.replace(/[^a-zA-Z0-9äöüÄÖÜß._-]/g, '_');
}

export async function openAuthenticatedFile(file: ProjectFile, token: string): Promise<void> {
  if (!file.url) throw new Error('Für dieses Dokument ist kein Download verfügbar.');

  const target = new File(Paths.cache, `${file.id}-${safeFilename(file)}`);
  const downloaded = await File.downloadFileAsync(getOpenableFileUrl(file.url), target, {
    headers: { Authorization: `Bearer ${token}` },
    idempotent: true,
  });

  if (!(await Sharing.isAvailableAsync())) {
    throw new Error('Die Dokumentvorschau ist auf diesem Gerät nicht verfügbar.');
  }

  await Sharing.shareAsync(downloaded.uri, {
    mimeType: file.mimeType || undefined,
    dialogTitle: safeFilename(file),
  });
}