// Gallery-facing photo metadata: the RC_ filename convention and the file-level
// EXIF helpers both export engines share (the codec itself lives in exifWrite.ts).
import { File } from 'expo-file-system';
import * as FileSystem from 'expo-file-system/legacy';
import RecipescamExport from '../../modules/recipescam-export';
import { writeJpegExif, SOFTWARE, type DeviceIdentity, type ExifStamp } from './exifWrite';

// RC_<yyyymmdd_hhmmss>[_exported].jpg — the name the gallery shows for a saved
// photo. The exported variant marks a photo re-exported from the library.
export function rcPhotoName(exported: boolean, date = new Date()): string {
  const p = (n: number) => String(n).padStart(2, '0');
  const stamp = `${date.getFullYear()}${p(date.getMonth() + 1)}${p(date.getDate())}_${p(date.getHours())}${p(date.getMinutes())}${p(date.getSeconds())}`;
  return `RC_${stamp}${exported ? '_exported' : ''}.jpg`;
}

// Cache path for the next export. Two renders landing in the same second would
// collide on the name AND on RN's <Image> cache (keyed by URI), so the
// timestamp walks forward a second at a time instead of taking a suffix.
export function nextPhotoPath(exported: boolean): string {
  let ms = Date.now();
  for (;;) {
    const path = `${FileSystem.cacheDirectory}${rcPhotoName(exported, new Date(ms))}`;
    if (!new File(path).exists) return path;
    ms += 1000;
  }
}

export async function readPhotoBytes(uri: string): Promise<Uint8Array | null> {
  try {
    return await new File(uri).bytes();
  } catch (e) {
    console.warn('EXIF source read failed:', e);
    return null;
  }
}

// Device identity for the Gallery watermark blob (exifWrite.watermarkBlob).
// Read once — the props cannot change while the app runs. null when the native
// module is older than this call, so stamping still works without it.
let deviceIdentity: DeviceIdentity | null | undefined;
export function getDeviceIdentity(): DeviceIdentity | null {
  if (deviceIdentity === undefined) {
    try {
      deviceIdentity = RecipescamExport.deviceInfo();
    } catch (e) {
      console.warn('deviceInfo unavailable:', e);
      deviceIdentity = null;
    }
  }
  return deviceIdentity;
}

// Stamp EXIF into a file already on disk (the native engine writes the JPEG
// itself, so those bytes never pass through JS). Never throws — a metadata
// failure must not cost the user the photo.
export async function stampExifOnFile(fileUri: string, stamp: ExifStamp, sourceUri?: string | null): Promise<void> {
  try {
    const target = new File(fileUri);
    const source = sourceUri ? await readPhotoBytes(sourceUri) : null;
    target.write(writeJpegExif(await target.bytes(), { software: SOFTWARE, device: getDeviceIdentity(), ...stamp }, source));
  } catch (e) {
    console.warn('EXIF stamp failed:', e);
  }
}