import { rgbaToThumbHash } from "thumbhash";
import ExifReader from 'exifreader';
import type { ImageMetadata } from "astro";

let s: typeof import("sharp") | undefined;
async function getSharp(): Promise<typeof import("sharp") | undefined> {
  if (s) return s;
  s = (await import("sharp")).default;
  return s;
}

export async function generateThumbHash(image: ImageMetadata & { fsPath?: string }) {

  const sharp = await getSharp();
  if (!sharp) return;

  const scaleFactor = 100 / Math.max(image.width, image.height);

  const smallWidth = Math.floor(image.width * scaleFactor);
  const smallHeight = Math.floor(image.height * scaleFactor);

  try {
    const smallImg = await sharp(image.fsPath)
      .resize(smallWidth, smallHeight)
      .withMetadata()
      .raw()
      .ensureAlpha()
      .toBuffer();

    const buffer = rgbaToThumbHash(smallWidth, smallHeight, smallImg);
    return Buffer.from(buffer).toString("base64");
  } catch (error) {
    console.log(`Could not generate thumbhash for ${image.fsPath}`, error)
    return ""
  }

}

const allowedExif = [
  "ApertureValue",
  "DateTimeOriginal",
  "ShutterSpeedValue",
  "ExposureTime",
  "ApertureValue",
  "FNumber",
  "FocalLength",
  "GPSLatitude",
  "GPSLongitude",
  "GPSAltitude",
  "IsoSpeedRatings",
  "Make",
  "Model",
];

export async function getExifData(image: ImageMetadata) {
  if (image.format === "svg") return undefined; // SVGs don't have EXIF data")
  const sharp = await getSharp();
  if (!sharp) return;
  const imagePath = (image as ImageMetadata & { fsPath: string }).fsPath;
  try {

    const buffer = await sharp(imagePath).toBuffer();

    const tags = await ExifReader.load(buffer, { async: true });

    const out: Record<string, any> = {};
    let hasExif = false;

    for (const key of allowedExif) {
      if (!tags[key]) continue;
      hasExif = true;
      out[key] = tags[key]?.description;
    }

    return hasExif ? out : undefined;
  } catch (error) {

    console.log(`Error reading EXIF data from ${imagePath}`, error);
    return undefined
  }

}