const randomChars = () => {
  const uppercaseAsciiStart = 65;
  const letterIndex = Math.floor(Math.random() * 26);
  const letter = String.fromCharCode(uppercaseAsciiStart + letterIndex);

  return letter;
};

const generateNumberPlate = () => {
  const numberPlateLetters = new Array(4);
  const characters: string[] = [];
  for (let index = 0; index <= numberPlateLetters.length; index++) {
    const letter = randomChars();
    characters.push(letter);
  }
  const number = Math.floor(Math.random() * 99);
  characters.splice(2, 0, number + " ");
  const numberPlate = characters.join("");

  return numberPlate;
};

export const generateNumberPlateList = (numberofSightings = 5) => {
  const numberPlates = [];

  for (let i = 0; i <= numberofSightings; i++) {
    numberPlates.push(generateNumberPlate());
  }

  return numberPlates;
};

export const formatNumberPlate = (plate: string) => {
  const splittedPlate = plate?.split("");
  splittedPlate?.splice(4, 0, " ");
  const formattedPlate = splittedPlate?.join("");
  return formattedPlate;
};

export const BLANK_IMG =
  "data:image/gif;base64,R0lGODlhAQABAAAAACH5BAEKAAEALAAAAAABAAEAAAICTAEAOw==";

export function capitalize(s?: string) {
  return s ? s.charAt(0).toUpperCase() + s.slice(1) : "";
}

export function formatAge(tsMillis: number) {
  const ms = Date.now() - tsMillis;
  const seconds = 5 * Math.floor(ms / 5000); // quantize to 5s like the original
  const d = Math.floor(seconds / (3600 * 24));
  const h = Math.floor((seconds % (3600 * 24)) / 3600);
  const m = Math.floor((seconds % 3600) / 60);
  const s = Math.floor(seconds % 60);
  if (d > 0) return `${d}d ago`;
  if (h > 0) return `${h}h ago`;
  if (m > 0) return `${m}m ago`;
  return `${s}s ago`;
}

export function drawRects(
  canvas: HTMLCanvasElement,
  imageEl: HTMLImageElement,
  rects: [number, number, number, number][],
  color: string
) {
  const ctx = canvas.getContext("2d");
  if (!ctx) return;
  // Ensure canvas size matches displayed image size
  const w = imageEl.clientWidth || imageEl.naturalWidth;
  const h = imageEl.clientHeight || imageEl.naturalHeight;
  if (canvas.width !== w) canvas.width = w;
  if (canvas.height !== h) canvas.height = h;

  ctx.imageSmoothingEnabled = false;
  ctx.lineWidth = 1;
  ctx.strokeStyle = color;

  rects.forEach((r) => {
    const [x, y, rw, rh] = r;
    ctx.beginPath();
    ctx.rect(
      Math.round(x * w),
      Math.round(y * h),
      Math.round(rw * w),
      Math.round(rh * h)
    );
    ctx.stroke();
  });
}