/**
 * Converts a File object to a base64 encoded string for Gemini API.
 * @param file - The file to convert.
 * @returns A promise that resolves to a Gemini-compatible `inlineData` object.
 */
export const fileToGenerativePart = async (file: File) => {
  const base64EncodedDataPromise = new Promise<string>((resolve) => {
    const reader = new FileReader();
    reader.onloadend = () => resolve((reader.result as string).split(',')[1]);
    reader.readAsDataURL(file);
  });
  return {
    inlineData: {
      data: await base64EncodedDataPromise,
      mimeType: file.type,
    },
  };
};

/**
 * Calculates the distance between two geographical points in meters using the Haversine formula.
 * @param coords1 - The first set of coordinates { lat, lng }.
 * @param coords2 - The second set of coordinates { lat, lng }.
 * @returns The distance in meters.
 */
export const getDistance = (
  coords1: { lat: number; lng: number },
  coords2: { lat: number; lng: number }
): number => {
  const R = 6371e3; // Earth's radius in metres
  const φ1 = (coords1.lat * Math.PI) / 180;
  const φ2 = (coords2.lat * Math.PI) / 180;
  const Δφ = ((coords2.lat - coords1.lat) * Math.PI) / 180;
  const Δλ = ((coords2.lng - coords1.lng) * Math.PI) / 180;

  const a =
    Math.sin(Δφ / 2) * Math.sin(Δφ / 2) +
    Math.cos(φ1) * Math.cos(φ2) * Math.sin(Δλ / 2) * Math.sin(Δλ / 2);
  const c = 2 * Math.atan2(Math.sqrt(a), Math.sqrt(1 - a));

  return R * c;
};

/**
 * Converts a File object to a data URL string.
 * @param file The file to convert.
 * @returns A promise that resolves with the data URL.
 */
export const fileToDataUrl = (file: File): Promise<string> => {
  return new Promise((resolve, reject) => {
    const reader = new FileReader();
    reader.onload = () => resolve(reader.result as string);
    reader.onerror = reject;
    reader.readAsDataURL(file);
  });
};

/**
 * Parses a data URL into its base64 content and MIME type.
 * @param dataUrl The data URL string.
 * @returns An object with base64 and mimeType, or null if parsing fails.
 */
export const dataUrlToParts = (dataUrl: string): { base64: string; mimeType: string } | null => {
  const match = dataUrl.match(/^data:(.+);base64,(.+)$/);
  if (!match) return null;
  return {
    mimeType: match[1],
    base64: match[2],
  };
};