/**
* Event ID validation utility for Google Calendar API
*/
/**
* Converts w-z characters to valid base32hex (a-d).
* Google Calendar event IDs use base32hex encoding: only a-v and 0-9.
*/
function toBase32Hex(char: string): string {
if (char >= 'w' && char <= 'z') {
return String.fromCharCode(char.charCodeAt(0) - 22); // w->a, x->b, y->c, z->d
}
return '';
}
/**
* Converts a string to valid base32hex by mapping w-z to a-d.
*/
function convertToBase32Hex(str: string): string {
return str.replace(/[w-z]/g, toBase32Hex);
}
/**
* Validates a custom event ID according to Google Calendar requirements
* @param eventId The event ID to validate
* @returns true if valid, false otherwise
*/
export function isValidEventId(eventId: string): boolean {
// Check length constraints (5-1024 characters)
if (eventId.length < 5 || eventId.length > 1024) {
return false;
}
// Check character constraints (base32hex encoding)
// Google Calendar allows only: lowercase letters a-v and digits 0-9
// Based on RFC2938 section 3.1.2
const validPattern = /^[a-v0-9]+$/;
return validPattern.test(eventId);
}
/**
* Validates and throws an error if the event ID is invalid
* @param eventId The event ID to validate
* @throws Error if the event ID is invalid
*/
export function validateEventId(eventId: string): void {
if (!isValidEventId(eventId)) {
const errors: string[] = [];
if (eventId.length < 5) {
errors.push("must be at least 5 characters long");
}
if (eventId.length > 1024) {
errors.push("must not exceed 1024 characters");
}
if (!/^[a-v0-9]+$/.test(eventId)) {
errors.push("can only contain lowercase letters a-v and digits 0-9 (base32hex encoding)");
}
throw new Error(`Invalid event ID: ${errors.join(", ")}`);
}
}
/**
* Sanitizes a string to make it a valid event ID
* Converts to base32hex encoding (lowercase a-v and 0-9 only)
* @param input The input string to sanitize
* @returns A valid event ID
*/
export function sanitizeEventId(input: string): string {
// Convert to lowercase first
let sanitized = input.toLowerCase();
// Replace invalid characters:
// - Keep digits 0-9 as is
// - Map letters w-z to a-d (shift back)
// - Remove other invalid characters
sanitized = sanitized.replace(/[^a-v0-9]/g, toBase32Hex);
// Remove any empty spaces from the mapping
sanitized = sanitized.replace(/\s+/g, '');
// Ensure minimum length
if (sanitized.length < 5) {
// Generate a base32hex timestamp
const timestamp = convertToBase32Hex(Date.now().toString(32));
if (sanitized.length === 0) {
sanitized = `event${timestamp}`.substring(0, 26); // Match Google's 26-char format
} else {
sanitized = `${sanitized}${timestamp}`.substring(0, 26);
}
}
// Ensure maximum length
if (sanitized.length > 1024) {
sanitized = sanitized.slice(0, 1024);
}
// Final validation - ensure only valid characters
sanitized = sanitized.replace(/[^a-v0-9]/g, '');
// If still too short after all operations, generate a default
if (sanitized.length < 5) {
const base32hex = convertToBase32Hex(Date.now().toString(32));
sanitized = `ev${base32hex}`.substring(0, 26);
}
return sanitized;
}
