/**
 * Shared validation utilities
 */

export class ValidationError extends Error {
  constructor(message: string, public field?: string) {
    super(message);
    this.name = 'ValidationError';
  }
}

export function validatePostBody(body: string): void {
  const trimmed = body.trim();

  if (trimmed.length === 0) {
    throw new ValidationError('Post cannot be empty.', 'body');
  }

  if (body.length > 500) {
    throw new ValidationError('Post is too long (max 500 characters).', 'body');
  }
}

export function validateCommentBody(body: string): void {
  const trimmed = body.trim();

  if (trimmed.length === 0) {
    throw new ValidationError('Comment cannot be empty.', 'body');
  }

  if (body.length > 300) {
    throw new ValidationError('Comment is too long (max 300 characters).', 'body');
  }
}

export function validateReportReason(reason: string): void {
  const trimmed = reason.trim();

  if (trimmed.length < 10) {
    throw new ValidationError('Report reason must be at least 10 characters.', 'reason');
  }

  if (reason.length > 500) {
    throw new ValidationError('Report reason is too long (max 500 characters).', 'reason');
  }
}

export function validateUUID(value: string, fieldName: string): void {
  const uuidRegex = /^[0-9a-f]{8}-[0-9a-f]{4}-[0-9a-f]{4}-[0-9a-f]{4}-[0-9a-f]{12}$/i;
  if (!uuidRegex.test(value)) {
    throw new ValidationError(`Invalid ${fieldName}.`, fieldName);
  }
}
