10DLC Phone Number formatting

exports.main = async (event, callback) => {
  var phone = event.inputFields['phone'];

  console.log("Input Phone: ", phone)

  const outputFields = {
    valid: false,
    validation_message: "",
    phone: ""
  }

  validatePhone(phone,outputFields);

  callback({
    outputFields: outputFields
  })

};

function validatePhone(phone, outputFields){
  // Regular expression to match US numbers with or without hyphens, with optional country code
  const regexWithCountryCode = /^\+1-?\d{3}-?\d{3}-?\d{4}$/;
  const regexWithoutCountryCode = /^(\d{3}-?\d{3}-?\d{4})$/;
  if (phone == null) {
    outputFields.valid = false;
    outputFields.validation_message = "Phone number is null";
    outputFields.phone = "";
  } else if (regexWithCountryCode.test(phone)) {
    // The number is in the correct format with the country code
    outputFields.valid = true;
    outputFields.phone = phone.replace(/-/g, ''); // Normalize by removing hyphens
  } else if (regexWithoutCountryCode.test(phone)) {
    // The number matches the US format but lacks the country code
    const normalizedNumber = phone.replace(/-/g, ''); // Remove hyphens for normalization
    outputFields.valid = true;
    outputFields.phone = `+1${normalizedNumber}`; // Prefix with the US country code
  } else {
    // Attempt to correct by stripping non-numeric characters and checking length
    const digitsOnly = phone.replace(/\D/g, '');
    if (digitsOnly.length === 10) {
      // Valid US number without country code
      outputFields.valid = true;
      outputFields.phone = `+1${digitsOnly}`;
    } else if (digitsOnly.length === 11 && digitsOnly.startsWith('1')) {
      // Includes country code but possibly entered with extra characters
      outputFields.valid = true;
      outputFields.phone = `+${digitsOnly}`;
    } else {
      // Cannot be corrected to a valid format
      outputFields.valid = false;
      outputFields.validation_error = 'Cannot correct the number to a valid US phone format';
    }
  }
}
// Author: Alex Carpenter, Feb 2024
// https://github.com/carpcarp/