import { buildMailtoUrl } from "./mailto.js";

/** The address the contact form messages are sent to. */
export const MAILTO_TARGET = "hello@example.com";

/**
 * Collect form field values by name.
 * Works with a real DOM form and with the minimal fake form used in tests.
 *
 * @param {{querySelectorAll(selector: string): ArrayLike<{name: string, value: string}>}} form
 * @returns {{name: string, email: string, message: string}}
 */
export function readFormValues(form) {
  const values = {};
  for (const el of form.querySelectorAll("[name]")) {
    values[el.name] = el.value;
  }
  return values;
}

/**
 * Build the mailto: URL for the contact form from the entered values.
 *
 * @param {{name: string, email: string, message: string}} values
 * @param {string} [to]
 * @returns {string}
 */
export function buildContactMailto(values, to = MAILTO_TARGET) {
  const subject = `Contact form submission from ${values.name || "someone"}`;
  const body = [
    `Name: ${values.name || ""}`,
    `Email: ${values.email || ""}`,
    "",
    "Message:",
    values.message || "",
  ].join("\n");
  return buildMailtoUrl({ to, subject, body });
}

/**
 * Handle a contact form submit: build the mailto: URL and send the
 * visitor to it so their mail client opens pre-filled.
 *
 * @param {HTMLFormElement} form
 * @param {{to?: string, navigate?: (url: string) => void}} [options]
 * @returns {string} the mailto: URL that was navigated to
 */
export function handleContactSubmit(
  form,
  { to = MAILTO_TARGET, navigate = (url) => { window.location.href = url; } } = {}
) {
  const url = buildContactMailto(readFormValues(form), to);
  navigate(url);
  return url;
}

/**
 * Wire the submit handler onto a contact form.
 * @param {HTMLFormElement} form
 */
export function initContactForm(form) {
  form.addEventListener("submit", (event) => {
    event.preventDefault();
    handleContactSubmit(form);
  });
}

// Browser-only wiring — guarded so this module stays importable in Node tests.
if (typeof window !== "undefined" && typeof document !== "undefined") {
  const form = document.getElementById("contact-form");
  if (form) initContactForm(form);
}