// The mail page's one script (novox/hq ADR 0515 §6; issue 1859). It talks only to the page's own origin:
// ticking, undoing, reminding and correcting post their form without a reload and put the list (and the
// reading pane) back as the page now answers it. Without it, every form still works by an ordinary post.
// An act that fails is said on the page, with its cause (ADR 0517 §5).
"use strict";

(function () {
  function say(text) {
    var list = document.getElementById("list");
    if (!list) {
      return;
    }
    var p = document.createElement("p");
    p.className = "notice failed";
    p.setAttribute("role", "alert");
    p.textContent = text;
    list.insertBefore(p, list.firstChild);
  }

  // Put back the parts of the page this address answers now.
  function refresh() {
    return fetch(location.href, { credentials: "same-origin" })
      .then(function (r) { return r.text(); })
      .then(function (html) {
        var fresh = new DOMParser().parseFromString(html, "text/html");
        ["list", "pane"].forEach(function (id) {
          var now = document.getElementById(id);
          var next = fresh.getElementById(id);
          if (now && next) {
            now.replaceWith(document.importNode(next, true));
          }
        });
      });
  }

  document.addEventListener("submit", function (event) {
    var form = event.target;
    if (!form.classList || !form.classList.contains("act")) {
      return;
    }
    event.preventDefault();
    var buttons = form.querySelectorAll("button");
    buttons.forEach(function (b) { b.disabled = true; });
    fetch(form.getAttribute("action"), {
      method: "POST",
      credentials: "same-origin",
      headers: { "X-Requested-With": "fetch" },
      body: new URLSearchParams(new FormData(form))
    })
      .then(function (r) {
        return r.json().catch(function () { return { failed: "the page answered " + r.status }; });
      })
      .then(function (answer) {
        if (answer.failed) {
          buttons.forEach(function (b) { b.disabled = false; });
          say(answer.failed);
          return;
        }
        if (answer.go) {
          location.assign(answer.go);
          return;
        }
        return refresh();
      })
      .catch(function (err) {
        buttons.forEach(function (b) { b.disabled = false; });
        say("That did not reach the page: " + err);
      });
  });
}());