/* Brain of Reese — Global Tuning view (phase 27; phase 76 task 01:
 * shell view module).
 *
 * The standalone manager for steering notes: create / list / edit /
 * delete WITHOUT a chat conversation. This module is the single owner
 * of the view's behaviour:
 *
 *   • loadNotes() — GET /api/steering → the newest-first note list
 *     (#tune-list) + the empty state. A failed fetch (API down, or the
 *     anonymous direct-URL 403) keeps the LAST RENDERED list —
 *     progressive enhancement, never a blanked panel.
 *   • create — #tune-form submit → POST /api/steering. 201 clears the
 *     textarea, announces through the live region, and reloads the
 *     list; any failure keeps the form (the instruction survives) and
 *     shows the API detail inline under the button (role=alert).
 *     #tune-save is disabled while the request is out.
 *   • edit — a row's Edit button swaps the text for an inline
 *     .tuning-edit-form: a prefilled textarea (maxlength 2000) +
 *     Save / Cancel. Save → PUT /api/steering/{id}; 200 replaces the
 *     form with the .tuning-saved status (role=status) and announces;
 *     a failure keeps the form + an inline error; Cancel reverts to
 *     the text span. The note id rides on the form (data attribute).
 *   • delete — DELETE /api/steering/{id}. 204 removes the row
 *     immediately (optimistic) and announces; 404 also drops the row
 *     and reloads to resync; other failures re-enable the button and
 *     announce a retry. The empty state is re-checked on every removal.
 *   • announce(msg) — #tune-announcer (role=status, aria-live=polite),
 *     the screen-reader confirmation for create / edit / delete.
 *
 * Phase 76 (task 01) — shell view module (the "Global Tuning" view of
 * the ONE-document shell; /tuning.html now serves the shell, and
 * assets/router.js lazy-imports THIS module on first show):
 *
 *   • the top-level boot is now `export async function mount(root)` —
 *     root is the view's <section id="view-tuning">, and every DOM
 *     lookup scopes to root (the view ids stay unique across the
 *     shell — scoped lookups keep the module honest and testable).
 *     The router mounts a view ONCE (mount-once, hide-forever), so
 *     the binding + state survive every switch.
 *   • the initSharedHeader() call is DROPPED: in the shell the shared
 *     header boots exactly once, via the chat module (app.js) at shell
 *     boot — the view never re-boots it. The admin gate keeps
 *     fetchIsAdmin() — the SAME cached /api/whoami promise header.js
 *     exports (zero extra requests; the flag decides whether the note
 *     list loads at all, the Sources-page gate pattern).
 *
 * Anonymous-safe (phase 27 task 03, unchanged in the shell): the
 * header hides the "Tuning" nav link for anonymous visitors; a DIRECT
 * anonymous URL still gets a safe view — loadNotes() only runs when
 * the cached whoami says admin, the list stays on its empty state,
 * and the create form 403s gracefully on submit (the inline error
 * carries the API detail). Note text is always rendered with
 * textContent — never innerHTML (XSS-safe, like app.js's steering
 * panel).
 *
 * The shared header module loads through this script's own relative
 * import ("./header.js") — a hoisted import evaluated before this body
 * runs (single-evaluation design: no direct <script> tag; in the
 * image the Containerfile's esbuild stage inlines it — today into the
 * router bundle, phase 76 task 01).
 */

import { fetchIsAdmin } from "./header.js";

export async function mount(root) {
  /* ---------- page elements (the view's section, scoped to root) ---------- */
  const tuneForm = root.querySelector("#tune-form");
  const tuneNote = root.querySelector("#tune-note");
  const tuneSave = root.querySelector("#tune-save");
  const tuneList = root.querySelector("#tune-list");
  const tuneEmpty = root.querySelector("#tune-empty");
  const tuneAnnouncer = root.querySelector("#tune-announcer");

  /* The create form's inline error (role=alert) — created once, hidden
     by default, and kept between attempts: a failed POST keeps the
     form AND its message until the next submit. */
  const createError = document.createElement("p");
  createError.className = "tuning-error";
  createError.setAttribute("role", "alert");
  createError.hidden = true;
  if (tuneForm) tuneForm.appendChild(createError);

  /* Polite live region: the screen-reader confirmation for create /
     edit / delete (task 03). */
  function announce(message) {
    if (tuneAnnouncer) tuneAnnouncer.textContent = message;
  }

  /* Row-action icons — inline SVG constants (aria-hidden; the buttons
     carry their own labels), the same marks as app.js's steering panel. */
  const EDIT_ICON =
    '<svg aria-hidden="true" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="1.7" stroke-linecap="round" stroke-linejoin="round"><path d="M4 20l1.2-4.2L16.7 4.3a2.1 2.1 0 0 1 3 3L8.2 18.8 4 20Z"/><path d="M14.7 6.3l3 3"/></svg>';
  const DELETE_ICON =
    '<svg aria-hidden="true" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="1.8" stroke-linecap="round"><path d="M5 7h14M10 7V5h4v2M8.5 7l.7 12h5.6l.7-12"/></svg>';

  /* FastAPI error bodies: a string detail or the validation-error array
     (the first entry's msg is the human line). Same extraction as app.js. */
  async function apiDetail(r, fallback) {
    try {
      const data = await r.json();
      if (Array.isArray(data.detail) && data.detail[0] && data.detail[0].msg) {
        return String(data.detail[0].msg);
      }
      if (typeof data.detail === "string" && data.detail) return data.detail;
    } catch {
      /* non-JSON error body */
    }
    return fallback;
  }

  /* ---------- load / render (newest first — the API's list order) ---------- */

  /* GET /api/steering → render. A failed fetch (API down, or the 403 on
     an anonymous direct-URL visit) keeps the last rendered list —
     progressive enhancement, never a blanked panel. */
  async function loadNotes() {
    let r;
    try {
      r = await fetch("/api/steering");
    } catch {
      return; // API unreachable: keep the last rendered list
    }
    if (!r.ok) return; // e.g. anonymous 403: keep the last rendered list
    let notes;
    try {
      notes = (await r.json()).notes || [];
    } catch {
      return; // corrupt body: keep the last rendered list
    }
    renderNotes(notes);
  }

  function renderNotes(notes) {
    if (!tuneList) return;
    tuneList.textContent = "";
    for (const n of notes) tuneList.appendChild(makeNoteRow(n));
    syncEmptyState(notes.length);
  }

  /* The empty state tracks the list's rendered rows (the HTML ships on
     the "No tuning notes yet" text; it hides as soon as one row shows). */
  function syncEmptyState(count) {
    if (!tuneEmpty || !tuneList) return;
    const rows = typeof count === "number" ? count : tuneList.children.length;
    tuneEmpty.hidden = rows > 0;
  }

  /* One list row: the note text (textContent — XSS-safe, never
     innerHTML) + the Edit and Delete buttons. */
  function makeNoteRow(n) {
    const li = document.createElement("li");
    li.className = "tuning-note";

    const text = document.createElement("span");
    text.className = "tuning-note-text";
    text.textContent = n.note; // rendered as text, never as HTML
    li.appendChild(text);

    const editBtn = document.createElement("button");
    editBtn.type = "button";
    editBtn.className = "tuning-edit";
    editBtn.innerHTML = EDIT_ICON + "<span>Edit</span>";
    editBtn.addEventListener("click", () => openEditForm(li, n));

    const delBtn = document.createElement("button");
    delBtn.type = "button";
    delBtn.className = "tuning-delete";
    delBtn.setAttribute("aria-label", `Delete tuning note: ${n.note}`);
    delBtn.innerHTML = DELETE_ICON + "<span>Delete</span>";
    delBtn.addEventListener("click", () => deleteNote(n.id, delBtn, li));

    li.append(editBtn, delBtn);
    return li;
  }

  /* ---------- create (POST /api/steering) ---------- */

  if (tuneForm) {
    tuneForm.addEventListener("submit", async (e) => {
      e.preventDefault();
      if (tuneSave) tuneSave.disabled = true; // one note per click
      createError.hidden = true;
      try {
        const r = await fetch("/api/steering", {
          method: "POST",
          headers: { "Content-Type": "application/json" },
          body: JSON.stringify({ note: tuneNote ? tuneNote.value : "" }),
        });
        if (r.ok) {
          if (tuneNote) tuneNote.value = ""; // 201: the note is stored
          announce("Tuning note added. Future answers will follow it.");
          await loadNotes(); // the new note lands in the list, newest first
        } else {
          createError.textContent = await apiDetail(r, "Could not add the note — try again.");
          createError.hidden = false; // form kept — the instruction survives
        }
      } catch {
        createError.textContent = "Could not add the note — is the app reachable?";
        createError.hidden = false;
      } finally {
        if (tuneSave) tuneSave.disabled = false;
      }
    });
  }

  /* ---------- edit (inline form → PUT /api/steering/{id}) ----------
   * The row swaps to the inline form — the is-editing class does the
   * visual swap (styles.css hides the text + the row buttons). One open
   * form view-wide: opening a new one reverts the others. Cancel reverts
   * to the text span; a failed save keeps the form + the inline error.
   */
  let editSeq = 0; // unique ids for the edit forms' labeled textareas

  function openEditForm(li, n) {
    if (li.classList.contains("is-editing")) return; // one per row
    // One open form view-wide: close any other row's first.
    root.querySelectorAll(".tuning-note.is-editing").forEach((other) => {
      other.classList.remove("is-editing");
      other.querySelector(".tuning-edit-form")?.remove();
    });
    li.querySelector(".tuning-saved")?.remove(); // a stale "Saved" pill
    li.classList.add("is-editing");

    editSeq += 1;
    const inputId = `tuning-edit-input-${editSeq}`;
    const form = document.createElement("form");
    form.className = "tuning-edit-form";
    form.dataset.noteId = n.id; // the note id rides on the form

    const label = document.createElement("label");
    label.className = "visually-hidden";
    label.htmlFor = inputId;
    label.textContent = `Edit tuning note: ${n.note}`;

    const textarea = document.createElement("textarea");
    textarea.id = inputId;
    textarea.className = "tuning-edit-input";
    textarea.rows = 2;
    textarea.maxLength = 2000; // client-side 1–2000 contract (server re-validates)
    textarea.required = true;
    textarea.value = n.note; // prefilled with the current text

    const actions = document.createElement("div");
    actions.className = "tuning-edit-form-actions";
    const saveBtn = document.createElement("button");
    saveBtn.type = "submit";
    saveBtn.className = "tune-save";
    saveBtn.textContent = "Save";
    const cancelBtn = document.createElement("button");
    cancelBtn.type = "button";
    cancelBtn.className = "tune-cancel";
    cancelBtn.textContent = "Cancel";
    actions.append(saveBtn, cancelBtn);

    const error = document.createElement("p");
    error.className = "tuning-error";
    error.setAttribute("role", "alert");
    error.hidden = true;

    form.append(label, textarea, actions, error);
    form.addEventListener("submit", (e) => handleEditSave(e, li, form, textarea, saveBtn, error));
    cancelBtn.addEventListener("click", () => {
      li.classList.remove("is-editing"); // revert to the text span
      form.remove();
      li.querySelector(".tuning-edit")?.focus();
    });

    li.insertBefore(form, li.querySelector(".tuning-edit"));
    textarea.focus();
  }

  async function handleEditSave(e, li, form, textarea, saveBtn, error) {
    e.preventDefault();
    saveBtn.disabled = true;
    error.hidden = true;
    const id = form.dataset.noteId;
    try {
      const r = await fetch(`/api/steering/${encodeURIComponent(id)}`, {
        method: "PUT",
        headers: { "Content-Type": "application/json" },
        body: JSON.stringify({ note: textarea.value }),
      });
      if (r.ok) {
        let saved = textarea.value.trim();
        try {
          saved = (await r.json()).note ?? saved;
        } catch {
          /* keep the trimmed local text */
        }
        const textEl = li.querySelector(".tuning-note-text");
        if (textEl) textEl.textContent = saved; // the list shows the stored text
        const savedPill = document.createElement("p");
        savedPill.className = "tuning-saved";
        savedPill.setAttribute("role", "status");
        savedPill.textContent = "Saved";
        form.replaceWith(savedPill);
        li.classList.remove("is-editing"); // updated text + row buttons come back
        announce("Tuning note updated.");
        return;
      }
      error.textContent = await apiDetail(r, "Could not update the note — try again.");
      error.hidden = false; // form kept — the edit survives the failure
      saveBtn.disabled = false;
    } catch {
      error.textContent = "Could not update the note — is the app reachable?";
      error.hidden = false;
      saveBtn.disabled = false;
    }
  }

  /* ---------- delete (DELETE /api/steering/{id}, optimistic) ----------
   * The row leaves the DOM the moment the server agrees (204); a 404
   * (already gone) also drops the row and reloads to resync; any other
   * failure re-enables the button and says to retry. */
  async function deleteNote(id, btn, li) {
    btn.disabled = true;
    try {
      const r = await fetch(`/api/steering/${encodeURIComponent(id)}`, { method: "DELETE" });
      if (r.status === 404) {
        li.remove(); // already gone on the server — drop it and resync
        syncEmptyState();
        announce("That note was already removed.");
        await loadNotes();
        return;
      }
      if (!r.ok) {
        announce("Could not delete the note — try again.");
        btn.disabled = false;
        return;
      }
      li.remove(); // 204: the server confirmed — the row goes now
      syncEmptyState();
      announce("Tuning note deleted.");
    } catch {
      announce("Could not delete the note — is the app reachable?");
      btn.disabled = false;
    }
  }

  /* ---------- view boot (phase 76 task 01) ----------
   * The New chat binding is module-owned (assets/header.js, phase 34
   * task 02 — the SINGLE binding) and lives in the chat view only.
   *
   * Boot: the shared header is NOT booted here — in the shell it runs
   * exactly once, via the chat module (app.js) at shell boot. The note
   * list is admin data (the Sources page gate pattern): the gate reads
   * fetchIsAdmin() — the SAME cached whoami promise the header uses
   * (zero extra requests). An anonymous visitor gets the view frame
   * with the empty state, and the create form 403s gracefully on
   * submit if one tries. */
  if (await fetchIsAdmin()) loadNotes(); // phase 27: the list is admin-only
}