/* Brain of Reese — History page (saved chats, phase 50 task 04).
 *
 * TODO.md L5 (owner 2026-08-29): "Need a way to save and view chat
 * history in a new page, then return to that history with a click."
 *
 * Wires the admin-only `GET /api/chats` + `POST /api/chats/<id>/share`
 * + `POST /api/chats/<id>/unshare` + `DELETE /api/chats/<id>`
 * endpoints (phase 50 task 02; phase 51 task 01+02) into the page's
 * full-width table:
 *
 *   • Title — an `<a href="/?chat=<id>">`: Open IS the title link
 *     ("return to that history with a click") — the chat page boots
 *     into the saved conversation through ?chat= (task 03);
 *   • Messages — the row's message_count;
 *   • Updated — locale date+time, the full ISO in the title attribute;
 *   • Stale — phase 53 (task 04): the READ-ONLY staleness marker,
 *     rendered from the row's `stale` flag (the server computes it —
 *     the client never does staleness math): a rose "Stale" pill when
 *     the row was saved before the last KB-changing sync, an em-dash
 *     when fresh. The Regenerate action is NOT here — it lives on the
 *     chat-page banner (task 05); opening the row is the action;
 *   • Share — phase 51 (owner-locked 2026-08-29, TODO.md L6): the
 *     row's share state, rendered from the list's OWN share_url (the
 *     GET /api/chats endpoint populates it — no second fetch per row).
 *     Three states: unshared → [Create link] (POST share → the cell
 *     re-renders shared + the link is offered for copying); shared →
 *     [Copy] [Unshare]; confirming → the inline two-step "Unshare?
 *     [Yes] [No]" (the phase-50 Delete-confirm pattern + CSS — no
 *     native dialog) — Yes POSTs /api/chats/<id>/unshare (revokes),
 *     the cell re-renders unshared + the live region;
 *   • Actions — Delete, inline TWO-STEP confirm (owner-locked
 *     2026-08-29: no native confirm dialog anywhere in this file) —
 *     the first click swaps the button for
 *     "Delete? [Yes] [No]" (focus moves to Yes, so the confirm is
 *     keyboard-reachable), Yes fires the DELETE and removes the row,
 *     No (or a failed request) keeps it.
 *
 * The share copy has the owner-locked inline-link fallback: a
 * non-secure (http) homelab origin rejects navigator.clipboard, so the
 * offer renders a transient .share-link-fallback <a> field (input-like,
 * selects its full URL on focus) in the row's share cell — this file
 * keeps its OWN copy of the ~10-line helper (the per-page duplication
 * house style; app.js keeps the chat page's) rather than a new shared
 * module.
 *
 * Every cell is built with the DOM APIs (textContent) — the title is
 * user-derived (the auto-title is the first question), so it NEVER
 * touches innerHTML (XSS-safe by construction, the sources.js house
 * rule).
 *
 * The whoami gate (phase 19 shared-header module, cached promise):
 *   • anonymous → the #history-gate is shown, the table is hidden,
 *     and NO /api/chats request is made at all (the router 403s
 *     anonymous — the story E2E pins the request log);
 *   • admin → the gate hides and `loadChats()` renders the rows; a
 *     0-row fetch reveals the empty-state row.
 *
 * Phase 19/34: the page joins the shared header — initSharedHeader()
 * runs first (whoami + nav reveal + the steering panel), and the gate
 * below reuses the SAME cached /api/whoami promise (one request per
 * page).
 */

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

const tableWrap = document.querySelector("#history-table-wrap");
const tbody = document.querySelector("#history-tbody");
const emptyRow = document.querySelector("#history-empty-row");
const gateEl = document.querySelector("#history-gate");
const statusEl = document.querySelector("#history-status");

/* Action feedback — the role="status" live region above the table
   (the "never stale" contract: every row action lands a line here,
   success or failure alike). */
function announce(message) {
  if (statusEl) statusEl.textContent = message;
}

function fmtDate(iso) {
  try {
    return new Date(iso).toLocaleString();
  } catch {
    return iso;
  }
}

/* One row. The Title cell carries the Open link (/?chat=<id> — the
   "return to that history with a click" requirement); the Updated
   cell renders the locale date+time with the full ISO on hover. */
function makeRow(chat) {
  const tr = document.createElement("tr");

  const titleTd = document.createElement("td");
  titleTd.className = "history-title-cell";
  titleTd.title = chat.title; // full title on hover (the column ellipsizes)
  const link = document.createElement("a");
  link.className = "history-title-link";
  link.href = "/?chat=" + chat.id; // Open: the chat page boots into this chat
  link.textContent = chat.title; // user-derived — textContent only
  titleTd.appendChild(link);
  tr.appendChild(titleTd);

  const countTd = document.createElement("td");
  countTd.className = "history-count-cell";
  countTd.textContent = String(chat.message_count);
  tr.appendChild(countTd);

  const updatedTd = document.createElement("td");
  updatedTd.className = "history-updated-cell";
  updatedTd.title = chat.updated_at; // full ISO on hover
  updatedTd.textContent = fmtDate(chat.updated_at);
  tr.appendChild(updatedTd);

  // Phase 53 (task 04): the Stale cell (between Updated and Share) —
  // the READ-ONLY staleness marker. `chat.stale` is computed server-
  // side (task 03), so this branches on the flag, never on versions.
  // Stale rows get the rose pill (the exact hover copy points at the
  // Regenerate action on the chat page, task 05); fresh rows get a
  // plain em-dash. The <td> carries its own aria-label in BOTH states
  // — the marker must be conveyed without the visual (WCAG 2.1 AA).
  const staleTd = document.createElement("td");
  staleTd.className = "history-stale-cell";
  if (chat.stale) {
    staleTd.setAttribute("aria-label", "Stale — sources have changed since this chat was saved");
    const pill = document.createElement("span");
    pill.className = "stale-pill";
    pill.title = "Sources have changed since this chat was saved — open the chat to Regenerate";
    pill.textContent = "Stale";
    staleTd.appendChild(pill);
  } else {
    staleTd.setAttribute("aria-label", "Current — saved against the latest sources");
    staleTd.textContent = "—"; // the em-dash: fresh rows' marker
  }
  tr.appendChild(staleTd);

  // Phase 51: the Share cell (between Updated and Actions) — the
  // three-state share control (unshared / shared / confirming-unshare).
  const shareTd = document.createElement("td");
  shareTd.className = "history-share-cell";
  shareTd.appendChild(makeShareControl(chat));
  tr.appendChild(shareTd);

  const actionsTd = document.createElement("td");
  actionsTd.className = "history-actions-cell";
  actionsTd.appendChild(makeDeleteControl(chat, tr));
  tr.appendChild(actionsTd);
  return tr;
}

/* The inline two-step Delete (owner-locked 2026-08-29 — NO native
   confirm dialog anywhere on this page). The Delete button is
   replaced, in place, by the "Delete? [Yes] [No]" pair; focus moves
   to Yes (keyboard-reachable confirm). Yes → DELETE /api/chats/<id>
   → the row is removed + the live region line; No or a failed
   request keeps the row (+ the error line on failure). */
function makeDeleteControl(chat, row) {
  const cell = document.createElement("span");
  cell.className = "history-actions";

  const del = document.createElement("button");
  del.type = "button";
  del.className = "history-delete";
  del.setAttribute("aria-label", `Delete saved chat: ${chat.title}`);
  del.textContent = "Delete";

  function restoreDelete() {
    cell.replaceChildren(del);
    del.focus(); // focus returns to the (restored) control
  }

  del.addEventListener("click", () => {
    const label = document.createElement("span");
    label.className = "history-confirm-text";
    label.textContent = "Delete?";
    const yes = document.createElement("button");
    yes.type = "button";
    yes.className = "history-confirm-yes";
    yes.textContent = "Yes";
    const no = document.createElement("button");
    no.type = "button";
    no.className = "history-confirm-no";
    no.textContent = "No";
    yes.addEventListener("click", () =>
      confirmDelete(chat, row, yes, restoreDelete));
    no.addEventListener("click", restoreDelete);
    cell.replaceChildren(label, yes, no);
    yes.focus(); // the confirm pair takes over the focus
  });

  cell.appendChild(del); // the shipped state IS the Delete button
  return cell;
}

/* The confirmed delete: DELETE /api/chats/<id> → the row is removed
   (+ the empty-state row reappears when it was the last one) and the
   live region gets `Deleted "<title>".` A 404 means the row is gone
   (deleted elsewhere) — drop the stale row and say so. Any other
   failure or a network error keeps the row, restores the Delete
   button (retryable), and lands the error line. */
async function confirmDelete(chat, row, yesBtn, restoreDelete) {
  yesBtn.disabled = true; // no double-fire while the request is in flight
  let r;
  try {
    r = await fetch(`/api/chats/${chat.id}`, { method: "DELETE" });
  } catch {
    announce(`Couldn't delete "${chat.title}" — is the app reachable?`);
    restoreDelete();
    return;
  }
  if (r.status === 404) {
    row.remove();
    showEmptyIfLast();
    announce("That chat was already deleted.");
    return;
  }
  if (!r.ok) {
    announce(`Couldn't delete "${chat.title}" — try again.`);
    restoreDelete();
    return;
  }
  row.remove();
  showEmptyIfLast();
  announce(`Deleted "${chat.title}".`);
}

/* ---------- share column (phase 51, owner-locked 2026-08-29) ---------- */

/* Select every text node in the link field (an <a> has no .select();
   a range does the job) — best-effort: a selection failure only means
   the user copies by hand. */
function selectAllInField(el) {
  try {
    const range = document.createRange();
    range.selectNodeContents(el);
    const sel = window.getSelection();
    sel.removeAllRanges();
    sel.addRange(range);
  } catch {
    /* selection is best-effort — the field still shows the full URL */
  }
}

/* Clipboard + the owner-locked inline-link fallback: a non-secure
   (http) homelab origin rejects navigator.clipboard, so the failure
   path renders a TRANSIENT <a> link field in the row's share cell —
   input-like, it selects its full URL on focus (click or Tab, then
   Ctrl/Cmd+C). One field at a time (a new offer replaces the old).
   Returns true when the clipboard took it. (The per-page duplication
   house style — this is history.js's OWN copy of the ~10-line helper;
   app.js keeps the chat page's, no new shared module.) */
async function copyShareLink(cell, absoluteUrl) {
  cell.querySelectorAll(".share-link-fallback").forEach((el) => el.remove());
  try {
    await navigator.clipboard.writeText(absoluteUrl);
    return true;
  } catch {
    const field = document.createElement("a");
    field.className = "share-link-fallback";
    field.href = absoluteUrl; // carries the full URL (copy link address works too)
    field.textContent = absoluteUrl; // the URL is data — textContent, never innerHTML
    field.title = "Share link — click, then copy (Ctrl/Cmd+C)";
    field.addEventListener("focus", () => selectAllInField(field));
    cell.appendChild(field);
    field.focus({ preventScroll: true }); // selects the URL — ready to copy
    return false;
  }
}

/* The unshared state: the [Create link] button (a failed share keeps
   the cell here — Create link is retryable). */
function renderShareUnshared(chat, cell) {
  const create = document.createElement("button");
  create.type = "button";
  create.className = "history-share-create";
  create.setAttribute("aria-label", `Create share link: ${chat.title}`);
  create.textContent = "Create link";
  create.addEventListener("click", () => void createShareLink(chat, cell, create));
  cell.replaceChildren(create);
}

/* The shared state: [Copy] [Unshare]. Unshare is the inline two-step
   (the phase-50 Delete-confirm pattern — same .history-confirm-* CSS,
   focus moves to Yes so the confirm is keyboard-reachable); No or a
   failed request restores this state (retryable). */
function renderShareShared(chat, cell) {
  const copy = document.createElement("button");
  copy.type = "button";
  copy.className = "history-share-copy";
  copy.setAttribute("aria-label", `Copy share link: ${chat.title}`);
  copy.textContent = "Copy";
  copy.addEventListener("click", () => void copyRowShareLink(chat, cell));
  const unshare = document.createElement("button");
  unshare.type = "button";
  unshare.className = "history-unshare";
  unshare.setAttribute("aria-label", `Unshare saved chat: ${chat.title}`);
  unshare.textContent = "Unshare";
  function restoreShared() {
    cell.replaceChildren(copy, unshare);
    unshare.focus({ preventScroll: true }); // focus returns to the (restored) control
  }
  unshare.addEventListener("click", () => {
    const label = document.createElement("span");
    label.className = "history-confirm-text";
    label.textContent = "Unshare?";
    const yes = document.createElement("button");
    yes.type = "button";
    yes.className = "history-confirm-yes";
    yes.textContent = "Yes";
    const no = document.createElement("button");
    no.type = "button";
    no.className = "history-confirm-no";
    no.textContent = "No";
    yes.addEventListener("click", () => void confirmUnshare(chat, cell, yes, restoreShared));
    no.addEventListener("click", restoreShared);
    cell.replaceChildren(label, yes, no);
    yes.focus({ preventScroll: true }); // the confirm pair takes over the focus
  });
  cell.replaceChildren(copy, unshare);
}

/* The Share cell (phase 51): the span the row's Share <td> carries.
   The shipped state comes from the row's share_url (the list endpoint
   populates it — no second fetch): shared → Copy + Unshare, unshared →
   Create link. No share action ever removes the ROW (only Delete
   does) — the cell just re-renders between its states. */
function makeShareControl(chat) {
  const cell = document.createElement("span");
  cell.className = "history-share";
  if (chat.share_url) {
    renderShareShared(chat, cell);
  } else {
    renderShareUnshared(chat, cell);
  }
  return cell;
}

/* Create the link: POST /api/chats/<id>/share → the response's
   share_url becomes the row's data (chat.share_url — the later Copy
   uses it), the cell re-renders to the shared state, and the ABSOLUTE
   link (the row's own origin supplies the scheme/host) is offered for
   copying — clipboard → the inline-field fallback in the cell. A
   non-2xx (a 404 — the row was deleted behind our back — or 5xx) or a
   network error keeps the unshared state (Create link re-enabled,
   retryable) and lands the error line. */
async function createShareLink(chat, cell, createBtn) {
  createBtn.disabled = true; // no double-fire while the request is in flight
  let r;
  try {
    r = await fetch(`/api/chats/${chat.id}/share`, { method: "POST" });
  } catch {
    announce(`Couldn't share "${chat.title}" — is the app reachable?`);
    createBtn.disabled = false;
    return;
  }
  if (!r.ok) {
    announce(`Couldn't share "${chat.title}" — try again.`);
    createBtn.disabled = false;
    return;
  }
  const { share_url } = await r.json();
  chat.share_url = share_url; // the row is shared from now on
  renderShareShared(chat, cell);
  const copied = await copyShareLink(
    cell,
    new URL(share_url, window.location.origin).toString(),
  );
  announce(copied ? "Share link copied." : "Share link ready — copy it from the field.");
}

/* Copy (shared state): re-copy the row's share_url — the per-page
   clipboard + fallback helper; the live region lands the outcome. */
async function copyRowShareLink(chat, cell) {
  const copied = await copyShareLink(
    cell,
    new URL(chat.share_url, window.location.origin).toString(),
  );
  announce(copied ? "Share link copied." : "Share link ready — copy it from the field.");
}

/* The confirmed unshare: POST /api/chats/<id>/unshare → the token is
   NULL (revoked — the public link 404s from now on), the cell
   re-renders to the unshared state (Create link) and the live region
   gets `Unshared "<title>".` A non-2xx / a network error keeps the
   shared state (restoreShared — Copy + Unshare, retryable) and lands
   the error line. */
async function confirmUnshare(chat, cell, yesBtn, restoreShared) {
  yesBtn.disabled = true; // no double-fire while the request is in flight
  let r;
  try {
    r = await fetch(`/api/chats/${chat.id}/unshare`, { method: "POST" });
  } catch {
    announce(`Couldn't unshare "${chat.title}" — is the app reachable?`);
    restoreShared();
    return;
  }
  if (!r.ok) {
    announce(`Couldn't unshare "${chat.title}" — try again.`);
    restoreShared();
    return;
  }
  chat.share_url = null; // revoked: the row is unshared again
  renderShareUnshared(chat, cell);
  announce(`Unshared "${chat.title}".`);
}

/* The empty-state row reappears exactly when the last data row was
   removed (the empty row itself ships in the tbody, hidden). */
function showEmptyIfLast() {
  if (!emptyRow || !tbody) return;
  emptyRow.hidden = tbody.querySelectorAll("tr").length > 1;
}

/* 0-row fetches, non-2xx, and network failures all land on the
   empty-state row (the sources.js house fallback — the safe state
   in every case). */
function showEmptyState() {
  if (!tbody) return;
  tbody.replaceChildren(emptyRow);
  if (emptyRow) emptyRow.hidden = false;
}

/* GET /api/chats → render the rows (latest activity first — the
   server's order). A 0-row fetch shows the empty-state row. */
async function loadChats() {
  if (emptyRow) emptyRow.hidden = true;
  let r;
  try {
    r = await fetch("/api/chats");
  } catch {
    showEmptyState();
    return;
  }
  if (!r.ok) {
    showEmptyState();
    return;
  }
  const { chats } = await r.json();
  if (!chats.length) {
    showEmptyState();
    return;
  }
  for (const chat of chats) {
    tbody.appendChild(makeRow(chat));
  }
}

(async () => {
  // Phase 19/34: the shared header first (whoami + nav reveal + the
  // steering panel) — the whoami promise is cached, so the gate below
  // reuses the SAME single /api/whoami request.
  await initSharedHeader();
  if (!(await fetchIsAdmin())) {
    // Anonymous: the gate in, the table out — and NO /api/chats
    // request at all: the router 403s anonymous, so the page must
    // never call it (the story E2E pins the request log).
    if (tableWrap) tableWrap.hidden = true;
    if (gateEl) gateEl.hidden = false;
    return;
  }
  if (gateEl) gateEl.hidden = true;
  loadChats();
})();