/* Brain of Reese — the phase-182 VERBATIM panel client (task 07).
 *
 * A ` ```bor <source/path>#12-40 ` locator fence is a CLAIM about a file,
 * never its contents: `markdown.js` (task 06) drops the model's body and
 * paints a `.verbatim.verbatim-pending` placeholder keyed by the canonical
 * locator, and the SERVER (`app.rag.verbatim.resolve_answer_blocks`,
 * task 05) puts the real bytes on the `done` frame as `answer_text`. This
 * file is the other half of that handshake: it RESOLVES the placeholders
 * against the frame's blocks (`hydrateVerbatim`), places the blocks the
 * answer never located (`appendUnlocatedVerbatim`), settles leftovers when
 * a turn ends without a `done` (`settleVerbatimPlaceholders`), gives every
 * settled answer code block a Copy button (`enhanceAnswerCodeBlocks`) and
 * owns the ONE clipboard path (`copyTextWithFallback`).
 *
 * WHY IT IS A CLASSIC SCRIPT, NOT A MODULE (the `markdown.js` pattern):
 * `index.html` and `shared.html` load it as a plain `<script>` right after
 * `markdown.js` and before their page modules, so the top-level function
 * declarations below are globals both module pages can call — the ONE
 * implementation shared by the live turn, the reload restore and the
 * anonymous shared page (parity is the phase's hard requirement). The
 * Containerfile minifies it WITHOUT `--bundle` for the same reason.
 *
 * NO LOCATOR GRAMMAR LIVES HERE (the phase's main drift risk): the canonical
 * string is produced in exactly ONE client place,
 * `markdown.js::borLocator` (the mirror of Python
 * `app.rag.verbatim.canonical_locator`). Hydration reads the already
 * normalized `data-bor-locator` attribute and compares it to the server's
 * `locator` with a plain string `===`. Nothing here re-parses a range,
 * canonicalizes an en dash, or normalizes a path.
 *
 * THE CONTRACT WITH THE SERVER (LOCKED A2/A4/A7):
 *   • `block.text` is painted with `textContent` and copied with
 *     `navigator.clipboard` VERBATIM — no trim, no re-wrap, no join, no
 *     model byte ever substituted in, and the line numbers never enter the
 *     clipboard (they live in the `user-select: none` gutter, a separate
 *     node the copy path never reads);
 *   • the caption's numbers are the SERVER's resolved extent, so a locator
 *     whose range the model got wrong shows what the server actually read
 *     (A2 made visible);
 *   • a locator the server could not resolve says so — the unresolved node
 *     carries NO badge, NO body and NONE of the model's bytes.
 *
 * The house frontend rules hold throughout: every node is built with
 * `createElement` + `textContent` (no HTML string anywhere — the data here
 * is model-written text and indexed file bytes), every handler is attached
 * with `addEventListener` (the CSP is `default-src 'self'`: no inline
 * handlers, no `onclick=`/`oncopy=` attribute), and the states are carried
 * by TEXT and STRUCTURE, never by colour alone (WCAG 1.4.1).
 */

/* The one honest sentence for a locator nothing resolved (the pinned copy —
 * the whole unresolved state is this sentence plus the document link, so a
 * screen reader, a monochrome theme and a screenshot all agree on it). */
function verbatimUnresolvedCopy() {
  return "I could not verify this against the knowledge base";
}

/* The badge's claim, spelled out for the pointer tooltip — the WORD is the
 * signal (locked A5), the tooltip only explains it. */
function verbatimBadgeTitle() {
  return "These bytes are copied from the knowledge base, not written by the model.";
}

/* ---------- the small guards (a malformed frame never throws) ----------
 * `answer_text` crosses the wire, so every field is treated as untrusted
 * shape: a block that is not a plain object with the three fields the panel
 * cannot live without is DROPPED, exactly like the restore path drops a
 * malformed timeline entry. */

function isVerbatimBlock(block) {
  return !!(
    block &&
    typeof block === "object" &&
    typeof block.source === "string" &&
    block.source &&
    typeof block.path === "string" &&
    block.path &&
    typeof block.text === "string"
  );
}

function verbatimBlocks(blocks) {
  return Array.isArray(blocks) ? blocks.filter(isVerbatimBlock) : [];
}

/* A positive line count, or null (a missing/garbage count never prints). */
function verbatimCount(value) {
  return Number.isInteger(value) && value > 0 ? value : null;
}

/* The one `source/path` identity the whole app uses (the read/grep
 * coordinate). NO normalization here — see the header: markdown.js owns the
 * grammar, this only joins the two halves the server already resolved. */
function verbatimIdentity(source, path) {
  return `${source}/${path}`;
}

/* Split a canonical locator into its identity half and its range suffix.
 * The split is on the `#` the server PUT THERE (canonical_locator's own
 * separator) — never a re-parse of the range. */
function verbatimSplitLocator(locator) {
  const text = typeof locator === "string" ? locator : "";
  const hash = text.indexOf("#");
  return hash === -1
    ? { identity: text, hasRange: false }
    : { identity: text.slice(0, hash), hasRange: true };
}

/* The plain viewer href (the shared page's whole affordance — that page has
 * no modal, and the documents API is admin-gated so a guest lands on the
 * sign-in page by design). app.js OVERRIDES this through
 * `opts.documentHref` with `documentUrl(…, "/")`, the chip's own
 * back-to-the-chat URL (phase 153). A rooted path built from
 * encodeURIComponent — never a `javascript:`/`data:` target. */
function verbatimDocumentHref(source, path) {
  return (
    "/document.html?source=" +
    encodeURIComponent(source) +
    "&path=" +
    encodeURIComponent(path)
  );
}

/* ---------- the panel's text pieces ---------- */

/* `homelab/a.md · lines 12–40 of 210`, or `homelab/a.md · all 210 lines`
 * when the block IS the whole document (the caption is the SERVER's extent:
 * `start_line`/`end_line` describe exactly the lines `text` contains after
 * any character cap, so a capped block reads as a range, never as "all"). */
function verbatimCaptionText(block) {
  const identity = verbatimIdentity(block.source, block.path);
  const start = verbatimCount(block.start_line);
  const end = verbatimCount(block.end_line);
  const total = verbatimCount(block.total_lines);
  if (start === null || end === null || end < start) return identity;
  if (!block.truncated && start === 1 && total !== null && end === total) {
    return `${identity} · all ${total} lines`;
  }
  return total === null
    ? `${identity} · lines ${start}–${end}`
    : `${identity} · lines ${start}–${end} of ${total}`;
}

/* `Verbatim text from homelab/a.md, lines 12–40` (the range clause only when
 * the panel shows a range — a whole-document panel is named by its file). */
function verbatimPanelLabel(block) {
  const identity = verbatimIdentity(block.source, block.path);
  const start = verbatimCount(block.start_line);
  const end = verbatimCount(block.end_line);
  if (start === null || end === null || end < start) {
    return `Verbatim text from ${identity}`;
  }
  if (start === end) return `Verbatim text from ${identity}, line ${start}`;
  return `Verbatim text from ${identity}, lines ${start}–${end}`;
}

/* The lines the gutter numbers: one entry per LINE OF THE SERVER TEXT, each
 * `{ shown, number }`. A truncated block's last line is the server's
 * `[…truncated…]` marker — a real line of the panel, but NOT a line of the
 * file, so it gets no number (an empty cell keeps the rows aligned; the
 * phase's rule is that the gutter never claims a coordinate the file does
 * not have). */
function verbatimGutter(block) {
  const lines = String(block.text).split("\n");
  const start = verbatimCount(block.start_line);
  const end = verbatimCount(block.end_line);
  const numbered = start !== null && end !== null && end >= start ? end - start + 1 : 0;
  return lines.map((_, i) => ({
    number: i < numbered ? String(start + i) : "\u00a0",
  }));
}

/* ---------- the controls ---------- */

/* The select-on-focus of the clipboard fallback field (an `<a>` has no
 * `.select()`, a range does the job). Best-effort: a selection failure only
 * means the reader copies by hand — the field still shows the whole text.
 * (app.js's `copyShareLinkWithFallback` used to own this; task 07 moved the
 * pair into verbatim.js so the code blocks and the share link share ONE
 * degradation.) */
function selectAllInFallbackField(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 carries the full text */
  }
}

/* The phase-55 degradation, generalized (LOCKED: the owner-locked share
 * strings and behaviour are unchanged — app.js delegates here).
 * `navigator.clipboard` is unavailable on a non-secure (http) homelab origin
 * and rejects outside a user gesture, so the failure path renders ONE
 * transient link field inside `hostEl` that selects its text on focus
 * (click or Tab, then Ctrl/Cmd+C). Returns true when the clipboard took it.
 * NEVER reads the DOM — the caller hands over the exact string, which is
 * what makes "the clipboard content equals the server text" true. */
async function copyTextWithFallback(text, hostEl, title) {
  const host = hostEl || document.body;
  document.querySelectorAll(".share-link-fallback").forEach((el) => el.remove());
  try {
    await navigator.clipboard.writeText(text);
    return true;
  } catch {
    const field = document.createElement("a");
    field.className = "share-link-fallback";
    // An <a> needs an href to focus; a code block has none, so it takes the
    // tabindex instead and stays a select-to-copy field either way.
    if (/^(?:https?:|mailto:|\/)/i.test(text)) field.href = text;
    else field.tabIndex = 0;
    field.textContent = text; // the text is data — textContent, never innerHTML
    field.title = title || "Click, then copy (Ctrl/Cmd+C)";
    field.addEventListener("focus", () => selectAllInFallbackField(field));
    host.appendChild(field); // beside the control that failed, never elsewhere
    field.focus({ preventScroll: true });
    return false;
  }
}

/* One pill: `Copy` → `Copied` (the TEXT carries the state; `.copied` only
 * supports it — WCAG 1.4.1). The label rides a `<span>` because the clipped
 * label is the CSS ellipsis target (the phase-156 rule) while the control's
 * `aria-label` names the full path. Sticky by design: no timer, so a reader
 * who tabs away and back finds the state the click left. */
function buildCopyButton(className, text, ariaLabel, hostEl) {
  const btn = document.createElement("button");
  btn.type = "button";
  btn.className = className;
  btn.setAttribute("aria-label", ariaLabel);
  const label = document.createElement("span");
  label.textContent = "Copy";
  btn.appendChild(label);
  btn.addEventListener("click", () => {
    copyTextWithFallback(text, hostEl || btn.parentElement, ariaLabel).then((ok) => {
      if (!ok) return; // the field is the feedback (it is focused and selected)
      btn.classList.add("copied");
      label.textContent = "Copied";
    });
  });
  return btn;
}

/* The panel's link to the document. `opts.onOpen(source, path, linkEl)` is
 * the chat page's modal hook (phase 26/153 — left-click opens the viewer IN
 * the page, the href stays the `/document.html` escape hatch for
 * middle-click and copy-link); with no hook the href simply navigates,
 * which is the shared page's whole affordance. */
function buildVerbatimOpenLink(source, path, opts, text) {
  const link = document.createElement("a");
  link.className = "verbatim-open";
  const identity = verbatimIdentity(source, path);
  const href =
    opts && typeof opts.documentHref === "function"
      ? opts.documentHref(source, path)
      : verbatimDocumentHref(source, path);
  link.href = href;
  link.textContent = text || identity;
  link.title = identity; // the full path as the native tooltip (chip pattern)
  if (opts && typeof opts.onOpen === "function") {
    link.addEventListener("click", (event) => {
      event.preventDefault(); // no new tab — the modal takes over
      event.stopPropagation();
      opts.onOpen(source, path, link);
    });
  }
  return link;
}

/* ---------- the panel ---------- */

/* buildVerbatimPanel(block, opts) → the `.verbatim` node.
 *
 *   .verbatim[role=group][aria-label][data-bor-locator]
 *     .verbatim-head                     sticky (PLAN §7.1)
 *       .verbatim-caption  source/path · lines 12–40 of 210   (clipped)
 *       .verbatim-badge    VERBATIM                            (a WORD)
 *       .verbatim-open     → the document viewer               (optional)
 *       .verbatim-copy     Copy → Copied                       (aria-label
 *                                                               names path)
 *     .verbatim-body                     the bounded scroll panel
 *       ol.verbatim-lines  the SERVER's line numbers (user-select: none)
 *       pre.verbatim-text  block.text, byte for byte
 *     .verbatim-more       the truncation line + the link        (optional)
 *
 * `opts = { documentHref, onOpen }` — both optional (see the two builders
 * above). Every value reaches the DOM through `textContent`/`title`/a
 * built `href`: the caption carries indexed text and the aria-labels carry
 * model-written locators, so there is no HTML string to escape. */
function buildVerbatimPanel(block, opts) {
  const identity = verbatimIdentity(block.source, block.path);
  const root = document.createElement("div");
  root.className = "verbatim";
  root.setAttribute("role", "group");
  root.setAttribute("aria-label", verbatimPanelLabel(block));
  // The SERVER's canonical locator is the identity of the placed block (the
  // pending placeholder's own attribute is replaced with it — that is how
  // `appendUnlocatedVerbatim` knows this block already has a home).
  root.dataset.borLocator =
    typeof block.locator === "string" && block.locator
      ? block.locator
      : identity;

  const head = document.createElement("div");
  head.className = "verbatim-head";
  const caption = document.createElement("span");
  caption.className = "verbatim-caption";
  caption.textContent = verbatimCaptionText(block);
  caption.title = verbatimCaptionText(block); // the clipped text stays reachable
  const badge = document.createElement("span");
  badge.className = "verbatim-badge";
  badge.textContent = "VERBATIM";
  badge.title = verbatimBadgeTitle();
  head.append(caption, badge);
  head.appendChild(buildVerbatimOpenLink(block.source, block.path, opts));

  const gutter = verbatimGutter(block);
  // The clipboard's line count (the aria-label's N): the SERVER's extent,
  // not the marker line the cap appended.
  const from = verbatimCount(block.start_line);
  const to = verbatimCount(block.end_line);
  const shown = from !== null && to !== null && to >= from ? to - from + 1 : gutter.length;
  head.appendChild(
    buildCopyButton(
      "verbatim-copy",
      block.text,
      `Copy ${shown} lines from ${identity}`,
      root
    )
  );
  root.appendChild(head);

  const body = document.createElement("div");
  body.className = "verbatim-body";
  const numbers = document.createElement("ol");
  numbers.className = "verbatim-lines";
  numbers.setAttribute("aria-hidden", "true"); // the range rides the panel's label
  for (const row of gutter) {
    const li = document.createElement("li");
    li.textContent = row.number;
    numbers.appendChild(li);
  }
  const pre = document.createElement("pre");
  pre.className = "verbatim-text";
  pre.textContent = block.text; // THE POINT OF THE PHASE: the server's bytes
  body.append(numbers, pre);
  root.appendChild(body);

  if (block.truncated) {
    // One muted line naming where the rest lives, plus the same viewer link
    // — the panel never pretends the slice is the file.
    const more = document.createElement("div");
    more.className = "verbatim-more";
    const note = document.createElement("span");
    note.textContent = "Cut short by the size limit — the rest is in the document. ";
    more.appendChild(note);
    more.appendChild(
      buildVerbatimOpenLink(block.source, block.path, opts, `open ${identity}`)
    );
    root.appendChild(more);
  }
  return root;
}

/* The honest state for a locator the server did not resolve (and for a
 * placeholder no terminal frame ever settled): the sentence, plus the
 * document link ONLY when the identity actually parsed into a
 * `source/path`. NO badge, NO body, NONE of the model's bytes — the fence's
 * own text is already gone (task 06 dropped it), so there is nothing here
 * to leak even by accident. */
function buildVerbatimUnresolved(locator, opts) {
  const root = document.createElement("div");
  root.className = "verbatim verbatim-unresolved";
  root.setAttribute("role", "note");
  const key = typeof locator === "string" ? locator : "";
  if (key) root.dataset.borLocator = key;
  root.dataset.verbatimState = (opts && opts.kind) || "unverified";
  const state = document.createElement("span");
  state.className = "verbatim-state";
  state.textContent = verbatimUnresolvedCopy();
  root.appendChild(state);
  const { identity } = verbatimSplitLocator(key);
  const slash = identity.indexOf("/");
  if (slash > 0 && slash < identity.length - 1) {
    root.appendChild(document.createTextNode(" — open "));
    root.appendChild(
      buildVerbatimOpenLink(identity.slice(0, slash), identity.slice(slash + 1), opts)
    );
  }
  return root;
}

/* ---------- hydration ---------- */

/* The ONE match rule (LOCKED A2 made visible):
 *   1. the canonical locator, compared as PLAIN STRINGS against the
 *      server's `locator` — the attribute markdown.js already normalized;
 *   2. failing that, exactly ONE block sharing the same `source/path`
 *      (the model's RANGE was wrong; the panel shows the server's extent);
 *   3. failing that, null → the unresolved state. An ambiguous identity
 *      (two blocks, same file, different ranges) never guesses. */
function matchVerbatimBlock(blocks, key) {
  for (const block of blocks) {
    if (block.locator === key) return block;
  }
  const identity = verbatimSplitLocator(key).identity;
  const samePath = blocks.filter(
    (block) => verbatimIdentity(block.source, block.path) === identity
  );
  return samePath.length === 1 ? samePath[0] : null;
}

/* hydrateVerbatim(root, blocks, opts) — replace every PENDING placeholder
 * under `root` with its panel, or with the unresolved state.
 *
 * Only `.verbatim-pending` is touched, so the pass is idempotent: a panel
 * this function built (or one restored from storage) is skipped on a re-run,
 * which keeps a `Copied` state and a scrolled body alive. Never throws —
 * a missing/malformed `blocks` settles every placeholder to the honest
 * state instead. Returns the number of placeholders settled. */
function hydrateVerbatim(root, blocks, opts) {
  if (!root || typeof root.querySelectorAll !== "function") return 0;
  const list = verbatimBlocks(blocks);
  let settled = 0;
  root.querySelectorAll(".verbatim-pending[data-bor-locator]").forEach((node) => {
    const key = node.getAttribute("data-bor-locator") || "";
    const block = matchVerbatimBlock(list, key);
    node.replaceWith(
      block ? buildVerbatimPanel(block, opts) : buildVerbatimUnresolved(key, opts)
    );
    settled += 1;
  });
  return settled;
}

/* appendUnlocatedVerbatim(wrap, blocks, opts) — the blocks NO placeholder
 * matched (a `show_text` call whose answer never located the file), appended
 * in the frame's order at the `answer_image` position: below the answer
 * text, above the source clusters (the phase-124/130 DOM order — callers run
 * this BEFORE `appendSources`).
 *
 * State-free idempotence: a block is already placed when the wrap holds a
 * resolved panel carrying its canonical `locator`, so calling this twice
 * (or after a hydration that matched) appends nothing. */
function appendUnlocatedVerbatim(wrap, blocks, opts) {
  if (!wrap || typeof wrap.querySelectorAll !== "function") return 0;
  const list = verbatimBlocks(blocks);
  if (!list.length) return 0;
  const host = wrap.querySelector(".msg-body") || wrap;
  const placed = new Set();
  wrap.querySelectorAll(".verbatim[data-bor-locator]").forEach((el) => {
    // An unresolved placeholder is NOT a placement (it names a locator the
    // server never returned, and the block belongs on screen anyway).
    if (el.classList.contains("verbatim-unresolved")) return;
    placed.add(el.getAttribute("data-bor-locator"));
  });
  let appended = 0;
  for (const block of list) {
    const key =
      typeof block.locator === "string" && block.locator
        ? block.locator
        : verbatimIdentity(block.source, block.path);
    if (placed.has(key)) continue;
    host.appendChild(buildVerbatimPanel(block, opts));
    placed.add(key);
    appended += 1;
  }
  return appended;
}

/* settleVerbatimPlaceholders(root, kind) — the terminal-frame sweep the
 * failure paths run (the `error` frame, the 300 s guard, the Stop action,
 * the failed-turn funnel): a panel NEVER sits at "Retrieving the exact
 * text…" once a turn is over. `kind` is recorded on the node
 * (`data-verbatim-state`) for the next reader; every kind renders the same
 * honest sentence, because "I could not verify this" is the truth for a
 * turn that ended before `done` too. */
function settleVerbatimPlaceholders(root, kind) {
  if (!root || typeof root.querySelectorAll !== "function") return 0;
  let settled = 0;
  root.querySelectorAll(".verbatim-pending").forEach((node) => {
    node.replaceWith(
      buildVerbatimUnresolved(node.getAttribute("data-bor-locator") || "", { kind })
    );
    settled += 1;
  });
  return settled;
}

/* ---------- the ordinary answer code block ---------- */

/* enhanceAnswerCodeBlocks(root) — every `<pre>` inside an answer bubble that
 * is NOT inside a `.verbatim` gets the `.code-block` wrapper and a Copy
 * button, ONCE the turn settled (the callers run it on the settled answer,
 * never mid-stream). NO badge, NO caption: a `VERBATIM` claim belongs only
 * to a server-resolved block (LOCKED A5) — plainly the model's, or verbatim
 * and badged, never a hybrid.
 *
 * Idempotent on re-render: a `<pre>` already inside a `.code-block` is left
 * alone (the live path re-runs the renderer per delta; the restore path runs
 * this once). Returns the number of blocks wrapped. */
function enhanceAnswerCodeBlocks(root) {
  if (!root || typeof root.querySelectorAll !== "function") return 0;
  const bubbles = [];
  if (root.classList && root.classList.contains("bubble")) bubbles.push(root);
  root.querySelectorAll(".bubble").forEach((el) => bubbles.push(el));
  let wrapped = 0;
  for (const bubble of bubbles) {
    bubble.querySelectorAll("pre").forEach((pre) => {
      if (pre.closest(".verbatim")) return; // the panel owns its own Copy
      const parent = pre.parentElement;
      if (!parent || parent.classList.contains("code-block")) return;
      const box = document.createElement("div");
      box.className = "code-block";
      parent.insertBefore(box, pre);
      box.appendChild(pre);
      box.appendChild(
        buildCopyButton(
          "code-block-copy",
          pre.textContent || "",
          "Copy this code block",
          box
        )
      );
      wrapped += 1;
    });
  }
  return wrapped;
}