/* Brain of Reese — document viewer (phase 10).
 *
 * Reads `source`/`path` query params, fetches the stateless content
 * endpoint (GET /api/documents/content — database only, no filesystem),
 * and renders:
 *
 *   • md / markdown  → the shared escape-first renderer (markdown.js) in a
 *                      ≤46rem centered column;
 *   • any other      → the raw content as a text node inside
 *                      <pre class="doc-raw"> (mono, horizontal scroll).
 *
 * XSS-safe by construction: markdown is escaped before transform, raw
 * formats are set via textContent, and every document-derived string
 * (title, badges, path) is written with textContent — never innerHTML.
 *
 * A missing document (unknown pair, missing params, network error) shows
 * the designed not-found card with a link back to the Sources page.
 */

const params = new URLSearchParams(window.location.search);
const source = params.get("source") || "";
const path = params.get("path") || "";

const titleEl = document.querySelector("#doc-title");
const metaEl = document.querySelector("#doc-meta");
const contentEl = document.querySelector("#doc-content");
const notFoundEl = document.querySelector("#doc-not-found");
const mainEl = document.querySelector("#main");
const backLink = document.querySelector("#doc-back");

/* Back: prefer the browser's own history when there is one (the viewer was
 * opened from this tab's session); a fresh tab lands on the Sources page. */
backLink.addEventListener("click", (e) => {
  if (window.history.length > 1) {
    e.preventDefault();
    window.history.back();
  }
});

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

function contentUrl(s, p) {
  return "/api/documents/content?source=" + encodeURIComponent(s) + "&path=" + encodeURIComponent(p);
}

function metaBadge(cls, text) {
  const el = document.createElement("span");
  el.className = cls;
  el.textContent = text;
  return el;
}

function render(doc) {
  titleEl.textContent = doc.title;
  document.title = `${doc.title} · Brain of Reese`;

  const pathCode = document.createElement("code");
  pathCode.className = "doc-path";
  pathCode.textContent = doc.path;
  metaEl.replaceChildren(
    metaBadge("doc-source-badge", doc.source),
    metaBadge("format-badge", doc.format),
    pathCode,
    metaBadge("doc-indexed", `Indexed ${fmtDate(doc.indexed_at)}`),
    metaBadge("doc-chunks", `${doc.chunks} chunk${doc.chunks === 1 ? "" : "s"}`),
  );

  notFoundEl.hidden = true;
  contentEl.replaceChildren();
  if (doc.format === "md" || doc.format === "markdown") {
    const wrap = document.createElement("div");
    wrap.className = "doc-md";
    wrap.innerHTML = renderMarkdown(doc.content); // escape-first: XSS-safe
    contentEl.appendChild(wrap);
  } else {
    const pre = document.createElement("pre");
    pre.className = "doc-raw";
    pre.textContent = doc.content; // text node: never parsed as HTML
    contentEl.appendChild(pre);
  }
}

function showNotFound() {
  titleEl.textContent = "Document not found";
  document.title = "Document not found · Brain of Reese";
  metaEl.replaceChildren();
  contentEl.replaceChildren();
  notFoundEl.hidden = false;
}

async function load() {
  try {
    if (!source || !path) {
      showNotFound();
      return;
    }
    const r = await fetch(contentUrl(source, path));
    if (!r.ok) {
      showNotFound();
      return;
    }
    render(await r.json());
  } catch {
    showNotFound();
  } finally {
    mainEl.focus(); // move focus to main on load (a11y)
  }
}

load();