/* <workshop-words> — the chain of eaten words, capped and pushed out smoothly.
 *
 * The fly eats rarely (~once per ten seconds), and only when hungry; each meal
 * carries the hunger it had, the entropy that drove the pause, and the seconds
 * since the previous meal. The chain is capped at `count` (the author's
 * decision: 20). A new word enters at the right and the oldest is pushed off
 * the left — animated with a FLIP shift so the eviction is a glide, not a jerk
 * (the task's "старые выталкиваются, плавно, без рывка").
 *
 * It is one line on purpose: a chain being pushed through reads as motion,
 * where a wrapping grid would read as a table.
 *
 * Honesty: the fly does not understand these words and does not eat — "eats"
 * and "hungry" are our layers over the brain's state. Only the *content*
 * (which word) is not chosen by anyone; the frame is the author's.
 */
class WorkshopWords extends HTMLElement {
  connectedCallback() {
    this.count = parseInt(this.getAttribute("count") || "20", 10);
    this.nodes = [];
    this.renderEmpty();
    this._off = WorkshopStream.on("word", (ev) => this.push(ev));
  }

  disconnectedCallback() {
    if (this._off) this._off();
  }

  push(ev) {
    const placeholder = this.querySelector(".ww-empty");
    if (placeholder) placeholder.remove();

    // Remember where each current word sits, so after the shift the survivors
    // can glide back to their new places instead of snapping. Both axes, so a
    // word that flows onto the next line moves smoothly too.
    const before = new Map();
    for (const el of this.nodes) {
      const r = el.getBoundingClientRect();
      before.set(el, { x: r.left, y: r.top });
    }

    for (const el of this.nodes) el.classList.remove("ww-fresh");
    const node = this._node(ev);
    node.classList.add("ww-fresh");
    this.appendChild(node);
    this.nodes.push(node);

    let removed = null;
    if (this.nodes.length > this.count) {
      removed = this.nodes.shift();
    }

    // FLIP: place every surviving word back at its old spot, then release it to
    // its real position — a smooth leftward push. The dropped word fades as it
    // leaves so the eviction is seen, not just felt.
    if (removed) {
      removed.classList.add("ww-out");
      const drop = removed;
      const gone = () => drop.remove();
      drop.addEventListener("animationend", gone);
      // Safety: if the animation event never lands (reduced motion, tab in the
      // background), still drop the node so ejected words cannot pile up.
      setTimeout(gone, 800);
      for (const el of this.nodes) {
        const old = before.get(el);
        if (!old) continue; // the just-entered word has no previous position
        const r = el.getBoundingClientRect();
        const dx = old.x - r.left;
        const dy = old.y - r.top;
        if (!dx && !dy) continue;
        el.style.transition = "none";
        el.style.transform = `translate(${dx}px, ${dy}px)`;
        el.getBoundingClientRect(); // force reflow so the reset below animates
        el.style.transition = "transform .34s cubic-bezier(.22,.61,.36,1)";
        el.style.transform = "";
      }
    }
  }

  _node(ev) {
    const el = document.createElement("span");
    el.className = "ww-word";
    const sim = typeof ev.sim === "number" ? ev.sim.toFixed(3) : "—";
    const hunger = typeof ev.hunger === "number" ? ev.hunger.toFixed(2) : "—";
    const entropy = typeof ev.entropy === "number" ? ev.entropy.toFixed(2) : "—";
    const since = typeof ev.since_last_s === "number"
      ? ev.since_last_s.toFixed(1) + "с" : "—";
    el.title = `lang=${ev.lang} sim=${sim} step=${ev.step} ` +
               `hunger=${hunger} entropy=${entropy} с прошлой еды=${since}`;
    el.innerHTML = `${escapeHtml(ev.term)}<i>${sim}</i>`;
    return el;
  }

  renderEmpty() {
    this.innerHTML =
      '<span class="ww-empty">ещё ничего не съедено — муха ждёт настроения и голода</span>';
  }
}

function escapeHtml(s) {
  return String(s).replace(/[&<>"']/g, (c) => ({
    "&": "&amp;", "<": "&lt;", ">": "&gt;", '"': "&quot;", "'": "&#39;",
  })[c]);
}

customElements.define("workshop-words", WorkshopWords);