*, *::before, *::after {
  box-sizing: border-box;
}

:root {
  --page: #f1f5f9;
  --card: #ffffff;
  --text: #0f172a;
  --muted: #64748b;
  --soft: #f1f5f9;
  --hover: #e2e8f0;
  --accent: #2563eb;
  --accent-soft: #eff6ff;
  --accent-text: #1d4ed8;
  --ring: rgba(15, 23, 42, 0.06);
  --shadow: 0 1px 2px rgba(15, 23, 42, 0.04), 0 16px 36px -12px rgba(15, 23, 42, 0.14);
  --menu-shadow: 0 2px 6px rgba(15, 23, 42, 0.05), 0 24px 48px -12px rgba(15, 23, 42, 0.18);
}

body {
  font-family: system-ui, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
  margin: 0;
  background: var(--page);
  color: var(--text);
}

.page {
  display: grid;
  grid-template-columns: minmax(0, 580px);
  justify-content: center;
  align-content: end;
  min-height: 100vh;
  padding: 20px 16px 36px;
}

.workspace {
  display: flex;
  flex-direction: column;
  gap: 12px;
}

.log {
  display: flex;
  flex-direction: column;
  gap: 8px;
  max-height: 110px;
  padding: 4px 2px;
  overflow-y: auto;
}

.log[hidden] {
  display: none;
}

.log:focus-visible {
  outline: 2px solid var(--accent);
  outline-offset: 2px;
  border-radius: 10px;
}

.sent {
  align-self: flex-end;
  max-width: 88%;
  margin: 0;
  padding: 10px 14px;
  border-radius: 18px 18px 4px 18px;
  background: var(--card);
  box-shadow: 0 1px 3px rgba(15, 23, 42, 0.06);
  font-size: 0.875rem;
  line-height: 1.45;
  overflow-wrap: anywhere;
}

.sent-files {
  display: flex;
  flex-wrap: wrap;
  gap: 6px;
  margin-bottom: 4px;
}

.sent-file {
  padding: 2px 8px;
  border-radius: 6px;
  background: var(--accent-soft);
  color: var(--accent-text);
  font-family: ui-monospace, Consolas, monospace;
  font-size: 0.75rem;
  font-weight: 600;
}

.composer {
  position: relative;
  padding: 14px 14px 12px;
  border-radius: 22px;
  background: var(--card);
  box-shadow: 0 0 0 1px var(--ring), var(--shadow);
  transition: box-shadow 0.15s ease;
}

.composer:focus-within {
  box-shadow: 0 0 0 2px var(--accent), var(--shadow);
}

.menu-wrap {
  position: absolute;
  right: 0;
  bottom: calc(100% + 10px);
  left: 0;
  z-index: 10;
  padding: 6px;
  border-radius: 18px;
  background: var(--card);
  box-shadow: 0 0 0 1px var(--ring), var(--menu-shadow);
}

.menu-wrap[hidden] {
  display: none;
}

.menu-head {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 6px 10px 8px;
}

.menu-title {
  font-size: 0.75rem;
  font-weight: 600;
  color: var(--muted);
}

.menu-kbd {
  font-family: ui-monospace, Consolas, monospace;
  font-size: 0.6875rem;
  color: var(--muted);
}

.menu {
  max-height: 224px;
  margin: 0;
  padding: 0;
  overflow-y: auto;
  list-style: none;
}

.menu-item {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 12px;
  padding: 9px 10px;
  border-radius: 12px;
  cursor: pointer;
}

.menu-item[aria-selected="true"] {
  background: var(--accent-soft);
}

.item-left {
  display: flex;
  align-items: center;
  gap: 10px;
  min-width: 0;
}

.item-ico {
  display: grid;
  place-items: center;
  flex-shrink: 0;
  width: 30px;
  height: 30px;
  border-radius: 8px;
  background: var(--soft);
  color: var(--muted);
}

.item-ico svg {
  width: 16px;
  height: 16px;
  fill: none;
  stroke: currentColor;
  stroke-width: 1.8;
  stroke-linecap: round;
  stroke-linejoin: round;
}

.menu-item[aria-selected="true"] .item-ico {
  background: var(--accent);
  color: #ffffff;
}

.item-key {
  font-family: ui-monospace, Consolas, monospace;
  font-size: 0.875rem;
  font-weight: 600;
  color: var(--text);
}

.menu-item[aria-selected="true"] .item-key {
  color: var(--accent-text);
}

.item-meta {
  overflow: hidden;
  font-size: 0.8125rem;
  color: var(--muted);
  text-overflow: ellipsis;
  white-space: nowrap;
}

.chips {
  display: flex;
  flex-wrap: wrap;
  gap: 6px;
  margin: 0;
  padding: 0 2px 10px;
  list-style: none;
}

.chips:empty {
  display: none;
}

.chip {
  display: inline-flex;
  align-items: center;
  gap: 7px;
  padding: 4px 6px 4px 8px;
  border-radius: 10px;
  background: var(--soft);
  font-size: 0.8125rem;
}

.chip-ico {
  display: grid;
  place-items: center;
  color: var(--accent);
}

.chip-ico svg {
  width: 15px;
  height: 15px;
  fill: none;
  stroke: currentColor;
  stroke-width: 1.9;
  stroke-linecap: round;
  stroke-linejoin: round;
}

.chip-name {
  font-family: ui-monospace, Consolas, monospace;
  font-weight: 600;
}

.chip-meta {
  color: var(--muted);
  font-size: 0.75rem;
}

.chip-remove {
  display: grid;
  place-items: center;
  width: 22px;
  height: 22px;
  padding: 0;
  border: 0;
  border-radius: 6px;
  background: transparent;
  color: var(--muted);
  cursor: pointer;
}

.chip-remove svg {
  width: 13px;
  height: 13px;
  fill: none;
  stroke: currentColor;
  stroke-width: 2;
  stroke-linecap: round;
}

.chip-remove:hover {
  background: var(--hover);
  color: var(--text);
}

textarea {
  display: block;
  width: 100%;
  padding: 2px 4px 8px;
  border: 0;
  outline: 0;
  resize: none;
  background: transparent;
  color: var(--text);
  font: inherit;
  font-size: 0.9375rem;
  line-height: 1.5;
}

textarea::placeholder {
  color: var(--muted);
}

.composer-bar {
  display: flex;
  align-items: center;
  gap: 6px;
  padding-top: 4px;
}

.trigger-btn {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  min-height: 32px;
  padding: 4px 11px 4px 8px;
  border: 0;
  border-radius: 999px;
  background: var(--soft);
  color: var(--text);
  font: inherit;
  font-size: 0.8125rem;
  font-weight: 600;
  cursor: pointer;
  transition: background 0.15s ease, color 0.15s ease;
}

.trigger-btn:hover {
  background: var(--hover);
}

.trigger-btn[aria-expanded="true"] {
  background: var(--accent-soft);
  color: var(--accent-text);
}

.trigger-key {
  display: grid;
  place-items: center;
  width: 18px;
  height: 18px;
  border-radius: 50%;
  background: var(--card);
  color: var(--muted);
  font-family: ui-monospace, Consolas, monospace;
  font-size: 0.75rem;
  font-weight: 700;
}

.trigger-btn[aria-expanded="true"] .trigger-key {
  background: var(--accent);
  color: #ffffff;
}

.hint {
  margin-left: auto;
  padding-right: 4px;
  font-size: 0.75rem;
  color: var(--muted);
}

.send-btn {
  display: grid;
  place-items: center;
  flex-shrink: 0;
  width: 34px;
  height: 34px;
  padding: 0;
  border: 0;
  border-radius: 50%;
  background: var(--text);
  color: var(--card);
  cursor: pointer;
  transition: transform 0.15s ease, opacity 0.15s ease;
}

.send-btn:hover:not(:disabled) {
  transform: translateY(-1px);
}

.send-btn:disabled {
  background: var(--soft);
  color: var(--muted);
  cursor: default;
}

.send-btn svg {
  width: 17px;
  height: 17px;
  fill: none;
  stroke: currentColor;
  stroke-width: 2.1;
  stroke-linecap: round;
  stroke-linejoin: round;
}

.trigger-btn:focus-visible,
.send-btn:focus-visible,
.chip-remove:focus-visible {
  outline: 2px solid var(--accent);
  outline-offset: 2px;
}

.sr-only {
  position: absolute;
  width: 1px;
  height: 1px;
  overflow: hidden;
  clip-path: inset(50%);
  white-space: nowrap;
}

@media (max-width: 480px) {
  .hint {
    display: none;
  }

  .send-btn {
    margin-left: auto;
  }
}

@media (pointer: coarse) {
  .trigger-btn,
  .menu-item,
  textarea {
    min-height: 44px;
  }

  .send-btn,
  .chip-remove {
    width: 44px;
    height: 44px;
  }
}

@media (prefers-color-scheme: dark) {
  :root {
    --page: #0b1120;
    --card: #151e30;
    --text: #f1f5f9;
    --muted: #94a3b8;
    --soft: #1e293b;
    --hover: #293548;
    --accent: #3b82f6;
    --accent-soft: #172554;
    --accent-text: #93c5fd;
    --ring: rgba(255, 255, 255, 0.08);
    --shadow: 0 18px 40px -14px rgba(0, 0, 0, 0.6);
    --menu-shadow: 0 24px 48px -12px rgba(0, 0, 0, 0.75);
  }
}

@media (forced-colors: active) {
  .composer,
  .menu-wrap {
    border: 1px solid CanvasText;
  }

  .menu-item[aria-selected="true"] {
    outline: 2px solid Highlight;
  }
}

const COMMANDS = [
  { key: "/explain", desc: "Explain how the selected code works", icon: "M9.09 9a3 3 0 0 1 5.83 1c0 2-3 3-3 3M12 17h.01M22 12a10 10 0 1 1-20 0 10 10 0 0 1 20 0Z" },
  { key: "/summarize", desc: "Summarize key points and decisions", icon: "M4 6h16M4 12h16M4 18h10" },
  { key: "/refactor", desc: "Clean up structure without changing behavior", icon: "M16 18l6-6-6-6M8 6l-6 6 6 6" },
  { key: "/tests", desc: "Write unit tests for edge cases", icon: "M9 12l2 2 4-4M22 12a10 10 0 1 1-20 0 10 10 0 0 1 20 0Z" }
];

const FILES = [
  { name: "schema.sql", meta: "42 lines", icon: "M12 8c4.42 0 8-1.34 8-3s-3.58-3-8-3-8 1.34-8 3 3.58 3 8 3ZM4 5v14c0 1.66 3.58 3 8 3s8-1.34 8-3V5M4 12c0 1.66 3.58 3 8 3s8-1.34 8-3" },
  { name: "router.js", meta: "118 lines", icon: "M14 2H6a2 2 0 0 0-2 2v16a2 2 0 0 0 2 2h12a2 2 0 0 0 2-2V8l-6-6ZM14 2v6h6M10 13l-2 2 2 2M14 13l2 2-2 2" },
  { name: "auth.js", meta: "84 lines", icon: "M12 22s8-4 8-10V5l-8-3-8 3v7c0 6 8 10 8 10Z" },
  { name: "README.md", meta: "64 lines", icon: "M14 2H6a2 2 0 0 0-2 2v16a2 2 0 0 0 2 2h12a2 2 0 0 0 2-2V8l-6-6ZM14 2v6h6M8 13h8M8 17h5" }
];

const composer = document.getElementById("composer");
const prompt = document.getElementById("prompt");
const menuWrap = document.getElementById("menu-wrap");
const menuTitle = document.getElementById("menu-title");
const menu = document.getElementById("menu");
const chips = document.getElementById("chips");
const log = document.getElementById("log");
const sendBtn = document.getElementById("send");
const slashBtn = document.getElementById("btn-slash");
const mentionBtn = document.getElementById("btn-mention");
const status = document.getElementById("status");

let attached = [];
let activeTrigger = null;
let matches = [];
let activeIndex = 0;

function el(tag, className, text) {
  const node = document.createElement(tag);
  if (className) node.className = className;
  if (text) node.textContent = text;
  return node;
}

function makeIcon(pathData) {
  const ns = "http://www.w3.org/2000/svg";
  const svg = document.createElementNS(ns, "svg");
  const path = document.createElementNS(ns, "path");
  svg.setAttribute("viewBox", "0 0 24 24");
  svg.setAttribute("aria-hidden", "true");
  path.setAttribute("d", pathData);
  svg.append(path);
  return svg;
}

// Match a / or @ token right before the caret
function readTrigger() {
  const caret = prompt.selectionStart;
  const before = prompt.value.slice(0, caret);
  const hit = before.match(/(?:^|\s)([/@])([^\s/@]*)$/);
  if (!hit) return null;
  const symbol = hit[1];
  const query = hit[2].toLowerCase();
  const start = caret - query.length - 1;
  return { symbol: symbol, query: query, start: start, end: caret };
}

function closeMenu() {
  activeTrigger = null;
  matches = [];
  activeIndex = 0;
  menuWrap.hidden = true;
  menu.textContent = "";
  slashBtn.setAttribute("aria-expanded", "false");
  mentionBtn.setAttribute("aria-expanded", "false");
  prompt.removeAttribute("aria-activedescendant");
}

function syncActiveOption() {
  const items = menu.querySelectorAll(".menu-item");
  items.forEach(function(item, i) {
    const selected = i === activeIndex;
    item.setAttribute("aria-selected", String(selected));
    if (selected) {
      prompt.setAttribute("aria-activedescendant", item.id);
      item.scrollIntoView({ block: "nearest" });
    }
  });
}

function renderMenu() {
  menu.textContent = "";
  const isCommand = activeTrigger.symbol === "/";
  menuTitle.textContent = isCommand ? "Commands" : "Workspace files";
  matches.forEach(function(item, i) {
    const li = el("li", "menu-item");
    const left = el("div", "item-left");
    const ico = el("span", "item-ico");
    ico.append(makeIcon(item.icon));
    const key = el("span", "item-key", isCommand ? item.key : "@" + item.name);
    const meta = el("span", "item-meta", isCommand ? item.desc : item.meta);
    li.id = "menu-opt-" + i;
    li.setAttribute("role", "option");
    li.setAttribute("aria-selected", String(i === activeIndex));
    left.append(ico, key);
    li.append(left, meta);
    li.addEventListener("mousedown", function(e) {
      e.preventDefault();
      pickItem(i);
    });
    menu.append(li);
  });
  menuWrap.hidden = false;
  slashBtn.setAttribute("aria-expanded", String(isCommand));
  mentionBtn.setAttribute("aria-expanded", String(!isCommand));
  syncActiveOption();
  status.textContent = matches.length + (matches.length === 1 ? " option" : " options") + " available";
}

function updateMenu() {
  const trigger = readTrigger();
  if (!trigger) {
    closeMenu();
    return;
  }
  const list = trigger.symbol === "/"
    ? COMMANDS.filter(function(c) { return c.key.slice(1).indexOf(trigger.query) === 0; })
    : FILES.filter(function(f) { return f.name.toLowerCase().indexOf(trigger.query) !== -1; });

  if (!list.length) {
    closeMenu();
    return;
  }
  activeTrigger = trigger;
  matches = list;
  if (activeIndex >= matches.length) activeIndex = 0;
  renderMenu();
}

function renderChips() {
  chips.textContent = "";
  attached.forEach(function(file) {
    const li = el("li", "chip");
    const ico = el("span", "chip-ico");
    ico.append(makeIcon(file.icon));
    const name = el("span", "chip-name", file.name);
    const meta = el("span", "chip-meta", file.meta);
    const btn = el("button", "chip-remove");
    btn.type = "button";
    btn.setAttribute("aria-label", "Remove " + file.name);
    btn.append(makeIcon("M18 6L6 18M6 6l12 12"));
    btn.addEventListener("click", function() {
      attached = attached.filter(function(f) { return f.name !== file.name; });
      renderChips();
      updateSend();
      status.textContent = "Removed " + file.name;
      prompt.focus();
    });
    li.append(ico, name, meta, btn);
    chips.append(li);
  });
}

function pickItem(index) {
  const item = matches[index];
  if (!item || !activeTrigger) return;
  if (activeTrigger.symbol === "/") {
    const replacement = item.key + " ";
    prompt.setRangeText(replacement, activeTrigger.start, activeTrigger.end, "end");
    status.textContent = "Inserted " + item.key;
  } else {
    prompt.setRangeText("", activeTrigger.start, activeTrigger.end, "end");
    if (!attached.some(function(f) { return f.name === item.name; })) {
      attached.push(item);
      renderChips();
    }
    status.textContent = "Attached " + item.name;
  }
  closeMenu();
  updateSend();
  prompt.focus();
}

function updateSend() {
  sendBtn.disabled = !prompt.value.trim() && !attached.length;
}

function insertTrigger(symbol) {
  prompt.focus();
  const pos = prompt.selectionStart;
  const before = prompt.value.slice(0, pos);
  const pad = before.length && !/\s$/.test(before) ? " " : "";
  prompt.setRangeText(pad + symbol, pos, prompt.selectionEnd, "end");
  updateMenu();
  updateSend();
}

function send() {
  const text = prompt.value.trim();
  if (!text && !attached.length) return;
  log.hidden = false;
  const card = el("div", "sent");
  if (attached.length) {
    const filesRow = el("div", "sent-files");
    attached.forEach(function(f) {
      filesRow.append(el("span", "sent-file", "@" + f.name));
    });
    card.append(filesRow);
  }
  if (text) card.append(el("div", "", text));
  log.append(card);
  log.scrollTop = log.scrollHeight;
  status.textContent = "Sent prompt";
  prompt.value = "";
  attached = [];
  renderChips();
  closeMenu();
  updateSend();
}

prompt.addEventListener("keydown", function(e) {
  if (e.isComposing || e.keyCode === 229) return;
  if (!menuWrap.hidden) {
    if (e.key === "ArrowDown") {
      e.preventDefault();
      activeIndex = (activeIndex + 1) % matches.length;
      syncActiveOption();
      return;
    }
    if (e.key === "ArrowUp") {
      e.preventDefault();
      activeIndex = (activeIndex - 1 + matches.length) % matches.length;
      syncActiveOption();
      return;
    }
    if (e.key === "Enter" || e.key === "Tab") {
      e.preventDefault();
      pickItem(activeIndex);
      return;
    }
    if (e.key === "Escape") {
      e.preventDefault();
      closeMenu();
      return;
    }
  }
  if (e.key === "Backspace" && !prompt.value && attached.length) {
    const removed = attached.pop();
    renderChips();
    updateSend();
    status.textContent = "Removed " + removed.name;
    return;
  }
  if (e.key === "Enter" && !e.shiftKey) {
    e.preventDefault();
    send();
  }
});

prompt.addEventListener("input", function() {
  updateMenu();
  updateSend();
});

prompt.addEventListener("click", updateMenu);
prompt.addEventListener("keyup", function(e) {
  if (e.key === "ArrowLeft" || e.key === "ArrowRight") updateMenu();
});

slashBtn.addEventListener("click", function() {
  insertTrigger("/");
});

mentionBtn.addEventListener("click", function() {
  insertTrigger("@");
});

composer.addEventListener("submit", function(e) {
  e.preventDefault();
  send();
});

document.addEventListener("pointerdown", function(e) {
  if (!composer.contains(e.target)) closeMenu();
});

// Start with a file attached and the command menu open
attached = [FILES[0]];
renderChips();
prompt.value = "/";
prompt.setSelectionRange(1, 1);
updateMenu();
updateSend();