const state = {
  page: null,
  selected: null,
  clipboard: null,
};

const el = {
  regions: document.querySelector("#regions"),
  reload: document.querySelector("#reload"),
  save: document.querySelector("#save"),
  render: document.querySelector("#render"),
  status: document.querySelector("#status"),
  empty: document.querySelector("#empty-state"),
  form: document.querySelector("#block-form"),
  selectedRegion: document.querySelector("#selected-region"),
  selectedTitle: document.querySelector("#selected-title"),
  id: document.querySelector("#block-id"),
  label: document.querySelector("#block-label"),
  template: document.querySelector("#block-template"),
  anchor: document.querySelector("#block-anchor"),
  enabled: document.querySelector("#block-enabled"),
  json: document.querySelector("#block-json"),
  moveUp: document.querySelector("#move-up"),
  moveDown: document.querySelector("#move-down"),
  duplicate: document.querySelector("#duplicate"),
  copy: document.querySelector("#copy"),
  pasteAfter: document.querySelector("#paste-after"),
  deleteBlock: document.querySelector("#delete-block"),
};

function setStatus(message) {
  el.status.textContent = message;
}

function clone(value) {
  return JSON.parse(JSON.stringify(value));
}

function activeRegion() {
  if (!state.selected) return null;
  return state.page.regions[state.selected.regionIndex];
}

function activeBlock() {
  const region = activeRegion();
  if (!region || state.selected.blockIndex == null) return null;
  return region.blocks[state.selected.blockIndex];
}

function uniqueId(base) {
  const ids = new Set(state.page.regions.flatMap((region) => region.blocks.map((block) => block.id)));
  let candidate = `${base}-copy`;
  let index = 2;

  while (ids.has(candidate)) {
    candidate = `${base}-copy-${index}`;
    index += 1;
  }

  return candidate;
}

function renderRegions() {
  el.regions.innerHTML = "";

  state.page.regions.forEach((region, regionIndex) => {
    const regionNode = document.createElement("section");
    const title = document.createElement("h3");
    const list = document.createElement("div");

    title.className = "region-title";
    title.textContent = region.label || region.id;
    list.className = "block-list";

    region.blocks.forEach((block, blockIndex) => {
      const button = document.createElement("button");
      const meta = document.createElement("span");
      const isActive =
        state.selected?.regionIndex === regionIndex && state.selected?.blockIndex === blockIndex;

      button.type = "button";
      button.className = `block-btn${isActive ? " active" : ""}${block.enabled === false ? " disabled" : ""}`;
      button.textContent = block.adminLabel || block.id;
      meta.className = "block-meta";
      meta.textContent = `${block.id} · ${block.template}`;
      button.append(meta);
      button.addEventListener("click", () => {
        state.selected = { regionIndex, blockIndex };
        renderAll();
      });

      list.append(button);
    });

    regionNode.append(title, list);
    el.regions.append(regionNode);
  });
}

function renderEditor() {
  const region = activeRegion();
  const block = activeBlock();

  if (!block) {
    el.empty.classList.remove("hidden");
    el.form.classList.add("hidden");
    el.selectedRegion.textContent = "Выберите блок";
    el.selectedTitle.textContent = "Контентный слой";
    return;
  }

  el.empty.classList.add("hidden");
  el.form.classList.remove("hidden");
  el.selectedRegion.textContent = region.label || region.id;
  el.selectedTitle.textContent = block.adminLabel || block.id;
  el.id.value = block.id || "";
  el.label.value = block.adminLabel || "";
  el.template.value = block.template || "";
  el.anchor.value = block.anchor || "";
  el.enabled.checked = block.enabled !== false;
  el.json.value = JSON.stringify(block, null, 2);
}

function renderAll() {
  renderRegions();
  renderEditor();
}

function syncBlockFromFields() {
  const block = activeBlock();
  if (!block) return;

  block.id = el.id.value.trim();
  block.adminLabel = el.label.value.trim();
  block.anchor = el.anchor.value.trim() || null;
  block.enabled = el.enabled.checked;
  el.json.value = JSON.stringify(block, null, 2);
  renderRegions();
}

function syncBlockFromJson() {
  const region = activeRegion();
  if (!region) return false;

  try {
    const parsed = JSON.parse(el.json.value);
    region.blocks[state.selected.blockIndex] = parsed;
    renderAll();
    setStatus("JSON блока применён локально. Нажмите «Сохранить JSON», чтобы записать файл.");
    return true;
  } catch (error) {
    setStatus(`Ошибка JSON: ${error.message}`);
    return false;
  }
}

async function loadPage() {
  const response = await fetch("/api/page/home");
  if (!response.ok) throw new Error(await response.text());
  state.page = await response.json();
  state.selected = null;
  renderAll();
  setStatus("Модель home.json загружена.");
}

async function savePage() {
  if (activeBlock()) syncBlockFromFields();

  const response = await fetch("/api/page/home", {
    method: "PUT",
    headers: { "content-type": "application/json" },
    body: JSON.stringify(state.page),
  });

  if (!response.ok) throw new Error(await response.text());
  setStatus("content/pages/home.json сохранён.");
}

async function renderHome() {
  const response = await fetch("/api/render/home", { method: "POST" });
  const payload = await response.json();

  if (!response.ok || !payload.ok) {
    throw new Error(payload.error || "Render failed");
  }

  setStatus(payload.stdout || "index.html собран.");
}

function moveSelected(delta) {
  const region = activeRegion();
  const index = state.selected?.blockIndex;
  if (!region || index == null) return;

  const nextIndex = index + delta;
  if (nextIndex < 0 || nextIndex >= region.blocks.length) return;

  const [block] = region.blocks.splice(index, 1);
  region.blocks.splice(nextIndex, 0, block);
  state.selected.blockIndex = nextIndex;
  renderAll();
}

function duplicateSelected() {
  const region = activeRegion();
  const block = activeBlock();
  if (!region || !block) return;

  const duplicate = clone(block);
  duplicate.id = uniqueId(block.id);
  duplicate.adminLabel = `${block.adminLabel || block.id} — копия`;
  duplicate.scopeIds = true;
  region.blocks.splice(state.selected.blockIndex + 1, 0, duplicate);
  state.selected.blockIndex += 1;
  renderAll();
}

function copySelected() {
  const block = activeBlock();
  if (!block) return;

  state.clipboard = clone(block);
  setStatus(`Скопирован блок: ${block.adminLabel || block.id}`);
}

function pasteAfterSelected() {
  const region = activeRegion();
  if (!region || !state.clipboard) return;

  const pasted = clone(state.clipboard);
  pasted.id = uniqueId(pasted.id);
  pasted.adminLabel = `${pasted.adminLabel || pasted.id} — вставка`;
  pasted.scopeIds = true;
  region.blocks.splice(state.selected.blockIndex + 1, 0, pasted);
  state.selected.blockIndex += 1;
  renderAll();
}

function deleteSelected() {
  const region = activeRegion();
  if (!region || state.selected.blockIndex == null) return;

  region.blocks.splice(state.selected.blockIndex, 1);
  state.selected.blockIndex = Math.min(state.selected.blockIndex, region.blocks.length - 1);
  if (state.selected.blockIndex < 0) state.selected = null;
  renderAll();
}

for (const input of [el.id, el.label, el.anchor, el.enabled]) {
  input.addEventListener("input", syncBlockFromFields);
  input.addEventListener("change", syncBlockFromFields);
}

el.json.addEventListener("blur", syncBlockFromJson);
el.reload.addEventListener("click", () => loadPage().catch((error) => setStatus(error.message)));
el.save.addEventListener("click", () => savePage().catch((error) => setStatus(error.message)));
el.render.addEventListener("click", () => renderHome().catch((error) => setStatus(error.message)));
el.moveUp.addEventListener("click", () => moveSelected(-1));
el.moveDown.addEventListener("click", () => moveSelected(1));
el.duplicate.addEventListener("click", duplicateSelected);
el.copy.addEventListener("click", copySelected);
el.pasteAfter.addEventListener("click", pasteAfterSelected);
el.deleteBlock.addEventListener("click", deleteSelected);

loadPage().catch((error) => setStatus(error.message));