export function initMiniProjectsMasonry() {
  const lists = document.querySelectorAll("[data-mini-projects-list]");
  if (!lists.length) return null;
  if (lists.length === 1) return initMiniProjectsMasonryList(lists[0]);
  return Array.from(lists, initMiniProjectsMasonryList);
}

function initMiniProjectsMasonryList(list) {
  if (!list) return null;

  const allItems = Array.from(list.querySelectorAll(".mini-projects-grid__item"));
  const extraItems = allItems.filter((el) => el.hasAttribute("data-mp-extra"));
  const baseItems = allItems.filter((el) => !el.hasAttribute("data-mp-extra"));
  const gap = 16;
  let rafId = 0;
  let expanded = false;
  let fullHeight = 0;
  let collapsedHeight = 0;

  extraItems.forEach((el) => el.removeAttribute("hidden"));

  function rowCellsForWidth(w) {
    if (w >= 1180) return 6;
    if (w >= 880) return 4;
    if (w >= 520) return 2;
    return 1;
  }

  function readDeclaredCells(el, rowCells) {
    const full = Number.parseInt(String(el.getAttribute("data-mp-cells")), 10) || 1;
    if (rowCells <= 2) {
      const xs = el.getAttribute("data-mp-cells-xs");
      if (xs != null) {
        const n = Number.parseInt(String(xs), 10);
        if (Number.isFinite(n)) return Math.min(Math.max(n, 1), rowCells);
      }
    }
    if (rowCells <= 4) {
      const sm = el.getAttribute("data-mp-cells-sm");
      if (sm != null) {
        const n = Number.parseInt(String(sm), 10);
        if (Number.isFinite(n)) return Math.min(Math.max(n, 1), rowCells);
      }
    }
    return Math.min(Math.max(full, 1), rowCells);
  }

  function pickStartColumn(heights, rowCells, wCells) {
    let bestC = 0;
    let bestTop = Infinity;
    for (let c = 0; c <= rowCells - wCells; c += 1) {
      let top = 0;
      for (let k = 0; k < wCells; k += 1) {
        top = Math.max(top, heights[c + k]);
      }
      if (top < bestTop || (top === bestTop && c < bestC)) {
        bestTop = top;
        bestC = c;
      }
    }
    return bestC;
  }

  /** Целые ширины клеток в сумме дают внутреннюю ширину ряда (без промежутков между колонками). */
  function integerCellWidths(innerPx, rowCells) {
    if (rowCells <= 0) return [];
    const base = Math.floor(innerPx / rowCells);
    const remainder = innerPx % rowCells;
    const widths = [];
    for (let i = 0; i < rowCells; i += 1) {
      widths.push(base + (i < remainder ? 1 : 0));
    }
    return widths;
  }

  function spanInnerWidth(cellWidths, startCol, wCells) {
    let sum = 0;
    for (let i = 0; i < wCells; i += 1) {
      sum += cellWidths[startCol + i];
    }
    return sum;
  }

  function xAtColumn(cellWidths, startCol) {
    let x = 0;
    for (let i = 0; i < startCol; i += 1) {
      x += cellWidths[i] + gap;
    }
    return x;
  }

  function performLayout() {
    if (!allItems.length) {
      list.style.height = "0px";
      return;
    }

    const listWidth = list.clientWidth;
    const rowCells = rowCellsForWidth(listWidth);
    const innerPx = Math.max(0, listWidth - gap * (rowCells - 1));
    const cellWidths = integerCellWidths(innerPx, rowCells);
    const heights = Array(rowCells).fill(0);
    const positions = new Map();

    allItems.filter((item) => !item.hidden).forEach((item) => {
      const want = readDeclaredCells(item, rowCells);
      let hVal = 0;
      if (rowCells <= 2) {
        const xs = item.getAttribute("data-mp-height-xs");
        if (xs != null) hVal = Number.parseInt(xs, 10) || 0;
      }
      if (!hVal && rowCells <= 4) {
        const sm = item.getAttribute("data-mp-height-sm");
        if (sm != null) hVal = Number.parseInt(sm, 10) || 0;
      }
      if (!hVal) {
        const hAttr = item.getAttribute("data-mp-height");
        if (hAttr) hVal = Number.parseInt(hAttr, 10) || 0;
      }
      item.style.height = hVal > 0 ? `${hVal}px` : "";
      const wCells = Math.min(want, rowCells);
      const c = pickStartColumn(heights, rowCells, wCells);
      let y = 0;
      for (let k = 0; k < wCells; k += 1) {
        y = Math.max(y, heights[c + k]);
      }
      y = Math.round(y);
      const widthPx = spanInnerWidth(cellWidths, c, wCells) + (wCells - 1) * gap;
      const x = xAtColumn(cellWidths, c);
      item.style.width = `${widthPx}px`;
      item.style.transform = `translate(${x}px, ${y}px)`;
      const h = item.offsetHeight;
      const next = y + h + gap;
      for (let k = 0; k < wCells; k += 1) {
        heights[c + k] = next;
      }
      positions.set(item, { y, h });
    });

    fullHeight = Math.max(0, Math.round(Math.max(...heights, 0) - gap) + 1);
    collapsedHeight = 0;
    baseItems.filter((item) => !item.hidden).forEach((item) => {
      const p = positions.get(item);
      if (!p) return;
      collapsedHeight = Math.max(collapsedHeight, Math.round(p.y + p.h) + 1);
    });
    list.style.height = `${expanded ? fullHeight : collapsedHeight}px`;
  }

  function relayout() {
    if (rafId) window.cancelAnimationFrame(rafId);
    rafId = window.requestAnimationFrame(performLayout);
  }

  function relayoutAfterThemeChange() {
    relayout();
    if (document.fonts?.ready) {
      document.fonts.ready.then(relayout);
    }
    window.requestAnimationFrame(() => {
      relayout();
      window.requestAnimationFrame(relayout);
    });
  }

  window.addEventListener("site-theme-applied", relayoutAfterThemeChange, { passive: true });
  window.addEventListener("resize", relayout, { passive: true });
  window.addEventListener("load", relayout, { once: true });
  list.querySelectorAll("img").forEach((img) => {
    if (img.complete) return;
    img.addEventListener("load", () => relayout(), { passive: true });
  });
  relayout();

  function setExpanded(next) {
    expanded = next;
    list.style.height = `${Math.round(expanded ? fullHeight : collapsedHeight)}px`;
  }

  return { list, relayout, setExpanded, extraItems };
}