/* exporter.js — collect busbars into the backend payload and download file. */

const Exporter = (() => {

  function buildPayload(state, params) {
    const cellsById = new Map(state.cells.map((c) => [c.id, c]));
    const busbars = state.busbars.map((bb) => ({
      name: bb.name,
      color: bb.color,
      shape: bb.shape || "panel",
      strip_width:     params.stripWidth,
      pad_radius:      params.padRadius,
      hole_radius:     params.holeRadius,
      hole_shape:      params.holeShape || "cross",
      slit_width:      params.slitWidth,
      neighbor_factor: params.neighborFactor,
      cells: bb.cells
        .map((cid) => {
          const c = cellsById.get(cid);
          return c ? { id: c.id, x: c.x, y: c.y } : null;
        })
        .filter(Boolean),
    }));
    return {
      units: "mm",
      extrude: !!params.extrude,
      thickness: params.thickness,
      busbars,
    };
  }

  async function exportFormat(fmt, state, params) {
    if (!state.busbars.length) {
      alert("Create at least one busbar before exporting.");
      return;
    }
    const payload = buildPayload(state, params);
    const res = await fetch(`/api/export/${fmt}`, {
      method: "POST",
      headers: { "content-type": "application/json" },
      body: JSON.stringify(payload),
    });
    if (!res.ok) {
      let msg;
      try { msg = (await res.json()).error; } catch { msg = await res.text(); }
      alert(`Export failed: ${msg}`);
      return;
    }
    const blob = await res.blob();
    const url = URL.createObjectURL(blob);
    const a = document.createElement("a");
    a.href = url;
    a.download = `busbars.${fmt}`;
    document.body.appendChild(a);
    a.click();
    setTimeout(() => { URL.revokeObjectURL(url); a.remove(); }, 100);
  }

  return { exportFormat, buildPayload };
})();