Add JSON import and export

app.js

@@ -43,6 +43,7 @@ const PROFILES = {
 
 const STORAGE_KEY = "forgeMasterOptimizer.v1";
 const DRAFT_KEY = "forgeMasterOptimizer.draft.v1";
+const EXPORT_VERSION = 1;
 const slots = [
   ...Array.from({ length: 8 }, (_, i) => ({ type: "item", title: `Item ${i + 1}` })),
   { type: "mount", title: "Mount" },
@@ -358,6 +359,100 @@ function setStatus(message, danger = false) {
   node.style.color = danger ? "var(--danger)" : "var(--good)";
 }
 
+function setImportExportStatus(message, danger = false) {
+  const node = $("#importExportStatus");
+  node.textContent = message;
+  node.style.color = danger ? "var(--danger)" : "var(--good)";
+}
+
+function createExportPayload() {
+  return {
+    app: "forge-master-strategy-optimizer",
+    version: EXPORT_VERSION,
+    exportedAt: new Date().toISOString(),
+    build: normalizeState(state),
+  };
+}
+
+function createExportJson() {
+  return JSON.stringify(createExportPayload(), null, 2);
+}
+
+async function generateExportJson() {
+  const json = createExportJson();
+  const textarea = $("#jsonTransfer");
+  textarea.value = json;
+  textarea.focus();
+  textarea.select();
+  try {
+    await navigator.clipboard.writeText(json);
+    setImportExportStatus("Export JSON generated and copied to clipboard.");
+  } catch {
+    setImportExportStatus("Export JSON generated. Copy it from the text box or download it as a file.");
+  }
+}
+
+function downloadExportJson() {
+  const json = createExportJson();
+  $("#jsonTransfer").value = json;
+  const blob = new Blob([json], { type: "application/json" });
+  const url = URL.createObjectURL(blob);
+  const link = document.createElement("a");
+  link.href = url;
+  link.download = `forge-master-build-${new Date().toISOString().slice(0, 10)}.json`;
+  document.body.appendChild(link);
+  link.click();
+  link.remove();
+  URL.revokeObjectURL(url);
+  setImportExportStatus("Downloaded current build as JSON.");
+}
+
+function parseImportedState(jsonText) {
+  if (!jsonText.trim()) throw new Error("Paste JSON first or upload a JSON file.");
+  let parsed;
+  try {
+    parsed = JSON.parse(jsonText);
+  } catch {
+    throw new Error("Invalid JSON. Check that the full export was copied.");
+  }
+  const build = parsed?.build || parsed;
+  if (!build || typeof build !== "object" || !Array.isArray(build.pieces)) {
+    throw new Error("JSON does not look like a Forge Master build export.");
+  }
+  return normalizeState(build);
+}
+
+function importJsonText(jsonText, sourceLabel = "JSON") {
+  try {
+    state = parseImportedState(jsonText);
+    render();
+    setImportExportStatus(`Imported ${sourceLabel}. Draft autosaved.`);
+  } catch (error) {
+    setImportExportStatus(error.message, true);
+  }
+}
+
+function importPastedJson() {
+  importJsonText($("#jsonTransfer").value, "pasted JSON");
+}
+
+function importUploadedJson(event) {
+  const file = event.target.files?.[0];
+  if (!file) return;
+  const reader = new FileReader();
+  reader.addEventListener("load", () => {
+    const text = String(reader.result || "");
+    $("#jsonTransfer").value = text;
+    importJsonText(text, file.name);
+    event.target.value = "";
+  });
+  reader.addEventListener("error", () => {
+    setImportExportStatus("Could not read the selected file.", true);
+    event.target.value = "";
+  });
+  reader.readAsText(file);
+}
+
 function bindEvents() {
   $("#profileSelect").addEventListener("change", (event) => {
     state.profile = event.target.value;
@@ -381,6 +476,10 @@ function bindEvents() {
   $("#saveSlot").addEventListener("click", saveNamedSlot);
   $("#loadSlot").addEventListener("click", loadNamedSlot);
   $("#deleteSlot").addEventListener("click", deleteNamedSlot);
+  $("#copyExport").addEventListener("click", generateExportJson);
+  $("#downloadExport").addEventListener("click", downloadExportJson);
+  $("#importJson").addEventListener("click", importPastedJson);
+  $("#importFile").addEventListener("change", importUploadedJson);
 }
 
 function handleGearInput(event) {