release: 0.2.0421.2

src/background/index.ts

@@ -0,0 +1,95 @@
+interface ChromeDownloadsLike {
+  download(
+    options: {
+      filename: string;
+      saveAs?: boolean;
+      url: string;
+    },
+    callback?: () => void
+  ): Promise<unknown> | void;
+}
+
+interface ChromeRuntimeLike {
+  onMessage?: {
+    addListener(
+      listener: (
+        message: unknown,
+        sender: unknown,
+        sendResponse: (response: unknown) => void
+      ) => boolean | void
+    ): void;
+  };
+}
+
+interface ChromeLike {
+  downloads?: ChromeDownloadsLike;
+  runtime?: ChromeRuntimeLike;
+}
+
+type DownloadMarketCsvMessage = {
+  csv: string;
+  filename: string;
+  type: "download-market-csv";
+};
+
+export function registerBackgroundMessageHandler(
+  chromeLike: ChromeLike = (
+    globalThis as typeof globalThis & {
+      chrome?: ChromeLike;
+    }
+  ).chrome ?? {}
+): void {
+  chromeLike.runtime?.onMessage?.addListener((message, _sender, sendResponse) => {
+    if (!isDownloadMarketCsvMessage(message)) {
+      return;
+    }
+
+    void triggerCsvDownload(chromeLike, message)
+      .then(() => {
+        sendResponse({ ok: true });
+      })
+      .catch((error) => {
+        sendResponse({
+          error: error instanceof Error ? error.message : String(error),
+          ok: false
+        });
+      });
+
+    return true;
+  });
+}
+
+async function triggerCsvDownload(
+  chromeLike: ChromeLike,
+  message: DownloadMarketCsvMessage
+): Promise<void> {
+  if (!chromeLike.downloads?.download) {
+    throw new Error("chrome.downloads.download is unavailable");
+  }
+
+  const csvUrl = `data:text/csv;charset=utf-8,${encodeURIComponent(`\uFEFF${message.csv}`)}`;
+  await Promise.resolve(
+    chromeLike.downloads.download({
+      filename: message.filename,
+      saveAs: false,
+      url: csvUrl
+    })
+  );
+}
+
+function isDownloadMarketCsvMessage(
+  message: unknown
+): message is DownloadMarketCsvMessage {
+  if (!message || typeof message !== "object") {
+    return false;
+  }
+
+  const candidate = message as Partial<DownloadMarketCsvMessage>;
+  return (
+    candidate.type === "download-market-csv" &&
+    typeof candidate.csv === "string" &&
+    typeof candidate.filename === "string"
+  );
+}
+
+registerBackgroundMessageHandler();