feat: add extension update check

src/shared/update-check.ts

@@ -0,0 +1,94 @@
+export interface UpdateManifest {
+  guideUrl: string;
+  latestVersion: string;
+  minSupportedVersion: string;
+  publishedAt: string;
+  releaseNotes: string[];
+  zipUrl: string;
+}
+
+export function compareExtensionVersions(left: string, right: string): number {
+  const leftParts = parseVersionParts(left);
+  const rightParts = parseVersionParts(right);
+  const maxLength = Math.max(leftParts.length, rightParts.length);
+
+  for (let index = 0; index < maxLength; index += 1) {
+    const leftValue = leftParts[index] ?? 0;
+    const rightValue = rightParts[index] ?? 0;
+    if (leftValue !== rightValue) {
+      return leftValue - rightValue;
+    }
+  }
+
+  return 0;
+}
+
+export function parseUpdateManifest(value: unknown): UpdateManifest | null {
+  if (!value || typeof value !== "object") {
+    return null;
+  }
+
+  const candidate = value as Partial<UpdateManifest>;
+  if (
+    !isVersionString(candidate.latestVersion) ||
+    !isVersionString(candidate.minSupportedVersion) ||
+    !isHttpsUrl(candidate.zipUrl) ||
+    !isHttpsUrl(candidate.guideUrl) ||
+    typeof candidate.publishedAt !== "string" ||
+    !Array.isArray(candidate.releaseNotes) ||
+    !candidate.releaseNotes.every((note) => typeof note === "string")
+  ) {
+    return null;
+  }
+
+  return {
+    guideUrl: candidate.guideUrl,
+    latestVersion: candidate.latestVersion,
+    minSupportedVersion: candidate.minSupportedVersion,
+    publishedAt: candidate.publishedAt,
+    releaseNotes: candidate.releaseNotes,
+    zipUrl: candidate.zipUrl
+  };
+}
+
+export async function fetchUpdateManifest(
+  manifestUrl: string,
+  fetchImpl: typeof fetch = fetch
+): Promise<UpdateManifest> {
+  const response = await fetchImpl(manifestUrl, {
+    cache: "no-store"
+  });
+  if (!response.ok) {
+    throw new Error(`update manifest request failed: ${response.status}`);
+  }
+
+  const manifest = parseUpdateManifest(await response.json());
+  if (!manifest) {
+    throw new Error("update manifest is invalid");
+  }
+
+  return manifest;
+}
+
+function parseVersionParts(value: string): number[] {
+  return value.split(".").map((part) => {
+    const parsed = Number.parseInt(part, 10);
+    return Number.isFinite(parsed) ? parsed : 0;
+  });
+}
+
+function isVersionString(value: unknown): value is string {
+  return typeof value === "string" && /^\d+(?:\.\d+)*$/.test(value);
+}
+
+function isHttpsUrl(value: unknown): value is string {
+  if (typeof value !== "string") {
+    return false;
+  }
+
+  try {
+    return new URL(value).protocol === "https:";
+  } catch {
+    return false;
+  }
+}

src/shared/update-config.ts

@@ -0,0 +1,2 @@
+export const UPDATE_MANIFEST_URL =
+  "https://example.com/star-chart-search-enhancer/latest.json";