1 files changed, 85 insertions, 0 deletions
diff --git a/octosentry/UpdateChecker.swift b/octosentry/UpdateChecker.swift
new file mode 100644
index 0000000..e90cab1
--- /dev/null
+++ b/octosentry/UpdateChecker.swift
@@ -0,0 +1,85 @@
+//
+//  UpdateChecker.swift
+//  octosentry
+//
+//  Polls this repo's own GitHub Releases API (spec §9) — no auto-install,
+//  no Sparkle, just a link to the release page. Skipped entirely on the
+//  Mac App Store build, detected at runtime via the presence of an App
+//  Store receipt rather than a separate build configuration: same
+//  outcome (this code never runs there) with far less project surface
+//  than maintaining a second Xcode configuration/scheme just for this.
+//
+
+import Foundation
+
+actor UpdateChecker {
+    private let session: URLSession
+    private let repoOwner = "zerolabsco"
+    private let repoName = "octosentry"
+
+    init(session: URLSession = .shared) {
+        self.session = session
+    }
+
+    struct LatestRelease: Sendable {
+        let version: String
+        let htmlURL: URL
+    }
+
+    func fetchLatestRelease() async throws -> LatestRelease {
+        var request = URLRequest(url: URL(string: "https://api.github.com/repos/\(repoOwner)/\(repoName)/releases/latest")!)
+        request.setValue("application/vnd.github+json", forHTTPHeaderField: "Accept")
+        request.setValue("2022-11-28", forHTTPHeaderField: "X-GitHub-Api-Version")
+
+        let data: Data
+        let response: URLResponse
+        do {
+            (data, response) = try await session.data(for: request)
+        } catch {
+            throw UpdateCheckError.network(error.localizedDescription)
+        }
+
+        guard let httpResponse = response as? HTTPURLResponse, httpResponse.statusCode == 200 else {
+            throw UpdateCheckError.requestFailed
+        }
+
+        let dto: GitHubReleaseDTO
+        do {
+            dto = try JSONDecoder().decode(GitHubReleaseDTO.self, from: data)
+        } catch {
+            throw UpdateCheckError.decodingFailed(error.localizedDescription)
+        }
+
+        guard let url = URL(string: dto.htmlUrl) else {
+            throw UpdateCheckError.decodingFailed("Malformed release URL.")
+        }
+        return LatestRelease(version: dto.tagName, htmlURL: url)
+    }
+}
+
+nonisolated struct GitHubReleaseDTO: Decodable {
+    let tagName: String
+    let htmlUrl: String
+
+    enum CodingKeys: String, CodingKey {
+        case tagName = "tag_name"
+        case htmlUrl = "html_url"
+    }
+}
+
+nonisolated enum UpdateCheckError: Error, LocalizedError {
+    case network(String)
+    case requestFailed
+    case decodingFailed(String)
+
+    var errorDescription: String? {
+        switch self {
+        case .network(let message):
+            "Network error checking for updates: \(message)"
+        case .requestFailed:
+            "Failed to check for updates."
+        case .decodingFailed(let message):
+            "Unexpected response checking for updates: \(message)"
+        }
+    }
+}