Add GitHub update checker and installer

Library/Update/GitHubUpdateChecker.swift

@@ -0,0 +1,181 @@
+import Darwin
+import Foundation
+import Libbox
+
+public enum GitHubUpdateChecker {
+    private static let releasesURL = "https://api.github.com/repos/SagerNet/sing-box/releases"
+    private static let releasesPerPage = 100
+    private static let minimumSemver = "0.0.0-0"
+
+    public static func checkAsync(track: UpdateTrack, force: Bool = false) async throws -> UpdateInfo? {
+        try await BlockingIO.run {
+            try check(track: track, force: force)
+        }
+    }
+
+    public static func check(track: UpdateTrack, force: Bool = false) throws -> UpdateInfo? {
+        let client = HTTPClient()
+        guard let releases = try fetchReleases(client: client, track: track) else {
+            return nil
+        }
+        let currentVersion = Bundle.main.version
+
+        var bestRelease: GitHubRelease?
+        var bestVersion: String?
+        var bestAsset: GitHubAsset?
+
+        for release in releases {
+            if release.draft { continue }
+            if track == .stable, release.prerelease { continue }
+            guard let pkgAsset = findPKGAsset(in: release.assets) else { continue }
+
+            let version = release.tagName.hasPrefix("v")
+                ? String(release.tagName.dropFirst())
+                : release.tagName
+
+            guard shouldIncludeRelease(
+                version: version,
+                currentVersion: currentVersion,
+                track: track,
+                force: force
+            ) else { continue }
+
+            if let best = bestVersion {
+                guard LibboxCompareSemver(version, best) else { continue }
+            }
+
+            bestRelease = release
+            bestVersion = version
+            bestAsset = pkgAsset
+        }
+
+        guard let release = bestRelease,
+              let version = bestVersion,
+              let pkgAsset = bestAsset
+        else {
+            return nil
+        }
+
+        return UpdateInfo(
+            versionName: version,
+            releaseURL: release.htmlURL,
+            downloadURL: pkgAsset.browserDownloadURL,
+            releaseNotes: release.body,
+            isPrerelease: release.prerelease,
+            fileSize: pkgAsset.size
+        )
+    }
+
+    private static func findPKGAsset(in assets: [GitHubAsset]) -> GitHubAsset? {
+        let pkgAssets = assets.filter { $0.name.hasSuffix(".pkg") }
+
+        let preferred = preferredPKGVariant()
+
+        if let match = pkgAssets.first(where: { $0.name.contains(preferred) }) {
+            return match
+        }
+        if let universal = pkgAssets.first(where: { $0.name.contains("Universal") }) {
+            return universal
+        }
+        return pkgAssets.first
+    }
+
+    private static func preferredPKGVariant() -> String {
+        if let hostSupportsArm64 = hostSupportsArm64() {
+            return hostSupportsArm64 ? "Apple" : "Intel"
+        }
+
+        #if arch(arm64)
+            return "Apple"
+        #else
+            return "Intel"
+        #endif
+    }
+
+    private static func hostSupportsArm64() -> Bool? {
+        var value: Int32 = 0
+        var size = MemoryLayout.size(ofValue: value)
+        let result = withUnsafeMutablePointer(to: &value) {
+            sysctlbyname("hw.optional.arm64", $0, &size, nil, 0)
+        }
+        guard result == 0 else {
+            return nil
+        }
+        return value != 0
+    }
+
+    private static func shouldIncludeRelease(
+        version: String,
+        currentVersion: String,
+        track: UpdateTrack,
+        force: Bool
+    ) -> Bool {
+        guard isValidSemver(version) else {
+            return false
+        }
+        if force || LibboxCompareSemver(version, currentVersion) {
+            return true
+        }
+        return track == .stable && isValidPrereleaseSemver(currentVersion)
+    }
+
+    private static func isValidSemver(_ version: String) -> Bool {
+        let trimmedVersion = version.trimmingCharacters(in: .whitespacesAndNewlines)
+        return trimmedVersion == minimumSemver || LibboxCompareSemver(trimmedVersion, minimumSemver)
+    }
+
+    private static func isValidPrereleaseSemver(_ version: String) -> Bool {
+        let trimmedVersion = version.trimmingCharacters(in: .whitespacesAndNewlines)
+        return trimmedVersion.contains("-") && isValidSemver(trimmedVersion)
+    }
+
+    private static func fetchReleases(client: HTTPClient, track: UpdateTrack) throws -> [GitHubRelease]? {
+        var allReleases: [GitHubRelease] = []
+        var page = 1
+
+        while true {
+            let releasesJSON = try client.getString("\(releasesURL)?per_page=\(releasesPerPage)&page=\(page)")
+            guard let data = releasesJSON.data(using: .utf8) else {
+                return nil
+            }
+
+            let pageReleases = try JSONDecoder().decode([GitHubRelease].self, from: data)
+            allReleases.append(contentsOf: pageReleases)
+
+            if track != .stable || pageReleases.count < releasesPerPage {
+                return allReleases
+            }
+            page += 1
+        }
+    }
+}
+
+private struct GitHubRelease: Decodable {
+    let tagName: String
+    let htmlURL: String
+    let body: String?
+    let draft: Bool
+    let prerelease: Bool
+    let assets: [GitHubAsset]
+
+    enum CodingKeys: String, CodingKey {
+        case tagName = "tag_name"
+        case htmlURL = "html_url"
+        case body
+        case draft
+        case prerelease
+        case assets
+    }
+}
+
+private struct GitHubAsset: Decodable {
+    let name: String
+    let browserDownloadURL: String
+    let size: Int64
+
+    enum CodingKeys: String, CodingKey {
+        case name
+        case browserDownloadURL = "browser_download_url"
+        case size
+    }
+}