first commit

node_modules/expo-asset/ios/AssetModule.swift

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+import ExpoModulesCore
+import CryptoKit
+
+internal final class UnableToDownloadAssetException: GenericException<URL> {
+  override var reason: String {
+    "Unable to download asset from url: '\(param.absoluteString)'"
+  }
+}
+
+internal final class UnableToSaveAssetToDirectoryException: GenericException<URL> {
+  override var reason: String {
+    "Unable to save asset to directory: '\(param.absoluteString)'"
+  }
+}
+
+public class AssetModule: Module {
+  public func definition() -> ModuleDefinition {
+    Name("ExpoAsset")
+
+    // NOTE: this is exposed in JS as globalThis.expo.modules.ExpoAsset.downloadAsync
+    // and potentially consumed outside of Expo (e.g. RN vector icons)
+    // do NOT change the function signature as it'll break consumers!
+    AsyncFunction("downloadAsync") { (url: URL, md5Hash: String?, type: String, promise: Promise) in
+      if url.isFileURL {
+        promise.resolve(url.standardizedFileURL.absoluteString)
+        return
+      }
+      guard let cacheFileId = md5Hash ?? getMD5Hash(fromURL: url),
+      let cachesDirectory = appContext?.fileSystem?.cachesDirectory,
+      let appContext = appContext else {
+        promise.reject(UnableToDownloadAssetException(url))
+        return
+      }
+
+      let localUrl = URL(fileURLWithPath: "\(cachesDirectory)/ExponentAsset-\(cacheFileId).\(type)")
+
+      guard let fileData = FileManager.default.contents(atPath: localUrl.path) else {
+        downloadAsset(appContext: appContext, url: url, localUrl: localUrl, promise: promise)
+        return
+      }
+      if md5Hash == nil || md5Hash == getMD5Hash(fromData: fileData) {
+        promise.resolve(localUrl.standardizedFileURL.absoluteString)
+        return
+      }
+      downloadAsset(appContext: appContext, url: url, localUrl: localUrl, promise: promise)
+    }
+  }
+
+  private func getMD5Hash(fromURL url: URL) -> String? {
+    guard let urlData = url.absoluteString.data(using: .utf8) else {
+      return nil
+    }
+    return getMD5Hash(fromData: urlData)
+  }
+
+  private func getMD5Hash(fromData data: Data?) -> String? {
+    guard let data = data else {
+      return nil
+    }
+    return Data(Insecure.MD5.hash(data: data)).map { String(format: "%02hhx", $0) }.joined()
+  }
+
+  func downloadAsset(appContext: AppContext, url: URL, localUrl: URL, promise: Promise) {
+    guard let fileSystem = appContext.fileSystem else {
+      promise.reject(UnableToSaveAssetToDirectoryException(url))
+      return
+    }
+    if !fileSystem.ensureDirExists(withPath: localUrl.path) {
+      promise.reject(UnableToSaveAssetToDirectoryException(localUrl))
+      return
+    }
+
+    guard fileSystem.permissions(forURI: localUrl).contains(EXFileSystemPermissionFlags.write) else {
+      promise.reject(UnableToSaveAssetToDirectoryException(localUrl))
+      return
+    }
+
+    let downloadTask = URLSession.shared.downloadTask(with: url) { urlOrNil, _, _ in
+      guard let fileURL = urlOrNil else {
+        promise.reject(UnableToDownloadAssetException(url))
+        return
+      }
+      do {
+        // the file may already exist, so we need to remove it first
+        try? FileManager.default.removeItem(at: localUrl)
+        try FileManager.default.moveItem(at: fileURL, to: localUrl)
+        promise.resolve(localUrl.standardizedFileURL.absoluteString)
+      } catch {
+        promise.reject(UnableToSaveAssetToDirectoryException(localUrl))
+      }
+    }
+    downloadTask.resume()
+  }
+}