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https://github.com/meshtastic/Meshtastic-Apple.git
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99 lines
2.9 KiB
Swift
99 lines
2.9 KiB
Swift
//
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// URL+fetch.swift
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// Meshtastic
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//
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// Created by jake on 12/6/25.
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//
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import Foundation
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extension URL {
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/// Custom error type for the URL extension
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enum TimeoutError: Error, LocalizedError {
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case timedOut(TimeInterval)
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var errorDescription: String? {
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switch self {
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case .timedOut(let seconds):
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return "The operation timed out after \(seconds) seconds."
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}
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}
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}
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/// Fetches data from the URL (local or remote) with a strict timeout.
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/// - Parameter timeout: The duration in seconds to wait before throwing an error.
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/// - Returns: The `Data` retrieved.
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func data(timeout: TimeInterval) async throws -> Data {
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return try await withThrowingTaskGroup(of: Data.self) { group in
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// Task 1: The Fetch Operation
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group.addTask {
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if self.isFileURL {
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// Handle Local Files
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// Note: Data(contentsOf:) is synchronous (blocking).
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// Running it inside a Task allows it to be raced, though
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// the underlying thread may remain blocked until OS IO completes
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// if cancellation occurs.
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return try Data(contentsOf: self)
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} else {
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// Handle Remote Network Requests
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let (data, _) = try await URLSession.shared.data(from: self)
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return data
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}
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}
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// Task 2: The Timer
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group.addTask {
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// Convert seconds to nanoseconds
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let nanoseconds = UInt64(timeout * 1_000_000_000)
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try await Task.sleep(nanoseconds: nanoseconds)
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// If we wake up, it means the fetch hasn't finished yet
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throw TimeoutError.timedOut(timeout)
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}
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// Race Handling
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// Wait for the first task to finish (either success or error)
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guard let result = try await group.next() else {
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// Should not be reachable, but required by compiler
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throw URLError(.unknown)
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}
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// If we are here, one task finished successfully.
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// Cancel the other task immediately.
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group.cancelAll()
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return result
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}
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}
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/// Performs a HEAD request to fetch the ETag header for the URL.
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/// - Parameter session: The URLSession to use (defaults to .shared).
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/// - Returns: The ETag string if found and the request is successful, otherwise nil.
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func eTag(using session: URLSession = .shared) async throws -> String? {
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var request = URLRequest(url: self)
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request.httpMethod = "HEAD"
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// Ensure we don't use the local cache so we get the real ETag from the server
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request.cachePolicy = .reloadIgnoringLocalCacheData
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let (_, response) = try await session.data(for: request)
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guard let httpResponse = response as? HTTPURLResponse else {
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return nil
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}
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// Optional: Check for success status codes (200-299)
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guard (200...299).contains(httpResponse.statusCode) else {
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// You might want to return nil or throw a specific error here
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// depending on your requirements (e.g. 404 Not Found)
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return nil
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}
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// Header lookup is case-insensitive
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return httpResponse.value(forHTTPHeaderField: "ETag")
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}
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}
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