feat: add HTTPBody progress tracking

Sources/HTTPClient/Base/PrettyStringConvertible.swift

@@ -15,6 +15,6 @@
 /// A helper protocol for customizing descriptions.
 internal protocol PrettyStringConvertible {
 
-    /// A pretty string description.
-    var prettyDescription: String { get }
-}
+  /// A pretty string description.
+  var prettyDescription: String { get }
+}

Sources/HTTPClient/Interface/HTTPBody+Extensions.swift

@@ -1,32 +1,32 @@
 import Foundation
 
 extension HTTPBody {
-    /// Decodes the HTTP body as the specified type using the provided decoder.
-    /// - Parameters:
-    ///   - type: The type to decode the HTTP body as.
-    ///   - decoder: The decoder to use for decoding the HTTP body.
-    /// - Returns: The decoded value.
-    /// - Throws: An error if the HTTP body cannot be decoded.
-    public func decode<T: Decodable>(
-        as type: T.Type,
-        using decoder: JSONDecoder = JSONDecoder()
-    ) async throws -> T {
-        let data = try await Data(collecting: self, upTo: .max)
-        return try decoder.decode(type, from: data)
-    }
+  /// Decodes the HTTP body as the specified type using the provided decoder.
+  /// - Parameters:
+  ///   - type: The type to decode the HTTP body as.
+  ///   - decoder: The decoder to use for decoding the HTTP body.
+  /// - Returns: The decoded value.
+  /// - Throws: An error if the HTTP body cannot be decoded.
+  public func decode<T: Decodable>(
+    as type: T.Type,
+    using decoder: JSONDecoder = JSONDecoder()
+  ) async throws -> T {
+    let data = try await Data(collecting: self, upTo: .max)
+    return try decoder.decode(type, from: data)
+  }
 
-    /// Decodes the HTTP body as a JSON object.
-    /// - Returns: The decoded JSON object.
-    /// - Throws: An error if the HTTP body cannot be decoded as JSON.
-    public func json() async throws -> Any {
-        let data = try await Data(collecting: self, upTo: .max)
-        return try JSONSerialization.jsonObject(with: data)
-    }
+  /// Decodes the HTTP body as a JSON object.
+  /// - Returns: The decoded JSON object.
+  /// - Throws: An error if the HTTP body cannot be decoded as JSON.
+  public func json() async throws -> Any {
+    let data = try await Data(collecting: self, upTo: .max)
+    return try JSONSerialization.jsonObject(with: data)
+  }
 
-    /// Decodes the HTTP body as a string.
-    /// - Returns: The decoded string.
-    /// - Throws: An error if the HTTP body cannot be decoded as a string.
-    public func string() async throws -> String {
-        try await String(collecting: self, upTo: .max)
-    }
+  /// Decodes the HTTP body as a string.
+  /// - Returns: The decoded string.
+  /// - Throws: An error if the HTTP body cannot be decoded as a string.
+  public func string() async throws -> String {
+    try await String(collecting: self, upTo: .max)
+  }
 }

Sources/HTTPClient/Interface/HTTPBody+Progress.swift

@@ -0,0 +1,40 @@
+import Foundation
+
+extension HTTPBody {
+  /// Tracks the progress of the body and calls the handler.
+  public func trackingProgress(handler: @escaping (Progress) -> Void) -> HTTPBody {
+    var totalBytesProcessed: Int64 = 0
+    let totalLength: Int64? =
+      switch self.length {
+      case .known(let length):
+        length
+      case .unknown:
+        nil
+      }
+
+    let sequence = self.map { chunk in
+      let chunkSize = Int64(chunk.count)
+      totalBytesProcessed += chunkSize
+
+      let progress = Progress(completed: totalBytesProcessed, total: totalLength)
+      handler(progress)
+      return chunk
+    }
+
+    return HTTPBody(sequence, length: self.length, iterationBehavior: self.iterationBehavior)
+  }
+}
+
+/// A progress object that tracks the progress of a body.
+public struct Progress: Sendable, Hashable {
+  /// The number of bytes processed.
+  public let completed: Int64
+  /// The total number of bytes to process.
+  public let total: Int64?
+
+  /// The fraction of the body that has been processed.
+  public var fractionCompleted: Double? {
+    guard let total = total, total > 0 else { return nil }
+    return Double(completed) / Double(total)
+  }
+}