feat(imap): complete decoding for IMAP headers

Feature/Sources/IMAP/EmailAddress.swift

@@ -1,4 +1,5 @@
 import EmailAddress
+import MIME
 import NIOIMAPCore
 
 extension [EmailAddressListElement] {
@@ -17,7 +18,10 @@ extension EmailAddressListElement {
 extension NIOIMAPCore.EmailAddressGroup: @retroactive CustomStringConvertible {
 
     // MARK: CustomStringConvertible
-    public var description: String { groupName.readableBytesView.description }  // TODO: Decode quoted-printable/base64 (RFC 2047)
+    public var description: String {
+        let description: String = groupName.readableBytesView.description
+        return (try? description.headerDecoded()) ?? description
+    }
 }
 
 extension NIOIMAPCore.EmailAddress: @retroactive CustomStringConvertible {
@@ -32,7 +36,7 @@ extension NIOIMAPCore.EmailAddress: @retroactive CustomStringConvertible {
             return ""
         }
         let description: String = "\(mailbox)@\(host)"
-        if let personName: String = personName?.readableBytesView.description,  // TODO: Decode quoted-printable/base64 (RFC 2047)
+        if let personName: String = try? personName?.readableBytesView.description.headerDecoded(),
             !personName.isEmpty
         {
             return "\(personName) <\(description)>"

Feature/Sources/IMAP/Envelope.swift

@@ -40,7 +40,7 @@ public struct Envelope: Sendable {
     }
 
     init(_ envelope: NIOIMAPCore.Envelope) {
-        subject = envelope.subject?.readableBytesView.description  // TODO: Decode quoted-printable/base64 (RFC 2047)
+        subject = try? envelope.subject?.readableBytesView.description.headerDecoded()
         from = envelope.from.addresses
         sender = envelope.sender.addresses
         reply = envelope.reply.addresses

Feature/Sources/IMAP/FetchAttribute.swift

@@ -4,37 +4,32 @@ public typealias FetchAttribute = NIOIMAPCore.FetchAttribute
 
 extension [FetchAttribute] {
 
-    // Add supported fetch attributes according to set of server capabilities
-    static func extended(_ capabilities: Set<Capability>) -> Self {
-        Array(Set(capabilities.flatMap { extended($0) }))
-    }
-
-    // Add supported fetch attributes according to server capability
-    static func extended(_ capability: Capability) -> Self {
-        switch capability {
-        case .gmailExtensions:
-            [
-                .gmailLabels,
-                .gmailMessageID,
-                .gmailThreadID
-            ]
-        case .objectID:
-            [
-                .emailID,
-                .threadID
-            ]
-        default: []
-        }
-    }
+    /// Fetch complete, raw message data in one blob.
+    public static let complete: Self =
+        [
+            .bodySection(peek: true, .complete, nil)
+        ] + standard
 
-    // Standard set of fetch attributes supported by all IMAP4 servers
-    static var standard: Self {
+    /// Fetch all message headers and body structure map.
+    public static let header: Self =
         [
-            .envelope,
-            .flags,
-            .uid
-        ]
-    }
+            .bodySection(peek: true, .header, nil),
+            .bodyStructure(extensions: true)
+        ] + standard
+
+    /// Fetch message envelope, IDs, flags and Gmail labels.
+    public static let standard: Self = [
+        .emailID,
+        .envelope,
+        .flags,
+        .gmailLabels,
+        .gmailMessageID,
+        .gmailThreadID,
+        .internalDate,
+        .preview(lazy: true),
+        .threadID,
+        .uid
+    ]
 
     // Filter unsupported attributes according to server capabilities
     func filtered(_ capabilities: Set<Capability>) -> Self {

Feature/Sources/IMAP/FetchCommand.swift

@@ -28,8 +28,8 @@ class FetchHandler: IMAPCommandHandler, @unchecked Sendable {
     var isStreaming: Bool { streaming != nil }
 
     private var streaming: (kind: StreamingKind, data: Data, byteCount: Int)?
-    private var components: [Message.Component] = []
     private var sequenceNumber: SequenceNumber?
+    private var components: [Message.Component] = []
 
     // MARK: IMAPCommandHandler
     typealias InboundIn = Response
@@ -79,7 +79,7 @@ class FetchHandler: IMAPCommandHandler, @unchecked Sendable {
                 }
                 streaming = nil
             case .finish:
-                messages[sequenceNumber!] = Message(components: components)
+                messages[sequenceNumber!] = Message(components)
                 sequenceNumber = nil
                 components = []
             default:

Feature/Sources/IMAP/IMAPClient.swift

@@ -180,18 +180,38 @@ public class IMAPClient {
         try await execute(command: VoidCommand(.close))
     }
 
-    /// Fetch messages by mailbox sequence number.
-    public func fetch(_ set: SequenceSet = .all, attributes: [FetchAttribute]) async throws -> MessageSet {
+    /// Fetch a set of messages by mailbox ``SequenceNumber``; fetches all headers and omits message body by default.
+    public func fetch(_ set: SequenceSet = .all, attributes: [FetchAttribute] = .header) async throws -> MessageSet {
         logger?.info("Fetching messages by mailbox sequence number…")
         return try await execute(command: FetchCommand(set, attributes: attributes.filtered(capabilities)))
     }
 
-    /// Fetch messages by UID.
-    public func fetch(_ set: UIDSet, attributes: [FetchAttribute]) async throws -> MessageSet {
+    /// Fetch a specific message by ``SequenceNumber``; fetches complete message by default.
+    public func fetch(_ number: SequenceNumber, attributes: [FetchAttribute] = .complete) async throws -> Message {
+        logger?.info("Fetching message \(number)…")
+        let messages: MessageSet = try await fetch(SequenceSet(number), attributes: attributes)
+        guard let message: Message = messages.first?.value else {
+            throw IMAPError.commandFailed("Message \(number) not found")
+        }
+        return message
+    }
+
+    /// Fetch a set of messages by ``UID``; fetches all headers and omits message body by default.
+    public func fetch(uid set: UIDSet, attributes: [FetchAttribute] = .header) async throws -> MessageSet {
         logger?.info("Fetching messages by UID…")
         return try await execute(command: UIDFetchCommand(set, attributes: attributes.filtered(capabilities)))
     }
 
+    /// Fetch a specific message by ``UID``; fetches complete message by default.
+    public func fetch(uid: UID, attributes: [FetchAttribute] = .complete) async throws -> Message {
+        logger?.info("Fetching message UID \(uid)…")
+        let messages: MessageSet = try await fetch(uid: UIDSet(uid), attributes: attributes)
+        guard let message: Message = messages.first?.value else {
+            throw IMAPError.commandFailed("Message UID \(uid) not found")
+        }
+        return message
+    }
+
     public init(
         _ server: Server,
         logger: Logger? = Logger(subsystem: "net.thunderbird", category: "IMAP")

Feature/Sources/IMAP/IMAPCommand.swift

@@ -74,7 +74,7 @@ extension IMAPCommandHandler where InboundIn == Response, Result == Void {
 }
 
 extension Int64 {
-    static let timeout: Self = 30  // Practical default
+    static let timeout: Self = 60  // Practical default
 }
 
 // IMAP [CLIENTBUG] is an error code mail servers include in responses to