add SMTPClient module: connection layer, message formatter, public API, tests

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
2026-03-14 05:25:03 +01:00
parent 427f197bb3
commit 54ce92e280
9 changed files with 695 additions and 1 deletions
@@ -0,0 +1,110 @@
+import Foundation
+import Models
+
+/// Builds RFC 5322 formatted email messages.
+public enum MessageFormatter: Sendable {
+
+	/// Format an OutgoingMessage into a complete RFC 5322 message string with CRLF line endings.
+	public static func format(_ message: OutgoingMessage) -> String {
+		var headers: [(String, String)] = []
+
+		headers.append(("From", formatAddress(message.from)))
+		headers.append(("To", message.to.map(formatAddress).joined(separator: ", ")))
+
+		if !message.cc.isEmpty {
+			headers.append(("Cc", message.cc.map(formatAddress).joined(separator: ", ")))
+		}
+
+		// BCC intentionally omitted from headers per RFC 5322
+
+		headers.append(("Subject", message.subject))
+		headers.append(("Date", formatRFC2822Date(Date())))
+		headers.append(("Message-ID", "<\(message.messageId)>"))
+
+		if let inReplyTo = message.inReplyTo {
+			headers.append(("In-Reply-To", "<\(inReplyTo)>"))
+		}
+		if let references = message.references {
+			headers.append(("References", references))
+		}
+
+		headers.append(("MIME-Version", "1.0"))
+		headers.append(("Content-Type", "text/plain; charset=utf-8"))
+		headers.append(("Content-Transfer-Encoding", "quoted-printable"))
+
+		var result = ""
+		for (name, value) in headers {
+			result += "\(name): \(value)\r\n"
+		}
+		result += "\r\n"
+		result += quotedPrintableEncode(message.bodyText)
+
+		return result
+	}
+
+	/// Generate a unique Message-ID for the given domain.
+	public static func generateMessageId(domain: String) -> String {
+		"\(UUID().uuidString)@\(domain)"
+	}
+
+	/// Extract the domain part from an email address.
+	public static func domainFromEmail(_ email: String) -> String {
+		guard let atIndex = email.lastIndex(of: "@") else { return email }
+		return String(email[email.index(after: atIndex)...])
+	}
+
+	/// Format an EmailAddress as RFC 5322 address: `"Name" <addr>` or bare `addr`.
+	public static func formatAddress(_ addr: EmailAddress) -> String {
+		if let name = addr.name, !name.isEmpty {
+			return "\"\(name)\" <\(addr.address)>"
+		}
+		return addr.address
+	}
+
+	/// Format a Date as RFC 2822 date string.
+	public static func formatRFC2822Date(_ date: Date) -> String {
+		let formatter = DateFormatter()
+		formatter.locale = Locale(identifier: "en_US_POSIX")
+		formatter.dateFormat = "EEE, dd MMM yyyy HH:mm:ss Z"
+		formatter.timeZone = TimeZone.current
+		return formatter.string(from: date)
+	}
+
+	/// Encode a string using quoted-printable encoding (RFC 2045).
+	public static func quotedPrintableEncode(_ text: String) -> String {
+		var result = ""
+		let data = Array(text.utf8)
+		var lineLength = 0
+
+		for byte in data {
+			let encoded: String
+			if byte == 0x0A {
+				// LF → CRLF
+				encoded = "\r\n"
+				result += encoded
+				lineLength = 0
+				continue
+			} else if byte == 0x0D {
+				// CR — skip, we handle LF → CRLF above
+				continue
+			} else if byte == 0x09 || (byte >= 0x20 && byte <= 0x7E && byte != 0x3D) {
+				// Printable ASCII (except =) and tab: literal
+				encoded = String(UnicodeScalar(byte))
+			} else {
+				// Everything else: =XX hex encoding
+				encoded = String(format: "=%02X", byte)
+			}
+
+			// Soft line break if line would exceed 76 chars
+			if lineLength + encoded.count > 76 {
+				result += "=\r\n"
+				lineLength = 0
+			}
+
+			result += encoded
+			lineLength += encoded.count
+		}
+
+		return result
+	}
+}