Add HTMLMetadataCache.

Modules/FoundationExtras/Sources/FoundationExtras/Date+Extensions.swift

@@ -21,7 +21,7 @@ public extension Date {
 	}
 }
 
-private extension TimeInterval {
+public extension TimeInterval {
 
 	init(days: Int) {
 		self.init(days * 24 * 60 * 60)

Modules/Images/Sources/Images/HTMLMetadataCache.swift

@@ -0,0 +1,48 @@
+//
+//  HTMLMetadataCache.swift
+//
+//
+//  Created by Brent Simmons on 10/13/24.
+//
+
+import Foundation
+import Core
+import Parser
+import FoundationExtras
+
+extension Notification.Name {
+	// Sent when HTMLMetadata is cached. Posted on any thread.
+	static let htmlMetadataAvailable = Notification.Name("htmlMetadataAvailable")
+}
+
+final class HTMLMetadataCache: Sendable {
+
+	static let shared = HTMLMetadataCache()
+	
+	// Sent along with .htmlMetadataAvailable notification
+	struct UserInfoKey {
+		static let htmlMetadata = "htmlMetadata"
+		static let url = "url" // String value
+	}
+
+	private struct HTMLMetadataCacheRecord: CacheRecord {
+		let metadata: HTMLMetadata
+		let dateCreated = Date()
+	}
+
+	private let cache = Cache<HTMLMetadataCacheRecord>(timeToLive: TimeInterval(days: 2), timeBetweenCleanups: TimeInterval(days: 1))
+
+	subscript(_ url: String) -> HTMLMetadata? {
+		get {
+			return cache[url]?.metadata
+		}
+		set {
+			guard let htmlMetadata = newValue else {
+				return
+			}
+			let cacheRecord = HTMLMetadataCacheRecord(metadata: htmlMetadata)
+			cache[url] = cacheRecord
+			NotificationCenter.default.post(name: .htmlMetadataAvailable, object: self, userInfo: [UserInfoKey.htmlMetadata: htmlMetadata, UserInfoKey.url: url])
+		}
+	}
+}