Add HTMLMetadataCache to RSWeb.

RSWeb/Package.swift

@@ -3,23 +3,33 @@
 import PackageDescription
 
 let package = Package(
-    name: "RSWeb",
+	name: "RSWeb",
 	platforms: [.macOS(.v13), .iOS(.v16)],
 	products: [
-        .library(
-            name: "RSWeb",
-            type: .dynamic,
-            targets: ["RSWeb"]),
-    ],
-    dependencies: [
-    ],
-    targets: [
-        .target(
-            name: "RSWeb",
+		.library(
+			name: "RSWeb",
+			type: .dynamic,
+			targets: ["RSWeb"]),
+	],
+	dependencies: [
+		.package(url: "https://github.com/Ranchero-Software/RSParser.git", .upToNextMinor(from: "2.0.2")),
+		.package(path: "../Core")
+	],
+	targets: [
+		.target(
+			name: "RSWeb",
+			dependencies: [
+				"RSParser",
+				"Core"
+			],
 			resources: [.copy("UTS46/uts46")],
 			swiftSettings: [.define("SWIFT_PACKAGE")]),
-        .testTarget(
-            name: "RSWebTests",
-            dependencies: ["RSWeb"]),
-    ]
+		.testTarget(
+			name: "RSWebTests",
+			dependencies: [
+				"RSWeb",
+				"RSParser",
+				"Core"
+			]),
+	]
 )

RSWeb/Sources/RSWeb/HTMLMetadataCache.swift

@@ -0,0 +1,47 @@
+//
+//  HTMLMetadataCache.swift
+//
+//
+//  Created by Brent Simmons on 10/13/24.
+//
+
+import Foundation
+import Core
+@preconcurrency import RSParser
+
+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: RSHTMLMetadata
+		let dateCreated = Date()
+	}
+
+	private let cache = Cache<HTMLMetadataCacheRecord>(timeToLive: TimeInterval(21 * 60 * 60), timeBetweenCleanups: TimeInterval(10 * 60 * 60))
+
+	subscript(_ url: String) -> RSHTMLMetadata? {
+		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])
+		}
+	}
+}