import Foundation
import Observation

@Observable
final class ReadTracker {
	private static let storeKey = "mm.readTimestamps"
	private(set) var timestamps: [String: TimeInterval]

	init() {
		let raw = UserDefaults.standard.dictionary(forKey: Self.storeKey) ?? [:]
		var dict: [String: TimeInterval] = [:]
		for (k, v) in raw {
			if let n = v as? Double { dict[k] = n }
			else if let n = v as? Int { dict[k] = TimeInterval(n) }
		}
		self.timestamps = dict
	}

	func lastRead(for nodeId: String) -> TimeInterval {
		timestamps[nodeId] ?? 0
	}

	func markRead(_ nodeId: String, at time: Date) {
		let ts = time.timeIntervalSince1970
		if (timestamps[nodeId] ?? 0) < ts {
			timestamps[nodeId] = ts
			persist()
		}
	}

	private func persist() {
		UserDefaults.standard.set(timestamps, forKey: Self.storeKey)
	}
}