import Foundation

/// Rates are computed per container so new or removed containers do not cause
/// spikes from their lifetime counters. Counter resets contribute zero.
public struct NetworkRateTracker: Sendable {
    private struct Counter: Sendable { var date: Date; var rx: Double; var tx: Double }
    private var counters: [String: Counter] = [:]
    public init() {}
    public mutating func sample(_ resources: [Resource], at date: Date) -> (rx: Double, tx: Double) {
        var next: [String: Counter] = [:], rxRate = 0.0, txRate = 0.0
        for resource in resources {
            guard let rx = resource.rxBytes, let tx = resource.txBytes else { continue }
            if let previous = counters[resource.id] {
                let seconds = date.timeIntervalSince(previous.date)
                if seconds > 0 { rxRate += max(0, rx - previous.rx) / seconds; txRate += max(0, tx - previous.tx) / seconds }
            }
            next[resource.id] = Counter(date: date, rx: rx, tx: tx)
        }
        counters = next
        return (rxRate, txRate)
    }
}