import Foundation

/// Naming scheme for the ephemeral runners this host registers with Gitea.
///
/// Every booted VM registers under a **globally unique** name. That uniqueness
/// is what makes the reconcile loop safe: when a VM dies uncleanly, Gitea keeps
/// the runner row forever (rows are only swept at midnight, and never at all if
/// the runner never claimed a task), so we must be able to look at a runner row
/// and decide "this name is mine and no live VM of mine owns it" without any
/// ambiguity. A shared or reused name would make that decision impossible.
public enum RunnerNaming {
    /// Generates a fresh runner name.
    ///
    /// - Parameter prefix: The configured prefix, e.g. `macos-vm-`.
    /// - Returns: `prefix` followed by a lowercase UUID, e.g.
    ///   `macos-vm-3f1c2f8e-...`.
    public static func makeRunnerName(prefix: String) -> String {
        prefix + UUID().uuidString.lowercased()
    }

    /// Whether a runner name reported by Gitea was minted by this host.
    ///
    /// - Parameters:
    ///   - name: A runner name from `GET /api/v1/admin/actions/runners`.
    ///   - prefix: The configured prefix.
    /// - Returns: `true` when the reconcile loop may consider deleting it.
    public static func hasPrefix(_ name: String, prefix: String) -> Bool {
        // An empty prefix would match every runner on the instance, including
        // other people's. The reconcile loop deletes what this returns true for,
        // so refuse rather than match everything. `validated()` also rejects an
        // empty `namePrefix`; this is the second line of defence.
        guard !prefix.isEmpty else { return false }
        return name.hasPrefix(prefix)
    }
}