namespace SQLInsight.Core.Data;

/// <summary>
/// CPU use per minute from the scheduler monitor ring buffer (<c>sys.dm_os_ring_buffers</c>, 2005+).
/// Distinguishes SQL Server's own CPU from other processes on the host.
/// </summary>
public sealed record CpuUtilization
{
    public required DateTimeOffset CapturedAt { get; init; }

    /// <summary>
    /// Windows or Linux (2017+). On Linux the ring buffer's SystemIdle is not reliable (it reads near 0 in
    /// containers), so CPU used by other processes cannot be derived.
    /// </summary>
    public string? HostPlatform { get; init; }

    public bool OtherProcessesMeasurable => !string.Equals(HostPlatform, "Linux", StringComparison.OrdinalIgnoreCase);

    /// <summary>One sample per minute, oldest first.</summary>
    public required IReadOnlyList<CpuSample> Samples { get; init; }
}

public sealed record CpuSample(DateTimeOffset Time, int SqlServerPercent, int IdlePercent)
{
    public int OtherProcessesPercent => Math.Max(0, 100 - SqlServerPercent - IdlePercent);
}