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using System;
using XenAPI;

namespace XenAdmin.Actions
{
    public class ChangeVCPUSettingsAction : PureAsyncAction
    {
        private long m_VCPUs_max;
        private long m_VCPUs_at_startup;
        private VM m_VM;
        public ChangeVCPUSettingsAction(VM vm, long VCPUs_max, long VCPUs_at_startup)
            : base(vm.Connection, "", true)
        {
            m_VM = vm;
            m_VCPUs_max = VCPUs_max;
            m_VCPUs_at_startup = VCPUs_at_startup;
        }

        protected override void Run()
        {
            // get the VM from the cache again, to check its vCPU fields before trying to change them
            m_VM = Connection.Resolve(new XenRef<VM>(m_VM.opaque_ref));
            if (m_VM == null) // VM has disappeared
                return;

            if (m_VM.power_state == vm_power_state.Running) // if the VM is running, we can only change the vCPUs number, not the max.
            {
                if (m_VM.VCPUs_at_startup > m_VCPUs_at_startup) // reducing VCPU_at_startup is not allowed for live VMs
                {
                    throw new Exception(string.Format(Messages.VM_VCPU_CANNOT_UNPLUG_LIVE, m_VM.VCPUs_at_startup));
                }
                VM.set_VCPUs_number_live(Session, m_VM.opaque_ref, m_VCPUs_at_startup);
                return;
            }

            if (m_VM.VCPUs_at_startup > m_VCPUs_at_startup) // reducing VCPUs_at_startup: we need to change this value first, and then the VCPUs_max
            {
                VM.set_VCPUs_at_startup(Session, m_VM.opaque_ref, m_VCPUs_at_startup);
                VM.set_VCPUs_max(Session, m_VM.opaque_ref, m_VCPUs_max);
            }
            else // increasing VCPUs_at_startup: we need to change the VCPUs_max first
            {
                VM.set_VCPUs_max(Session, m_VM.opaque_ref, m_VCPUs_max);
                VM.set_VCPUs_at_startup(Session, m_VM.opaque_ref, m_VCPUs_at_startup);
            }
        }
    }
}