// Package host provides utilities and data structures in relation to a libvirt host.
// This includes getting a list of virtual machines running on a host, launching
// a new virtual machine on a host, triggering a virtual machine migration to another
// host, getting hardware and resource usage from a host, and eventually more.
// Most of this is data at the moment, ensuring data can be gathered efficiently without
// slowing down the host from it's main job of running virtual machines.
package host

import (
	"log"
	"sync"

	"git.staur.ca/stobbsm/clustvirt/lib/guest"
	"git.staur.ca/stobbsm/clustvirt/lib/secret"
	"git.staur.ca/stobbsm/clustvirt/util"
	"libvirt.org/go/libvirt"
)

// Host holds information and acts as a connection handle for a Host
// If a connection is closed prematurely, will re-open the connection and
// try the attempted method again
type Host struct {
	// HostName used to make the connection
	HostName string
	// SystemHostName is the hostname as reported by the system itself
	SystemHostName string
	// FreeMemory is the available free memory
	FreeMemory uint64
	// LibVersion is the version of Libvirt on the host
	LibVersion uint32
	// HostInfo provides basic HW information about a host
	HostInfo NodeInfo
	// HostSEVInfo provides informatoin about AMD SEV extentions available on the host
	HostSEVInfo SEVInfo
	// AvailableCPUTypes are the available types of CPUs that can be used for VM creation
	AvailableCPUTypes []string
	// NodeMemory provides basic memory information about the Host
	NodeMemory NodeMemoryInfo
	// StorageCapabilities is the XML representation of the hosts storage capabilities
	StorageCapabilities string
	// SysInfo is the XML representation of the host system information
	SysInfo string
	// Alive indicates if the connection is alive
	Alive bool
	// Encrypted indicates if the connection is encrypted
	Encrypted bool
	// Secure indicates if the connection is secure
	Secure bool
	// VMList is the list of virtual machines available to the host
	VMList []VMInfo
	// NetIfList is the list of network interfaces on the host
	NetIfFList []NetIfInfo
	// NetworkList is the list of defined networks on the host
	NetworkList []NetworkInfo
	// DeviceList is the list of devices on the host
	DeviceList []DeviceInfo
	// SecretList provides a list of secrets available to the host
	SecretList []SecretInfo
	// StoragePoolList provides the list of stoarge ppols available to the host
	StoragePoolList []StoragePoolInfo

	uri      *URI
	conn     *libvirt.Connect
	close    chan struct{}
	closeErr chan error
}

// DeviceInfo holds basic information for host devices
type DeviceInfo struct {
	Name         string
	Capabilities []string
	XML          string
}

// VMInfo holds basic VM information, like the name and ID
type VMInfo struct {
	Name string
	ID   uint
	UUID []byte
	XML  string
	// States are the current states active on the host
	States []guest.VMState
}

// SecretInfo doesn't let you see the contents of secrets, but does let you see what secrets have
// been defined in a simple format.
type SecretInfo struct {
	UUID string
	XML  string
	Type string
}

// StoragePoolInfo holds basic information on storage pools
type StoragePoolInfo struct {
	Name       string
	UUID       []byte
	Type       string
	XML        string
	Active     bool
	Persistent bool
	// HAEnabled indicates if the storage pool has High Availability
	HAEnabled bool
	// Volumes defined in the storage pool
	Volumes []VolumeInfo
}

// VolumeInfo holds basic information about Volumes available in storage pools
type VolumeInfo struct {
	Name string
	// StoragePool this volume is part of
	StoragePool StoragePoolInfo
	Type        string
	Size        uint
	XML         string
}

// NetIfInfo holds basic information about available network interfaces (not their connections, the devices themselves)
type NetIfInfo struct {
	Name    string
	MacAddr string
	XML     string
}

// NetworkInfo holds basic information about network connections
type NetworkInfo struct {
	Name string
	UUID []byte
	XML  string
	// NetIf is the network interface this connection is applied to
	NetIf NetIfInfo
}

// NodeInfo represents the basic HW info for a host node
type NodeInfo struct {
	// livirt.NodeInfo section
	Model   string
	Memory  uint64
	Cpus    uint
	MHz     uint
	Nodes   uint32
	Sockets uint32
	Cores   uint32
	Threads uint32
}

// SEVInfo provides information about AMD SEV support
type SEVInfo struct {
	// livirt.NodeSEVParameters section
	SEVEnabled      bool
	PDH             string
	CertChain       string
	CBitPos         uint
	ReducedPhysBits uint
	MaxGuests       uint
	MaxEsGuests     uint
	CPU0ID          string
}

// NodeMemoryInfo provides statistis about node memory usage from libvirt.NodeMemoryStats
type NodeMemoryInfo struct {
	Total   uint64
	Free    uint64
	Buffers uint64
	Cached  uint64
}

// ConnectHost creates a host connection wrapper that can be used regularly
func ConnectHost(uri *URI, host string) (*Host, error) {
	h := &Host{
		HostName: host,
		uri:      uri,
	}

	if err := h.connect(); err != nil {
		return nil, err
	}

	h.close = make(chan struct{})
	h.closeErr = make(chan error)

	h.getInfo()

	go func() {
		defer close(h.closeErr)
		<-h.close
		_, err := h.conn.Close()
		h.closeErr <- err
	}()
	return h, nil
}

// connect creates a host connection
func (h *Host) connect() error {
	var err error
	h.conn, err = libvirt.NewConnect(h.uri.ConnectionString(h.HostName))
	return err
}

// GetGuestByName returns a GuestVM instance that exists on the given host
func (h *Host) GetGuestByName(name string) (*guest.VM, error) {
	g, err := guest.GetGuest(name, h.conn)
	if err == nil {
		return g, nil
	}
	lverr, ok := err.(libvirt.Error)
	if ok && lverr.Code == libvirt.ERR_INVALID_CONN {
		// try again after creating a new connection
		return guest.GetGuest(name, h.conn)
	}
	return nil, err
}

// Close triggers closing the host connection
func (h *Host) Close() error {
	log.Println("Closing Host", h.HostName)
	close(h.close)
	return <-h.closeErr
}

// private methods that load the different informational parts

func (h *Host) getInfo() {
	var wg sync.WaitGroup

	infoFuncs := []func(*sync.WaitGroup){
		h.getDevicesInfo,
		h.getDomainInfo,
		h.getIfaceInfo,
		h.getNetsInfo,
		h.getNodeInfo,
		h.getSEVInfo,
		h.getSecretsInfo,
		h.getStoragePools,
	}

	for _, f := range infoFuncs {
		wg.Add(1)
		f(&wg)
	}

	wg.Wait()
}

func (h *Host) getStoragePools(wg *sync.WaitGroup) {
	defer wg.Done()
	spools, err := h.conn.ListAllStoragePools(0)
	if err != nil {
		log.Println(err)
	}
	if len(spools) > 0 {
		h.StoragePoolList = make([]StoragePoolInfo, len(spools))
		for i, s := range spools {
			if h.StoragePoolList[i].XML, err = s.GetXMLDesc(0); err != nil {
				log.Println(err)
			}
			if h.StoragePoolList[i].Name, err = s.GetName(); err != nil {
				log.Println(err)
			}
			if h.StoragePoolList[i].UUID, err = s.GetUUID(); err != nil {
				log.Println(err)
			}
			if h.StoragePoolList[i].Active, err = s.IsActive(); err != nil {
				log.Println(err)
			}
			if h.StoragePoolList[i].Persistent, err = s.IsPersistent(); err != nil {
				log.Println(err)
			}

			s.Free()
		}
	}
}

func (h *Host) getSecretsInfo(wg *sync.WaitGroup) {
	defer wg.Done()
	nsecrets, err := h.conn.ListAllSecrets(0)
	if err != nil {
		log.Println(err)
	}
	if len(nsecrets) > 0 {
		h.SecretList = make([]SecretInfo, len(nsecrets))
		for i, s := range nsecrets {
			if h.SecretList[i].XML, err = s.GetXMLDesc(0); err != nil {
				log.Println(err)
			}
			stype, err := s.GetUsageType()
			if err != nil {
				log.Println(err)
			}
			h.SecretList[i].Type = secret.SecretUsageTypeMap[stype]

			s.Free()
		}
	}
}

func (h *Host) getNodeInfo(wg *sync.WaitGroup) {
	defer wg.Done()
	var err error
	h.AvailableCPUTypes, err = h.conn.GetCPUModelNames("x86_64", 0)
	if err != nil {
		log.Println("Error getting cpu model names", err)
	}

	ni, err := h.conn.GetNodeInfo()
	if err != nil {
		log.Println(err)
	}
	h.HostInfo.Model = ni.Model
	h.HostInfo.Memory = ni.Memory
	h.HostInfo.Cpus = ni.Cpus
	h.HostInfo.MHz = ni.MHz
	h.HostInfo.Nodes = ni.Nodes
	h.HostInfo.Sockets = ni.Sockets
	h.HostInfo.Cores = ni.Cores
	h.HostInfo.Threads = ni.Threads
	h.SystemHostName, err = h.conn.GetHostname()
	if err != nil {
		log.Println(err)
	}
	if h.SystemHostName == "" {
		h.SystemHostName = h.HostName
	}
	h.LibVersion, err = h.conn.GetLibVersion()
	if err != nil {
		log.Println(err)
	}
	h.FreeMemory, err = h.conn.GetFreeMemory()
	if err != nil {
		log.Println(err)
	}

	mi, err := h.conn.GetMemoryStats(libvirt.NODE_MEMORY_STATS_ALL_CELLS, 0)
	if err != nil {
		log.Println(err)
	}
	h.NodeMemory.Total = mi.Total
	h.NodeMemory.Free = mi.Free
	h.NodeMemory.Buffers = mi.Buffers
	h.NodeMemory.Cached = mi.Cached

	h.StorageCapabilities, err = h.conn.GetStoragePoolCapabilities(0)
	if err != nil {
		log.Println(err)
	}

	h.SysInfo, err = h.conn.GetSysinfo(0)
	if err != nil {
		log.Println(err)
	}

	h.Alive, err = h.conn.IsAlive()
	if err != nil {
		log.Println(err)
	}
	h.Encrypted, err = h.conn.IsEncrypted()
	if err != nil {
		log.Println(err)
	}
	h.Secure, err = h.conn.IsSecure()
	if err != nil {
		log.Println(err)
	}
}

func (h *Host) getSEVInfo(wg *sync.WaitGroup) {
	defer wg.Done()
	// getSEVInfo
	h.HostSEVInfo.SEVEnabled = true
	ns, err := h.conn.GetSEVInfo(0)
	if err != nil {
		log.Println(err)
		lverr, ok := err.(libvirt.Error)
		if ok {
			switch lverr.Code {
			case 84:
				log.Println("SEV functions not supported")
				h.HostSEVInfo.SEVEnabled = false
			default:
				log.Println("Error encountered", lverr.Error())
			}
		}
	}
	if h.HostSEVInfo.SEVEnabled {
		h.HostSEVInfo.PDH = util.SetNotSet(ns.PDH, ns.PDHSet)
		h.HostSEVInfo.CertChain = util.SetNotSet(ns.CertChain, ns.CertChainSet)
		h.HostSEVInfo.CBitPos = ns.CBitPos
		h.HostSEVInfo.ReducedPhysBits = ns.ReducedPhysBits
		h.HostSEVInfo.MaxGuests = ns.MaxGuests
		h.HostSEVInfo.MaxEsGuests = ns.MaxEsGuests
		h.HostSEVInfo.CPU0ID = util.SetNotSet(ns.CPU0ID, ns.CPU0IDSet)
	}
}

func (h *Host) getDomainInfo(wg *sync.WaitGroup) {
	defer wg.Done()
	// getDomainInfo
	doms, err := h.conn.ListAllDomains(0)
	if err != nil {
		log.Println(err)
	}
	if len(doms) > 0 {
		h.VMList = make([]VMInfo, len(doms))
		for i, d := range doms {
			// Just going to log errors here, and free the dom after getting what we can
			if h.VMList[i].Name, err = d.GetName(); err != nil {
				log.Println(err)
			}
			if h.VMList[i].UUID, err = d.GetUUID(); err != nil {
				log.Println(err)
			}
			if h.VMList[i].ID, err = d.GetID(); err != nil {
				log.Println(err)
			}
			if h.VMList[i].XML, err = d.GetXMLDesc(0); err != nil {
				log.Println(err)
			}

			d.Free()
		}
	}
}

func (h *Host) getIfaceInfo(wg *sync.WaitGroup) {
	defer wg.Done()
	// getIfaceInfo
	ifaces, err := h.conn.ListInterfaces()
	if err != nil {
		log.Println(err)
	}
	if len(ifaces) > 0 {
		h.NetIfFList = make([]NetIfInfo, len(ifaces))
		for i, ni := range ifaces {
			h.NetIfFList[i].Name = ni
			iface, err := h.conn.LookupInterfaceByName(ni)
			if err != nil {
				log.Println(err)
			}
			if h.NetIfFList[i].MacAddr, err = iface.GetMACString(); err != nil {
				log.Println(err)
			}
			if h.NetIfFList[i].XML, err = iface.GetXMLDesc(0); err != nil {
				log.Println(err)
			}

			iface.Free()
		}
	}
}

func (h *Host) getNetsInfo(wg *sync.WaitGroup) {
	defer wg.Done()
	// getNetsInfo
	nets, err := h.conn.ListNetworks()
	if err != nil {
		log.Println(err)
	}
	if len(nets) > 0 {
		h.NetworkList = make([]NetworkInfo, len(nets))
		for i, netName := range nets {
			net, err := h.conn.LookupNetworkByName(netName)
			if err != nil {
				log.Println(err)
			}
			if h.NetworkList[i].Name, err = net.GetName(); err != nil {
				log.Println(err)
			}
			if h.NetworkList[i].UUID, err = net.GetUUID(); err != nil {
				log.Println(err)
			}
			if h.NetworkList[i].XML, err = net.GetXMLDesc(0); err != nil {
				log.Println(err)
			}

			net.Free()
		}
	}
}

func (h *Host) getDevicesInfo(wg *sync.WaitGroup) {
	defer wg.Done()
	ndevs, err := h.conn.ListAllNodeDevices(0)
	if err != nil {
		log.Println(err)
	}
	if len(ndevs) > 0 {
		h.DeviceList = make([]DeviceInfo, len(ndevs))
		for i, dev := range ndevs {
			if h.DeviceList[i].Name, err = dev.GetName(); err != nil {
				log.Println(err)
			}
			if h.DeviceList[i].Capabilities, err = dev.ListCaps(); err != nil {
				log.Println(err)
			}
			if h.DeviceList[i].XML, err = dev.GetXMLDesc(0); err != nil {
				log.Println(err)
			}

			dev.Free()
		}
	}
}