// 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"

	"git.staur.ca/stobbsm/clustvirt/lib/guest"
	"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            string
	SystemHostName      string
	FreeMemory          uint64
	LibVersion          uint32
	HostInfo            NodeInfo
	HostSEVInfo         SEVInfo
	AvailableCPUTypes   []string
	NodeMemory          NodeMemoryInfo
	StorageCapabilities string
	SysInfo             string
	Alive               bool
	Encrypted           bool
	Secure              bool
	// alldomains
	VMList []string
	// allinterfaces
	IFList []string
	// allnetworks
	NetList []string
	// alldevices
	DeviceList []string
	// allsecrets
	SecretList []string
	// allstoragepools
	StoragePoolList []string
	// defineddomains
	// definedinterfaces
	// definednetworks
	// definedstoragepools
	// listdomains []int id
	// listinterfaces []string interfacename
	// listnetworks []string networkname
	// listserets []string secretname
	// liststoragepools []string storagepoolname

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

// 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)

	var err error
	h.AvailableCPUTypes, err = h.conn.GetCPUModelNames("x86_64", 0)
	if err != nil {
		log.Println("Error getting cpu model names", err)
	}

	// Extract libvirt.NodeInfo and libvirt.NodeSEVParameters
	ni, err := h.conn.GetNodeInfo()
	if err != nil {
		return nil, 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

	// Assume SEV is enabled, until we know otherwise
	h.HostSEVInfo.SEVEnabled = true
	ns, err := h.conn.GetSEVInfo(0)
	if err != nil {
		lverr, ok := err.(libvirt.Error)
		if !ok {
			return nil, err
		}
		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)
	}

	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)
	}

	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
}