// Package guest implements utilities and structured data for libvirt virtual machines
package guest

import (
	"errors"
	"log"
	"time"

	"libvirt.org/go/libvirt"
)

// Errors

// ErrVMNotFound error when virtual machine is not found
var ErrVMNotFound = errors.New("virtual machine not found")

// VM holds a handle is used to communicate to Domains
type VM struct {
	Name              string
	HostName          string
	ID                uint
	BackupXML         string
	Autostart         bool
	BlockIOParameters BlockIOParametersInfo
	Disks             []DiskInfo
	Users             []UserInfo
	OS                OSInfo
	TimeZone          TimeZoneInfo
	NetIFace          []NetIFaceInfo

	close    chan struct{}
	closeErr chan error
	dom      *libvirt.Domain
}

// BlockIOParametersInfo is the struct describing VM block IO parameters
type BlockIOParametersInfo struct {
	Weight          uint
	DeviceWeight    string
	DeviceReadIops  string
	DeviceWriteIops string
	DeviceReadBps   string
	DeviceWriteBps  string
}

// DiskInfo is the struct for guest disk information, and is used in VM
type DiskInfo struct {
	Name           string
	Partition      bool
	Alias          string
	GuestAlias     string
	DiskDependency []string
}

// UserInfo is the struct for VM user information, and is used in VM
type UserInfo struct {
	Name      string
	Domain    string
	LoginTime time.Time
}

// OSInfo is the struct for guest operating system information, and is used in VM
type OSInfo struct {
	ID            string
	Name          string
	PrettyName    string
	Version       string
	VersionID     string
	KernelRelease string
	KernelVersion string
	Machine       string
	Variant       string
	VariantID     string
}

// TimeZoneInfo provides guest timezone information, and is used in VM
type TimeZoneInfo struct {
	Name   string
	Offset int
}

// NetIFaceInfo provides guest Network Interface information, and is used in VM
type NetIFaceInfo struct {
	Name   string
	HWAddr string
	IP     []IPInfo
}

// IPInfo provides guest IP network information, and is used in NetIFaceInfo
type IPInfo struct {
	Type   string
	Addr   string
	Prefix uint
}

// GetGuest loads guest information by name and returns it
func GetGuest(name string, conn *libvirt.Connect) (*VM, error) {
	g := &VM{
		Name:     name,
		close:    make(chan struct{}),
		closeErr: make(chan error),
	}

	var err error

	// If the domain can't be found by name, exit early with an error
	if g.dom, err = conn.LookupDomainByName(name); err != nil {
		return g, err
	}
	if g.ID, err = g.dom.GetID(); err != nil {
		return g, err
	}

	if g.Autostart, err = g.dom.GetAutostart(); err != nil {
		return g, err
	}

	blkiop, err := g.dom.GetBlkioParameters(0)
	if err != nil {
		return g, err
	}
	g.BlockIOParameters.Weight = blkiop.Weight
	g.BlockIOParameters.DeviceWeight = setNotSet(blkiop.DeviceWeight, blkiop.DeviceWeightSet)
	g.BlockIOParameters.DeviceReadIops = setNotSet(blkiop.DeviceReadIops, blkiop.DeviceReadIopsSet)
	g.BlockIOParameters.DeviceWriteIops = setNotSet(blkiop.DeviceWriteIops, blkiop.DeviceWriteIopsSet)
	g.BlockIOParameters.DeviceReadBps = setNotSet(blkiop.DeviceReadBps, blkiop.DeviceReadBpsSet)
	g.BlockIOParameters.DeviceWriteBps = setNotSet(blkiop.DeviceWriteBps, blkiop.DeviceWriteBpsSet)

	// Set as much guest info as possible
	info, err := g.dom.GetGuestInfo(
		libvirt.DOMAIN_GUEST_INFO_USERS|libvirt.DOMAIN_GUEST_INFO_OS|
			libvirt.DOMAIN_GUEST_INFO_DISKS|libvirt.DOMAIN_GUEST_INFO_HOSTNAME|
			libvirt.DOMAIN_GUEST_INFO_INTERFACES|libvirt.DOMAIN_GUEST_INFO_TIMEZONE|
			libvirt.DOMAIN_GUEST_INFO_FILESYSTEM,
		0,
	)
	if err != nil {
		return g, err
	}
	// Set disk info
	if len(info.Disks) > 0 {
		g.Disks = make([]DiskInfo, len(info.Disks))
		for i, n := range info.Disks {
			g.Disks[i].Name = setNotSet(n.Name, n.NameSet)
			g.Disks[i].Alias = setNotSet(n.Alias, n.AliasSet)
			g.Disks[i].Partition = n.Partition
			g.Disks[i].GuestAlias = setNotSet(n.GuestAlias, n.GuestAliasSet)
			g.Disks[i].DiskDependency = make([]string, len(n.Dependencies))
			for j, k := range n.Dependencies {
				g.Disks[i].DiskDependency[j] = setNotSet(k.Name, k.NameSet)
			}
		}
	}

	if len(info.Users) > 0 {
		g.Users = make([]UserInfo, len(info.Users))
		for i, n := range info.Users {
			g.Users[i].Name = setNotSet(n.Name, n.NameSet)
			g.Users[i].Domain = setNotSet(n.Domain, n.DomainSet)
			g.Users[i].LoginTime = time.Unix(int64(n.LoginTime), 0)
		}
	}

	g.OS.ID = setNotSet(info.OS.ID, info.OS.IDSet)
	g.OS.Name = setNotSet(info.OS.Name, info.OS.NameSet)
	g.OS.Machine = setNotSet(info.OS.Machine, info.OS.MachineSet)
	g.OS.Variant = setNotSet(info.OS.Variant, info.OS.VariantSet)
	g.OS.Version = setNotSet(info.OS.Version, info.OS.VersionSet)
	g.OS.VariantID = setNotSet(info.OS.VariantID, info.OS.VariantIDSet)
	g.OS.VersionID = setNotSet(info.OS.VersionID, info.OS.VersionIDSet)
	g.OS.PrettyName = setNotSet(info.OS.PrettyName, info.OS.PrettyNameSet)
	g.OS.KernelRelease = setNotSet(info.OS.KernelRelease, info.OS.KernelReleaseSet)
	g.OS.KernelVersion = setNotSet(info.OS.KernelVersion, info.OS.KernelVersionSet)
	g.TimeZone.Name = setNotSet(info.TimeZone.Name, info.TimeZone.NameSet)
	g.TimeZone.Offset = info.TimeZone.Offset

	// Set the hostname from the guest if it is set, otherwise use the VM name
	if info.HostnameSet {
		g.HostName = info.Hostname
	} else {
		g.HostName = g.Name
	}
	if len(info.Interfaces) > 0 {
		g.NetIFace = make([]NetIFaceInfo, len(info.Interfaces))
		for i, n := range info.Interfaces {
			g.NetIFace[i].HWAddr = setNotSet(n.Hwaddr, n.HwaddrSet)
			g.NetIFace[i].Name = setNotSet(n.Name, n.NameSet)
			if len(n.Addrs) > 0 {
				g.NetIFace[i].IP = make([]IPInfo, len(n.Addrs))
				for j, a := range n.Addrs {
					g.NetIFace[i].IP[j].Addr = setNotSet(a.Addr, a.AddrSet)
					g.NetIFace[i].IP[j].Type = setNotSet(a.Type, a.TypeSet)
					g.NetIFace[i].IP[j].Prefix = a.Prefix
				}
			}
		}
	}

	// Not errors, but still log the warnings when this happens
	if g.BackupXML, err = g.dom.BackupGetXMLDesc(0); err != nil {
		log.Printf("WARNING: While loading backup information: %s", err)
	}

	go func() {
		defer close(g.closeErr)
		<-g.close
		g.closeErr <- g.dom.Free()
	}()

	return g, nil
}

// helper function to set a string value to "NotSet" if it wasn't actually set
func setNotSet(v string, s bool) string {
	if s {
		return v
	}
	return "Notset"
}

// Close closes an open connection
func (g *VM) Close() error {
	log.Println("Closing VM", g.Name)
	close(g.close)
	return <-g.closeErr
}