package host

import (
	"net"
	"runtime"
	"time"

	"github.com/weaveworks/scope/common/mtime"
	"github.com/weaveworks/scope/probe/controls"
	"github.com/weaveworks/scope/report"
)

// Keys for use in Node.Latest.
const (
	Timestamp     = "ts"
	HostName      = "host_name"
	LocalNetworks = "local_networks"
	OS            = "os"
	KernelVersion = "kernel_version"
	Uptime        = "uptime"
	Load1         = "load1"
	CPUUsage      = "host_cpu_usage_percent"
	MemoryUsage   = "host_mem_usage_bytes"
	ScopeVersion  = "host_scope_version"
)

// Exposed for testing.
const (
	ProcUptime  = "/proc/uptime"
	ProcLoad    = "/proc/loadavg"
	ProcStat    = "/proc/stat"
	ProcMemInfo = "/proc/meminfo"
)

// Exposed for testing.
var (
	MetadataTemplates = report.MetadataTemplates{
		KernelVersion: {ID: KernelVersion, Label: "Kernel Version", From: report.FromLatest, Priority: 1},
		Uptime:        {ID: Uptime, Label: "Uptime", From: report.FromLatest, Priority: 2},
		HostName:      {ID: HostName, Label: "Hostname", From: report.FromLatest, Priority: 11},
		OS:            {ID: OS, Label: "OS", From: report.FromLatest, Priority: 12},
		LocalNetworks: {ID: LocalNetworks, Label: "Local Networks", From: report.FromSets, Priority: 13},
		ScopeVersion:  {ID: ScopeVersion, Label: "Scope Version", From: report.FromLatest, Priority: 14},
	}

	MetricTemplates = report.MetricTemplates{
		CPUUsage:    {ID: CPUUsage, Label: "CPU", Format: report.PercentFormat, Priority: 1},
		MemoryUsage: {ID: MemoryUsage, Label: "Memory", Format: report.FilesizeFormat, Priority: 2},
		Load1:       {ID: Load1, Label: "Load (1m)", Format: report.DefaultFormat, Group: "load", Priority: 11},
	}
)

// Reporter generates Reports containing the host topology.
type Reporter struct {
	hostID       string
	hostName     string
	probeID      string
	version      string
	pipes        controls.PipeClient
	hostShellCmd []string
}

// NewReporter returns a Reporter which produces a report containing host
// topology for this host.
func NewReporter(hostID, hostName, probeID, version string, pipes controls.PipeClient) *Reporter {
	r := &Reporter{
		hostID:       hostID,
		hostName:     hostName,
		probeID:      probeID,
		pipes:        pipes,
		version:      version,
		hostShellCmd: getHostShellCmd(),
	}
	r.registerControls()
	return r
}

// Name of this reporter, for metrics gathering
func (Reporter) Name() string { return "Host" }

// GetLocalNetworks is exported for mocking
var GetLocalNetworks = func() ([]*net.IPNet, error) {
	addrs, err := net.InterfaceAddrs()
	if err != nil {
		return nil, err
	}
	localNets := report.Networks{}
	for _, addr := range addrs {
		// Not all addrs are IPNets.
		if ipNet, ok := addr.(*net.IPNet); ok {
			localNets = append(localNets, ipNet)
		}
	}
	return localNets, nil
}

// Report implements Reporter.
func (r *Reporter) Report() (report.Report, error) {
	var (
		rep        = report.MakeReport()
		localCIDRs []string
	)

	localNets, err := GetLocalNetworks()
	if err != nil {
		return rep, nil
	}
	for _, localNet := range localNets {
		localCIDRs = append(localCIDRs, localNet.String())
	}

	uptime, err := GetUptime()
	if err != nil {
		return rep, err
	}

	kernel, err := GetKernelVersion()
	if err != nil {
		return rep, err
	}

	rep.Host = rep.Host.WithMetadataTemplates(MetadataTemplates)
	rep.Host = rep.Host.WithMetricTemplates(MetricTemplates)

	now := mtime.Now()
	metrics := GetLoad(now)
	cpuUsage, max := GetCPUUsagePercent()
	metrics[CPUUsage] = report.MakeMetric().Add(now, cpuUsage).WithMax(max)
	memoryUsage, max := GetMemoryUsageBytes()
	metrics[MemoryUsage] = report.MakeMetric().Add(now, memoryUsage).WithMax(max)

	rep.Host.AddNode(
		report.MakeNodeWith(report.MakeHostNodeID(r.hostID), map[string]string{
			report.ControlProbeID: r.probeID,
			Timestamp:             mtime.Now().UTC().Format(time.RFC3339Nano),
			HostName:              r.hostName,
			OS:                    runtime.GOOS,
			KernelVersion:         kernel,
			Uptime:                uptime.String(),
			ScopeVersion:          r.version,
		}).
			WithSets(report.EmptySets.
				Add(LocalNetworks, report.MakeStringSet(localCIDRs...)),
			).
			WithMetrics(metrics).
			WithControls(ExecHost),
	)

	rep.Host.Controls.AddControl(report.Control{
		ID:    ExecHost,
		Human: "Exec shell",
		Icon:  "fa-terminal",
	})

	return rep, nil
}

// Stop stops the reporter.
func (r *Reporter) Stop() {
	r.deregisterControls()
}