/*
Copyright (c) 2017 VMware, Inc. All Rights Reserved.

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

    http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
*/

package metric

import (
	"context"
	"encoding/json"
	"flag"
	"fmt"
	"io"
	"text/tabwriter"

	"github.com/vmware/govmomi/govc/cli"
	"github.com/vmware/govmomi/performance"
	"github.com/vmware/govmomi/vim25/types"
)

type ls struct {
	*PerformanceFlag

	group    string
	long     bool
	longlong bool
}

func init() {
	cli.Register("metric.ls", &ls{})
}

func (cmd *ls) Register(ctx context.Context, f *flag.FlagSet) {
	cmd.PerformanceFlag, ctx = NewPerformanceFlag(ctx)
	cmd.PerformanceFlag.Register(ctx, f)

	f.StringVar(&cmd.group, "g", "", "List a specific Group")
	f.BoolVar(&cmd.long, "l", false, "Long listing format")
	f.BoolVar(&cmd.longlong, "L", false, "Longer listing format")
}

func (cmd *ls) Usage() string {
	return "PATH"
}

func (cmd *ls) Description() string {
	return `List available metrics for PATH.

The default output format is the metric name.
The '-l' flag includes the metric description.
The '-L' flag includes the metric units, instance count (if any) and description.
The instance count is prefixed with a single '@'.
If no aggregate is provided for the metric, instance count is prefixed with two '@@'.

Examples:
  govc metric.ls /dc1/host/cluster1
  govc metric.ls datastore/*
  govc metric.ls -L -g CPU /dc1/host/cluster1/host1
  govc metric.ls vm/* | grep mem. | xargs govc metric.sample vm/*`
}

func (cmd *ls) Process(ctx context.Context) error {
	if err := cmd.PerformanceFlag.Process(ctx); err != nil {
		return err
	}
	return nil
}

type lsResult struct {
	cmd      *ls
	counters map[int32]*types.PerfCounterInfo
	performance.MetricList
}

func (r *lsResult) Write(w io.Writer) error {
	tw := tabwriter.NewWriter(w, 2, 0, 2, ' ', 0)

	type count struct {
		aggregate bool
		instances int
	}
	seen := make(map[int32]*count)
	var res []types.PerfMetricId

	for _, id := range r.MetricList {
		if r.cmd.group != "" {
			info := r.counters[id.CounterId]
			if info.GroupInfo.GetElementDescription().Label != r.cmd.group {
				continue
			}
		}

		c := seen[id.CounterId]
		if c == nil {
			c = new(count)
			seen[id.CounterId] = c
			res = append(res, id)
		}

		if id.Instance == "" {
			c.aggregate = true
		} else {
			c.instances++
		}
	}

	for _, id := range res {
		info := r.counters[id.CounterId]

		switch {
		case r.cmd.long:
			fmt.Fprintf(tw, "%s\t%s\n", info.Name(),
				info.NameInfo.GetElementDescription().Label)
		case r.cmd.longlong:
			i := ""
			c := seen[id.CounterId]
			if !c.aggregate {
				i = "@"
			}
			if c.instances > 0 {
				i += fmt.Sprintf("@%d", c.instances)
			}
			fmt.Fprintf(tw, "%s\t%s\t%s\t%s\n", info.Name(),
				i,
				info.UnitInfo.GetElementDescription().Label,
				info.NameInfo.GetElementDescription().Label)
		default:
			fmt.Fprintln(w, info.Name())
		}
	}

	return tw.Flush()
}

func (r *lsResult) MarshalJSON() ([]byte, error) {
	m := make(map[string]*types.PerfCounterInfo)

	for _, id := range r.MetricList {
		info := r.counters[id.CounterId]

		m[info.Name()] = info
	}

	return json.Marshal(m)
}

func (cmd *ls) Run(ctx context.Context, f *flag.FlagSet) error {
	if f.NArg() != 1 {
		return flag.ErrHelp
	}

	objs, err := cmd.ManagedObjects(ctx, f.Args())
	if err != nil {
		return err
	}

	m, err := cmd.Manager(ctx)
	if err != nil {
		return err
	}

	s, err := m.ProviderSummary(ctx, objs[0])
	if err != nil {
		return err
	}

	mids, err := m.AvailableMetric(ctx, objs[0], cmd.Interval(s.RefreshRate))
	if err != nil {
		return err
	}

	counters, err := m.CounterInfoByKey(ctx)
	if err != nil {
		return err
	}

	return cmd.WriteResult(&lsResult{cmd, counters, mids})
}