// Copyright 2017 CoreOS, Inc.
//
// 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 agent

import (
	"fmt"
	"os"
	"time"

	"github.com/gyuho/linux-inspect/inspect"
	"github.com/gyuho/linux-inspect/top"
	"go.uber.org/zap"
)

// startMetrics starts collecting metrics.
func startMetrics(fs *flags, t *transporterServer) (err error) {
	if fs == nil || t == nil || t.cmd == nil {
		return fmt.Errorf("cannot find process to track (%+v, %+v)", fs, t)
	}

	t.lg.Info(
		"starting collecting system metrics",
		zap.String("database", t.req.DatabaseID.String()),
		zap.String("disk-device", fs.diskDevice),
		zap.String("network-device", fs.networkInterface),
		zap.Int64("pid", t.pid),
	)
	if err = os.RemoveAll(fs.systemMetricsCSV); err != nil {
		return err
	}
	if err = toFile(fmt.Sprintf("%d", t.req.CurrentClientNumber), t.clientNumPath); err != nil {
		return err
	}

	tcfg := &top.Config{
		Exec:           top.DefaultExecPath,
		IntervalSecond: 1,
		PID:            t.pid,
	}
	t.metricsCSV, err = inspect.NewCSV(
		fs.systemMetricsCSV,
		t.pid,
		fs.diskDevice,
		fs.networkInterface,
		t.clientNumPath,
		tcfg,
	)
	if err := t.metricsCSV.Add(); err != nil {
		return err
	}

	go func() {
		for {
			select {
			case <-time.After(time.Second):
				if err := t.metricsCSV.Add(); err != nil {
					t.lg.Warn("inspect.CSV.Add error", zap.Error(err))
					continue
				}

			case <-t.uploadSig:
				t.lg.Info("upload requested, saving CSV", zap.String("path", t.metricsCSV.FilePath))
				if err := t.metricsCSV.Save(); err != nil {
					t.lg.Warn("failed to save CSV", zap.Error(err))
				} else {
					t.lg.Info("saved CSV", zap.String("path", t.metricsCSV.FilePath))
				}

				interpolated, err := t.metricsCSV.Interpolate()
				if err != nil {
					t.lg.Fatal("failed to inspect.CSV.Interpolate", zap.Error(err))
				}
				interpolated.FilePath = fs.systemMetricsCSVInterpolated

				if err := interpolated.Save(); err != nil {
					t.lg.Warn("failed to save CSV", zap.Error(err))
				} else {
					t.lg.Info("saved CSV", zap.String("path", interpolated.FilePath))
				}

				close(t.csvReady)
				return

			case sig := <-t.notifier:
				t.lg.Info("received a signal", zap.String("signal", sig.String()))
				return
			}
		}
	}()
	return nil
}