// Copyright 2018 The Fuchsia Authors. All rights reserved.
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are
// met:
//
//    * Redistributions of source code must retain the above copyright
// notice, this list of conditions and the following disclaimer.
//    * Redistributions in binary form must reproduce the above
// copyright notice, this list of conditions and the following disclaimer
// in the documentation and/or other materials provided with the
// distribution.
//    * Neither the name of Google Inc. nor the names of its
// contributors may be used to endorse or promote products derived from
// this software without specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

package main

import (
	"context"
	"encoding/csv"
	"flag"
	"log"
	"os"
	"os/signal"
	"strconv"

	"fuchsia.googlesource.com/zedmon"
	"github.com/google/subcommands"
)

type recordCmd struct{}

// Flag-controlled values.
var out string
var writeHeader bool
var resistance float64

func (*recordCmd) Name() string { return "record" }
func (*recordCmd) Synopsis() string {
	return "Record data from zedmon.  Saves to zedmon.csv or streams to stdout."
}
func (*recordCmd) Usage() string {
	return `record
`
}

func (*recordCmd) SetFlags(flags *flag.FlagSet) {
	setCommonFlags(flags)
	flags.StringVar(&out, "out", "zedmon.csv", "Output file. Specify \"-\" for stdout.")
	flags.BoolVar(&writeHeader, "header", false, "Whether to include a header line in the output.")
	flags.Float64Var(&resistance, "resistance", -1.0,
		"Shunt resistance in Ohms. If set to a positive value, power will be included in the output.")
}

// If a positive resistance and field names including "v_bus" and "v_shunt" are provided, returns a
// function that calculates power from zedmon-provided values. Returns nil otherwise.
func getPowerCalculator(resistance float64, fieldNames []string) func(values []float64) float64 {
	if resistance <= 0.0 {
		return nil
	}

	vBusIndex := -1
	vShuntIndex := -1
	for i, name := range fieldNames {
		if name == "v_bus" {
			vBusIndex = i
		} else if name == "v_shunt" {
			vShuntIndex = i
		}
	}
	if vBusIndex < 0 || vShuntIndex < 0 {
		return nil
	}

	return func(values []float64) float64 {
		return values[vShuntIndex] * values[vBusIndex] / resistance
	}
}

func (*recordCmd) Execute(_ context.Context, _ *flag.FlagSet, _ ...interface{}) subcommands.ExitStatus {
	zedmon, err := zedmon.OpenZedmon(getConfig())
	if err != nil {
		log.Printf("Can't open zendmon: %v", err)
		return subcommands.ExitFailure
	}
	defer zedmon.Close()

	var f *os.File
	if out == "-" {
		f = os.Stdout
	} else {
		f, err = os.OpenFile(out, os.O_CREATE|os.O_WRONLY|os.O_TRUNC, 0666)
		if err != nil {
			log.Printf("Can't open %s: %v", out, err)
			return subcommands.ExitFailure
		}
		defer f.Close()
	}

	offset, delta, err := zedmon.GetTimeOffset()
	if err != nil {
		log.Printf("Get time offset: %v", err)
		return subcommands.ExitFailure
	}
	log.Printf("Time offset: %dns ± %dns\n", offset.Nanoseconds(), delta.Nanoseconds())

	termChan := make(chan os.Signal, 1)
	signal.Notify(termChan, os.Interrupt)

	writer := csv.NewWriter(f)
	defer writer.Flush()

	log.Println("Starting report recording. Send ^C to stop.")
	zedmon.EnableReporting()

	fieldNames := zedmon.GetFieldNames()

	calculatePower := getPowerCalculator(resistance, fieldNames)
	if calculatePower != nil {
		fieldNames = append(fieldNames, "power")
	}

	if writeHeader {
		header := make([]string, 1+len(fieldNames))
		header[0] = "timestamp"
		copy(header[1:], fieldNames)
		writer.Write(header)
	}

RecordSampling:
	for {
		reports, err := zedmon.ReadReports()
		if err != nil {
			log.Printf("Error reading reports: %v", err)
			continue
		}
		for _, report := range reports {
			record := make([]string, 0, len(fieldNames))
			record = append(record, strconv.FormatUint(report.Timestamp, 10))
			for _, value := range report.Values {
				record = append(record, strconv.FormatFloat(value, 'g', -1, 64))
			}
			if calculatePower != nil {
				power := calculatePower(report.Values)
				record = append(record, strconv.FormatFloat(power, 'g', -1, 64))
			}
			writer.Write(record)
		}

		select {
		case <-termChan:
			break RecordSampling
		default:
		}
	}
	log.Println("Stopping report recording.")

	return subcommands.ExitSuccess
}