// Copyright (C) 2015-2017 Mikael Berthe <mikael@lilotux.net>. All rights reserved.

// Use of this source code is governed by the MIT license,

// which can be found in the LICENSE file.

//

// Thanks to atbrask's blog post <http://www.atbrask.dk/?p=98> for the

// protocol details.

// gobm65 is a Beurer BM65 Blood Pressure Monitor CLI reader.

package main

// Installation:

//

// % go get hg.lilotux.net/golang/mikael/gobm65

//

// Examples:

//

// Get help:

// % gobm65 --help

//

// Get records and display the average:

// % gobm65 --average

//

// Display the latest 3 records with the average:

// % gobm65 -l 3 --average

// Display all records since a specific date:

// % gobm65 --since "2016-06-01"

// Display all records of the last 7 days:

// % gobm65 --since "$(date "+%F" -d "7 days ago")"

//

// Display the last/first 10 records in JSON:

// % gobm65 -l 10 --format json

//

// Save the records to a JSON file:

// % gobm65 -o data_u2.json

//

// Read a JSON file and display average of the last 3 records:

// % gobm65 -i data_u2.json -l 3 --average

// Read a JSON file, merge with device records, and save to another file:

// % gobm65 -i data_u2.json --merge -o data_u2-new.json

import (

	"encoding/json"

	"fmt"

	"io"

	"io/ioutil"

	"log"

	"math"

	"sort"

	"time"

	flag "github.com/docker/docker/pkg/mflag"

	"github.com/tarm/serial"

)

type measurement struct {

	Header    int

	Systolic  int

	Diastolic int

	Pulse     int

	Month     int

	Day       int

	Hour      int

	Minute    int

	Year      int

}

func getData(s io.ReadWriteCloser, buf []byte, size int) (int, error) {

	t := 0

	b := buf

	for t < size {

		n, err := s.Read(b[t:])

		if err != nil {

			log.Fatal(err) // XXX

			return t, err

		}

		//log.Printf("(%d bytes) %q\n", n, b[t:t+1])

		t = t + n

	}

	return t, nil

}

func fetchData(dev string) (items []measurement, err error) {

	c := &serial.Config{Name: dev, Baud: 4800}

	var s *serial.Port

	s, err = serial.OpenPort(c)

	if err != nil {

		return items, err

	}

	// =================== Handshake =====================

	q := []byte("\xaa")

	//log.Printf("Query: %q\n", q)

	log.Println("Starting handshake...")

	n, err := s.Write(q)

	if err != nil {

		return items, err

	}

	buf := make([]byte, 128)

	n, err = getData(s, buf, 1)

	if err != nil {

		return items, err

	}

	if n == 1 && buf[0] == '\x55' {

		log.Println("Handshake successful.")

	} else {

		log.Printf("(%d bytes) %q\n", n, buf[:n])

		s.Close()

		return items, fmt.Errorf("handshake failed")

	}

	// =================== Desc =====================

	q = []byte("\xa4")

	//log.Printf("Query: %q\n", q)

	log.Println("Requesting device description...")

	n, err = s.Write(q)

	if err != nil {

		return items, err

	}

	n, err = getData(s, buf, 32)

	log.Printf("DESC> %q\n", buf[:n])

	// =================== Count =====================

	q = []byte("\xa2")

	//log.Printf("Query: %q\n", q)

	log.Println("Requesting data counter...")

	n, err = s.Write(q)

	if err != nil {

		return items, err

	}

	n, err = getData(s, buf, 1)

	if err != nil {

		return items, err

	}

	var nRecords int

	if n == 1 {

		log.Printf("%d item(s) available.", buf[0])

		nRecords = int(buf[0])

	} else {

		log.Printf("(%d bytes) %q\n", n, buf[:n])

		return items, fmt.Errorf("no measurement found")

	}

	// =================== Records =====================

	for i := 0; i < nRecords; i++ {

		q = []byte{'\xa3', uint8(i + 1)}

		//log.Printf("Query: %q\n", q)

		//log.Printf("Requesting measurement %d...", i+1)

		n, err = s.Write(q)

		if err != nil {

			return items, err

		}

		n, err = getData(s, buf, 9)

		//log.Printf("DESC> %q\n", buf[:n])

		var data measurement

		data.Header = int(buf[0])

		data.Systolic = int(buf[1]) + 25

		data.Diastolic = int(buf[2]) + 25

		data.Pulse = int(buf[3])

		data.Month = int(buf[4])

		data.Day = int(buf[5])

		data.Hour = int(buf[6])

		data.Minute = int(buf[7])

		data.Year = int(buf[8]) + 2000

		items = append(items, data)

	}

	s.Close()

	return items, nil

}

func loadFromJSONFile(filename string) (items []measurement, err error) {

	data, err := ioutil.ReadFile(filename)

	if err != nil {

		return items, err

	}

	err = json.Unmarshal(data, &items)

	return items, err

}

func mergeItems(newItems, oldItems []measurement) []measurement {

	var result []measurement

	var j int

	// TODO: Would be better to compare dates and merge chronologically...

	for _, nItem := range newItems {

		result = append(result, nItem)

		if j+1 <= len(oldItems) && nItem == oldItems[j] {

			j++

		}

	}

	if j+1 <= len(oldItems) {

		result = append(result, oldItems[j:]...)

	}

	return result

}

func parseDate(dateStr string) (date time.Time, err error) {

	if dateStr == "" {

		return

	}

	var yy, mm, dd, h, m, s int

	n, e := fmt.Sscanf(dateStr, "%d-%d-%d %d:%d:%d", &yy, &mm, &dd, &h, &m, &s)

	if e != nil && n < 3 {

		err = e

		return

	}

	if n < 6 {

		log.Printf("Date parsed with only %d fields\n", n)

	}

	date = time.Date(yy, time.Month(mm), dd, h, m, s, 0, time.Local)

	return

}

func average(items []measurement) (measurement, error) {

	var avgMeasure measurement

	var avgCount int

	for _, data := range items {

		avgMeasure.Systolic += data.Systolic

		avgMeasure.Diastolic += data.Diastolic

		avgMeasure.Pulse += data.Pulse

		avgCount++

	}

	roundDivision := func(a, b int) int {

		return int(0.5 + float64(a)/float64(b))

	}

	if avgCount == 0 {

		return avgMeasure, fmt.Errorf("cannot compute average: empty set")

	}

	avgMeasure.Systolic = roundDivision(avgMeasure.Systolic, avgCount)

	avgMeasure.Diastolic = roundDivision(avgMeasure.Diastolic, avgCount)

	avgMeasure.Pulse = roundDivision(avgMeasure.Pulse, avgCount)

	return avgMeasure, nil

}

func intMedian(numbers []int) int {

	middle := len(numbers) / 2

	med := numbers[middle]

	if len(numbers)%2 == 0 {

		med = (med + numbers[middle-1]) / 2

	}

	return med

}

func median(items []measurement) (measurement, error) {

	var med measurement

	if len(items) == 0 {

		return med, fmt.Errorf("cannot compute average: empty set")

	}

	var sys, dia, pul []int

	for _, data := range items {

		sys = append(sys, data.Systolic)

		dia = append(dia, data.Diastolic)

		pul = append(pul, data.Pulse)

	}

	sort.Ints(sys)

	sort.Ints(dia)

	sort.Ints(pul)

	med.Systolic = intMedian(sys)

	med.Diastolic = intMedian(dia)

	med.Pulse = intMedian(pul)

	return med, nil

}

func stdDeviation(items []measurement) (measurement, error) {

	var sDev measurement

	if len(items) <= 1 {

		return sDev, fmt.Errorf("cannot compute deviation: set too small")

	}

	var sumSys, sumDia, sumPul float64

	avg, err := average(items)

	if err != nil {

		return sDev, err

	}

	for _, data := range items {

		sumSys += math.Pow(float64(data.Systolic-avg.Systolic), 2)

		sumDia += math.Pow(float64(data.Diastolic-avg.Diastolic), 2)

		sumPul += math.Pow(float64(data.Pulse-avg.Pulse), 2)

	}

	sDev.Systolic = int(math.Sqrt(sumSys / float64(len(items)-1)))

	sDev.Diastolic = int(math.Sqrt(sumDia / float64(len(items)-1)))

	sDev.Pulse = int(math.Sqrt(sumPul / float64(len(items)-1)))

	return sDev, nil

}

func main() {

	inFile := flag.String([]string{"-input-file", "i"}, "", "Input JSON file")

	outFile := flag.String([]string{"-output-file", "o"}, "", "Output JSON file")

	limit := flag.Uint([]string{"-limit", "l"}, 0, "Limit number of items to N first")

	since := flag.String([]string{"-since"}, "",

		"Filter records from date (YYYY-mm-dd HH:MM:SS)")

	format := flag.String([]string{"-format", "f"}, "", "Output format (csv, json)")

	avg := flag.Bool([]string{"-average", "a"}, false, "Compute average")

	stats := flag.Bool([]string{"-stats"}, false, "Compute statistics")

	merge := flag.Bool([]string{"-merge", "m"}, false,

		"Try to merge input JSON file with fetched data")

	device := flag.String([]string{"-device", "d"}, "/dev/ttyUSB0", "Serial device")

	flag.Parse()

	switch *format {

	case "":

		if *outFile == "" {

			*format = "csv"

		}

		break

	case "json", "csv":

		break

	default:

		log.Fatal("Unknown output format.  Possible choices are csv, json.")

	}

	startDate, err := parseDate(*since)

	if err != nil {

		log.Fatal("Could not parse date: ", err)

	}

	var items []measurement

	if *inFile == "" {

		// Read from device

		if items, err = fetchData(*device); err != nil {

			log.Fatal(err)

		}

	} else {

		// Read from file

		var fileItems []measurement

		if fileItems, err = loadFromJSONFile(*inFile); err != nil {

			log.Fatal(err)

		}

		if *merge {