gen.go

package main

import (
	"encoding/csv"
	"flag"
	"log"
	"math/rand"
	"os"
	"strconv"
	"time"

	"github.com/bxcodec/faker/v3"
)

const dateFormat = "2006/01/02"

func main() {
	var (
		start   = flag.String("start", "", "start date")
		end     = flag.String("end", "", "end date")
		testN   = flag.Uint("initTest", 100, "number of tests on first day")
		testMul = flag.Float64("testMul", 1.2, "test result multiplier per day")
		prob    = flag.Float64("prob", 0.1, "start probability to get positive test result")
		posMul  = flag.Float64("posMul", 1.2, "positive probability multiplier per day")
		city    = flag.String("city", "", "name of city")
	)

	flag.Parse()

	d, err := time.Parse(dateFormat, *start)
	checkErr(err)

	endDate, err := time.Parse(dateFormat, *end)
	checkErr(err)

	w := csv.NewWriter(os.Stdout)
	checkErr(w.Write([]string{
		"first_name",
		"last_name",
		"birth_year",
		"personal_id",
		"test_location_latitude",
		"test_location_longitude",
		"area",
		"test_date",
		"test_result",
		"unique_test_id",
	}))

	day := 0
	for ; endDate.After(d); d = d.AddDate(0, 0, 1) {
		for i := uint(0); i < *testN; i++ {
			checkErr(w.Write([]string{
				faker.FirstName(),
				faker.LastName(),
				strconv.Itoa(1940 + rand.Intn(80)),
				strconv.Itoa(1000000000 + rand.Intn(8999999999)),
				"",
				"",
				*city,
				d.Format(dateFormat),
				strconv.FormatBool(rand.Float64() < *prob),
				faker.UUIDHyphenated(),
			}))
		}
		*testN = uint(*testMul * float64(*testN))
		day++
		*prob *= *posMul
	}
	w.Flush()
	checkErr(w.Error())
}

func checkErr(err error) {
	if err != nil {
		log.Fatal(err)
	}
}