main.go

package main

import (
	"compress/gzip"
	"encoding/csv"
	"fmt"
	"log"
	"os"
	"path/filepath"
	"strconv"
	"time"
)

func count(fn string, index int) (int, int) {
	fmt.Printf("%d %v\n", index, fn)
	f, err := os.Open(fn)
	if err != nil {
		log.Fatal(err)
	}
	defer f.Close()
	gr, err := gzip.NewReader(f)
	if err != nil {
		log.Fatal(err)
	}
	defer gr.Close()

	cr := csv.NewReader(gr)
	rec, err := cr.ReadAll()
	if err != nil {
		log.Fatal(err)
	}
	var count = 0
	var total = 0
	layout := "2006-01-02T15:04:05.000Z"

	minimum, err := time.Parse(layout, "2017-11-02T00:00:00.000Z")
	if err != nil {
		log.Fatal(err)
	}

	for _, v := range rec {
		last_modified := v[3]

		t, err := time.Parse(layout, last_modified)
		if err != nil {
			log.Fatal(err)
		}
		if t.After(minimum) {
			count += 1
		}
		total += 1
	}
	return total, count
}

func FloatToString(input_num float64) string {
	// to convert a float number to a string
	return strconv.FormatFloat(input_num, 'f', 2, 64)
}

func main() {
	var pattern = "*.csv.gz"

	files, err := filepath.Glob(pattern)
	if err != nil {
		panic(err)
	}
	total := int(0)
	recent := int(0)
	for i, fn := range files {
		if len(fn) == 39 {
			// fmt.Println(fn)
			c, t := count(fn, i)
			total += t
			recent += c
		}
	}
	fmt.Println(total)
	fmt.Println(recent)
	ratio := float64(recent) / float64(total)
	fmt.Println(FloatToString(100.0 * ratio))
}