package main

import (
	e "codeberg.org/pebbe/errors"

	"encoding/json"
	"fmt"
	"os"
	"slices"
	"strconv"
	"strings"
	"time"
)

type Date struct {
	Week  string `json:"week"`
	First string `json:"first"`
	Last  string `json:"last"`
}

var (
	x = e.ExitErr

	dates = make([]Date, 0)
)

func main() {

	files, err := os.ReadDir("/net/corpora/nlnieuws/data/json")
	x(err)

	for _, file := range files {
		filename := file.Name()
		if strings.HasPrefix(filename, "DATA-") && strings.HasSuffix(filename, "-4.json") {
			addWeek(filename[5:12])
		}
	}

	slices.Reverse(dates)
	b, err := json.Marshal(dates)
	x(err)
	fmt.Println(string(b))

}

func addWeek(s string) {

	week, err := strconv.Atoi(s[5:])
	x(err)
	year, err := strconv.Atoi(s[:4])
	x(err)

	// 1 januari
	t := time.Date(year, 1, 1, 12, 0, 0, 0, time.UTC)

	// zoek eerste donderdag
	day := int(t.Weekday()) // 0 = zondag
	donderdag := 4 - day
	if donderdag < 0 {
		donderdag = donderdag + 7
	}

	// schuif naar maandag voor eerste donderdag: donderdag - 3
	// in de gewenste week: 7 * (week - 1)
	t = t.AddDate(0, 0, donderdag-3+7*(week-1))
	t2 := t.AddDate(0, 0, 6)

	dates = append(dates, Date{
		Week:  s,
		First: makeDate(t),
		Last:  makeDate(t2),
	})
}

func makeDate(d time.Time) string {
	return fmt.Sprintf("%d-%02d-%02d", d.Year(), int(d.Month()), d.Day())
}