// Package hu holds the Hungarian-locale formatting the server needs for share
// metadata and share images. The browser keeps using Intl for everything it
// renders itself; this exists because og: tags and PNGs are produced here.
package hu

import (
	"strconv"
	"strings"
	"time"
	"unicode"
)

// groupSeparator is U+00A0, which is what Intl.NumberFormat("hu-HU") emits.
// A plain space here would make the share card disagree with the page.
const groupSeparator = " "

func FormatNumber(n int) string {
	s := strconv.Itoa(n)
	neg := strings.HasPrefix(s, "-")
	s = strings.TrimPrefix(s, "-")

	var b strings.Builder
	for i, r := range s {
		if i > 0 && (len(s)-i)%3 == 0 {
			b.WriteString(groupSeparator)
		}
		b.WriteRune(r)
	}
	if neg {
		return "-" + b.String()
	}
	return b.String()
}

// FormatHUF renders 1351600 as "1 351 600 Ft".
func FormatHUF(n int) string { return FormatNumber(n) + " Ft" }

func ProgressPct(raised, goal int) int {
	if goal <= 0 {
		return 0
	}
	return int(float64(raised)/float64(goal)*100 + 0.5)
}

// DaysLeft counts whole days until the end of the closing day in Budapest —
// SPEC.md section 6. Never negative: a finished campaign has zero days left,
// not a negative countdown.
func DaysLeft(endsAt string, loc *time.Location, now time.Time) int {
	d, err := time.ParseInLocation("2006-01-02", endsAt, loc)
	if err != nil {
		return 0
	}
	end := d.Add(24*time.Hour - time.Second)
	diff := end.Sub(now)
	if diff <= 0 {
		return 0
	}
	days := int(diff / (24 * time.Hour))
	if diff%(24*time.Hour) > 0 {
		days++
	}
	return days
}

var accentFolds = map[rune]rune{
	'á': 'a', 'é': 'e', 'í': 'i', 'ó': 'o', 'ö': 'o', 'ő': 'o',
	'ú': 'u', 'ü': 'u', 'ű': 'u',
}

// Slugify mirrors the browser-side helper so a slug the editor previews is the
// slug that gets stored.
func Slugify(input string) string {
	var b strings.Builder
	for _, r := range strings.ToLower(input) {
		if folded, ok := accentFolds[r]; ok {
			r = folded
		}
		if (r >= 'a' && r <= 'z') || unicode.IsDigit(r) {
			b.WriteRune(r)
		} else {
			b.WriteRune('-')
		}
	}
	slug := b.String()
	for strings.Contains(slug, "--") {
		slug = strings.ReplaceAll(slug, "--", "-")
	}
	slug = strings.Trim(slug, "-")
	if len(slug) > 80 {
		slug = strings.Trim(slug[:80], "-")
	}
	return slug
}