package i18n

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

// ── Dates and numbers per language (R-562, v0.308.0, `09` §3 decision 223) ────────────────────────
//
// The ONE place the dashboard decides how a date, a time or a decimal number looks:
//
//	Hungarian  2026. 10. 10. 15:04   1,5 GB   (the Hungarian date order with its dots; decimal COMMA)
//	English    2026-10-10 15:04      1.5 GB   (ISO-like; decimal point)
//
// Every function takes the time ALREADY in the zone it is shown in (the dashboard shows Budapest
// local time; the callers convert). An unknown language formats as Hungarian, like every other
// fallback in this package. Pinned by TestFormat_* in format_test.go.

// FormatDateTime renders a date with hour and minute.
func FormatDateTime(lang string, t time.Time) string {
	if Normalize(lang) == "en" {
		return t.Format("2006-01-02 15:04")
	}
	return t.Format("2006. 01. 02. 15:04")
}

// FormatDate renders a date alone.
func FormatDate(lang string, t time.Time) string {
	if Normalize(lang) == "en" {
		return t.Format("2006-01-02")
	}
	return t.Format("2006. 01. 02.")
}

// FormatMonthDayTime renders a date in the current year: month, day, hour and minute.
func FormatMonthDayTime(lang string, t time.Time) string {
	if Normalize(lang) == "en" {
		return t.Format("01-02 15:04")
	}
	return t.Format("01. 02. 15:04")
}

// FormatDecimal renders v with prec digits after the decimal separator of lang.
func FormatDecimal(lang string, v float64, prec int) string {
	s := strconv.FormatFloat(v, 'f', prec, 64)
	if Normalize(lang) == "en" {
		return s
	}
	return strings.Replace(s, ".", ",", 1)
}

// LocalizeDecimals rewrites the decimal POINT of every number in an already formatted short string
// ("1.5 GB", "Immich (95.0 GB)") into lang's separator. Only a point with a digit on BOTH sides is
// touched, so a sentence's full stop, a version ("0.307.0" — see below) or an address is not a target
// by accident: a dot preceded by a digit and followed by a digit is rewritten only when the number it
// belongs to has exactly ONE dot. English returns s unchanged.
//
// For strings another package formatted with %.1f (appbackup.HumanizeBytes and its siblings) and
// handed to a page as data. A new formatter should call FormatDecimal instead.
func LocalizeDecimals(lang, s string) string {
	if Normalize(lang) == "en" || !strings.Contains(s, ".") {
		return s
	}
	b := []byte(s)
	isDigit := func(c byte) bool { return c >= '0' && c <= '9' }
	for i := 1; i < len(b)-1; i++ {
		if b[i] != '.' || !isDigit(b[i-1]) || !isDigit(b[i+1]) {
			continue
		}
		// The whole digit-and-dot run around this dot: more than one dot is a version or an address.
		start, end := i, i
		for start > 0 && (isDigit(b[start-1]) || b[start-1] == '.') {
			start--
		}
		for end < len(b)-1 && (isDigit(b[end+1]) || b[end+1] == '.') {
			end++
		}
		if strings.Count(string(b[start:end+1]), ".") != 1 {
			i = end
			continue
		}
		b[i] = ','
	}
	return string(b)
}