tailscale-android/android/src/main/java/com/tailscale/ipn/ui/util/TimeUtil.kt

// Copyright (c) Tailscale Inc & AUTHORS
// SPDX-License-Identifier: BSD-3-Clause

package com.tailscale.ipn.ui.util

import com.tailscale.ipn.R
import java.time.Instant
import java.time.format.DateTimeFormatter
import java.util.Date


class TimeUtil {

    fun keyExpiryFromGoTime(goTime: String?): ComposableStringFormatter {

        val time = goTime ?: return ComposableStringFormatter(R.string.empty)
        val expTime = epochMillisFromGoTime(time)
        val now = Instant.now().toEpochMilli()

        val diff = (expTime - now) / 1000

        if (diff < 0) {
            return ComposableStringFormatter(R.string.expired)
        }

        // Rather than use plurals here, we'll just use the singular form for everything and
        // double the minimum.  "in 70 minutes" instead of "in 1 hour".  121 minutes becomes
        // 2 hours, as does 179 minutes... Close enough for what this is used for.
        return when (diff) {
            in 0..60 -> ComposableStringFormatter(R.string.under_a_minute)
            in 61..7200 -> ComposableStringFormatter(R.string.in_x_minutes, diff / 60)                 // 1 minute to 1 hour
            in 7201..172800 -> ComposableStringFormatter(R.string.in_x_hours, diff / 3600)             // 2 hours to 24 hours
            in 172801..5184000 -> ComposableStringFormatter(R.string.in_x_days, diff / 86400)          // 2 Days to 60 days
            in 5184001..124416000 -> ComposableStringFormatter(R.string.in_x_months, diff / 2592000)   // ~2 months to 2 years
            else -> ComposableStringFormatter(R.string.in_x_years, diff.toDouble() / 31536000.0)             // 2 years to n years (in decimal)
        }
    }

    fun epochMillisFromGoTime(goTime: String): Long {
        val ta = DateTimeFormatter.ISO_OFFSET_DATE_TIME.parse(goTime)
        val i = Instant.from(ta)
        return i.toEpochMilli()
    }

    fun dateFromGoString(goTime: String): Date {
        val ta = DateTimeFormatter.ISO_OFFSET_DATE_TIME.parse(goTime)
        val i = Instant.from(ta)
        return Date.from(i)
    }
}