/*
 * This file is part of Breezy Weather.
 *
 * Breezy Weather is free software: you can redistribute it and/or modify it
 * under the terms of the GNU Lesser General Public License as published by the
 * Free Software Foundation, version 3 of the License.
 *
 * Breezy Weather is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
 * or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public
 * License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public License
 * along with Breezy Weather. If not, see <https://www.gnu.org/licenses/>.
 */

package org.breezyweather.unit.formatting

import java.math.RoundingMode
import java.text.DecimalFormat
import kotlin.concurrent.getOrSet

data class UnitDecimals(
    val short: Int,
    val narrow: Int = short,
    val long: Int = short,
) {
    companion object {
        private val precisionFormats = Array(4) { ThreadLocal<DecimalFormat>() }

        private fun createFormatForDecimals(decimals: Int) = DecimalFormat("0").apply {
            if (decimals > 0) minimumFractionDigits = decimals
            roundingMode = RoundingMode.HALF_UP
        }

        internal fun formatToExactDecimals(value: Double, decimals: Int): String {
            val format = if (decimals < precisionFormats.size) {
                precisionFormats[decimals].getOrSet { createFormatForDecimals(decimals) }
            } else {
                createFormatForDecimals(decimals)
            }
            return format.format(value)
        }
    }
}
