Added more date difference modes

closes: #129

feature/datecalculator/build.gradle.kts

@@ -31,6 +31,7 @@ android {
 dependencies {
     testImplementation(libs.junit.junit)
 
+    implementation(project(":data:common"))
     implementation(project(":data:model"))
     implementation(project(":data:userprefs"))
 }

feature/datecalculator/src/main/java/com/sadellie/unitto/feature/datecalculator/ZonedDateTimeUtils.kt

@@ -0,0 +1,32 @@
+/*
+ * Unitto is a unit converter for Android
+ * Copyright (c) 2023 Elshan Agaev
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program 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 General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+package com.sadellie.unitto.feature.datecalculator
+
+import java.time.ZonedDateTime
+import java.time.temporal.ChronoUnit
+
+internal object ZonedDateTimeUtils {
+    /**
+     * Get current [ZonedDateTime] with seconds and nanoseconds set to zero. Used in date calculator
+     * module.
+     *
+     * @return [ZonedDateTime] with units less than minutes zeroed out.
+     */
+    fun nowWithMinutes(): ZonedDateTime = ZonedDateTime.now().truncatedTo(ChronoUnit.MINUTES)
+}

feature/datecalculator/src/main/java/com/sadellie/unitto/feature/datecalculator/addsubtract/AddSubtractPage.kt

@@ -80,6 +80,7 @@ import com.sadellie.unitto.core.ui.common.textfield.addTokens
 import com.sadellie.unitto.core.ui.common.textfield.deleteTokens
 import com.sadellie.unitto.core.ui.isPortrait
 import com.sadellie.unitto.core.ui.showToast
+import com.sadellie.unitto.feature.datecalculator.ZonedDateTimeUtils
 import com.sadellie.unitto.feature.datecalculator.components.AddSubtractKeyboard
 import com.sadellie.unitto.feature.datecalculator.components.DateTimeDialogs
 import com.sadellie.unitto.feature.datecalculator.components.DateTimeSelectorBlock
@@ -193,7 +194,7 @@ private fun AddSubtractView(
                             containerColor = MaterialTheme.colorScheme.secondaryContainer,
                             title = stringResource(R.string.date_calculator_start),
                             dateTime = uiState.start,
-                            onLongClick = { updateStart(ZonedDateTime.now()) },
+                            onLongClick = { updateStart(ZonedDateTimeUtils.nowWithMinutes()) },
                             onClick = { dialogState = DialogState.FROM },
                             onTimeClick = { dialogState = DialogState.FROM_TIME },
                             onDateClick = { dialogState = DialogState.FROM_DATE },
@@ -402,8 +403,8 @@ fun AddSubtractViewPreview() {
     AddSubtractView(
         uiState = AddSubtractState(
             years = TextFieldValue("12"),
-            start = ZonedDateTime.now(),
-            result = ZonedDateTime.now().plusSeconds(1)
+            start = ZonedDateTimeUtils.nowWithMinutes(),
+            result = ZonedDateTimeUtils.nowWithMinutes().plusSeconds(1)
         ),
         toggleTopBar = {},
         showKeyboard = false,

feature/datecalculator/src/main/java/com/sadellie/unitto/feature/datecalculator/addsubtract/AddSubtractUIState.kt

@@ -20,11 +20,12 @@ package com.sadellie.unitto.feature.datecalculator.addsubtract
 
 import androidx.compose.ui.text.input.TextFieldValue
 import com.sadellie.unitto.core.ui.common.textfield.FormatterSymbols
+import com.sadellie.unitto.feature.datecalculator.ZonedDateTimeUtils
 import java.time.ZonedDateTime
 
 internal data class AddSubtractState(
-    val start: ZonedDateTime = ZonedDateTime.now(),
-    val result: ZonedDateTime = ZonedDateTime.now(),
+    val start: ZonedDateTime = ZonedDateTimeUtils.nowWithMinutes(),
+    val result: ZonedDateTime = ZonedDateTimeUtils.nowWithMinutes(),
     val years: TextFieldValue = TextFieldValue(),
     val months: TextFieldValue = TextFieldValue(),
     val days: TextFieldValue = TextFieldValue(),

feature/datecalculator/src/main/java/com/sadellie/unitto/feature/datecalculator/components/DateTimeResultBlock.kt

@@ -19,112 +19,155 @@
 package com.sadellie.unitto.feature.datecalculator.components
 
 import androidx.annotation.StringRes
-import androidx.compose.animation.AnimatedVisibility
-import androidx.compose.animation.expandVertically
-import androidx.compose.animation.shrinkVertically
-import androidx.compose.foundation.background
-import androidx.compose.foundation.interaction.MutableInteractionSource
-import androidx.compose.foundation.layout.Arrangement
 import androidx.compose.foundation.layout.Column
-import androidx.compose.foundation.layout.Row
-import androidx.compose.foundation.layout.fillMaxWidth
-import androidx.compose.foundation.layout.padding
-import androidx.compose.material.icons.Icons
-import androidx.compose.material.icons.filled.ContentCopy
-import androidx.compose.material3.Icon
-import androidx.compose.material3.IconButton
+import androidx.compose.foundation.text.selection.SelectionContainer
 import androidx.compose.material3.MaterialTheme
 import androidx.compose.material3.Text
 import androidx.compose.runtime.Composable
-import androidx.compose.runtime.ReadOnlyComposable
-import androidx.compose.runtime.remember
-import androidx.compose.ui.Alignment
 import androidx.compose.ui.Modifier
-import androidx.compose.ui.platform.LocalClipboardManager
 import androidx.compose.ui.res.stringResource
-import androidx.compose.ui.text.AnnotatedString
 import androidx.compose.ui.tooling.preview.Preview
-import androidx.compose.ui.unit.dp
 import com.sadellie.unitto.core.base.R
-import com.sadellie.unitto.core.ui.common.squashable
+import com.sadellie.unitto.core.ui.common.PagedIsland
 import com.sadellie.unitto.feature.datecalculator.difference.ZonedDateTimeDifference
+import java.math.BigDecimal
 
 @Composable
 internal fun DateTimeResultBlock(
     modifier: Modifier = Modifier,
-    zonedDateTimeDifference: ZonedDateTimeDifference
+    diff: ZonedDateTimeDifference.Default,
+    format: (BigDecimal) -> String
 ) {
-    val clipboardManager = LocalClipboardManager.current
-
-    val years = zonedDateTimeDifference.years.formatDateTimeValue(R.string.date_calculator_years)
-    val months = zonedDateTimeDifference.months.formatDateTimeValue(R.string.date_calculator_months)
-    val days = zonedDateTimeDifference.days.formatDateTimeValue(R.string.date_calculator_days)
-    val hours = zonedDateTimeDifference.hours.formatDateTimeValue(R.string.date_calculator_hours)
-    val minutes = zonedDateTimeDifference.minutes.formatDateTimeValue(R.string.date_calculator_minutes)
-
-    val texts = listOf(years, months, days, hours, minutes)
-
-    Column(
-        modifier = modifier
-            .squashable(
-                onClick = {},
-                interactionSource = remember { MutableInteractionSource() },
-                cornerRadiusRange = 8.dp..32.dp,
-            )
-            .background(MaterialTheme.colorScheme.tertiaryContainer)
-            .padding(16.dp),
-        horizontalAlignment = Alignment.Start
-    ) {
-        Row(
-            modifier = Modifier.fillMaxWidth(),
-            horizontalArrangement = Arrangement.SpaceBetween,
-            verticalAlignment = Alignment.Bottom
-        ) {
+    PagedIsland(
+        modifier = modifier,
+        pagesCount = 6,
+        backgroundColor = MaterialTheme.colorScheme.tertiaryContainer
+    ) { currentPage ->
+        when(currentPage) {
+            0 -> {
                 Text(
-                stringResource(R.string.date_calculator_difference),
+                    text = stringResource(R.string.date_calculator_difference),
                     style = MaterialTheme.typography.labelMedium
                 )
-            IconButton(
-                onClick = {
-                    clipboardManager.setText(
-                        AnnotatedString(texts.filter { it.isNotEmpty() }.joinToString(" "))
-                    )
+                SelectionContainer {
+                    Column {
+                        // Years
+                        if (diff.years > 0) {
+                            DateText(R.string.date_calculator_years, diff.years.toBigDecimal(), format)
+                        }
+
+                        // Months
+                        if (diff.months > 0) {
+                            DateText(R.string.date_calculator_months, diff.months.toBigDecimal(), format)
+                        }
+
+                        // Days
+                        if (diff.days > 0) {
+                            DateText(R.string.date_calculator_days, diff.days.toBigDecimal(), format)
+                        }
+
+                        // Hours
+                        if (diff.hours > 0) {
+                            DateText(R.string.date_calculator_hours, diff.hours.toBigDecimal(), format)
+                        }
+
+                        // Minutes
+                        if (diff.minutes > 0) {
+                            DateText(R.string.date_calculator_minutes, diff.minutes.toBigDecimal(), format)
+                        }
                     }
-            ) {
-                Icon(Icons.Default.ContentCopy, null)
                 }
             }
 
-        texts.forEach {
-            AnimatedVisibility(
-                visible = it.isNotEmpty(),
-                enter = expandVertically(),
-                exit = shrinkVertically()
-            ) {
-                Text(it, style = MaterialTheme.typography.displaySmall)
+            1 -> {
+                Text(
+                    text = stringResource(R.string.date_calculator_years),
+                    style = MaterialTheme.typography.labelMedium
+                )
+                SelectionContainer {
+                    DateText(diff.sumYears, format)
+                }
+            }
+
+            2 -> {
+                Text(
+                    text = stringResource(R.string.date_calculator_months),
+                    style = MaterialTheme.typography.labelMedium
+                )
+                SelectionContainer {
+                    DateText(diff.sumMonths, format)
+                }
+            }
+
+            3 -> {
+                Text(
+                    text = stringResource(R.string.date_calculator_days),
+                    style = MaterialTheme.typography.labelMedium
+                )
+                SelectionContainer {
+                    DateText(diff.sumDays, format)
+                }
+            }
+
+            4 -> {
+                Text(
+                    text = stringResource(R.string.date_calculator_hours),
+                    style = MaterialTheme.typography.labelMedium
+                )
+                SelectionContainer {
+                    DateText(diff.sumHours, format)
+                }
+            }
+
+            5 -> {
+                Text(
+                    text = stringResource(R.string.date_calculator_minutes),
+                    style = MaterialTheme.typography.labelMedium
+                )
+                SelectionContainer {
+                    DateText(diff.sumMinutes, format)
+                }
             }
         }
     }
 }
 
 @Composable
-@ReadOnlyComposable
-private fun Long.formatDateTimeValue(@StringRes id: Int): String {
-    if (this <= 0) return ""
+private fun DateText(
+    @StringRes id: Int,
+    value: BigDecimal,
+    format: (BigDecimal) -> String,
+) = Text(
+    text = "${stringResource(id)}: ${format(value)}",
+    style = MaterialTheme.typography.displaySmall
+)
 
-    return "${stringResource(id)}: $this"
-}
+@Composable
+private fun DateText(
+    value: BigDecimal,
+    format: (BigDecimal) -> String,
+) = Text(
+    text = format(value),
+    style = MaterialTheme.typography.displaySmall
+)
 
 @Preview
 @Composable
 private fun DateTimeResultBlockPreview() {
     DateTimeResultBlock(
         modifier = Modifier,
-        zonedDateTimeDifference = ZonedDateTimeDifference.Default(
+        diff = ZonedDateTimeDifference.Default(
+            years = 0,
             months = 1,
-            days = 2,
-            hours = 3,
-            minutes = 4
-        )
+            days = 1,
+            hours = 0,
+            minutes = 0,
+            sumYears = BigDecimal.ZERO,
+            sumMonths = BigDecimal.ZERO,
+            sumDays = BigDecimal.ZERO,
+            sumHours = BigDecimal.ZERO,
+            sumMinutes = BigDecimal("46080"),
+        ),
+        format = { it.toPlainString() }
     )
 }

feature/datecalculator/src/main/java/com/sadellie/unitto/feature/datecalculator/components/DateTimeSelectorBlock.kt

@@ -50,6 +50,7 @@ import com.sadellie.unitto.core.ui.common.squashable
 import com.sadellie.unitto.core.ui.datetime.formatDateWeekDayMonthYear
 import com.sadellie.unitto.core.ui.datetime.formatTimeAmPm
 import com.sadellie.unitto.core.ui.datetime.formatTimeShort
+import com.sadellie.unitto.feature.datecalculator.ZonedDateTimeUtils
 import java.time.ZonedDateTime
 
 @Composable
@@ -162,6 +163,6 @@ fun DateTimeSelectorBlockPreview() {
             .width(224.dp),
         containerColor = MaterialTheme.colorScheme.secondaryContainer,
         title = "End",
-        dateTime = ZonedDateTime.now(),
+        dateTime = ZonedDateTimeUtils.nowWithMinutes(),
     )
 }

feature/datecalculator/src/main/java/com/sadellie/unitto/feature/datecalculator/difference/DateDifferencePage.kt

@@ -18,9 +18,7 @@
 
 package com.sadellie.unitto.feature.datecalculator.difference
 
-import androidx.compose.animation.AnimatedVisibility
-import androidx.compose.animation.expandVertically
-import androidx.compose.animation.shrinkVertically
+import androidx.compose.animation.AnimatedContent
 import androidx.compose.foundation.background
 import androidx.compose.foundation.layout.Arrangement
 import androidx.compose.foundation.layout.FlowRow
@@ -39,29 +37,36 @@ import androidx.compose.ui.tooling.preview.Preview
 import androidx.compose.ui.unit.dp
 import androidx.hilt.navigation.compose.hiltViewModel
 import androidx.lifecycle.compose.collectAsStateWithLifecycle
+import com.sadellie.unitto.core.base.OutputFormat
 import com.sadellie.unitto.core.base.R
+import com.sadellie.unitto.core.ui.common.textfield.FormatterSymbols
+import com.sadellie.unitto.core.ui.common.textfield.formatExpression
+import com.sadellie.unitto.data.common.format
+import com.sadellie.unitto.feature.datecalculator.ZonedDateTimeUtils
 import com.sadellie.unitto.feature.datecalculator.components.DateTimeDialogs
 import com.sadellie.unitto.feature.datecalculator.components.DateTimeResultBlock
 import com.sadellie.unitto.feature.datecalculator.components.DateTimeSelectorBlock
 import com.sadellie.unitto.feature.datecalculator.components.DialogState
 import java.time.ZonedDateTime
+import java.time.temporal.ChronoUnit
 
 @Composable
 internal fun DateDifferencePage(
     viewModel: DateDifferenceViewModel = hiltViewModel(),
 ) {
-    val uiState = viewModel.uiState.collectAsStateWithLifecycle()
-
-    DateDifferenceView(
-        uiState = uiState.value,
+    when (val uiState = viewModel.uiState.collectAsStateWithLifecycle().value) {
+        DifferenceUIState.Loading -> Unit
+        is DifferenceUIState.Ready -> DateDifferenceView(
+            uiState = uiState,
             setStartDate = viewModel::setStartDate,
             setEndDate = viewModel::setEndDate
         )
+    }
 }
 
 @Composable
 private fun DateDifferenceView(
-    uiState: DifferenceUIState,
+    uiState: DifferenceUIState.Ready,
     setStartDate: (ZonedDateTime) -> Unit,
     setEndDate: (ZonedDateTime) -> Unit,
 ) {
@@ -83,7 +88,7 @@ private fun DateDifferenceView(
             title = stringResource(R.string.date_calculator_start),
             dateTime = uiState.start,
             onClick = { dialogState = DialogState.FROM },
-            onLongClick = { setStartDate(ZonedDateTime.now()) },
+            onLongClick = { setStartDate(ZonedDateTimeUtils.nowWithMinutes()) },
             onTimeClick = { dialogState = DialogState.FROM_TIME },
             onDateClick = { dialogState = DialogState.FROM_DATE },
             containerColor = MaterialTheme.colorScheme.secondaryContainer
@@ -97,24 +102,30 @@ private fun DateDifferenceView(
             title = stringResource(R.string.date_calculator_end),
             dateTime = uiState.end,
             onClick = { dialogState = DialogState.TO },
-            onLongClick = { setStartDate(ZonedDateTime.now()) },
+            onLongClick = { setEndDate(ZonedDateTimeUtils.nowWithMinutes()) },
             onTimeClick = { dialogState = DialogState.TO_TIME },
             onDateClick = { dialogState = DialogState.TO_DATE },
             containerColor = MaterialTheme.colorScheme.secondaryContainer
         )
 
-        AnimatedVisibility(
-            visible = uiState.result is ZonedDateTimeDifference.Default,
-            enter = expandVertically(),
-            exit = shrinkVertically()
-        ) {
+        AnimatedContent(
+            targetState = uiState.result,
+            modifier = Modifier.weight(2f)
+        ) { result ->
+            when (result) {
+                is ZonedDateTimeDifference.Default -> {
                     DateTimeResultBlock(
-                modifier = Modifier
-                    .weight(2f)
-                    .fillMaxWidth(),
-                zonedDateTimeDifference = uiState.result,
+                        modifier = Modifier.fillMaxWidth(),
+                        diff = result,
+                        format = {
+                            it.format(uiState.precision, uiState.outputFormat)
+                                .formatExpression(uiState.formatterSymbols)
+                        }
                     )
                 }
+                ZonedDateTimeDifference.Zero -> Unit
+            }
+        }
     }
 
     DateTimeDialogs(
@@ -143,7 +154,14 @@ private fun DateDifferenceView(
 @Composable
 fun DateDifferenceViewPreview() {
     DateDifferenceView(
-        uiState = DifferenceUIState(),
+        uiState = DifferenceUIState.Ready(
+            start = ZonedDateTimeUtils.nowWithMinutes(),
+            end = ZonedDateTimeUtils.nowWithMinutes().truncatedTo(ChronoUnit.MINUTES),
+            result = ZonedDateTimeDifference.Zero,
+            precision = 3,
+            outputFormat = OutputFormat.PLAIN,
+            formatterSymbols = FormatterSymbols.Spaces
+        ),
         setStartDate = {},
         setEndDate = {},
     )

feature/datecalculator/src/main/java/com/sadellie/unitto/feature/datecalculator/difference/DateDifferenceViewModel.kt

@@ -20,32 +20,70 @@ package com.sadellie.unitto.feature.datecalculator.difference
 
 import androidx.lifecycle.ViewModel
 import androidx.lifecycle.viewModelScope
+import com.sadellie.unitto.core.ui.common.textfield.AllFormatterSymbols
+import com.sadellie.unitto.data.common.stateIn
+import com.sadellie.unitto.data.model.repository.UserPreferencesRepository
+import com.sadellie.unitto.feature.datecalculator.ZonedDateTimeUtils
 import dagger.hilt.android.lifecycle.HiltViewModel
 import kotlinx.coroutines.Dispatchers
 import kotlinx.coroutines.flow.MutableStateFlow
-import kotlinx.coroutines.flow.SharingStarted
-import kotlinx.coroutines.flow.onEach
-import kotlinx.coroutines.flow.stateIn
+import kotlinx.coroutines.flow.StateFlow
+import kotlinx.coroutines.flow.combine
+import kotlinx.coroutines.flow.mapLatest
 import kotlinx.coroutines.flow.update
 import kotlinx.coroutines.launch
 import java.time.ZonedDateTime
 import javax.inject.Inject
 
 @HiltViewModel
-internal class DateDifferenceViewModel @Inject constructor() : ViewModel() {
-    private val _uiState = MutableStateFlow(DifferenceUIState())
+internal class DateDifferenceViewModel @Inject constructor(
+    userPrefsRepository: UserPreferencesRepository,
+) : ViewModel() {
+    private val _start = MutableStateFlow(ZonedDateTimeUtils.nowWithMinutes())
+    private val _end = MutableStateFlow(ZonedDateTimeUtils.nowWithMinutes())
+    private val _result = MutableStateFlow<ZonedDateTimeDifference>(ZonedDateTimeDifference.Zero)
 
-    val uiState = _uiState
-        .onEach { updateResult() }
-        .stateIn(
-            viewModelScope, SharingStarted.WhileSubscribed(5000L), DifferenceUIState()
+    val uiState: StateFlow<DifferenceUIState> = combine(
+        userPrefsRepository.formattingPrefs,
+        _start,
+        _end,
+        _result
+    ) { prefs, start, end, result ->
+            return@combine DifferenceUIState.Ready(
+                start = start,
+                end = end,
+                result = result,
+                precision = prefs.digitsPrecision,
+                outputFormat = prefs.outputFormat,
+                formatterSymbols = AllFormatterSymbols.getById(prefs.separator)
+            )
+        }
+        .mapLatest { ui ->
+            updateResult(
+                start = ui.start,
+                end = ui.end
             )
 
-    fun setStartDate(newValue: ZonedDateTime) = _uiState.update { it.copy(start = newValue) }
+            ui
+        }
+        .stateIn(
+            viewModelScope, DifferenceUIState.Loading
+        )
 
-    fun setEndDate(newValue: ZonedDateTime) = _uiState.update { it.copy(end = newValue) }
+    fun setStartDate(newValue: ZonedDateTime) = _start.update { newValue }
 
-    private fun updateResult() = viewModelScope.launch(Dispatchers.Default) {
-        _uiState.update { ui -> ui.copy(result = ui.start - ui.end) }
+    fun setEndDate(newValue: ZonedDateTime) = _end.update { newValue }
+
+    private fun updateResult(
+        start: ZonedDateTime,
+        end: ZonedDateTime
+    ) = viewModelScope.launch(Dispatchers.Default) {
+        _result.update {
+            try {
+                start - end
+            } catch (e: Exception) {
+                ZonedDateTimeDifference.Zero
+            }
+        }
     }
 }

feature/datecalculator/src/main/java/com/sadellie/unitto/feature/datecalculator/difference/DifferenceUIState.kt

@@ -18,10 +18,18 @@
 
 package com.sadellie.unitto.feature.datecalculator.difference
 
+import com.sadellie.unitto.core.ui.common.textfield.FormatterSymbols
 import java.time.ZonedDateTime
 
-internal data class DifferenceUIState(
-    val start: ZonedDateTime = ZonedDateTime.now(),
-    val end: ZonedDateTime = ZonedDateTime.now(),
-    val result: ZonedDateTimeDifference = ZonedDateTimeDifference.Zero
-)
+internal sealed class DifferenceUIState {
+    data object Loading : DifferenceUIState()
+
+    data class Ready(
+        val start: ZonedDateTime,
+        val end: ZonedDateTime,
+        val result: ZonedDateTimeDifference,
+        val precision: Int,
+        val outputFormat: Int,
+        val formatterSymbols: FormatterSymbols,
+    ) : DifferenceUIState()
+}

feature/datecalculator/src/main/java/com/sadellie/unitto/feature/datecalculator/difference/ZonedDateTimeDifference.kt

@@ -18,43 +18,65 @@
 
 package com.sadellie.unitto.feature.datecalculator.difference
 
+import com.sadellie.unitto.core.base.MAX_PRECISION
+import java.math.BigDecimal
+import java.math.RoundingMode
 import java.time.ZonedDateTime
 import java.time.temporal.ChronoUnit
 
-internal sealed class ZonedDateTimeDifference(
-    open val years: Long = 0,
-    open val months: Long = 0,
-    open val days: Long = 0,
-    open val hours: Long = 0,
-    open val minutes: Long = 0,
-) {
+internal sealed class ZonedDateTimeDifference {
     data class Default(
-        override val years: Long = 0,
-        override val months: Long = 0,
-        override val days: Long = 0,
-        override val hours: Long = 0,
-        override val minutes: Long = 0,
-    ) : ZonedDateTimeDifference(
-        years = years,
-        months = months,
-        days = days,
-        hours = hours,
-        minutes = minutes,
-    )
+        val years: Long,
+        val months: Long,
+        val days: Long,
+        val hours: Long,
+        val minutes: Long,
+        val sumYears: BigDecimal,
+        val sumMonths: BigDecimal,
+        val sumDays: BigDecimal,
+        val sumHours: BigDecimal,
+        val sumMinutes: BigDecimal,
+    ) : ZonedDateTimeDifference()
 
     data object Zero : ZonedDateTimeDifference()
 }
 
-// https://stackoverflow.com/a/25760725
-internal infix operator fun ZonedDateTime.minus(localDateTime: ZonedDateTime): ZonedDateTimeDifference {
-    if (this == localDateTime) return ZonedDateTimeDifference.Zero
+/**
+ * Same as other [ZonedDateTime.minus] but `MAX_PRECISION` passed as scale.
+ *
+ * @receiver First [ZonedDateTime].
+ * @param zonedDateTime Second [ZonedDateTime].
+ * @return [ZonedDateTimeDifference.Default] (_always positive_) or [ZonedDateTimeDifference.Zero]
+ */
+internal infix operator fun ZonedDateTime.minus(
+    zonedDateTime: ZonedDateTime
+): ZonedDateTimeDifference = this.minus(zonedDateTime = zonedDateTime, scale = MAX_PRECISION)
+
+/**
+ * Calculate difference between [this] and [zonedDateTime]. Return absolute value, order of operands
+ * doesn't matter.
+ *
+ * @receiver First [ZonedDateTime].
+ * @param zonedDateTime Second [ZonedDateTime].
+ * @param scale Scale that will be used to calculate [ZonedDateTimeDifference.Default.sumDays] and
+ * others summed values.
+ * @return [ZonedDateTimeDifference.Default] (_always positive_) or [ZonedDateTimeDifference.Zero]
+ */
+internal fun ZonedDateTime.minus(
+    zonedDateTime: ZonedDateTime,
+    scale: Int
+): ZonedDateTimeDifference {
+    // https://stackoverflow.com/a/25760725
+
+    if (this == zonedDateTime) return ZonedDateTimeDifference.Zero
 
     var fromDateTime: ZonedDateTime = this
-    var toDateTime: ZonedDateTime = localDateTime
+    var toDateTime: ZonedDateTime = zonedDateTime
+    val epSeconds: BigDecimal = (this.toEpochSecond() - zonedDateTime.toEpochSecond()).toBigDecimal().abs()
 
     // Swap to avoid negative
-    if (this > localDateTime) {
-        fromDateTime = localDateTime
+    if (this > zonedDateTime) {
+        fromDateTime = zonedDateTime
         toDateTime = this
     }
 
@@ -77,6 +99,21 @@ internal infix operator fun ZonedDateTime.minus(localDateTime: ZonedDateTime): Z
     if (listOf(years, months, days, hours, minutes).sum() == 0L) return ZonedDateTimeDifference.Zero
 
     return ZonedDateTimeDifference.Default(
-        years = years, months = months, days = days, hours = hours, minutes = minutes
+        years = years,
+        months = months,
+        days = days,
+        hours = hours,
+        minutes = minutes,
+        sumYears = epSeconds.divide(yearInSeconds, scale, RoundingMode.HALF_EVEN),
+        sumMonths = epSeconds.divide(monthsInSeconds, scale, RoundingMode.HALF_EVEN),
+        sumDays = epSeconds.divide(dayInSeconds, scale, RoundingMode.HALF_EVEN),
+        sumHours = epSeconds.divide(hourInSeconds, scale, RoundingMode.HALF_EVEN),
+        sumMinutes = epSeconds.divide(minuteInSeconds, scale, RoundingMode.HALF_EVEN),
     )
 }
+
+private val yearInSeconds by lazy { BigDecimal("31104000") }
+private val monthsInSeconds by lazy { BigDecimal("2592000") }
+private val dayInSeconds by lazy { BigDecimal("86400") }
+private val hourInSeconds by lazy { BigDecimal("3600") }
+private val minuteInSeconds by lazy { BigDecimal("60") }

feature/datecalculator/src/test/java/com/sadellie/unitto/feature/datecalculator/difference/ZonedDateTimeDifferenceKtTest.kt

@@ -20,32 +20,128 @@ package com.sadellie.unitto.feature.datecalculator.difference
 
 import org.junit.Assert.assertEquals
 import org.junit.Test
+import java.math.BigDecimal
 import java.time.ZonedDateTime
 import java.time.format.DateTimeFormatter
 
 class ZonedDateTimeDifferenceKtTest {
     private val formatter: DateTimeFormatter = DateTimeFormatter.ISO_ZONED_DATE_TIME
-    private val `may 1 2023`: ZonedDateTime = ZonedDateTime.parse("2023-05-01T12:00+01:00[Europe/Paris]", formatter)
-    private val `may 2 2023`: ZonedDateTime = ZonedDateTime.parse("2023-05-02T12:00+01:00[Europe/Paris]", formatter)
-    private val `june 1 2023`: ZonedDateTime = ZonedDateTime.parse("2023-06-01T12:00+01:00[Europe/Paris]", formatter)
 
     @Test
     fun `same dates`() {
-        assertEquals(ZonedDateTimeDifference.Zero, `may 1 2023` - `may 1 2023`)
+        val date1: ZonedDateTime = ZonedDateTime.parse("2023-05-01T12:00+01:00[Europe/Paris]", formatter)
+
+        assertEquals(ZonedDateTimeDifference.Zero, date1 - date1)
     }
 
     @Test
-    fun `positive difference dates one day`() {
-        assertEquals(ZonedDateTimeDifference.Default(days = 1), `may 1 2023` - `may 2 2023`)
+    fun `positive difference one day`() {
+        val date1: ZonedDateTime = ZonedDateTime.parse("2023-05-01T12:00+01:00[Europe/Paris]", formatter)
+        val date2: ZonedDateTime = ZonedDateTime.parse("2023-05-02T12:00+01:00[Europe/Paris]", formatter)
+
+        assertEquals(
+            ZonedDateTimeDifference.
+            Default(
+                years = 0,
+                months = 0,
+                days = 1,
+                hours = 0,
+                minutes = 0,
+                sumYears = BigDecimal("0.003"),
+                sumMonths = BigDecimal("0.033"),
+                sumDays = BigDecimal("1.000"),
+                sumHours = BigDecimal("24.000"),
+                sumMinutes = BigDecimal("1440.000"),
+            ),
+            date1.minus(date2, 3)
+        )
     }
 
     @Test
-    fun `positive difference dates one minth`() {
-        assertEquals(ZonedDateTimeDifference.Default(months = 1), `may 1 2023` - `june 1 2023`)
+    fun `positive difference one month`() {
+        val date1: ZonedDateTime = ZonedDateTime.parse("2023-05-01T12:00+01:00[Europe/Paris]", formatter)
+        val date2: ZonedDateTime = ZonedDateTime.parse("2023-06-01T12:00+01:00[Europe/Paris]", formatter)
+
+        assertEquals(
+            ZonedDateTimeDifference.Default(
+                years = 0,
+                months = 1,
+                days = 0,
+                hours = 0,
+                minutes = 0,
+                sumYears = BigDecimal("0.086"),
+                sumMonths = BigDecimal("1.033"),
+                sumDays = BigDecimal("31.000"),
+                sumHours = BigDecimal("744.000"),
+                sumMinutes = BigDecimal("44640.000"),
+            ),
+            date1.minus(date2, 3)
+        )
     }
 
     @Test
-    fun `negative difference dates one day`() {
-        assertEquals(ZonedDateTimeDifference.Default(days = 1), `may 2 2023` - `may 1 2023`)
+    fun `negative difference one day`() {
+        val date1: ZonedDateTime = ZonedDateTime.parse("2023-05-02T12:00+01:00[Europe/Paris]", formatter)
+        val date2: ZonedDateTime = ZonedDateTime.parse("2023-05-01T12:00+01:00[Europe/Paris]", formatter)
+
+        assertEquals(
+            ZonedDateTimeDifference.Default(
+                years = 0,
+                months = 0,
+                days = 1,
+                hours = 0,
+                minutes = 0,
+                sumYears = BigDecimal("0.003"),
+                sumMonths = BigDecimal("0.033"),
+                sumDays = BigDecimal("1.000"),
+                sumHours = BigDecimal("24.000"),
+                sumMinutes = BigDecimal("1440.000"),
+            ),
+            date1.minus(date2, 3)
+        )
+    }
+
+    @Test
+    fun `positive big difference`() {
+        val date1: ZonedDateTime = ZonedDateTime.parse("2023-10-25T12:00+01:00[Europe/Paris]", formatter)
+        val date2: ZonedDateTime = ZonedDateTime.parse("2023-11-25T12:00+01:00[Europe/Paris]", formatter)
+
+        assertEquals(
+            ZonedDateTimeDifference.Default(
+                years = 0,
+                months = 0,
+                days = 30,
+                hours = 23,
+                minutes = 0,
+                sumYears = BigDecimal("0.086"),
+                sumMonths = BigDecimal("1.033"),
+                sumDays = BigDecimal("31.000"),
+                sumHours = BigDecimal("744.000"),
+                sumMinutes = BigDecimal("44640.000"),
+            ),
+            date1.minus(date2, 3)
+        )
+    }
+
+    @Test
+    fun `positive big difference 2`() {
+        val date1: ZonedDateTime = ZonedDateTime.parse("2023-11-25T12:00+01:00[Europe/Paris]", formatter)
+        val date2: ZonedDateTime = ZonedDateTime.parse("2023-12-25T12:00+01:00[Europe/Paris]", formatter)
+
+        assertEquals(
+            ZonedDateTimeDifference.Default(
+                years = 0,
+                months = 1,
+                days = 0,
+                hours = 0,
+                minutes = 0,
+                sumYears = BigDecimal("0.083"),
+                sumMonths = BigDecimal("1.000"),
+                sumDays = BigDecimal("30.000"),
+                sumHours = BigDecimal("720.000"),
+                sumMinutes = BigDecimal("43200.000"),
+            ),
+            date1.minus(date2, 3)
+        )
     }
 }