Expression formatting and cursor fixes

P.S. This commit is a mess, lots of hardcoded stuff and weird decisions.

core/ui/src/main/java/com/sadellie/unitto/core/ui/Formatter.kt

@@ -25,23 +25,28 @@ import com.sadellie.unitto.core.base.KEY_0
 import com.sadellie.unitto.core.base.KEY_COMMA
 import com.sadellie.unitto.core.base.KEY_DOT
 import com.sadellie.unitto.core.base.KEY_E
-import com.sadellie.unitto.core.base.KEY_LEFT_BRACKET
 import com.sadellie.unitto.core.base.KEY_MINUS
-import com.sadellie.unitto.core.base.KEY_RIGHT_BRACKET
-import com.sadellie.unitto.core.base.OPERATORS
 import com.sadellie.unitto.core.base.Separator
 import java.math.BigDecimal
 import java.math.RoundingMode
 
-object Formatter {
-    private const val SPACE = " "
-    private const val PERIOD = "."
-    private const val COMMA = ","
+// Legacy, LOL. Will change later
+object Formatter : UnittoFormatter()
+
+open class UnittoFormatter {
+    /**
+     * This regex will catch things like "123.456", "123", ".456"
+     */
+    private val numbersRegex = Regex("[\\d.]+")
+
+    private val SPACE = " "
+    private val PERIOD = "."
+    private val COMMA = ","
 
     /**
      * Grouping separator.
      */
-    private var grouping: String = SPACE
+    var grouping: String = SPACE
 
     /**
      * Fractional part separator.
@@ -91,11 +96,8 @@ object Formatter {
 
         var output = input
 
-        // We may receive expressions
-        // Find all numbers in that expression
-        val allNumbers: List<String> = input.split(
-            *OPERATORS.toTypedArray(), KEY_LEFT_BRACKET, KEY_RIGHT_BRACKET
-        )
+        // We may receive expressions. Find all numbers in this expression
+        val allNumbers: List<String> = input.getOnlyNumbers()
 
         allNumbers.forEach {
             output = output.replace(it, formatNumber(it))
@@ -108,34 +110,50 @@ object Formatter {
         return output
     }
 
+    /**
+     * Remove formatting. Reverses [format]
+     */
+    fun reFormat(input: String): String {
+        // We get  123.45,6789
+        // We need 12.345,6789
+
+        // 123.45,6789
+        // Remove grouping
+        // 12345,6789
+        // Replace fractional with "." because formatter accepts only numbers where fractional is a dot
+
+        val cleanString = input
+            .replace(grouping, "")
+            .replace(fractional, KEY_DOT)
+        return format(cleanString)
+    }
+
     /**
      * Format given [input].
      *
-     * Input must be a number. Will replace grouping separators and fractional part separators.
+     * Input must be a number with dot!!!. Will replace grouping separators and fractional part (dot)
+     * separators.
      *
      * @see grouping
      * @see fractional
      */
     private fun formatNumber(input: String): String {
-        val splitInput = input.split(".")
-        var firstPart = splitInput[0]
+        if (input.any { it.isLetter() }) return input
+
+        var firstPart = input.takeWhile { it != '.' }
+        val remainingPart = input.removePrefix(firstPart)
 
         // Number of empty symbols (spaces) we need to add to correctly split into chunks.
         val offset = 3 - firstPart.length.mod(3)
-        var output = if (offset != 3) {
-            // We add some spaces at the begging so that last chunk has 3 symbols
+        val output = if (offset != 3) {
+            // We add some spaces at the beginning so that last chunk has 3 symbols
             firstPart = " ".repeat(offset) + firstPart
             firstPart.chunked(3).joinToString(grouping).drop(offset)
         } else {
             firstPart.chunked(3).joinToString(grouping)
         }
 
-        // Handling fractional part
-        if (input.contains(".")) {
-            output = output + fractional + splitInput.getOrElse(1) { "" }
-        }
-
-        return output
+        return (output + remainingPart.replace(".", fractional))
     }
 
     /**
@@ -175,4 +193,10 @@ object Formatter {
         }
         return result.trimEnd()
     }
+
+    /**
+     * @receiver Must be a string with a dot (".") used as a fractional.
+     */
+    private fun String.getOnlyNumbers(): List<String> =
+        numbersRegex.findAll(this).map(MatchResult::value).toList()
 }

core/ui/src/test/java/com/sadellie/unitto/core/ui/FormatterTest.kt

@@ -36,6 +36,7 @@ private const val INCOMPLETE_VALUE = "123456."
 private const val NO_FRACTIONAL_VALUE = "123456"
 private const val INCOMPLETE_EXPR = "50+123456÷8×0.8–12+"
 private const val COMPLETE_EXPR = "50+123456÷8×0.8–12+0-√9*4^9+2×(9+8×7)"
+private const val LONG_HALF_COMPLETE_EXPR = "50+123456÷89078..9×0.8–12+0-√9*4^9+2×(9+8×7)×sin(13sin123cos"
 private const val SOME_BRACKETS = "(((((((("
 
 @RunWith(RobolectricTestRunner::class)
@@ -55,6 +56,7 @@ class FormatterTest {
         assertEquals("123 456", formatter.format(NO_FRACTIONAL_VALUE))
         assertEquals("50+123 456÷8×0.8–12+", formatter.format(INCOMPLETE_EXPR))
         assertEquals("50+123 456÷8×0.8–12+0–√9×4^9+2×(9+8×7)", formatter.format(COMPLETE_EXPR))
+        assertEquals("50+123 456÷89 078..9×0.8–12+0–√9×4^9+2×(9+8×7)×sin(13sin123cos", formatter.format(LONG_HALF_COMPLETE_EXPR))
         assertEquals("((((((((", formatter.format(SOME_BRACKETS))
     }
 
@@ -69,6 +71,7 @@ class FormatterTest {
         assertEquals("123,456", formatter.format(NO_FRACTIONAL_VALUE))
         assertEquals("50+123,456÷8×0.8–12+", formatter.format(INCOMPLETE_EXPR))
         assertEquals("50+123,456÷8×0.8–12+0–√9×4^9+2×(9+8×7)", formatter.format(COMPLETE_EXPR))
+        assertEquals("50+123,456÷89,078..9×0.8–12+0–√9×4^9+2×(9+8×7)×sin(13sin123cos", formatter.format(LONG_HALF_COMPLETE_EXPR))
         assertEquals("((((((((", formatter.format(SOME_BRACKETS))
     }
 
@@ -83,6 +86,7 @@ class FormatterTest {
         assertEquals("123.456", formatter.format(NO_FRACTIONAL_VALUE))
         assertEquals("50+123.456÷8×0,8–12+", formatter.format(INCOMPLETE_EXPR))
         assertEquals("50+123.456÷8×0,8–12+0–√9×4^9+2×(9+8×7)", formatter.format(COMPLETE_EXPR))
+        assertEquals("50+123.456÷89.078,,9×0,8–12+0–√9×4^9+2×(9+8×7)×sin(13sin123cos", formatter.format(LONG_HALF_COMPLETE_EXPR))
         assertEquals("((((((((", formatter.format(SOME_BRACKETS))
     }
 
@@ -91,96 +95,96 @@ class FormatterTest {
         formatter.setSeparator(Separator.SPACES)
         composeTestRule.setContent {
             var basicValue = BigDecimal.valueOf(1)
-            assertEquals("-28", Formatter.formatTime("-28", basicValue))
-            assertEquals("-0.05", Formatter.formatTime("-0.05", basicValue))
-            assertEquals("0", Formatter.formatTime("0", basicValue))
-            assertEquals("0", Formatter.formatTime("-0", basicValue))
+            assertEquals("-28", formatter.formatTime("-28", basicValue))
+            assertEquals("-0.05", formatter.formatTime("-0.05", basicValue))
+            assertEquals("0", formatter.formatTime("0", basicValue))
+            assertEquals("0", formatter.formatTime("-0", basicValue))
 
             basicValue = BigDecimal.valueOf(86_400_000_000_000_000_000_000.0)
-            assertEquals("-28d", Formatter.formatTime("-28", basicValue))
-            assertEquals("-1h 12m", Formatter.formatTime("-0.05", basicValue))
-            assertEquals("0", Formatter.formatTime("0", basicValue))
-            assertEquals("0", Formatter.formatTime("-0", basicValue))
+            assertEquals("-28d", formatter.formatTime("-28", basicValue))
+            assertEquals("-1h 12m", formatter.formatTime("-0.05", basicValue))
+            assertEquals("0", formatter.formatTime("0", basicValue))
+            assertEquals("0", formatter.formatTime("-0", basicValue))
 
             // DAYS
             basicValue = BigDecimal.valueOf(86_400_000_000_000_000_000_000.0)
-            assertEquals("12h", Formatter.formatTime("0.5", basicValue))
-            assertEquals("1h 12m", Formatter.formatTime("0.05", basicValue))
-            assertEquals("7m 12s", Formatter.formatTime("0.005", basicValue))
-            assertEquals("28d", Formatter.formatTime("28", basicValue))
-            assertEquals("90d", Formatter.formatTime("90", basicValue))
-            assertEquals("90d 12h", Formatter.formatTime("90.5", basicValue))
-            assertEquals("90d 7m 12s", Formatter.formatTime("90.005", basicValue))
+            assertEquals("12h", formatter.formatTime("0.5", basicValue))
+            assertEquals("1h 12m", formatter.formatTime("0.05", basicValue))
+            assertEquals("7m 12s", formatter.formatTime("0.005", basicValue))
+            assertEquals("28d", formatter.formatTime("28", basicValue))
+            assertEquals("90d", formatter.formatTime("90", basicValue))
+            assertEquals("90d 12h", formatter.formatTime("90.5", basicValue))
+            assertEquals("90d 7m 12s", formatter.formatTime("90.005", basicValue))
 
             // HOURS
             basicValue = BigDecimal.valueOf(3_600_000_000_000_000_000_000.0)
-            assertEquals("30m", Formatter.formatTime("0.5", basicValue))
-            assertEquals("3m", Formatter.formatTime("0.05", basicValue))
-            assertEquals("18s", Formatter.formatTime("0.005", basicValue))
-            assertEquals("1d 4h", Formatter.formatTime("28", basicValue))
-            assertEquals("3d 18h", Formatter.formatTime("90", basicValue))
-            assertEquals("3d 18h 30m", Formatter.formatTime("90.5", basicValue))
-            assertEquals("3d 18h 18s", Formatter.formatTime("90.005", basicValue))
+            assertEquals("30m", formatter.formatTime("0.5", basicValue))
+            assertEquals("3m", formatter.formatTime("0.05", basicValue))
+            assertEquals("18s", formatter.formatTime("0.005", basicValue))
+            assertEquals("1d 4h", formatter.formatTime("28", basicValue))
+            assertEquals("3d 18h", formatter.formatTime("90", basicValue))
+            assertEquals("3d 18h 30m", formatter.formatTime("90.5", basicValue))
+            assertEquals("3d 18h 18s", formatter.formatTime("90.005", basicValue))
 
             // MINUTES
             basicValue = BigDecimal.valueOf(60_000_000_000_000_000_000.0)
-            assertEquals("30s", Formatter.formatTime("0.5", basicValue))
-            assertEquals("3s", Formatter.formatTime("0.05", basicValue))
-            assertEquals("300ms", Formatter.formatTime("0.005", basicValue))
-            assertEquals("28m", Formatter.formatTime("28", basicValue))
-            assertEquals("1h 30m", Formatter.formatTime("90", basicValue))
-            assertEquals("1h 30m 30s", Formatter.formatTime("90.5", basicValue))
-            assertEquals("1h 30m 300ms", Formatter.formatTime("90.005", basicValue))
+            assertEquals("30s", formatter.formatTime("0.5", basicValue))
+            assertEquals("3s", formatter.formatTime("0.05", basicValue))
+            assertEquals("300ms", formatter.formatTime("0.005", basicValue))
+            assertEquals("28m", formatter.formatTime("28", basicValue))
+            assertEquals("1h 30m", formatter.formatTime("90", basicValue))
+            assertEquals("1h 30m 30s", formatter.formatTime("90.5", basicValue))
+            assertEquals("1h 30m 300ms", formatter.formatTime("90.005", basicValue))
 
             // SECONDS
             basicValue = BigDecimal.valueOf(1_000_000_000_000_000_000)
-            assertEquals("500ms", Formatter.formatTime("0.5", basicValue))
-            assertEquals("50ms", Formatter.formatTime("0.05", basicValue))
-            assertEquals("5ms", Formatter.formatTime("0.005", basicValue))
-            assertEquals("28s", Formatter.formatTime("28", basicValue))
-            assertEquals("1m 30s", Formatter.formatTime("90", basicValue))
-            assertEquals("1m 30s 500ms", Formatter.formatTime("90.5", basicValue))
-            assertEquals("1m 30s 5ms", Formatter.formatTime("90.005", basicValue))
+            assertEquals("500ms", formatter.formatTime("0.5", basicValue))
+            assertEquals("50ms", formatter.formatTime("0.05", basicValue))
+            assertEquals("5ms", formatter.formatTime("0.005", basicValue))
+            assertEquals("28s", formatter.formatTime("28", basicValue))
+            assertEquals("1m 30s", formatter.formatTime("90", basicValue))
+            assertEquals("1m 30s 500ms", formatter.formatTime("90.5", basicValue))
+            assertEquals("1m 30s 5ms", formatter.formatTime("90.005", basicValue))
 
             // MILLISECONDS
             basicValue = BigDecimal.valueOf(1_000_000_000_000_000)
-            assertEquals("500µs", Formatter.formatTime("0.5", basicValue))
-            assertEquals("50µs", Formatter.formatTime("0.05", basicValue))
-            assertEquals("5µs", Formatter.formatTime("0.005", basicValue))
-            assertEquals("28ms", Formatter.formatTime("28", basicValue))
-            assertEquals("90ms", Formatter.formatTime("90", basicValue))
-            assertEquals("90ms 500µs", Formatter.formatTime("90.5", basicValue))
-            assertEquals("90ms 5µs", Formatter.formatTime("90.005", basicValue))
+            assertEquals("500µs", formatter.formatTime("0.5", basicValue))
+            assertEquals("50µs", formatter.formatTime("0.05", basicValue))
+            assertEquals("5µs", formatter.formatTime("0.005", basicValue))
+            assertEquals("28ms", formatter.formatTime("28", basicValue))
+            assertEquals("90ms", formatter.formatTime("90", basicValue))
+            assertEquals("90ms 500µs", formatter.formatTime("90.5", basicValue))
+            assertEquals("90ms 5µs", formatter.formatTime("90.005", basicValue))
 
             // MICROSECONDS
             basicValue = BigDecimal.valueOf(1_000_000_000_000)
-            assertEquals("500ns", Formatter.formatTime("0.5", basicValue))
-            assertEquals("50ns", Formatter.formatTime("0.05", basicValue))
-            assertEquals("5ns", Formatter.formatTime("0.005", basicValue))
-            assertEquals("28µs", Formatter.formatTime("28", basicValue))
-            assertEquals("90µs", Formatter.formatTime("90", basicValue))
-            assertEquals("90µs 500ns", Formatter.formatTime("90.5", basicValue))
-            assertEquals("90µs 5ns", Formatter.formatTime("90.005", basicValue))
+            assertEquals("500ns", formatter.formatTime("0.5", basicValue))
+            assertEquals("50ns", formatter.formatTime("0.05", basicValue))
+            assertEquals("5ns", formatter.formatTime("0.005", basicValue))
+            assertEquals("28µs", formatter.formatTime("28", basicValue))
+            assertEquals("90µs", formatter.formatTime("90", basicValue))
+            assertEquals("90µs 500ns", formatter.formatTime("90.5", basicValue))
+            assertEquals("90µs 5ns", formatter.formatTime("90.005", basicValue))
 
             // NANOSECONDS
             basicValue = BigDecimal.valueOf(1_000_000_000)
-            assertEquals("500 000 000as", Formatter.formatTime("0.5", basicValue))
-            assertEquals("50 000 000as", Formatter.formatTime("0.05", basicValue))
-            assertEquals("5 000 000as", Formatter.formatTime("0.005", basicValue))
-            assertEquals("28ns", Formatter.formatTime("28", basicValue))
-            assertEquals("90ns", Formatter.formatTime("90", basicValue))
-            assertEquals("90ns 500 000 000as", Formatter.formatTime("90.5", basicValue))
-            assertEquals("90ns 5 000 000as", Formatter.formatTime("90.005", basicValue))
+            assertEquals("500 000 000as", formatter.formatTime("0.5", basicValue))
+            assertEquals("50 000 000as", formatter.formatTime("0.05", basicValue))
+            assertEquals("5 000 000as", formatter.formatTime("0.005", basicValue))
+            assertEquals("28ns", formatter.formatTime("28", basicValue))
+            assertEquals("90ns", formatter.formatTime("90", basicValue))
+            assertEquals("90ns 500 000 000as", formatter.formatTime("90.5", basicValue))
+            assertEquals("90ns 5 000 000as", formatter.formatTime("90.005", basicValue))
 
             // ATTOSECONDS
             basicValue = BigDecimal.valueOf(1)
-            assertEquals("0.5", Formatter.formatTime("0.5", basicValue))
-            assertEquals("0.05", Formatter.formatTime("0.05", basicValue))
-            assertEquals("0.005", Formatter.formatTime("0.005", basicValue))
-            assertEquals("28", Formatter.formatTime("28", basicValue))
-            assertEquals("90", Formatter.formatTime("90", basicValue))
-            assertEquals("90.5", Formatter.formatTime("90.5", basicValue))
-            assertEquals("90.005", Formatter.formatTime("90.005", basicValue))
+            assertEquals("0.5", formatter.formatTime("0.5", basicValue))
+            assertEquals("0.05", formatter.formatTime("0.05", basicValue))
+            assertEquals("0.005", formatter.formatTime("0.005", basicValue))
+            assertEquals("28", formatter.formatTime("28", basicValue))
+            assertEquals("90", formatter.formatTime("90", basicValue))
+            assertEquals("90.5", formatter.formatTime("90.5", basicValue))
+            assertEquals("90.005", formatter.formatTime("90.005", basicValue))
         }
     }
 }

feature/calculator/src/main/java/com/sadellie/unitto/feature/calculator/CalculatorScreen.kt

@@ -54,16 +54,15 @@ import androidx.compose.ui.Alignment
 import androidx.compose.ui.Modifier
 import androidx.compose.ui.layout.onPlaced
 import androidx.compose.ui.res.stringResource
-import androidx.compose.ui.text.TextRange
 import androidx.compose.ui.text.input.TextFieldValue
 import androidx.compose.ui.text.style.TextAlign
 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.ui.Formatter
 import com.sadellie.unitto.core.ui.common.MenuButton
 import com.sadellie.unitto.core.ui.common.UnittoScreenWithTopBar
-import com.sadellie.unitto.core.ui.Formatter
 import com.sadellie.unitto.core.ui.theme.NumbersTextStyleDisplayMedium
 import com.sadellie.unitto.data.model.HistoryItem
 import com.sadellie.unitto.feature.calculator.components.CalculatorKeyboard
@@ -205,10 +204,7 @@ private fun CalculatorScreen(
                         modifier = Modifier
                             .fillMaxWidth()
                             .padding(horizontal = 8.dp),
-                        value = TextFieldValue(
-                            text = uiState.input,
-                            selection = TextRange(uiState.selection.first, uiState.selection.last)
-                        ),
+                        value = uiState.input,
                         onCursorChange = onCursorChange,
                         pasteCallback = addSymbol,
                         cutCallback = deleteSymbol
@@ -306,7 +302,7 @@ private fun PreviewCalculatorScreen() {
 
     CalculatorScreen(
         uiState = CalculatorUIState(
-            input = "12345",
+            input = TextFieldValue("12345"),
             output = "12345",
             history = historyItems
         ),

feature/calculator/src/main/java/com/sadellie/unitto/feature/calculator/CalculatorUIState.kt

@@ -18,12 +18,12 @@
 
 package com.sadellie.unitto.feature.calculator
 
+import androidx.compose.ui.text.input.TextFieldValue
 import com.sadellie.unitto.data.model.HistoryItem
 
 internal data class CalculatorUIState(
-    val input: String = "",
+    val input: TextFieldValue = TextFieldValue(),
     val output: String = "",
-    val selection: IntRange = 0..0,
     val angleMode: AngleMode = AngleMode.RAD,
     val history: List<HistoryItem> = emptyList()
 )

feature/calculator/src/main/java/com/sadellie/unitto/feature/calculator/CalculatorViewModel.kt

@@ -45,11 +45,13 @@ import org.mariuszgromada.math.mxparser.Expression
 import java.math.BigDecimal
 import javax.inject.Inject
 import org.mariuszgromada.math.mxparser.mXparser as MathParser
+import org.mariuszgromada.math.mxparser.License as MathParserLicense
 
 @HiltViewModel
 internal class CalculatorViewModel @Inject constructor(
     userPrefsRepository: UserPreferencesRepository,
-    private val calculatorHistoryRepository: CalculatorHistoryRepository
+    private val calculatorHistoryRepository: CalculatorHistoryRepository,
+    private val textFieldController: TextFieldController
 ) : ViewModel() {
     private val _userPrefs: StateFlow<UserPreferences> =
         userPrefsRepository.userPreferencesFlow.stateIn(
@@ -58,19 +60,16 @@ internal class CalculatorViewModel @Inject constructor(
             UserPreferences()
         )
 
-    private val _input: MutableStateFlow<String> = MutableStateFlow("")
     private val _output: MutableStateFlow<String> = MutableStateFlow("")
-    private val _selection: MutableStateFlow<IntRange> = MutableStateFlow(IntRange(0, 0))
     private val _angleMode: MutableStateFlow<AngleMode> = MutableStateFlow(AngleMode.RAD)
     private val _history = calculatorHistoryRepository.historyFlow
 
     val uiState = combine(
-        _input, _output, _selection, _angleMode, _history
-    ) { input, output, selection, angleMode, history ->
+        textFieldController.input, _output, _angleMode, _history, _userPrefs
+    ) { input, output, angleMode, history, _ ->
         return@combine CalculatorUIState(
             input = input,
             output = output,
-            selection = selection,
             angleMode = angleMode,
             history = history
         )
@@ -78,30 +77,11 @@ internal class CalculatorViewModel @Inject constructor(
         viewModelScope, SharingStarted.WhileSubscribed(5000L), CalculatorUIState()
     )
 
-    fun addSymbol(symbol: String) {
-        val selection = _selection.value
-        _input.update {
-            if (it.isEmpty()) symbol else it.replaceRange(selection.first, selection.last, symbol)
-        }
-        _selection.update { it.first + symbol.length..it.first + symbol.length }
-    }
+    fun addSymbol(symbol: String) = textFieldController.addToInput(symbol)
 
-    fun deleteSymbol() {
-        val selection = _selection.value
-        val newSelectionStart = when (selection.last) {
-            0 -> return
-            selection.first -> _selection.value.first - 1
-            else -> _selection.value.first
-        }
+    fun deleteSymbol() = textFieldController.delete()
 
-        _selection.update { newSelectionStart..newSelectionStart }
-        _input.update { it.removeRange(newSelectionStart, selection.last) }
-    }
-
-    fun clearSymbols() {
-        _selection.update { 0..0 }
-        _input.update { "" }
-    }
+    fun clearSymbols() = textFieldController.clearInput()
 
     fun toggleCalculatorMode() {
         _angleMode.update {
@@ -117,44 +97,37 @@ internal class CalculatorViewModel @Inject constructor(
 
     // Called when user clicks "=" on a keyboard
     fun evaluate() {
-        if (!Expression(_input.value.clean).checkSyntax()) return
-
         // Input and output can change while saving in history. This way we cache it here (i think)
-        val input = _input.value
+        val currentInput = textFieldController.input.value.text
         val output = _output.value
+        if (!Expression(currentInput.clean).checkSyntax()) return
 
+        // Save to history
         viewModelScope.launch(Dispatchers.IO) {
             calculatorHistoryRepository.add(
-                expression = input,
+                expression = textFieldController.inputTextWithoutFormatting(),
                 result = output
             )
         }
 
-        _input.update { _output.value }
-        _selection.update { _input.value.length.._input.value.length }
         _output.update { "" }
     }
 
-    fun clearHistory() {
-        viewModelScope.launch(Dispatchers.IO) {
+    fun clearHistory() = viewModelScope.launch(Dispatchers.IO) {
         calculatorHistoryRepository.clear()
     }
-    }
 
-    fun onCursorChange(selection: IntRange) {
-        // When we paste, selection is set to the length of the pasted text (start and end)
-        if (selection.first > _input.value.length) return
-        _selection.update { selection }
-    }
+    fun onCursorChange(selection: IntRange) = textFieldController.moveCursor(selection)
 
     private fun calculateInput() {
+        val currentInput = textFieldController.input.value.text
         // Input is empty, don't calculate
-        if (_input.value.isEmpty()) {
+        if (currentInput.isEmpty()) {
             _output.update { "" }
             return
         }
 
-        val calculated = Expression(_input.value.clean).calculate()
+        val calculated = Expression(currentInput.clean).calculate()
 
         // Calculation error, return NaN
         if (calculated.isNaN() or calculated.isInfinite()) {
@@ -168,7 +141,7 @@ internal class CalculatorViewModel @Inject constructor(
             .trimZeros()
 
         try {
-            val inputBigDecimal = BigDecimal(_input.value)
+            val inputBigDecimal = BigDecimal(currentInput)
 
             // Input and output are identical values
             if (inputBigDecimal.compareTo(calculatedBigDecimal) == 0) {
@@ -192,8 +165,7 @@ internal class CalculatorViewModel @Inject constructor(
             val leftBrackets = count { it.toString() == KEY_LEFT_BRACKET }
             val rightBrackets = count { it.toString() == KEY_RIGHT_BRACKET }
             val neededBrackets = leftBrackets - rightBrackets
-            return this
-                .replace(KEY_MINUS_DISPLAY, KEY_MINUS)
+            return replace(KEY_MINUS_DISPLAY, KEY_MINUS)
                 .plus(KEY_RIGHT_BRACKET.repeat(neededBrackets.coerceAtLeast(0)))
         }
 
@@ -203,10 +175,11 @@ internal class CalculatorViewModel @Inject constructor(
          * to load CPU very much. We use BigDecimal to achieve same result without CPU overload.
          */
         MathParser.setCanonicalRounding(false)
+        MathParserLicense.iConfirmNonCommercialUse("Sad Ellie")
 
         // Observe and invoke calculation without UI lag.
         viewModelScope.launch(Dispatchers.Default) {
-            merge(_userPrefs, _input, _angleMode).collectLatest {
+            merge(_userPrefs, textFieldController.input, _angleMode).collectLatest {
                 calculateInput()
             }
         }

feature/calculator/src/main/java/com/sadellie/unitto/feature/calculator/TextFieldController.kt

@@ -0,0 +1,190 @@
+/*
+ * 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.calculator
+
+import androidx.compose.ui.text.TextRange
+import androidx.compose.ui.text.input.TextFieldValue
+import com.sadellie.unitto.core.base.KEY_COS
+import com.sadellie.unitto.core.base.KEY_DOT
+import com.sadellie.unitto.core.base.KEY_LN
+import com.sadellie.unitto.core.base.KEY_LOG
+import com.sadellie.unitto.core.base.KEY_SIN
+import com.sadellie.unitto.core.base.KEY_TAN
+import com.sadellie.unitto.core.ui.UnittoFormatter
+import kotlinx.coroutines.flow.MutableStateFlow
+import kotlinx.coroutines.flow.update
+import javax.inject.Inject
+import kotlin.math.abs
+
+class TextFieldController @Inject constructor() {
+    // Internally we don't care about user preference here, because during composition this
+    // symbols will be replaced to those that user wanted.
+    // We do this because it adds unnecessary logic: it requires additional logic to observe and
+    // react to formatting preferences at this level.
+    private val localFormatter: UnittoFormatter by lazy {
+        UnittoFormatter().also {
+            it.grouping = "`"
+            it.fractional = "|"
+        }
+    }
+
+    var input: MutableStateFlow<TextFieldValue> = MutableStateFlow(TextFieldValue())
+
+    fun addToInput(symbols: String) {
+
+        val text = input.value.text
+        val selection = input.value.selection
+        val lastToEndDistance = text.length - selection.end
+
+        val newInput = if (text.isEmpty()) {
+            symbols
+        } else {
+            text.replaceRange(selection.start, selection.end, symbols)
+        }
+
+        val inputFormatted = newInput.fixFormat()
+        val newSelectionStartEnd = inputFormatted.length - lastToEndDistance
+
+        input.update {
+            it.copy(
+                text = inputFormatted,
+                selection = TextRange(newSelectionStartEnd, newSelectionStartEnd)
+            )
+        }
+    }
+
+    fun moveCursor(newPosition: IntRange) {
+        val cursorFixer = CursorFixer(grouping = localFormatter.grouping)
+        val currentInput = input.value.text
+        val fixedLeftCursor = cursorFixer.fixCursorIfNeeded(currentInput, newPosition.first)
+        val fixedRightCursor = cursorFixer.fixCursorIfNeeded(currentInput, newPosition.last)
+
+        // Will modify
+        input.update {
+            it.copy(
+                selection = TextRange(fixedLeftCursor, fixedRightCursor)
+            )
+        }
+    }
+
+    fun delete() {
+        val selection = input.value.selection
+        val distanceFromEnd = input.value.text.length - selection.end
+
+        val newSelectionStart = when (selection.end) {
+            // Don't delete if at the start of the text field
+            0 -> return
+            // We don't have anything selected (cursor in one position)
+            // like this 1234|56 => after deleting will be like this 123|56
+            // Cursor moved one symbol left
+            selection.start -> selection.start - 1
+            // We have multiple symbols selected
+            // like this 123[45]6 => after deleting will be like this 123|6
+            // Cursor will be placed where selection start was
+            else -> selection.start
+        }
+
+        input.update {
+            val newText = it.text
+                .removeRange(newSelectionStart, it.selection.end)
+                .fixFormat()
+            it.copy(
+                text = newText,
+                selection = TextRange(newText.length - distanceFromEnd, newText.length - distanceFromEnd)
+            )
+        }
+    }
+
+    fun clearInput() = input.update { TextFieldValue() }
+
+    fun inputTextWithoutFormatting() = input.value.text
+        .replace(localFormatter.grouping, "")
+        .replace(localFormatter.fractional, KEY_DOT)
+
+    private fun String.fixFormat(): String = localFormatter.reFormat(this)
+
+    inner class CursorFixer(private val grouping: String) {
+        fun fixCursorIfNeeded(str: String, pos: Int): Int {
+            // First we check if try to place cursors at illegal position
+            // If yes,
+            // we go left until cursor is position legally. Remember the distance
+            val bestLeft = bestPositionLeft(str, pos)
+            // we go right until cursor is position legally. Remember the distance
+            val bestRight = bestPositionRight(str, pos)
+            // Now we compare left and right distance
+            val bestPosition = listOf(bestLeft, bestRight)
+                // We move to the that's smaller
+                .minBy { abs(it - pos) }
+
+            return bestPosition
+        }
+
+        fun bestPositionLeft(str: String, pos: Int): Int {
+            var cursorPosition = pos
+            while (placedIllegally(str, cursorPosition)) cursorPosition--
+            return cursorPosition
+        }
+
+        private fun bestPositionRight(str: String, pos: Int): Int {
+            var cursorPosition = pos
+            while (placedIllegally(str, cursorPosition)) cursorPosition++
+            return cursorPosition
+        }
+
+        private fun placedIllegally(str: String, pos: Int): Boolean {
+            // For things like "123,|456" - this is illegal
+            if (pos.afterToken(str, grouping)) return true
+
+            // For things like "123,456+c|os(8)" - this is illegal
+            val illegalTokens = listOf(
+                KEY_COS, KEY_SIN, KEY_LN, KEY_LOG, KEY_TAN
+            )
+
+            illegalTokens.forEach {
+                if (pos.atToken(str, it)) return true
+            }
+
+            return false
+        }
+
+        /**
+         * Don't use if token is 1 symbol long, it wouldn't make sense! Use [afterToken] instead.
+         * @see [afterToken]
+         */
+        private fun Int.atToken(str: String, token: String): Boolean {
+            val checkBound = (token.length - 1).coerceAtLeast(1)
+
+            val stringToScan = str.substring(
+                startIndex = (this - checkBound).coerceAtLeast(0),
+                endIndex = (this + checkBound).coerceAtMost(str.length)
+            )
+
+            return stringToScan.contains(token)
+        }
+
+        private fun Int.afterToken(str: String, token: String): Boolean {
+            val stringToScan = str.substring(
+                startIndex = (this - token.length).coerceAtLeast(0),
+                endIndex = this
+            )
+
+            return stringToScan.contains(token)
+        }
+    }
+}

feature/calculator/src/main/java/com/sadellie/unitto/feature/calculator/components/HistoryList.kt

@@ -120,7 +120,7 @@ private fun HistoryListItem(
             Modifier.clickable { onTextClick(historyItem.expression) }
         ) {
             Text(
-                text = historyItem.expression,
+                text = Formatter.format(historyItem.expression),
                 maxLines = 1,
                 modifier = Modifier
                     .fillMaxWidth()

feature/calculator/src/main/java/com/sadellie/unitto/feature/calculator/components/InputTextField.kt

@@ -22,6 +22,9 @@ import androidx.compose.foundation.text.BasicTextField
 import androidx.compose.material3.MaterialTheme
 import androidx.compose.runtime.Composable
 import androidx.compose.runtime.CompositionLocalProvider
+import androidx.compose.runtime.derivedStateOf
+import androidx.compose.runtime.getValue
+import androidx.compose.runtime.remember
 import androidx.compose.ui.Modifier
 import androidx.compose.ui.platform.LocalClipboardManager
 import androidx.compose.ui.platform.LocalTextInputService
@@ -29,6 +32,7 @@ import androidx.compose.ui.platform.LocalTextToolbar
 import androidx.compose.ui.platform.LocalView
 import androidx.compose.ui.text.input.TextFieldValue
 import androidx.compose.ui.text.style.TextAlign
+import com.sadellie.unitto.core.ui.Formatter
 import com.sadellie.unitto.core.ui.theme.NumbersTextStyleDisplayLarge
 
 @Composable
@@ -40,6 +44,18 @@ internal fun InputTextField(
     cutCallback: () -> Unit
 ) {
     val clipboardManager = LocalClipboardManager.current
+    val formattedInput: TextFieldValue by remember(value) {
+        derivedStateOf {
+            value.copy(
+                // We replace this because internally input value is already formatted, but uses
+                // "|" as grouping and "-" as fractional.
+                value.text
+                    .replace("`", Formatter.grouping)
+                    .replace("|", Formatter.fractional)
+            )
+        }
+    }
+
     CompositionLocalProvider(
         LocalTextInputService provides null,
         LocalTextToolbar provides UnittoTextToolbar(
@@ -51,7 +67,7 @@ internal fun InputTextField(
         BasicTextField(
             modifier = modifier,
             singleLine = true,
-            value = value,
+            value = formattedInput,
             onValueChange = {
                 onCursorChange(it.selection.start..it.selection.end)
             },

feature/calculator/src/test/java/com/sadellie/unitto/feature/calculator/TextFieldControllerTest.kt

@@ -0,0 +1,191 @@
+/*
+ * 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.calculator
+
+import com.sadellie.unitto.core.base.Separator
+import com.sadellie.unitto.core.ui.Formatter
+import org.junit.Assert.assertEquals
+import org.junit.Before
+import org.junit.Test
+
+internal class TextFieldControllerTest {
+    private lateinit var textFieldController: TextFieldController
+
+    private val TextFieldController.text: String
+        get() = this.input.value.text
+            .replace("`", ",")
+            .replace("|", ".")
+
+    private val TextFieldController.selection: IntRange
+        get() = this.input.value.selection.start..this.input.value.selection.end
+
+    @Before
+    fun setUp() {
+        textFieldController = TextFieldController()
+        Formatter.setSeparator(Separator.COMMA)
+    }
+
+    @Test
+    fun `add when empty`() {
+        // Add one symbol
+        textFieldController.addToInput("1")
+        assertEquals("1", textFieldController.text)
+        assertEquals(1..1, textFieldController.selection)
+        textFieldController.clearInput()
+
+        // Add multiple
+        textFieldController.addToInput("123")
+        assertEquals("123", textFieldController.text)
+        assertEquals(3..3, textFieldController.selection)
+        textFieldController.clearInput()
+
+        // Add multiple
+        textFieldController.addToInput("1234")
+        assertEquals("1,234", textFieldController.text)
+        assertEquals(5..5, textFieldController.selection)
+        textFieldController.clearInput()
+
+        // Add multiple
+        textFieldController.addToInput("123456.789")
+        assertEquals("123,456.789", textFieldController.text)
+        assertEquals(11..11, textFieldController.selection)
+        textFieldController.clearInput()
+    }
+
+    @Test
+    fun `Add when not empty one symbol at a time (check formatting)`() {
+        // Should be 1|
+        textFieldController.addToInput("1")
+        assertEquals("1", textFieldController.text)
+        assertEquals(1..1, textFieldController.selection)
+
+        // Should be 12|
+        textFieldController.addToInput("2")
+        assertEquals("12", textFieldController.text)
+        assertEquals(2..2, textFieldController.selection)
+
+        // Should be 123|
+        textFieldController.addToInput("3")
+        assertEquals("123", textFieldController.text)
+        assertEquals(3..3, textFieldController.selection)
+
+        // Should be 1,234|
+        textFieldController.addToInput("4")
+        assertEquals("1,234", textFieldController.text)
+        assertEquals(5..5, textFieldController.selection)
+
+        // Should be 12,345|
+        textFieldController.addToInput("5")
+        assertEquals("12,345", textFieldController.text)
+        assertEquals(6..6, textFieldController.selection)
+    }
+
+    @Test
+    fun `Delete on empty input`() {
+        // Delete on empty input
+        textFieldController.delete()
+        assertEquals("", textFieldController.text)
+        assertEquals(0..0, textFieldController.selection)
+        textFieldController.clearInput()
+    }
+
+    @Test
+    fun `Delete last remaining symbol`() {
+        textFieldController.addToInput("1")
+        textFieldController.delete()
+        assertEquals("", textFieldController.text)
+        assertEquals(0..0, textFieldController.selection)
+        textFieldController.clearInput()
+    }
+
+    @Test
+    fun `Delete by one symbol (check formatting)`() {
+        textFieldController.addToInput("123456")
+        // Input is formatted into 123,456
+        textFieldController.delete()
+        assertEquals("12,345", textFieldController.text)
+        assertEquals(6..6, textFieldController.selection)
+        textFieldController.delete()
+        assertEquals("1,234", textFieldController.text)
+        assertEquals(5..5, textFieldController.selection)
+        textFieldController.delete()
+        assertEquals("123", textFieldController.text)
+        println("in 123: ${textFieldController.selection}")
+        assertEquals(3..3, textFieldController.selection)
+        textFieldController.clearInput()
+    }
+
+    @Test
+    fun `Delete multiple symbols, selected before separator`() {
+        textFieldController.addToInput("123789456")
+        // Input is formatted to 123,789,456
+        textFieldController.moveCursor(3..7)
+        textFieldController.delete()
+        assertEquals("123,456", textFieldController.text)
+        assertEquals(3..3, textFieldController.selection)
+        textFieldController.clearInput()
+    }
+
+    @Test
+    fun `Delete multiple symbols, selected not near separator`() {
+        textFieldController.addToInput("123789456")
+        // Input is formatted to 123,789,456
+        textFieldController.moveCursor(3..9)
+        textFieldController.delete()
+        assertEquals("12,356", textFieldController.text)
+        assertEquals(4..4, textFieldController.selection)
+        textFieldController.clearInput()
+    }
+
+    @Test
+    fun `Delete multiple symbols in weird input`() {
+        textFieldController.addToInput("123...789456")
+        // Input is formatted to 123...789456
+        textFieldController.moveCursor(3..9)
+        textFieldController.delete()
+        assertEquals(4..4, textFieldController.selection)
+        assertEquals("123,456", textFieldController.text)
+        textFieldController.clearInput()
+    }
+
+    @Test
+    fun `placed cursor illegally`() {
+        textFieldController.addToInput("123456.789")
+        // Input is 123,456.789
+        textFieldController.moveCursor(4..4)
+        // Cursor should be placed like this 123|,456.789
+        assertEquals(3..3, textFieldController.selection)
+        textFieldController.clearInput()
+
+        textFieldController.addToInput("123456.789+cos(")
+        // Input is 123,456.789+cos(
+        textFieldController.moveCursor(13..13)
+        // Cursor should be placed like this 123,456.789+c|os(
+        assertEquals(12..12, textFieldController.selection)
+        textFieldController.clearInput()
+    }
+
+    @Test
+    fun `get clear input text without formatting`() {
+        textFieldController.addToInput("123456.789+cos(..)")
+        // Input is 123,456.789
+
+        assertEquals("123456.789+cos(..)", textFieldController.inputTextWithoutFormatting())
+    }
+}