From caa2979d429a39eef8e1ed2ea59916b87f0471d9 Mon Sep 17 00:00:00 2001
From: Sad Ellie <sadellie.dev@gmail.com>
Date: Sun, 7 Jan 2024 01:01:36 +0300
Subject: [PATCH] Place cursor at the start of input after evaluating

closes #151
---
 .../feature/calculator/CalculatorViewModel.kt | 23 +++++++++++++++----
 1 file changed, 18 insertions(+), 5 deletions(-)

diff --git a/feature/calculator/src/main/java/com/sadellie/unitto/feature/calculator/CalculatorViewModel.kt b/feature/calculator/src/main/java/com/sadellie/unitto/feature/calculator/CalculatorViewModel.kt
index f44dc574..ca806864 100644
--- a/feature/calculator/src/main/java/com/sadellie/unitto/feature/calculator/CalculatorViewModel.kt
+++ b/feature/calculator/src/main/java/com/sadellie/unitto/feature/calculator/CalculatorViewModel.kt
@@ -116,12 +116,16 @@ internal class CalculatorViewModel @Inject constructor(
         .stateIn(viewModelScope, CalculatorUIState.Loading)
 
     fun addTokens(tokens: String) = _input.update {
-        val newValue = if (_equalClicked.value and Token.Digit.allWithDot.contains(tokens)) {
+        var newValue = if (_equalClicked.value and Token.Digit.allWithDot.contains(tokens)) {
             // Clean input after clicking "=" and any token that is a Digit
             TextFieldValue().addTokens(tokens)
         } else {
             it.addTokens(tokens)
         }
+        // Cursor is set to 0 when equal is clicked
+        if (_equalClicked.value) {
+            newValue = newValue.copy(selection = TextRange(it.text.length))
+        }
         _equalClicked.update { false }
         _fractionJob?.cancel()
         savedStateHandle[_inputKey] = newValue.text
@@ -129,7 +133,11 @@ internal class CalculatorViewModel @Inject constructor(
     }
 
     fun addBracket() = _input.update {
-        val newValue = it.addBracket()
+        var newValue = it.addBracket()
+        // Cursor is set to 0 when equal is clicked
+        if (_equalClicked.value) {
+            newValue = newValue.copy(selection = TextRange(it.text.length))
+        }
         _equalClicked.update { false }
         _fractionJob?.cancel()
         savedStateHandle[_inputKey] = newValue.text
@@ -138,7 +146,7 @@ internal class CalculatorViewModel @Inject constructor(
 
     fun deleteTokens() = _input.update {
         val newValue = if (_equalClicked.value) {
-            TextFieldValue().deleteTokens()
+            TextFieldValue()
         } else {
             it.deleteTokens()
         }
@@ -155,7 +163,12 @@ internal class CalculatorViewModel @Inject constructor(
         TextFieldValue()
     }
 
-    fun onCursorChange(selection: TextRange) = _input.update { it.copy(selection = selection) }
+    fun onCursorChange(selection: TextRange) = _input.update {
+        // Without this line: will place token (even in the middle of the input) and place cursor at
+        // the end. This line also removes fractional output once user touches input text field
+        _equalClicked.update { false }
+        it.copy(selection = selection)
+    }
 
     fun updateRadianMode(newValue: Boolean) = viewModelScope.launch {
         userPrefsRepository.updateRadianMode(newValue)
@@ -203,7 +216,7 @@ internal class CalculatorViewModel @Inject constructor(
         _fractionJob = launch(Dispatchers.Default) {
             val fraction = result.toFractionalString()
 
-            _input.update { TextFieldValue(resultFormatted, TextRange(resultFormatted.length)) }
+            _input.update { TextFieldValue(resultFormatted, TextRange.Zero) }
             _result.update { CalculationResult.Fraction(fraction) }
         }
     }