try to fix some selection bugs

src/main/kotlin/ru/dbotthepony/mc/otm/client/screen/panels/TextInputPanel.kt

@@ -6,7 +6,6 @@ import com.mojang.blaze3d.systems.RenderSystem
 import com.mojang.blaze3d.vertex.DefaultVertexFormat
 import com.mojang.blaze3d.vertex.PoseStack
 import com.mojang.blaze3d.vertex.VertexFormat
-import it.unimi.dsi.fastutil.chars.Char2IntAVLTreeMap
 import it.unimi.dsi.fastutil.chars.Char2IntFunction
 import it.unimi.dsi.fastutil.chars.Char2IntOpenHashMap
 import it.unimi.dsi.fastutil.chars.CharOpenHashSet
@@ -16,7 +15,6 @@ import net.minecraft.client.gui.screens.Screen
 import net.minecraft.client.renderer.GameRenderer
 import org.joml.Vector2i
 import ru.dbotthepony.mc.otm.client.isCtrlDown
-import ru.dbotthepony.mc.otm.client.isKeyDown
 import ru.dbotthepony.mc.otm.client.isShiftDown
 import ru.dbotthepony.mc.otm.client.minecraft
 import ru.dbotthepony.mc.otm.client.render.DynamicBufferSource
@@ -35,40 +33,35 @@ open class TextInputPanel<out S : Screen>(
 	width: Float = 10f,
 	height: Float = 10f,
 ) : EditablePanel<S>(screen, parent, x, y, width, height) {
-	private data class TextSelection(val start: Int, val end: Int) {
+	private data class TextSelection(val cursor: Int, val shift: Int) {
-		val isInversed get() = start > end
+		val isLeft get() = shift < 0
-		val isNotEmpty get() = start != end
+		val isRight get() = shift > 0
-		val isValid get() = start != end
 
-		val actualStart get() = if (isInversed) this.end else this.start
+		fun move(value: Int, lineLength: Int): TextSelection {
-		val actualEnd get() = if (isInversed) this.start else this.end
+			return TextSelection(cursor, (shift + value).coerceIn(-cursor, lineLength - cursor + 1))
+		}
+
+		val isValid get() = shift != 0
+		val start get() = if (isRight) cursor else cursor + shift
+		val end get() = if (isRight) cursor + shift else cursor
 
 		fun sub(line: String): Pair<String, String> {
-			val before = line.substring(0, actualStart.coerceIn(0, line.length))
+			val before = line.substring(0, start.coerceIn(0, line.length))
-			val selected = line.substring(actualStart.coerceIn(0, line.length), actualEnd.coerceAtMost(line.length))
+			val selected = line.substring(start.coerceIn(0, line.length), end.coerceAtMost(line.length))
 
 			return before to selected
 		}
 
-		fun coversEntireString(value: String?): Boolean {
+		fun coversEntireString(value: String): Boolean {
-			if (value == null)
+			return start <= 0 && value.length <= end
-				return false
-
-			return value.length <= actualEnd && actualStart <= 0
 		}
 
-		fun coversEntireLine(value: String?): Boolean {
+		fun coversEntireLine(value: String): Boolean {
-			if (value == null)
+			return start <= 0 && value.length < end
-				return true
-
-			return value.length < actualEnd && actualStart <= 0
 		}
 
-		fun coversNewline(value: String?): Boolean {
+		fun coversNewline(value: String): Boolean {
-			if (value == null)
+			return value.length < end
-				return actualEnd == Int.MAX_VALUE
-
-			return value.length < actualEnd
 		}
 	}
 
@@ -306,7 +299,8 @@ open class TextInputPanel<out S : Screen>(
 		val selection = selections[line]
 
 		if (selection != null) {
-			val (start, end) = selection
+			val start = selection.start
+			val end = selection.end
 
 			if (character < start) {
 				putSelection(line, TextSelection(start + moveBy, end + moveBy))
@@ -345,7 +339,7 @@ open class TextInputPanel<out S : Screen>(
 			} else if (selection.coversEntireString(line)) {
 				this[lineNumber] = ""
 			} else if (selection.coversNewline(line)) {
-				val before = line.substring(0, selection.actualStart.coerceIn(0, line.length))
+				val before = line.substring(0, selection.start.coerceIn(0, line.length))
 				val next = this[lineNumber + 1]
 
 				if (next == null) {
@@ -355,22 +349,20 @@ open class TextInputPanel<out S : Screen>(
 					removeLine(lineNumber + 1)
 				}
 			} else {
-				val before = line.substring(0, selection.actualStart.coerceIn(0, line.length))
+				val before = line.substring(0, selection.start.coerceIn(0, line.length))
-				val after = line.substring(selection.actualEnd.coerceIn(0, line.length))
+				val after = line.substring(selection.end.coerceIn(0, line.length))
 				this[lineNumber] = before + after
 			}
 
 			if (lineNumber < cursorLine) {
 				cursorLine = lineNumber
-				cursorCharacter = selection.actualStart
+				cursorCharacter = selection.start
-			} else if (lineNumber == cursorLine && cursorCharacter > selection.actualStart) {
+			} else if (lineNumber == cursorLine && cursorCharacter > selection.start) {
-				cursorCharacter = selection.actualStart
+				cursorCharacter = selection.start
 			}
 		}
 	}
 
-	protected open fun textChanged(oldText: String, newText: String) {}
-
 	var text: String
 		get() {
 			var textCache = textCache
@@ -410,14 +402,17 @@ open class TextInputPanel<out S : Screen>(
 
 	fun advanceCursorLeft(greedy: Boolean = false): CursorAdvanceResult {
 		val oldLine = cursorLine
-		val oldChar = cursorCharacter
 		val line = this[cursorLine]
 		var couldHaveChangedLine = false
 
 		if (line != null && cursorCharacter > line.length) {
-			cursorCharacter = line.length - 1
+			cursorCharacter = line.length
+		} else if (cursorCharacter < 0) {
+			cursorCharacter = 0
 		}
 
+		val oldChar = cursorCharacter
+
 		if (cursorCharacter > 0) {
 			if (greedy && line != null) {
 				cursorCharacter = greedyAdvanceLeft(line, cursorCharacter)
@@ -444,11 +439,18 @@ open class TextInputPanel<out S : Screen>(
 
 	fun advanceCursorRight(greedy: Boolean = false): CursorAdvanceResult {
 		val oldLine = cursorLine
-		val oldChar = cursorCharacter
 		var couldHaveChangedLine = false
 
 		val line = this[cursorLine]
 
+		if (line != null && cursorCharacter > line.length) {
+			cursorCharacter = line.length
+		} else if (cursorCharacter < 0) {
+			cursorCharacter = 0
+		}
+
+		val oldChar = cursorCharacter
+
 		if (greedy && line != null && cursorCharacter + 1 < line.length) {
 			cursorCharacter = greedyAdvanceRight(line, cursorCharacter)
 		} else {
@@ -472,47 +474,39 @@ open class TextInputPanel<out S : Screen>(
 	}
 
 	private fun simulateSelectLeft(greedy: Boolean) {
-		val thisLine = this[cursorLine] ?: return
+		val line = this[cursorLine] ?: return
-
+		val existing = selections[cursorLine] ?: TextSelection(cursorCharacter, 0)
-		val existing = selections[cursorLine]
 		val result = advanceCursorLeft(greedy)
 
-		if (!result.linesChanged)
+		if (result.couldHaveChangedLine) {
-			putSelection(result.oldLine, TextSelection(
+			putSelection(result.oldLine, existing.move(-line.length, line.length))
-				existing?.start ?: result.oldCharacter,
-				result.newCharacter))
-		else {
-			this[result.newLine]?.let {
-				val existingNewline = selections[result.newLine]
-
-				if (existingNewline == null) {
-					putSelection(result.newLine, TextSelection(
-						Int.MAX_VALUE,
-						it.length))
 		} else {
-					if (!existingNewline.isInversed) {
+			putSelection(result.oldLine, existing.move(result.newCharacter - result.oldCharacter, line.length))
-						putSelection(result.newLine, TextSelection(
-							existingNewline.start,
-							result.newCharacter))
-					}
-				}
 		}
 
-			if (existing != null && existing.actualStart == 0 && thisLine.isEmpty() && !existing.isInversed) {
+		if (result.linesChanged) {
-				selections.remove(result.oldLine)
+			val existingNew = selections[result.newLine]
+			val lineNew = this[result.newLine] ?: return
+
+			if (existingNew == null) {
+				putSelection(result.newLine, TextSelection(result.newCharacter + 1, -1))
+			} else {
+				putSelection(result.newLine, existingNew.move(-1, lineNew.length))
 			}
 		}
 	}
 
 	private fun simulateSelectRight(greedy: Boolean) {
-		this[cursorLine] ?: return
+		val line = this[cursorLine] ?: return
-
+		val existing = selections[cursorLine] ?: TextSelection(cursorCharacter, 0)
-		val existing = selections[cursorLine]
 		val result = advanceCursorRight(greedy)
 
-		putSelection(result.oldLine, TextSelection(
+		if (result.couldHaveChangedLine) {
-			existing?.start ?: result.oldCharacter,
+			if (result.oldLine != lines.size - 1)
-			if (result.couldHaveChangedLine) Int.MAX_VALUE else result.newCharacter))
+				putSelection(result.oldLine, existing.move(line.length.coerceAtLeast(1), line.length))
+		} else {
+			putSelection(result.oldLine, existing.move(result.newCharacter - result.oldCharacter, line.length))
+		}
 	}
 
 	private fun simulateSelectionUp(): Boolean {
@@ -559,6 +553,13 @@ open class TextInputPanel<out S : Screen>(
 			while (this.cursorCharacter < cursorCharacter) {
 				simulateSelectRight(false)
 			}
+		} else {
+			if (line.isEmpty()) {
+				val existing = selections[this.cursorLine]
+
+				if (existing != null && existing.isLeft) {
+					selections.remove(this.cursorLine)
+				}
 			} else {
 				val store = this.cursorLine
 
@@ -568,6 +569,7 @@ open class TextInputPanel<out S : Screen>(
 
 				this.cursorLine = store
 			}
+		}
 
 		this.cursorCharacter = cursorCharacter
 		return true
@@ -842,7 +844,7 @@ open class TextInputPanel<out S : Screen>(
 				color = textColor
 			)
 
-			if (selection != null && selection.isValid && (selection.isNotEmpty || selection.coversEntireLine(line))) {
+			if (selection != null && selection.isValid) {
 				val (before, selected) = selection.sub(line)
 
 				var x = 0f
@@ -851,7 +853,7 @@ open class TextInputPanel<out S : Screen>(
 					x = font.width(before).toFloat()
 				}
 
-				val width = if (selection.coversNewline(line)) this.width - x else font.width(selected).toFloat()
+				val width = if (selection.coversNewline(line) && i != lines.size - 1) this.width - x else font.width(selected).toFloat()
 
 				RenderSystem.setShader(GameRenderer::getPositionShader)
 				RenderSystem.setShaderColor(0.0f, 0.0f, 1.0f, 1.0f)