feat: добавить TextSelectionHelper — core state, word snap, char offset

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

app/src/main/java/com/rosetta/messenger/ui/chats/components/TextSelectionHelper.kt

@@ -0,0 +1,132 @@
+package com.rosetta.messenger.ui.chats.components
+
+import android.content.ClipData
+import android.content.ClipboardManager
+import android.content.Context
+import android.text.Layout
+import android.view.HapticFeedbackConstants
+import android.view.View
+import android.widget.Toast
+import androidx.compose.runtime.getValue
+import androidx.compose.runtime.mutableFloatStateOf
+import androidx.compose.runtime.mutableIntStateOf
+import androidx.compose.runtime.mutableStateOf
+import androidx.compose.runtime.setValue
+
+data class LayoutInfo(
+    val layout: Layout,
+    val windowX: Int,
+    val windowY: Int,
+    val text: CharSequence
+)
+
+class TextSelectionHelper {
+
+    var selectionStart by mutableIntStateOf(-1)
+        private set
+    var selectionEnd by mutableIntStateOf(-1)
+        private set
+    var selectedMessageId by mutableStateOf<String?>(null)
+        private set
+    var layoutInfo by mutableStateOf<LayoutInfo?>(null)
+        private set
+    var isActive by mutableStateOf(false)
+        private set
+    var handleViewProgress by mutableFloatStateOf(0f)
+        private set
+
+    val isInSelectionMode: Boolean get() = isActive && selectionStart >= 0 && selectionEnd > selectionStart
+
+    fun startSelection(
+        messageId: String,
+        info: LayoutInfo,
+        touchX: Int,
+        touchY: Int,
+        view: View?
+    ) {
+        val layout = info.layout
+        val localX = touchX - info.windowX
+        val localY = touchY - info.windowY
+
+        val line = layout.getLineForVertical(localY)
+        val hx = localX.toFloat().coerceIn(layout.getLineLeft(line), layout.getLineRight(line))
+        val offset = layout.getOffsetForHorizontal(line, hx)
+
+        val text = info.text
+        var start = offset
+        var end = offset
+
+        while (start > 0 && Character.isLetterOrDigit(text[start - 1])) start--
+        while (end < text.length && Character.isLetterOrDigit(text[end])) end++
+
+        if (start == end && end < text.length) end++
+
+        selectedMessageId = messageId
+        layoutInfo = info
+        selectionStart = start
+        selectionEnd = end
+        isActive = true
+        handleViewProgress = 1f
+
+        view?.performHapticFeedback(HapticFeedbackConstants.LONG_PRESS)
+    }
+
+    fun updateSelectionStart(charOffset: Int) {
+        if (!isActive) return
+        val text = layoutInfo?.text ?: return
+        var newStart = charOffset.coerceIn(0, text.length)
+        while (newStart > 0 && Character.isLetterOrDigit(text[newStart - 1])) newStart--
+        if (newStart >= selectionEnd) return
+        selectionStart = newStart
+    }
+
+    fun updateSelectionEnd(charOffset: Int) {
+        if (!isActive) return
+        val text = layoutInfo?.text ?: return
+        var newEnd = charOffset.coerceIn(0, text.length)
+        while (newEnd < text.length && Character.isLetterOrDigit(text[newEnd])) newEnd++
+        if (newEnd <= selectionStart) return
+        selectionEnd = newEnd
+    }
+
+    fun getCharOffsetFromCoords(x: Int, y: Int): Int {
+        val info = layoutInfo ?: return -1
+        val localX = x - info.windowX
+        val localY = y - info.windowY
+        val layout = info.layout
+        val line = layout.getLineForVertical(localY.coerceIn(0, layout.height))
+        val hx = localX.toFloat().coerceIn(layout.getLineLeft(line), layout.getLineRight(line))
+        return layout.getOffsetForHorizontal(line, hx)
+    }
+
+    fun getSelectedText(): CharSequence? {
+        if (!isInSelectionMode) return null
+        val text = layoutInfo?.text ?: return null
+        val start = selectionStart.coerceIn(0, text.length)
+        val end = selectionEnd.coerceIn(start, text.length)
+        return text.subSequence(start, end)
+    }
+
+    fun copySelectedText(context: Context) {
+        val selectedText = getSelectedText() ?: return
+        val clipboard = context.getSystemService(Context.CLIPBOARD_SERVICE) as ClipboardManager
+        clipboard.setPrimaryClip(ClipData.newPlainText("selected_text", selectedText))
+        Toast.makeText(context, "Copied", Toast.LENGTH_SHORT).show()
+        clear()
+    }
+
+    fun selectAll() {
+        val text = layoutInfo?.text ?: return
+        selectionStart = 0
+        selectionEnd = text.length
+    }
+
+    fun clear() {
+        selectionStart = -1
+        selectionEnd = -1
+        selectedMessageId = null
+        layoutInfo = null
+        isActive = false
+        handleViewProgress = 0f
+    }
+}