From a232f32ea46c99417c21669167c549160a5d9a94 Mon Sep 17 00:00:00 2001
From: jahorton <jahorton@sil.org>
Date: Fri, 26 Feb 2021 10:32:48 +0700
Subject: [PATCH] chore: reverts right-delete changes

---
 .../java/com/tavultesoft/kmea/KMManager.java  |  27 +--
 .../worker/model-compositor.ts                |  13 --
 .../Classes/InputViewController.swift         | 176 ++++--------------
 .../Classes/KeymanWebDelegate.swift           |   2 +-
 .../Classes/KeymanWebViewController.swift     |   8 +-
 .../KMEI/KeymanEngine/Classes/TextView.swift  |   7 +
 6 files changed, 51 insertions(+), 182 deletions(-)

diff --git a/android/KMEA/app/src/main/java/com/tavultesoft/kmea/KMManager.java b/android/KMEA/app/src/main/java/com/tavultesoft/kmea/KMManager.java
index 6a0eecac0c..dce7a688ef 100644
--- a/android/KMEA/app/src/main/java/com/tavultesoft/kmea/KMManager.java
+++ b/android/KMEA/app/src/main/java/com/tavultesoft/kmea/KMManager.java
@@ -36,7 +36,6 @@ import android.os.Bundle;
 import android.os.Handler;
 import android.os.IBinder;
 import android.os.Looper;
-import android.text.Editable;
 import android.text.InputType;
 import android.util.Log;
 import android.view.KeyEvent;
@@ -2350,6 +2349,10 @@ public final class KMManager {
     // This annotation is required in Jelly Bean and later:
     @JavascriptInterface
     public void insertText(final int dn, final String s, final int dr) {
+      if(dr != 0) {
+        Log.d(TAG, "Right deletions requested but are not presently supported by the in-app keyboard.");
+      }
+
       Handler mainLoop = new Handler(Looper.getMainLooper());
       mainLoop.post(new Runnable() {
         public void run() {
@@ -2381,28 +2384,6 @@ public final class KMManager {
             start = temp;
           }
 
-          // As we depend upon the caret's current position for the in-app implementation,
-          // we need to perform right-deletions BEFORE left-deletions & text insertion.
-          if(dr > 0) {
-            for (int i = 0; i < dr; i++) {
-              Editable context = textView.getText();
-              CharSequence chars = context.subSequence(end, context.length());
-              if (chars != null && chars.length() > 0) {
-                char c = chars.charAt(0);
-                InAppKeyboardShouldIgnoreTextChange = true;
-                InAppKeyboardShouldIgnoreSelectionChange = true;
-                if (Character.isHighSurrogate(c)) {
-                  textView.getText().delete(start, end+2);
-                } else {
-                  textView.getText().delete(start, end+1);
-                }
-
-                start = textView.getSelectionStart();
-                end = textView.getSelectionEnd();
-              }
-            }
-          }
-
           if (dn <= 0) {
             if (start == end) {
               if (!s.isEmpty() && s.charAt(0) == '\n') {
diff --git a/common/predictive-text/worker/model-compositor.ts b/common/predictive-text/worker/model-compositor.ts
index 213164a014..ef03d5b706 100644
--- a/common/predictive-text/worker/model-compositor.ts
+++ b/common/predictive-text/worker/model-compositor.ts
@@ -341,12 +341,6 @@ class ModelCompositor {
           // A predictive text default (on iOS, at least) - immediately wordbreak 
           // on suggestions accepted mid-word.
           suggestion.transform.insert += punctuation.insertAfterWord;
-
-          // // Unfortunately, we can't quite enable the next two lines in iOS yet; there's an
-          // // odd issue with its textDocumentProxy that gives us the wrong results.
-          // 
-          // let righthandSplit = tokenization.right[0];
-          // suggestion.transform.deleteRight = (suggestion.transform.deleteRight || 0) + righthandSplit.kmwLength();
         }
       }
 
@@ -458,7 +452,6 @@ class ModelCompositor {
     // Step 1:  generate and save the reversion's Transform.
     let sourceTransform = suggestion.transform;
     let deletedLeftChars = context.left.kmwSubstr(-sourceTransform.deleteLeft, sourceTransform.deleteLeft);
-    let deletedRightChars = context.right ? context.right.kmwSubstr(0, sourceTransform.deleteRight || 0) : '';
     let insertedLength = sourceTransform.insert.kmwLength();
 
     let reversionTransform: Transform = {
@@ -466,18 +459,12 @@ class ModelCompositor {
       deleteLeft: insertedLength
     };
 
-    let postCaretReversionTransform: Transform = {
-      insert: deletedRightChars,
-      deleteLeft: 0
-    }
-
     // Step 2:  building the proper 'displayAs' string for the Reversion
     let postContext = context;
     if(postTransform) {
       // The code above restores the state to the context at the time the `Suggestion` was created.
       // `postTransform` handles any missing context that came later.
       reversionTransform = models.buildMergedTransform(reversionTransform, postTransform);
-      reversionTransform = models.buildMergedTransform(reversionTransform, postCaretReversionTransform);
 
       // Now that we've built the reversion based upon the Suggestion's original context,
       // we manipulate it in order to get a proper 'displayAs' string.
diff --git a/ios/engine/KMEI/KeymanEngine/Classes/InputViewController.swift b/ios/engine/KMEI/KeymanEngine/Classes/InputViewController.swift
index cd4092140f..35cabcb4b3 100644
--- a/ios/engine/KMEI/KeymanEngine/Classes/InputViewController.swift
+++ b/ios/engine/KMEI/KeymanEngine/Classes/InputViewController.swift
@@ -168,7 +168,6 @@ open class InputViewController: UIInputViewController, KeymanWebDelegate {
   private var keymanWeb: KeymanWebViewController
   
   private var swallowBackspaceTextChange: Bool = false
-  private var swallowContextChangeCount: Int = 0
 
   open class var isPortrait: Bool {
     return UIScreen.main.bounds.width < UIScreen.main.bounds.height
@@ -322,13 +321,6 @@ open class InputViewController: UIInputViewController, KeymanWebDelegate {
       self.swallowBackspaceTextChange = false
       return
     }
-
-    // Currently motivated by the need to shift caret position to perform
-    // right-deletions.
-    if self.swallowContextChangeCount > 0 {
-      self.swallowContextChangeCount -= 1
-      return
-    }
     
     let contextBeforeInput = textDocumentProxy.documentContextBeforeInput ?? ""
     let contextAfterInput = textDocumentProxy.documentContextAfterInput ?? ""
@@ -346,7 +338,7 @@ open class InputViewController: UIInputViewController, KeymanWebDelegate {
     // We should NOT call .resetContext() here for this reason.
   }
   
-  func insertText(_ keymanWeb: KeymanWebViewController, numCharsToLeftDelete: Int, newText: String, numCharsToRightDelete: Int) {
+  func insertText(_ keymanWeb: KeymanWebViewController, numCharsToDelete: Int, newText: String) {
     if keymanWeb.isSubKeysMenuVisible {
       return
     }
@@ -359,7 +351,9 @@ open class InputViewController: UIInputViewController, KeymanWebDelegate {
       perform(#selector(self.enableInputClickSound), with: nil, afterDelay: 0.1)
     }
 
-    if numCharsToLeftDelete <= 0 {
+    if numCharsToDelete <= 0 {
+      textDocumentProxy.insertText(newText)
+
       // A full-context deletion will report numCharsToDelete == 0 and won't
       // otherwise delete selected text.
       if #available(iOSApplicationExtension 11.0, *) {
@@ -369,143 +363,43 @@ open class InputViewController: UIInputViewController, KeymanWebDelegate {
           }
         }
       }
-    } else {
-      for _ in 0..<numCharsToLeftDelete {
-        let oldContext = textDocumentProxy.documentContextBeforeInput ?? ""
-        textDocumentProxy.deleteBackward()
-        let newContext = textDocumentProxy.documentContextBeforeInput ?? ""
-        let unitsDeleted = oldContext.utf16.count - newContext.utf16.count
-        if unitsDeleted > 1 {
-          if !InputViewController.isSurrogate(oldContext.utf16.last!) {
-            let lowerIndex = oldContext.utf16.index(oldContext.utf16.startIndex,
-                                                    offsetBy: newContext.utf16.count)
-            let upperIndex = oldContext.utf16.index(lowerIndex, offsetBy: unitsDeleted - 1)
-            let remnant = String(oldContext.utf16[lowerIndex..<upperIndex]) ?? ""
-            textDocumentProxy.insertText(remnant)
-          }
-        }
+      return
+    }
 
-        // Refer to `func textDidChange()` and https://github.com/keymanapp/keyman/pull/2770 for context.
-        if textDocumentProxy.documentContextBeforeInput == nil ||
-           (textDocumentProxy.documentContextBeforeInput == "\n" && Manager.shared.isSystemKeyboard) {
-          if(self.swallowBackspaceTextChange) {
-            // A single keyboard processing command should never trigger two of these in a row;
-            // only one output function will perform deletions.
-
-            // This should allow us to debug any failures of this assumption.
-            // So far, only occurs when debugging a breakpoint during a touch event on BKSP,
-            // so all seems good.
-            log.verbose("Failed to swallow a recent textDidChange call!")
-          }
-          self.swallowBackspaceTextChange = true
-          break
+    for _ in 0..<numCharsToDelete {
+      let oldContext = textDocumentProxy.documentContextBeforeInput ?? ""
+      textDocumentProxy.deleteBackward()
+      let newContext = textDocumentProxy.documentContextBeforeInput ?? ""
+      let unitsDeleted = oldContext.utf16.count - newContext.utf16.count
+      if unitsDeleted > 1 {
+        if !InputViewController.isSurrogate(oldContext.utf16.last!) {
+          let lowerIndex = oldContext.utf16.index(oldContext.utf16.startIndex,
+                                                  offsetBy: newContext.utf16.count)
+          let upperIndex = oldContext.utf16.index(lowerIndex, offsetBy: unitsDeleted - 1)
+          textDocumentProxy.insertText(String(oldContext[lowerIndex..<upperIndex]))
         }
       }
+
+      // Refer to `func textDidChange()` and https://github.com/keymanapp/keyman/pull/2770 for context.
+      if textDocumentProxy.documentContextBeforeInput == nil ||
+         (textDocumentProxy.documentContextBeforeInput == "\n" && Manager.shared.isSystemKeyboard) {
+        if(self.swallowBackspaceTextChange) {
+          // A single keyboard processing command should never trigger two of these in a row;
+          // only one output function will perform deletions.
+
+          // This should allow us to debug any failures of this assumption.
+          // So far, only occurs when debugging a breakpoint during a touch event on BKSP,
+          // so all seems good.
+          log.verbose("Failed to swallow a recent textDidChange call!")
+        }
+        self.swallowBackspaceTextChange = true
+        break
+      }
     }
 
     if !newText.isEmpty {
       textDocumentProxy.insertText(newText)
     }
-
-    // NOTE:  when a script uses character clusters, the code below fails to
-    // produce the correct effects despite `textDocumentProxy` reporting that
-    // the code correctly manipulates the text.  There's either a bug in Apple's
-    // code or something critical that we're missing here.
-    //
-    // The `textDidChange` call that occurs after this `insertText` will
-    // report the final, 'incorrect' details, rather than what is reported
-    // at the end of this method.
-    if numCharsToRightDelete > 0 {
-      // Should never change throughout the next loop; right-deletions only!
-      let oldLeftContext = textDocumentProxy.documentContextBeforeInput ?? ""
-      var pointsToDelete = numCharsToRightDelete
-      while pointsToDelete > 0 {
-        let oldContext = textDocumentProxy.documentContextAfterInput ?? ""
-        self.swallowContextChangeCount += 1
-        // Asynchronously triggers a context change.
-        textDocumentProxy.adjustTextPosition(byCharacterOffset: 1)
-        let newContext = textDocumentProxy.documentContextAfterInput ?? ""
-
-        var failsafeCount = 0
-        while (textDocumentProxy.documentContextBeforeInput ?? "" != oldLeftContext)
-              && failsafeCount < numCharsToRightDelete { // mild breakage > locked kbd
-          // While adjustTextPosition makes cluster-based jumps...
-          // deleteBackward does not.  So, we 'force' it.
-          textDocumentProxy.deleteBackward()
-          failsafeCount += 1
-        }
-
-        // Determine the removed codepoint count.  Also, find the index
-        // of the first character that shouldn't be removed, if possible.
-        let unitsDeleted = oldContext.utf16.count - newContext.utf16.count
-        var pointsDeleted = 0
-
-        // Our current index within the deleted context.
-        var deletedIndex = oldContext.utf16.startIndex
-        // Marks the first index we wish to NOT remove.
-        var remnantIndex: String.Index? = nil
-        // Marks the first index that was NOT removed by deleteBackward.
-        let undeletedStartIndex = oldContext.utf16.index(deletedIndex, offsetBy: unitsDeleted)
-
-        while deletedIndex < undeletedStartIndex {
-          if(InputViewController.isSurrogate(oldContext.utf16[deletedIndex])) {
-            // Check - is it truly a surrogate pair?
-            let pairedIndex = oldContext.utf16.index(after: deletedIndex)
-            if(InputViewController.isSurrogate(oldContext.utf16[pairedIndex])) {
-              // If so, pre-emptively increase the index - the pair will count
-              // as a single character as a result.
-              deletedIndex = pairedIndex
-            }
-          }
-          pointsDeleted += 1
-          deletedIndex = oldContext.utf16.index(after: deletedIndex)
-
-          // Intended end of deletion found!
-          if pointsDeleted == pointsToDelete {
-            remnantIndex = deletedIndex
-            break // There's nothing to be gained by further loop iterations.
-          }
-        }
-
-        if let remnantIndex = remnantIndex, remnantIndex < undeletedStartIndex {
-          // We need to restore some of the deleted text!
-          let remnant = String(oldContext.utf16[remnantIndex..<undeletedStartIndex]) ?? ""
-          textDocumentProxy.insertText(remnant)
-
-          // Must place the caret back in its correct position!
-          // Unfortunately, Apple's adjustTextPosition is definitely cluster-based.
-
-          var leftContext = textDocumentProxy.documentContextBeforeInput ?? ""
-          // Ideally, we want to stop at the exact position, but the lack of
-          // granularity on adjustTextPosition may not cooperate with that goal.
-          while(leftContext.count > oldLeftContext.count) {
-            textDocumentProxy.adjustTextPosition(byCharacterOffset: -remnant.count)
-            leftContext = textDocumentProxy.documentContextBeforeInput ?? ""
-          }
-
-          // FAILSAFE, non-ideal behavior below.
-          //
-          // It's probably (?) better to keep the caret at the end of a cluster that
-          // previously started before the caret, even if right-deletions add new
-          // characters to the cluster.  I think.
-          //
-          // Khmer example:  if right-deletes leave a joeung-S that can attach
-          // to a main consonant to the left of my cursor, it will 'snap' into
-          // a cluster.  It'd be more natural to have that cluster on the left,
-          // so I can add more chars to the cluster if desired.
-          //
-          // It's also easier to immediately backspace the extra chars if needed
-          // this way, rather than forcing a caret reposition.
-          if(leftContext.count < oldLeftContext.count) {
-            log.debug("Could not reposition caret perfectly after a right-delete!")
-            textDocumentProxy.adjustTextPosition(byCharacterOffset: 1)
-          }
-        }
-
-        // We've handled a set of code points; make sure we mark our progress!
-        pointsToDelete -= pointsDeleted
-      }
-    }
   }
 
   func menuKeyUp(_ keymanWeb: KeymanWebViewController) {
@@ -657,9 +551,7 @@ open class InputViewController: UIInputViewController, KeymanWebDelegate {
   }
   
   func resetContext() {
-    if self.swallowContextChangeCount <= 0 {
-      keymanWeb.resetContext()
-    }
+    keymanWeb.resetContext()
   }
 
   internal func setSentryState(enabled: Bool) {
diff --git a/ios/engine/KMEI/KeymanEngine/Classes/KeymanWebDelegate.swift b/ios/engine/KMEI/KeymanEngine/Classes/KeymanWebDelegate.swift
index f931b25bfa..a176a2d1ed 100644
--- a/ios/engine/KMEI/KeymanEngine/Classes/KeymanWebDelegate.swift
+++ b/ios/engine/KMEI/KeymanEngine/Classes/KeymanWebDelegate.swift
@@ -16,7 +16,7 @@ protocol KeymanWebDelegate: class {
   /// - Parameters:
   ///   - numCharsToDelete: The number of UTF-16 code units to delete before inserting the new text.
   ///   - newText: The string to insert.
-  func insertText(_ keymanWeb: KeymanWebViewController, numCharsToLeftDelete: Int, newText: String, numCharsToRightDelete: Int)
+  func insertText(_ keymanWeb: KeymanWebViewController, numCharsToDelete: Int, newText: String)
   
   /// - Parameters:
   func beep(_ keymanWeb: KeymanWebViewController)
diff --git a/ios/engine/KMEI/KeymanEngine/Classes/KeymanWebViewController.swift b/ios/engine/KMEI/KeymanEngine/Classes/KeymanWebViewController.swift
index 113dc6c861..e20c4f7112 100644
--- a/ios/engine/KMEI/KeymanEngine/Classes/KeymanWebViewController.swift
+++ b/ios/engine/KMEI/KeymanEngine/Classes/KeymanWebViewController.swift
@@ -388,14 +388,16 @@ extension KeymanWebViewController: WKScriptMessageHandler {
       let dn = Int(fragment[dnRange.upperBound..<sRange.lowerBound])!
       let s = fragment[sRange.upperBound..<drRange.lowerBound]
       // This computes the number of requested right-deletion characters.
-      let dr = Int(fragment[drRange.upperBound...])!
+      // Use it when we're ready to implement that.
+      // Our .insertText will need to be adjusted accordingly.
+      _ = Int(fragment[drRange.upperBound...])!
 
       // KMW uses dn == -1 to perform special processing of deadkeys.
       // This is handled outside of Swift so we don't delete any characters.
       let numCharsToDelete = max(0, dn)
       let newText = String(s).stringFromUTF16CodeUnits() ?? ""
       insertText(self, numCharsToDelete: numCharsToDelete, newText: newText)
-      delegate?.insertText(self, numCharsToLeftDelete: numCharsToDelete, newText: newText, numCharsToRightDelete: dr)
+      delegate?.insertText(self, numCharsToDelete: numCharsToDelete, newText: newText)
     } else if fragment.hasPrefix("#showKeyPreview-") {
       let xKey = fragment.range(of: "+x=")!
       let yKey = fragment.range(of: "+y=")!
@@ -636,7 +638,7 @@ extension KeymanWebViewController: KeymanWebDelegate {
     }
   }
   
-  func insertText(_ view: KeymanWebViewController, numCharsToLeftDelete: Int, newText: String, numCharsToRightDelete: Int) {
+  func insertText(_ view: KeymanWebViewController, numCharsToDelete: Int, newText: String) {
     dismissHelpBubble()
     Manager.shared.isKeymanHelpOn = false
   }
diff --git a/ios/engine/KMEI/KeymanEngine/Classes/TextView.swift b/ios/engine/KMEI/KeymanEngine/Classes/TextView.swift
index e120d530ad..87fe2fde28 100644
--- a/ios/engine/KMEI/KeymanEngine/Classes/TextView.swift
+++ b/ios/engine/KMEI/KeymanEngine/Classes/TextView.swift
@@ -114,6 +114,13 @@ public class TextView: UITextView, KeymanResponder {
     }
   }
 
+  public override var selectedTextRange: UITextRange? {
+    didSet {
+      Manager.shared.setContextState(text: self.text, range: selectedRange)
+      Manager.shared.resetContext()
+    }
+  }
+
   // MARK: - Keyman notifications
   private func keyboardChanged(_ kb: InstallableKeyboard) {
     if !shouldSetCustomFontOnKeyboardChange {