From b375da5c9566e7c33fb3c26ac984b563eee66fbf Mon Sep 17 00:00:00 2001
From: ShikiSuen <shikisuen@outlook.com>
Date: Fri, 11 Aug 2023 16:18:55 +0800
Subject: [PATCH] InputHandler // Properly handle arrow keys for certain
 submodes.

---
 Source/Modules/InputHandler_Core.swift        |  6 +++---
 .../InputHandler_HandleComposition.swift      |  5 +++--
 .../Modules/InputHandler_HandleStates.swift   | 20 ++++++++++++++-----
 3 files changed, 21 insertions(+), 10 deletions(-)

diff --git a/Source/Modules/InputHandler_Core.swift b/Source/Modules/InputHandler_Core.swift
index 13f9edf0..6c143e27 100644
--- a/Source/Modules/InputHandler_Core.swift
+++ b/Source/Modules/InputHandler_Core.swift
@@ -31,7 +31,7 @@ public protocol InputHandlerProtocol {
   func ensureKeyboardParser()
   func triageInput(event input: InputSignalProtocol) -> Bool
   func generateStateOfCandidates() -> IMEStateProtocol
-  func generateStateOfInputting(sansReading: Bool) -> IMEStateProtocol
+  func generateStateOfInputting(sansReading: Bool, guarded: Bool) -> IMEStateProtocol
   func generateStateOfAssociates(withPair pair: Megrez.KeyValuePaired) -> IMEStateProtocol
   func consolidateNode(
     candidate: (keyArray: [String], value: String), respectCursorPushing: Bool, preConsolidate: Bool, skipObservation: Bool
@@ -41,8 +41,8 @@ public protocol InputHandlerProtocol {
 }
 
 extension InputHandlerProtocol {
-  func generateStateOfInputting(sansReading: Bool = false) -> IMEStateProtocol {
-    generateStateOfInputting(sansReading: sansReading)
+  func generateStateOfInputting(sansReading: Bool = false, guarded: Bool = false) -> IMEStateProtocol {
+    generateStateOfInputting(sansReading: sansReading, guarded: guarded)
   }
 
   func consolidateNode(candidate: (keyArray: [String], value: String), respectCursorPushing: Bool, preConsolidate: Bool) {
diff --git a/Source/Modules/InputHandler_HandleComposition.swift b/Source/Modules/InputHandler_HandleComposition.swift
index f4c8a7c2..184771b9 100644
--- a/Source/Modules/InputHandler_HandleComposition.swift
+++ b/Source/Modules/InputHandler_HandleComposition.swift
@@ -391,7 +391,7 @@ extension InputHandler {
     case 0 ..< 4:
       if strCodePointBuffer.count < 3 {
         strCodePointBuffer.append(input.text)
-        var updatedState = generateStateOfInputting()
+        var updatedState = generateStateOfInputting(guarded: true)
         updatedState.tooltipDuration = 0
         updatedState.tooltip = tooltipCodePointInputMode
         delegate.switchState(updatedState)
@@ -418,7 +418,8 @@ extension InputHandler {
       }
       // 某些舊版 macOS 會在這裡生成的字元後面插入垃圾字元。這裡只保留起始字元。
       if char.count > 1 { char = char.map(\.description)[0] }
-      var updatedState = IMEState.ofCommitting(textToCommit: char)
+      delegate.switchState(IMEState.ofCommitting(textToCommit: char))
+      var updatedState = generateStateOfInputting(guarded: true)
       updatedState.tooltipDuration = 0
       updatedState.tooltip = tooltipCodePointInputMode
       delegate.switchState(updatedState)
diff --git a/Source/Modules/InputHandler_HandleStates.swift b/Source/Modules/InputHandler_HandleStates.swift
index 550c0e56..6fd6342c 100644
--- a/Source/Modules/InputHandler_HandleStates.swift
+++ b/Source/Modules/InputHandler_HandleStates.swift
@@ -18,8 +18,12 @@ extension InputHandler {
   // MARK: - 構築狀態（State Building）
 
   /// 生成「正在輸入」狀態。相關的內容會被拿給狀態機械用來處理在電腦螢幕上顯示的內容。
-  public func generateStateOfInputting(sansReading: Bool = false) -> IMEStateProtocol {
-    if isConsideredEmptyForNow { return IMEState.ofAbortion() }
+  /// - Parameters:
+  ///   - sansReading: 不顯示組音區/組筆區。
+  ///   - guarded: 是否在該狀態的顯示文字為空的時候顯示替補空格，否則 InputMethodKit 無法正常攔截方向鍵事件。
+  /// - Returns: 生成的「正在輸入」狀態。
+  public func generateStateOfInputting(sansReading: Bool = false, guarded: Bool = false) -> IMEStateProtocol {
+    if isConsideredEmptyForNow, !guarded { return IMEState.ofAbortion() }
     var segHighlightedAt: Int?
     let cpInput = isCodePointInputMode && !sansReading
     /// 「更新內文組字區 (Update the composing buffer)」是指要求客體軟體將組字緩衝區的內容
@@ -68,6 +72,12 @@ extension InputHandler {
       cursor: cursor, highlightAt: segHighlightedAt
     )
     result.marker = cursorSansReading
+    /// 特殊情形，否則方向鍵事件無法正常攔截。
+    if guarded, result.displayTextSegments.joined().isEmpty {
+      result.data.displayTextSegments = [" "]
+      result.cursor = 0
+      result.marker = 0
+    }
     return result
   }
 
@@ -440,7 +450,7 @@ extension InputHandler {
     if isCodePointInputMode {
       if !strCodePointBuffer.isEmpty {
         func refreshState() {
-          var updatedState = generateStateOfInputting()
+          var updatedState = generateStateOfInputting(guarded: true)
           updatedState.tooltipDuration = 0
           updatedState.tooltip = tooltipCodePointInputMode
           delegate.switchState(updatedState)
@@ -895,7 +905,7 @@ extension InputHandler {
     }
     var updatedState = generateStateOfInputting(sansReading: true)
     delegate.switchState(IMEState.ofCommitting(textToCommit: updatedState.displayedText))
-    updatedState = IMEState.ofEmpty()
+    updatedState = generateStateOfInputting(guarded: true)
     updatedState.tooltipDuration = 0
     updatedState.tooltip = tooltipCodePointInputMode
     delegate.switchState(updatedState)
@@ -915,7 +925,7 @@ extension InputHandler {
     }
     var updatedState = generateStateOfInputting(sansReading: true)
     delegate.switchState(IMEState.ofCommitting(textToCommit: updatedState.displayedText))
-    updatedState = IMEState.ofEmpty()
+    updatedState = generateStateOfInputting(guarded: true)
     updatedState.tooltipDuration = 0
     updatedState.tooltip = Self.tooltipHaninKeyboardSymbolMode
     delegate.switchState(updatedState)