From 29b89518c0a17d48c906155926840079491b18de Mon Sep 17 00:00:00 2001
From: ShikiSuen <shikisuen@outlook.com>
Date: Fri, 14 Oct 2022 17:52:39 +0800
Subject: [PATCH] InputHandler // Simplify the arrow handling in handleInput().

---
 Source/Modules/InputHandler_Core.swift        |  1 +
 Source/Modules/InputHandler_HandleInput.swift | 21 ++++++++++---------
 Source/Modules/InputHandler_States.swift      |  2 +-
 3 files changed, 13 insertions(+), 11 deletions(-)

diff --git a/Source/Modules/InputHandler_Core.swift b/Source/Modules/InputHandler_Core.swift
index 6ac00fe4..7fe92f22 100644
--- a/Source/Modules/InputHandler_Core.swift
+++ b/Source/Modules/InputHandler_Core.swift
@@ -34,6 +34,7 @@ public protocol InputHandlerProtocol {
 
 /// InputHandler 委任協定
 public protocol InputHandlerDelegate {
+  var isVerticalTyping: Bool { get }
   var selectionKeys: String { get }
   var state: IMEStateProtocol { get set }
   var clientBundleIdentifier: String { get }
diff --git a/Source/Modules/InputHandler_HandleInput.swift b/Source/Modules/InputHandler_HandleInput.swift
index 3661f1ad..f591d7ca 100644
--- a/Source/Modules/InputHandler_HandleInput.swift
+++ b/Source/Modules/InputHandler_HandleInput.swift
@@ -136,7 +136,7 @@ extension InputHandler {
           }
           return true
         } else if input.isShiftHold {  // 臉書等網站會攔截 Tab 鍵，所以用 Shift+Command+Space 對候選字詞做正向/反向輪替。
-          return handleInlineCandidateRotation(reverseOrder: input.isCommandHold)
+          return rotateCandidate(reverseOrder: input.isCommandHold)
         }
       }
       // 開始決定是否切換至選字狀態。
@@ -150,16 +150,17 @@ extension InputHandler {
     if let keyCodeType = KeyCode(rawValue: input.keyCode) {
       switch keyCodeType {
         case .kEscape: return handleEsc()
-        case .kTab: return handleInlineCandidateRotation(reverseOrder: input.isShiftHold)
+        case .kTab: return rotateCandidate(reverseOrder: input.isShiftHold)
         case .kUpArrow, .kDownArrow, .kLeftArrow, .kRightArrow:
-          if input.isCursorBackward { return handleBackward(input: input) }  // Forward
-          if input.isCursorForward { return handleForward(input: input) }  // Backward
-          if input.isCursorClockLeft || input.isCursorClockRight {  // Clock keys
-            if input.isOptionHold, state.type == .ofInputting {
-              if input.isCursorClockRight { return handleInlineCandidateRotation(reverseOrder: false) }
-              if input.isCursorClockLeft { return handleInlineCandidateRotation(reverseOrder: true) }
-            }
-            return handleClockKey()
+          let rotation: Bool = input.isOptionHold && state.type == .ofInputting
+          handleArrowKey: switch (keyCodeType, delegate.isVerticalTyping) {
+            case (.kLeftArrow, false), (.kUpArrow, true): return handleBackward(input: input)
+            case (.kRightArrow, false), (.kDownArrow, true): return handleForward(input: input)
+            case (.kUpArrow, false), (.kLeftArrow, true):
+              return rotation ? rotateCandidate(reverseOrder: true) : handleClockKey()
+            case (.kDownArrow, false), (.kRightArrow, true):
+              return rotation ? rotateCandidate(reverseOrder: false) : handleClockKey()
+            default: break handleArrowKey  // 該情況應該不會發生，因為上面都有處理過。
           }
         case .kHome: return handleHome()
         case .kEnd: return handleEnd()
diff --git a/Source/Modules/InputHandler_States.swift b/Source/Modules/InputHandler_States.swift
index 95e4793c..a14fbfbb 100644
--- a/Source/Modules/InputHandler_States.swift
+++ b/Source/Modules/InputHandler_States.swift
@@ -640,7 +640,7 @@ extension InputHandler {
   /// - Parameters:
   ///   - reverseOrder: 是否有控制輪替方向的修飾鍵輸入。
   /// - Returns: 將按鍵行為「是否有處理掉」藉由 SessionCtl 回報給 IMK。
-  func handleInlineCandidateRotation(reverseOrder: Bool) -> Bool {
+  func rotateCandidate(reverseOrder: Bool) -> Bool {
     guard let delegate = delegate else { return false }
     let state = delegate.state
     if composer.isEmpty, compositor.isEmpty || compositor.walkedNodes.isEmpty { return false }