Refactor ContactListUI and related modules

submodules/ContactListUI/Sources/ContactListNameIndexHeader.swift

@@ -0,0 +1,60 @@
+import Foundation
+import Display
+import UIKit
+import TelegramPresentationData
+import ListSectionHeaderNode
+
+final class ContactListNameIndexHeader: Equatable, ListViewItemHeader {
+    let id: Int64
+    let theme: PresentationTheme
+    let letter: unichar
+    let stickDirection: ListViewItemHeaderStickDirection = .top
+    
+    let height: CGFloat = 29.0
+    
+    init(theme: PresentationTheme, letter: unichar) {
+        self.theme = theme
+        self.letter = letter
+        self.id = Int64(letter)
+    }
+    
+    func node() -> ListViewItemHeaderNode {
+        return ContactListNameIndexHeaderNode(theme: self.theme, letter: self.letter)
+    }
+    
+    static func ==(lhs: ContactListNameIndexHeader, rhs: ContactListNameIndexHeader) -> Bool {
+        return lhs.id == rhs.id
+    }
+}
+
+final class ContactListNameIndexHeaderNode: ListViewItemHeaderNode {
+    private var theme: PresentationTheme
+    private let letter: unichar
+    
+    private let sectionHeaderNode: ListSectionHeaderNode
+    
+    init(theme: PresentationTheme, letter: unichar) {
+        self.theme = theme
+        self.letter = letter
+        
+        self.sectionHeaderNode = ListSectionHeaderNode(theme: theme)
+        
+        super.init()
+        
+        if let scalar = UnicodeScalar(letter) {
+            self.sectionHeaderNode.title = "\(Character(scalar))"
+        }
+        
+        self.addSubnode(self.sectionHeaderNode)
+    }
+    
+    func updateTheme(theme: PresentationTheme) {
+        self.theme = theme
+        self.sectionHeaderNode.updateTheme(theme: theme)
+    }
+    
+    override func updateLayout(size: CGSize, leftInset: CGFloat, rightInset: CGFloat) {
+        self.sectionHeaderNode.frame = CGRect(origin: CGPoint(), size: size)
+        self.sectionHeaderNode.updateLayout(size: size, leftInset: leftInset, rightInset: rightInset)
+    }
+}