1 files changed, 187 insertions, 0 deletions
diff --git a/Sources/NorgEditor/EditorTheme.swift b/Sources/NorgEditor/EditorTheme.swift
new file mode 100644
index 0000000..2ceb596
--- /dev/null
+++ b/Sources/NorgEditor/EditorTheme.swift
@@ -0,0 +1,187 @@
+#if canImport(UIKit)
+  import UIKit
+
+  public typealias PlatformFont = UIFont
+  public typealias PlatformColor = UIColor
+#elseif canImport(AppKit)
+  import AppKit
+
+  public typealias PlatformFont = NSFont
+  public typealias PlatformColor = NSColor
+#endif
+
+#if canImport(UIKit) || canImport(AppKit)
+  import NorgKit
+
+  /// Typography and colours used when highlighting a Norg document.
+  public struct EditorTheme {
+
+    /// Base font for source text. Inline `bold`/`italic` runs derive bold and
+    /// italic variants from this font's descriptor.
+    public var font: PlatformFont
+    /// Base foreground colour for plain, unstyled source.
+    public var textColor: PlatformColor
+    /// Color for a heading marker run (`*`…) at the given 1-based level.
+    public var headingColor: @Sendable (Int) -> PlatformColor
+    /// Color for structural markers and delimiters: list/quote/definition/
+    /// footnote/table-cell runs, delimiting lines, rules, inline-modifier
+    /// delimiters, link brackets and escapes.
+    public var markerColor: PlatformColor
+    /// Color for a task status marker, e.g. `(x)`.
+    public var taskStatusColor: @Sendable (TaskStatus) -> PlatformColor
+    /// Color for a ranged-tag header: the `@` and the tag name/parameters.
+    public var tagColor: PlatformColor
+    /// Color for verbatim content: inline `` `verbatim` `` and ranged-tag
+    /// (`@code` … `@end`) body lines.
+    public var verbatimColor: PlatformColor
+    /// Color for inline comments (`%…%`).
+    public var commentColor: PlatformColor
+    /// Color for link/anchor locations and descriptions.
+    public var linkColor: PlatformColor
+    /// Color for `spoiler` inline runs.
+    public var spoilerColor: PlatformColor
+
+    public init(
+      font: PlatformFont,
+      textColor: PlatformColor,
+      headingColor: @escaping @Sendable (Int) -> PlatformColor,
+      markerColor: PlatformColor,
+      taskStatusColor: @escaping @Sendable (TaskStatus) -> PlatformColor,
+      tagColor: PlatformColor,
+      verbatimColor: PlatformColor,
+      commentColor: PlatformColor,
+      linkColor: PlatformColor,
+      spoilerColor: PlatformColor
+    ) {
+      self.font = font
+      self.textColor = textColor
+      self.headingColor = headingColor
+      self.markerColor = markerColor
+      self.taskStatusColor = taskStatusColor
+      self.tagColor = tagColor
+      self.verbatimColor = verbatimColor
+      self.commentColor = commentColor
+      self.linkColor = linkColor
+      self.spoilerColor = spoilerColor
+    }
+
+    public static let `default` = EditorTheme(
+      font: .monospacedSystemFont(ofSize: 16, weight: .regular),
+      textColor: .norgLabel,
+      headingColor: { _ in .systemBlue },
+      markerColor: .norgSecondaryLabel,
+      taskStatusColor: { status in
+        switch status {
+        case .done, .recurring: return .systemGreen
+        case .urgent: return .systemRed
+        case .pending, .onHold: return .systemBlue
+        case .cancelled: return .norgTertiaryLabel
+        case .undone, .needsInput: return .norgSecondaryLabel
+        }
+      },
+      tagColor: .systemPurple,
+      verbatimColor: .systemPink,
+      commentColor: .norgTertiaryLabel,
+      linkColor: .norgLink,
+      spoilerColor: .norgSecondaryLabel
+    )
+  }
+
+  #if canImport(UIKit)
+    extension EditorTheme: Sendable {}
+  #elseif canImport(AppKit)
+    extension EditorTheme: @unchecked Sendable {}
+  #endif
+
+  extension EditorTheme {
+
+    public func attributes(for kind: NorgToken.Kind) -> [NSAttributedString.Key: Any] {
+      switch kind {
+      case .heading(let level):
+        return [.foregroundColor: headingColor(level)]
+      case .unorderedList, .orderedList, .quote, .definition, .footnote,
+        .tableCell, .weakDelimiter, .strongDelimiter, .horizontalRule,
+        .modifierDelimiter, .linkDelimiter, .escape:
+        return [.foregroundColor: markerColor]
+      case .taskStatus(let status):
+        return [.foregroundColor: taskStatusColor(status)]
+      case .tagDelimiter, .tagName:
+        return [.foregroundColor: tagColor]
+      case .verbatimBlock:
+        return [.foregroundColor: verbatimColor]
+      case .comment:
+        return [.foregroundColor: commentColor]
+      case .linkTarget:
+        return [
+          .foregroundColor: linkColor,
+          .underlineStyle: NSUnderlineStyle.single.rawValue,
+        ]
+      case .linkDescription:
+        return [.foregroundColor: linkColor]
+      case .styledText(let style):
+        return styledAttributes(style)
+      }
+    }
+
+    private func styledAttributes(_ style: InlineStyle) -> [NSAttributedString.Key: Any] {
+      var attributes: [NSAttributedString.Key: Any] = [:]
+
+      if let traited = traitedFont(bold: style.contains(.bold), italic: style.contains(.italic)) {
+        attributes[.font] = traited
+      }
+
+      if style.contains(.underline) {
+        attributes[.underlineStyle] = NSUnderlineStyle.single.rawValue
+      }
+      if style.contains(.strikethrough) {
+        attributes[.strikethroughStyle] = NSUnderlineStyle.single.rawValue
+      }
+      if style.contains(.verbatim) || style.contains(.math) {
+        attributes[.foregroundColor] = verbatimColor
+      } else if style.contains(.spoiler) {
+        attributes[.foregroundColor] = spoilerColor
+      }
+      return attributes
+    }
+
+    private func traitedFont(bold: Bool, italic: Bool) -> PlatformFont? {
+      guard bold || italic else { return nil }
+      #if canImport(UIKit)
+        var traits: UIFontDescriptor.SymbolicTraits = []
+        if bold { traits.insert(.traitBold) }
+        if italic { traits.insert(.traitItalic) }
+        guard let descriptor = font.fontDescriptor.withSymbolicTraits(traits) else { return nil }
+        return UIFont(descriptor: descriptor, size: font.pointSize)
+      #elseif canImport(AppKit)
+        var traits: NSFontDescriptor.SymbolicTraits = []
+        if bold { traits.insert(.bold) }
+        if italic { traits.insert(.italic) }
+        let descriptor = font.fontDescriptor.withSymbolicTraits(traits)
+        return NSFont(descriptor: descriptor, size: font.pointSize)
+      #endif
+    }
+
+    public func applyHighlighting(to storage: NSTextStorage) {
+      let text = storage.string
+      let full = NSRange(location: 0, length: (text as NSString).length)
+      storage.setAttributes([.font: font, .foregroundColor: textColor], range: full)
+      for highlight in NorgHighlighter.highlights(in: text) {
+        storage.addAttributes(attributes(for: highlight.kind), range: highlight.range)
+      }
+    }
+  }
+
+  extension PlatformColor {
+    #if canImport(UIKit)
+      fileprivate static var norgLabel: PlatformColor { .label }
+      fileprivate static var norgSecondaryLabel: PlatformColor { .secondaryLabel }
+      fileprivate static var norgTertiaryLabel: PlatformColor { .tertiaryLabel }
+      fileprivate static var norgLink: PlatformColor { .link }
+    #elseif canImport(AppKit)
+      fileprivate static var norgLabel: PlatformColor { .labelColor }
+      fileprivate static var norgSecondaryLabel: PlatformColor { .secondaryLabelColor }
+      fileprivate static var norgTertiaryLabel: PlatformColor { .tertiaryLabelColor }
+      fileprivate static var norgLink: PlatformColor { .linkColor }
+    #endif
+  }
+#endif