ノート表示の強化と柔軟なリンク・HTML対応の導入

- ノートの表示処理を、通常テキスト・リンク自動検出・HTML埋め込みの三通りで動的に切り替える新ロジックを導入
- ノート内にHTMLが含まれる場合のパース＆レンダリングをサポート
- テキストから自動でURLを抽出し、クリック可能なリンクとして表示できるように改良
- 表示部分の変更に合わせ、既存のTextウィジェット処理をattributedStringによる表示へと切り替え

Sources/ContentView.swift

@@ -232,7 +232,7 @@ struct EventDetailView: View {
                         Image(systemName: "note.text")
                             .foregroundColor(.secondary)
                             .frame(width: 20)
-                        Text(notes)
+                        Text(attributedString(from: notes))
                             .textSelection(.enabled)
                     }
                 }
@@ -257,4 +257,60 @@ struct EventDetailView: View {
         formatter.locale = Locale(identifier: "ja_JP")
         return formatter.string(from: date)
     }
+
+    private func isHTML(_ string: String) -> Bool {
+        let htmlPatterns = ["<a ", "<p>", "<p ", "<br", "<div", "<span", "<b>", "<i>", "<ul", "<ol", "<li"]
+        let lowercased = string.lowercased()
+        return htmlPatterns.contains { lowercased.contains($0) }
+    }
+
+    private func attributedString(from notes: String) -> AttributedString {
+        if isHTML(notes) {
+            return attributedStringFromHTML(notes)
+        } else {
+            return attributedStringWithLinks(notes)
+        }
+    }
+
+    private func attributedStringFromHTML(_ html: String) -> AttributedString {
+        let styledHTML = """
+        <style>
+        body { font-family: -apple-system, BlinkMacSystemFont, sans-serif; }
+        </style>
+        \(html)
+        """
+        guard let data = styledHTML.data(using: .utf8) else {
+            return AttributedString(html)
+        }
+        do {
+            let nsAttrStr = try NSAttributedString(
+                data: data,
+                options: [
+                    .documentType: NSAttributedString.DocumentType.html,
+                    .characterEncoding: String.Encoding.utf8.rawValue
+                ],
+                documentAttributes: nil
+            )
+            return AttributedString(nsAttrStr)
+        } catch {
+            return AttributedString(html)
+        }
+    }
+
+    private func attributedStringWithLinks(_ text: String) -> AttributedString {
+        var attributedString = AttributedString(text)
+        guard let detector = try? NSDataDetector(types: NSTextCheckingResult.CheckingType.link.rawValue) else {
+            return attributedString
+        }
+        let matches = detector.matches(in: text, options: [], range: NSRange(location: 0, length: text.utf16.count))
+        for match in matches {
+            guard let range = Range(match.range, in: text),
+                  let url = match.url,
+                  let attrRange = Range(range, in: attributedString) else {
+                continue
+            }
+            attributedString[attrRange].link = url
+        }
+        return attributedString
+    }
 }