Create extractLede function on PostListModel

Shared/PostList/PostListModel.swift

@@ -18,4 +18,45 @@ class PostListModel: ObservableObject {
             print("Error: Failed to purge cached posts.")
         }
     }
+
+    func getBodyPreview(of post: WFAPost) -> String {
+        var elidedPostBody: String = ""
+
+        // Strip any markdown from the post body.
+        let strippedPostBody = stripMarkdown(from: post.body)
+
+        // Get the first 80 characters.
+        let firstEightyChars = String(strippedPostBody.prefix(80))
+
+        // Extract lede from post.
+         elidedPostBody = extractLede(from: firstEightyChars)
+
+        return elidedPostBody
+    }
 }
+
+private extension PostListModel {
+
+    func stripMarkdown(from string: String) -> String {
+        return string
+    }
+
+    func extractLede(from string: String) -> String {
+        let terminatingCharacters = CharacterSet(charactersIn: ".。?").union(.newlines)
+
+        var lede: String
+
+        let sentences = string.components(separatedBy: terminatingCharacters)
+        let firstSentence = sentences.filter { !$0.isEmpty }[0]
+
+        if firstSentence == string {
+            let endOfStringIndex = string.lastIndex(of: " ")
+            lede = String(string[..<(endOfStringIndex ?? string.index(string.endIndex, offsetBy: -2))]) + "…"
+        } else {
+            lede = firstSentence
+        }
+
+        return lede
+    }
+}
+