1 files changed, 88 insertions, 0 deletions
diff --git a/Hutch/Views/Inbox/InboxThreadUtilities.swift b/Hutch/Views/Inbox/InboxThreadUtilities.swift
index 1dd88a3..6958b50 100644
--- a/Hutch/Views/Inbox/InboxThreadUtilities.swift
+++ b/Hutch/Views/Inbox/InboxThreadUtilities.swift
@@ -8,4 +8,92 @@ enum InboxThreadUtilities {
         }
         return nil
     }
+
+    /// Splits an email body into its commit message and diff, so patch mail can be
+    /// rendered as prose plus a diff rather than one undifferentiated blob.
+    ///
+    /// Shared by the inbox thread view and patchset review: sr.ht's `Patch` type
+    /// carries no diff, so the diff has to be recovered from the email body.
+    nonisolated static func segmentMessageBody(_ body: String, isPatch: Bool) -> [InboxMessageContentBlock] {
+        guard isPatch else {
+            let trimmedBody = body.trimmingCharacters(in: .whitespacesAndNewlines)
+            return trimmedBody.isEmpty ? [] : [.plainText(trimmedBody)]
+        }
+
+        let normalizedBody = normalizeLineEndings(in: body)
+        let lines = normalizedBody.components(separatedBy: "\n")
+        guard let diffStartIndex = actualDiffStartIndex(in: lines) else {
+            let trimmedBody = normalizedBody.trimmingCharacters(in: .whitespacesAndNewlines)
+            return trimmedBody.isEmpty ? [] : [.plainText(trimmedBody)]
+        }
+
+        var blocks: [InboxMessageContentBlock] = []
+        let leadingPlainText = lines[..<diffStartIndex]
+            .joined(separator: "\n")
+            .trimmingCharacters(in: .whitespacesAndNewlines)
+        if !leadingPlainText.isEmpty {
+            blocks.append(.plainText(leadingPlainText))
+        }
+
+        let remainingLines = Array(lines[diffStartIndex...])
+        let signatureIndex = remainingLines.firstIndex(where: isEmailSignatureSeparator)
+
+        let diffLines: ArraySlice<String>
+        let trailingPlainText: String
+        if let signatureIndex {
+            diffLines = remainingLines[..<signatureIndex]
+            trailingPlainText = remainingLines[signatureIndex...]
+                .joined(separator: "\n")
+                .trimmingCharacters(in: .whitespacesAndNewlines)
+        } else {
+            diffLines = remainingLines[...]
+            trailingPlainText = ""
+        }
+
+        let diff = diffLines.joined(separator: "\n").trimmingCharacters(in: .whitespacesAndNewlines)
+        if !diff.isEmpty {
+            blocks.append(.diff(diff))
+        }
+
+        if !trailingPlainText.isEmpty {
+            blocks.append(.plainText(trailingPlainText))
+        }
+        return blocks
+    }
+
+    nonisolated static func actualDiffStartIndex(in lines: [String]) -> Int? {
+        if let explicitDiffIndex = lines.firstIndex(where: { $0.hasPrefix("diff --git ") }) {
+            return explicitDiffIndex
+        }
+
+        for index in lines.indices {
+            let line = lines[index]
+            guard line.hasPrefix("--- ") else { continue }
+            let nextIndex = lines.index(after: index)
+            guard nextIndex < lines.endIndex else { continue }
+            let nextLine = lines[nextIndex]
+            guard nextLine.hasPrefix("+++ ") else { continue }
+
+            let oldPath = String(line.dropFirst(4))
+            let newPath = String(nextLine.dropFirst(4))
+            let looksLikeUnifiedDiff = (oldPath.hasPrefix("a/") || oldPath == "/dev/null") &&
+                (newPath.hasPrefix("b/") || newPath == "/dev/null")
+
+            if looksLikeUnifiedDiff {
+                return index
+            }
+        }
+
+        return nil
+    }
+
+    nonisolated static func isEmailSignatureSeparator(_ line: String) -> Bool {
+        line == "-- " || line == "--"
+    }
+
+    nonisolated static func normalizeLineEndings(in text: String) -> String {
+        text
+            .replacingOccurrences(of: "\r\n", with: "\n")
+            .replacingOccurrences(of: "\r", with: "\n")
+    }
 }