improve diff algorithm

Author: SamSaffron

lib/ai_bot/tools/update_artifact.rb

@@ -31,7 +31,18 @@ def self.unified_diff_tip
               <p>Some new text</p>
             </div>
 
-            If you need to supply multiple hunks for a diff use the @@@ separator between hunks.
+            If you need to supply multiple hunks for a diff use a @@ separator, for example:
+
+            @@ -1,3 +1,3 @@
+            - <p>Some text</p>
+            + <p>Some new text</p>
+            @@ -5,3 +5,3 @@
+            - </div>
+            + <p>more text</p>
+            </div>
+
+            If you supply text without @@ seperators or + and - prefixes, the entire text will be appended to the artifact section.
+
           TIP
         end
 
@@ -76,6 +87,10 @@ def self.allow_partial_tool_calls?
           true
         end
 
+        def chain_next_response?
+          @chain_next_response
+        end
+
         def partial_invoke
           @selected_tab = :html_diff
           if @prev_parameters
@@ -166,7 +181,8 @@ def success_response(artifact)
         end
 
         def error_response(message)
-          @chain_next_response = false
+          @chain_next_response = true
+          self.custom_raw = ""
 
           { status: "error", error: message }
         end

lib/utils/diff_utils.rb

@@ -85,6 +85,19 @@ def initialize(original_text:, diff_text:, issue:)
       end
 
       def self.apply_hunk(text, diff)
+
+        # we need to handle multiple hunks just in case
+        if diff.match?(/^\@\@.*\@\@$\n/)
+          hunks = diff.split(/^\@\@.*\@\@$\n/)
+          if hunks.present?
+            hunks.each do |hunk|
+              next if hunk.blank?
+              text = apply_hunk(text, hunk)
+            end
+            return text
+          end
+        end
+
         text = text.encode(universal_newline: true)
         diff = diff.encode(universal_newline: true)
         # we need this for matching
@@ -94,6 +107,10 @@ def self.apply_hunk(text, diff)
 
         validate_diff_format!(text, diff, diff_lines)
 
+        if diff_lines.all? { |marker, _| marker == " " }
+          return text.strip + "\n" + diff.strip
+        end
+
         lines_to_match = diff_lines.select { |marker, _| ["-", " "].include?(marker) }.map(&:last)
         match_start, match_end = find_unique_match(text, lines_to_match, diff)
         new_hunk = diff_lines.select { |marker, _| ["+", " "].include?(marker) }.map(&:last).join
@@ -146,14 +163,6 @@ def self.apply_hunk(text, diff)
         if diff_lines.empty?
           raise MalformedDiffError.new(original_text: text, diff_text: diff, issue: "Diff is empty")
         end
-
-        unless diff_lines.any? { |marker, _| %w[- +].include?(marker) }
-          raise MalformedDiffError.new(
-                  original_text: text,
-                  diff_text: diff,
-                  issue: "Diff must contain at least one change (+ or -)",
-                )
-        end
       end
 
       private_class_method def self.find_unique_match(text, context_lines, diff)

spec/lib/utils/diff_utils_spec.rb

@@ -175,22 +175,14 @@
             end
           end
         end
+      end
+    end
 
-        context "when missing changes" do
-          let(:diff) { <<~DIFF }
-               <div>
-                 <h1>Title</h1>
-               </div>
-            DIFF
-
-          it "raises a MalformedDiffError" do
-            expect { apply_hunk }.to raise_error(
-              DiscourseAi::Utils::DiffUtils::MalformedDiffError,
-            ) do |error|
-              expect(error.context["Issue"]).to match(/must contain at least one change/)
-            end
-          end
-        end
+    context "without markers" do
+      let(:original_text) { "hello" }
+      let(:diff) { "world" }
+      it "will append to the end" do
+        expect(apply_hunk).to eq("hello\nworld")
       end
     end
 
@@ -202,11 +194,49 @@
           +123
         DIFF
 
-      it "can append to file" do
+      it "can append to end" do
         expect(apply_hunk).to eq("hello\nworld\n123")
       end
     end
 
+    context "it can apply multiple hunks to a file" do
+      let(:original_text) do
+        <<~TEXT
+          1
+          2
+          3
+          4
+          5
+          6
+          7
+          8
+        TEXT
+      end
+
+      let(:diff) do
+        <<~DIFF
+          @@ -1,4 +1,4 @@
+          2
+          - 3
+          @@ -6,4 +6,4 @@
+          - 7
+        DIFF
+      end
+
+      it "can apply multiple hunks" do
+        expected = <<~TEXT
+          1
+          2
+          4
+          5
+          6
+          8
+        TEXT
+        expect(apply_hunk).to eq(expected.strip)
+      end
+
+    end
+
     context "with line ending variations" do
       let(:original_text) { "line1\r\nline2\nline3\r\n" }
       let(:diff) { <<~DIFF }