1 files changed, 61 insertions, 0 deletions
diff --git a/lib/error_tracking/stacktrace_builder.rb b/lib/error_tracking/stacktrace_builder.rb
new file mode 100644
index 00000000000..4f331bc4e06
--- /dev/null
+++ b/lib/error_tracking/stacktrace_builder.rb
@@ -0,0 +1,61 @@
+# frozen_string_literal: true
+
+module ErrorTracking
+  class StacktraceBuilder
+    attr_reader :stacktrace
+
+    def initialize(payload)
+      @stacktrace = build_stacktrace(payload)
+    end
+
+    private
+
+    def build_stacktrace(payload)
+      raw_stacktrace = raw_stacktrace_from_payload(payload)
+      return [] unless raw_stacktrace
+
+      raw_stacktrace.map do |entry|
+        {
+          'lineNo' => entry['lineno'],
+          'context' => build_stacktrace_context(entry),
+          'filename' => entry['filename'],
+          'function' => entry['function'],
+          'colNo' => 0 # we don't support colNo yet.
+        }
+      end
+    end
+
+    def raw_stacktrace_from_payload(payload)
+      exception_entry = payload['exception']
+      return unless exception_entry
+
+      exception_values = exception_entry['values']
+      stack_trace_entry = exception_values&.detect { |h| h['stacktrace'].present? }
+      stack_trace_entry&.dig('stacktrace', 'frames')
+    end
+
+    def build_stacktrace_context(entry)
+      error_line = entry['context_line']
+      error_line_no = entry['lineno']
+      pre_context = entry['pre_context']
+      post_context = entry['post_context']
+
+      context = []
+      context.concat lines_with_position(pre_context, error_line_no - pre_context.size) if pre_context
+      context.concat lines_with_position([error_line], error_line_no)
+      context.concat lines_with_position(post_context, error_line_no + 1) if post_context
+
+      context.reject(&:blank?)
+    end
+
+    def lines_with_position(lines, position)
+      return [] if lines.blank?
+
+      lines.map.with_index do |line, index|
+        next unless line
+
+        [position + index, line]
+      end
+    end
+  end
+end