changelog.rb in gfsm-0.5.0

- old
+ new

@@ -9,26 +9,31 @@
       def self.help
         cli_info = GFSM::Tools::VersionBumperSettings.cli_info
 
         <<~HELP
         Usage:
-        gfsm changelog [help|generate] [--output-file <path>] [--no-incremental] #{cli_info[:usage]}
+        gfsm changelog [help|generate|extract] [--output-file <path>] [--input-file <path>] [--no-incremental] [--only-new-entries] [--extract-version <version>] #{cli_info[:usage]}
 
         Commands:
         help                                  # Prints this help
         generate                              # Generate the changelog for the current version
+        extract                               # Extract the changelog for the latest or specified version
 
         Options:
         --output-file <path>                  # Path to the output changelog file. Defaults to 'CHANGELOG.md'. If not specified, the generate changelog content will be written to stdout
         --no-incremental                      # When provided, the generated changelog won't look for an existing changelog file. When outputting to stdout the changelog will never be incremental
         --only-new-entries                    # When provided, the generated changelog won't look for an existing changelog file and will contain only the new entries for the current version, without the Changelog or version headings
+        --input-file <path>                   # Path to the input changelog file. Defaults to 'CHANGELOG.md'
+        --extract-version <version>           # Version from which to extract the changelog. Defaults to the latest one on the changelog file
         #{cli_info[:options]}
 
         Environment variables:
         OUTPUT_FILE                           # Equivalent to --output-file
         NO_INCREMENTAL                        # Equivalent to --no-incremental
         ONLY_NEW_ENTRIES                      # Equivalent to --only-new-entries
+        INPUT_FILE                            # Equivalent to --input-file
+        EXTRACT_VERSION                       # Equivalent to --extract-version
         #{cli_info[:environment_variables]}
         HELP
       end
 
       def run(args = [])
@@ -62,12 +67,27 @@
                 #{changelog_section}
                 CHANGELOG
               end
             end
           end
+        when 'extract'
+          input_file_path = get_input_file_path(args)
+          version_to_extract = get_version_to_extract(args)
+
+          unless File.file?(input_file_path)
+            GFSM::Output.error "No changelog file found at #{input_file_path}"
+          else
+            section = extract_version_section(input_file_path, version_to_extract)
+
+            if section.nil?
+              GFSM::Output.error "No changelog section found for version #{version_to_extract}"
+            else
+              GFSM::Output.puts section
+            end
+          end
         else
-          GFSM::Output.warn(GFSM::Commands::Version.help)
+          GFSM::Output.warn GFSM::Commands::Version.help
         end
 
         true
       end
 
@@ -104,10 +124,48 @@
         return section if !subdivisions || subdivisions.empty?
 
         "#{section}\n\n#{changelog_entries}"
       end
 
+      def extract_version_section(input_file_path, version_to_extract)
+        file_content = File.read(input_file_path)
+
+        # Parse the file contect to subdivide the changelog sections based on the version
+        version_sections = file_content.split(/^## /)
+
+        # Remove the initial empty section
+        version_sections.shift
+
+        version_to_extract_index =  if version_to_extract.nil? || version_to_extract == "latest"
+                                      0
+                                    else
+                                      version_sections.find_index { |section| section.start_with?("#{version_to_extract}\n") }
+                                    end
+        return nil if version_to_extract_index.nil? || version_to_extract_index > version_sections.length
+
+        version_section = version_sections[version_to_extract_index]
+
+        # Remove the first line that contains version heading
+        version_section = version_section[version_section.index("\n")..-1]
+
+        # Remove the empty lines at the start and at the end of version_section
+        version_section = version_section.strip
+
+        return version_section
+      end
+
+      def extract_switch_value(args, switch, default_value, env_name = nil)
+        return ENV.fetch(env_name) if ENV.has_key?(env_name)
+
+        switch_index = args.find_index(switch)
+        
+        return default_value unless switch_index &&
+                                    (switch_index + 1) < args.length
+
+        args[switch_index + 1]
+      end
+
       def extract_switch_value_if_present(args, switch, default_value, env_name)
         return ENV.fetch(env_name) if ENV.has_key?(env_name)
 
         switch_index = args.find_index(switch)
 
@@ -117,9 +175,17 @@
         args[switch_index + 1]
       end
 
       def get_output_file_path(args)
         extract_switch_value_if_present(args, "--output-file", "./CHANGELOG.md", "OUTPUT_FILE")
+      end
+
+      def get_input_file_path(args)
+        extract_switch_value(args, "--input-file", "./CHANGELOG.md", "INPUT_FILE")
+      end
+
+      def get_version_to_extract(args)
+        extract_switch_value(args, "--extract-version", nil, "EXTRACT_VERSION")
       end
     end
   end
 end
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