defmodule Mix.Tasks.UsageRules.Sync.Docs do
  @moduledoc false

  @spec short_doc() :: String.t()
  def short_doc do
    "Combine the package rules for the provided packages into the provided file, or list/gather all dependencies."
  end

  @spec example() :: String.t()
  def example do
    "mix usage_rules.sync CLAUDE.md --all --link-to-folder deps"
  end

  @spec long_doc() :: String.t()
  def long_doc do
    """
    #{short_doc()}

    ## Options

    * `--all` - Gather usage rules from all dependencies that have them
    * `--list` - List all dependencies with usage rules. If a file is provided, shows status (present, missing, stale)
    * `--remove` - Remove specified packages from the target file instead of adding them
    * `--link-to-folder <folder>` - Save usage rules for each package in separate files within the specified folder and create links to them
    * `--link-style <style>` - Style of links to create when using --link-to-folder (markdown|at). Defaults to 'markdown'
    * `--builtins <builtins>` - Include built-in usage rules (comma-separated: elixir,otp)
    * `--builtins-link` - Make built-in usage rules honor the --link-to-folder option (default: false, builtins are inlined)

    ## Examples

    Combine specific packages:
    ```sh
    #{example()}
    ```

    Gather all dependencies with usage rules:
    ```sh
    mix usage_rules.sync CLAUDE.md --all
    ```

    List all dependencies with usage rules:
    ```sh
    mix usage_rules.sync --list
    ```

    Check status of dependencies against a specific file:
    ```sh
    mix usage_rules.sync CLAUDE.md --list
    ```

    Remove specific packages from a file:
    ```sh
    mix usage_rules.sync CLAUDE.md ash phoenix --remove
    ```

    Save usage rules to individual files in a folder with markdown links:
    ```sh
    mix usage_rules.sync CLAUDE.md ash phoenix --link-to-folder rules
    ```

    Save usage rules with @-style links:
    ```sh
    mix usage_rules.sync CLAUDE.md ash phoenix --link-to-folder rules --link-style at
    ```

    Link directly to deps files without copying:
    ```sh
    mix usage_rules.sync CLAUDE.md ash phoenix --link-to-folder deps
    ```

    Combine all dependencies with folder links:
    ```sh
    mix usage_rules.sync CLAUDE.md --all --link-to-folder docs
    ```

    Check status of packages using folder links:
    ```sh
    mix usage_rules.sync CLAUDE.md --list --link-to-folder rules
    ```

    Remove packages and their folder files:
    ```sh
    mix usage_rules.sync CLAUDE.md ash phoenix --remove --link-to-folder rules
    ```

    Include built-in Elixir and OTP usage rules:
    ```sh
    mix usage_rules.sync CLAUDE.md --all --link-to-folder deps --builtins elixir,otp
    ```
    Include built-in usage rules with links to folder:
    ```sh
    mix usage_rules.sync CLAUDE.md --all --link-to-folder docs --builtins elixir,otp --builtins-link
    ```
    """
  end
end

if Code.ensure_loaded?(Igniter) do
  defmodule Mix.Tasks.UsageRules.Sync do
    @shortdoc "#{__MODULE__.Docs.short_doc()}"

    @moduledoc __MODULE__.Docs.long_doc()

    use Igniter.Mix.Task

    @impl Igniter.Mix.Task
    def info(_argv, _composing_task) do
      %Igniter.Mix.Task.Info{
        # Groups allow for overlapping arguments for tasks by the same author
        # See the generators guide for more.
        group: :usage_rules,
        example: __MODULE__.Docs.example(),
        positional: [
          file: [optional: true],
          packages: [rest: true, optional: true]
        ],
        schema: [
          all: :boolean,
          list: :boolean,
          remove: :boolean,
          link_to_folder: :string,
          link_style: :string,
          builtins: :string,
          builtins_link: :boolean
        ]
      }
    end

    @impl Igniter.Mix.Task
    def igniter(igniter) do
      igniter =
        if is_nil(igniter.parent) do
          igniter
          |> Igniter.assign(:prompt_on_git_changes?, false)
          |> Igniter.assign(:quiet_on_no_changes?, true)
        else
          igniter
        end

      # Add all usage-rules.md files from deps directory to igniter
      igniter = Igniter.include_glob(igniter, "deps/*/usage-rules.md")

      top_level_deps =
        Mix.Project.get().project()[:deps] |> Enum.map(&elem(&1, 0))

      # Get all deps from both Mix.Project.deps_paths and Igniter rewrite sources
      mix_deps =
        Mix.Project.deps_paths()
        |> Enum.filter(fn {dep, _path} ->
          dep in top_level_deps
        end)
        |> Enum.map(fn {dep, path} ->
          {dep, Path.relative_to_cwd(path)}
        end)

      igniter_deps = get_deps_from_igniter(igniter)
      all_deps = (mix_deps ++ igniter_deps) |> Enum.uniq()

      all_option = igniter.args.options[:all]
      list_option = igniter.args.options[:list]
      remove_option = igniter.args.options[:remove]
      link_to_folder = igniter.args.options[:link_to_folder]
      link_style = igniter.args.options[:link_style] || "markdown"
      provided_packages = igniter.args.positional.packages
      builtins = parse_builtins(igniter.args.options[:builtins])
      builtins_link = igniter.args.options[:builtins_link]

      cond do
        # If --builtins contains invalid values, add error
        igniter.args.options[:builtins] &&
            parse_invalid_builtins(igniter.args.options[:builtins]) != [] ->
          invalid = parse_invalid_builtins(igniter.args.options[:builtins])

          Igniter.add_issue(
            igniter,
            "Invalid builtins: #{Enum.join(invalid, ", ")}. Valid options are: elixir, otp"
          )

        # If --link-style is used with invalid value, add error
        link_style && link_style not in ["markdown", "at"] ->
          Igniter.add_issue(igniter, "--link-style must be either 'markdown' or 'at'")

        # If --link-style is used without --link-to-folder, add error
        igniter.args.options[:link_style] && !link_to_folder ->
          Igniter.add_issue(igniter, "--link-style can only be used with --link-to-folder")

        # If --remove is used with --all or --list, add error
        remove_option && (all_option || list_option) ->
          Igniter.add_issue(igniter, "Cannot use --remove with --all or --list options")

        # If --remove is used without a file, add error
        remove_option && is_nil(igniter.args.positional[:file]) ->
          Igniter.add_issue(igniter, "--remove option requires a file to remove from")

        # If --remove is used without packages, add error
        remove_option && Enum.empty?(provided_packages) ->
          Igniter.add_issue(igniter, "--remove option requires packages to remove")

        # If --list or --all is given and packages list is not empty, add error
        (all_option || list_option) && !Enum.empty?(provided_packages) ->
          Igniter.add_issue(igniter, "Cannot specify packages when using --all or --list options")

        # If --all is used without a file, add error
        all_option && is_nil(igniter.args.positional[:file]) ->
          Igniter.add_issue(igniter, "--all option requires a file to write to")

        # If --link-to-folder is used without a file, add error
        link_to_folder && is_nil(igniter.args.positional[:file]) ->
          Igniter.add_issue(igniter, "--link-to-folder option requires a file to write to")

        # If no packages are given and neither --list nor --all nor --remove is set, add error
        Enum.empty?(provided_packages) && !all_option && !list_option && !remove_option ->
          add_usage_error(igniter)

        # Handle --remove option
        remove_option ->
          handle_remove_packages(igniter, provided_packages, link_to_folder)

        # Handle --all option
        all_option ->
          handle_all_option(
            igniter,
            all_deps,
            link_to_folder,
            link_style,
            builtins,
            builtins_link
          )

        # Handle --list option
        list_option ->
          handle_list_option(igniter, all_deps, link_to_folder)

        # Handle specific packages
        true ->
          handle_specific_packages(
            igniter,
            all_deps,
            provided_packages,
            link_to_folder,
            link_style,
            builtins,
            builtins_link
          )
      end
    end

    defp parse_builtins(nil), do: []

    defp parse_builtins(builtins_string) do
      builtins_string
      |> String.split(",")
      |> Enum.map(&String.trim/1)
      |> Enum.filter(fn builtin ->
        builtin in ["elixir", "otp"]
      end)
    end

    defp parse_invalid_builtins(nil), do: []

    defp parse_invalid_builtins(builtins_string) do
      builtins_string
      |> String.split(",")
      |> Enum.map(&String.trim/1)
      |> Enum.reject(fn builtin ->
        builtin in ["", "elixir", "otp"]
      end)
    end

    defp get_builtin_contents(builtins) do
      builtins
      |> Enum.map(fn builtin ->
        builtin_path = Path.join([:code.priv_dir(:usage_rules), "builtins", "#{builtin}.md"])
        content = File.read!(builtin_path)

        description =
          case builtin do
            "elixir" -> "Core Elixir language features and standard library"
            "otp" -> "OTP (Open Telecom Platform) behaviors and patterns"
            _ -> ""
          end

        description_part = if description == "", do: "", else: "_#{description}_\n\n"

        {String.to_atom(builtin),
         "<!-- #{builtin}-start -->\n" <>
           "## #{builtin} usage\n" <>
           description_part <>
           content <>
           "\n<!-- #{builtin}-end -->"}
      end)
    end

    defp usage_rules_header do
      """
      <!-- usage-rules-header -->
      # Usage Rules

      **IMPORTANT**: Consult these usage rules early and often when working with the packages listed below. 
      Before attempting to use any of these packages or to discover if you should use them, review their 
      usage rules to understand the correct patterns, conventions, and best practices.
      <!-- usage-rules-header-end -->
      """
    end

    defp get_package_description(name) do
      case Application.spec(name, :description) do
        nil -> ""
        desc -> to_string(desc)
      end
    end

    defp get_deps_from_igniter(igniter) do
      if igniter.assigns[:test_mode?] do
        igniter.rewrite.sources
        |> Enum.filter(fn {path, _source} ->
          String.match?(path, ~r|^deps/[^/]+/usage-rules\.md$|)
        end)
        |> Enum.map(fn {path, _source} ->
          # Extract package name from deps/package_name/usage-rules.md
          package_name =
            path
            |> String.split("/")
            |> Enum.at(1)
            |> String.to_atom()

          # Extract package path from deps/package_name/usage-rules.md
          package_path = Path.dirname(path)

          {package_name, package_path}
        end)
        |> Enum.uniq()
      else
        []
      end
    end

    defp add_usage_error(igniter) do
      Igniter.add_issue(igniter, """
      Usage:
        mix usage_rules.sync CLAUDE.md --all --link-to-folder deps
          Standard usage: gather all dependencies and link directly to deps files

        mix usage_rules.sync <file> <packages...>
          Combine specific packages' usage rules into the target file

        mix usage_rules.sync <file> --all
          Gather usage rules from all dependencies into the target file

        mix usage_rules.sync [file] --list
          List packages with usage rules (optionally check status against file)

        mix usage_rules.sync <file> <packages...> --remove
          Remove specific packages from the target file

        mix usage_rules.sync <file> <packages...> --link-to-folder <folder>
          Save usage rules for each package in separate files within the specified folder and create links to them

        mix usage_rules.sync <file> --list --link-to-folder <folder>
          List packages with usage rules and check status against folder links

        mix usage_rules.sync <file> <packages...> --remove --link-to-folder <folder>
          Remove specific packages from the target file and delete their folder files
      """)
    end

    defp handle_all_option(igniter, all_deps, link_to_folder, link_style, builtins, builtins_link) do
      all_packages_with_rules = get_packages_with_usage_rules(igniter, all_deps)

      igniter
      |> Igniter.add_notice(
        "Found #{length(all_packages_with_rules)} dependencies with usage rules"
      )
      |> then(fn igniter ->
        Enum.reduce(all_packages_with_rules, igniter, fn {name, _path}, acc ->
          Igniter.add_notice(acc, "Including usage rules for: #{name}")
        end)
      end)
      |> maybe_add_builtin_notices(builtins)
      |> generate_usage_rules_file(
        all_packages_with_rules,
        link_to_folder,
        link_style,
        builtins,
        builtins_link
      )
    end

    defp maybe_add_builtin_notices(igniter, []), do: igniter

    defp maybe_add_builtin_notices(igniter, builtins) do
      Enum.reduce(builtins, igniter, fn builtin, acc ->
        Igniter.add_notice(acc, "Including built-in usage rules for: #{builtin}")
      end)
    end

    defp handle_list_option(igniter, all_deps, link_to_folder) do
      packages_with_rules = get_packages_with_usage_rules(igniter, all_deps)

      if Enum.empty?(packages_with_rules) do
        Igniter.add_notice(igniter, "No packages found with usage-rules.md files")
      else
        file_path = igniter.args.positional[:file]

        if file_path do
          list_packages_with_file_comparison(
            igniter,
            packages_with_rules,
            file_path,
            link_to_folder
          )
        else
          list_packages_without_comparison(igniter, packages_with_rules)
        end
      end
    end

    defp handle_specific_packages(
           igniter,
           all_deps,
           provided_packages,
           link_to_folder,
           link_style,
           builtins,
           builtins_link
         ) do
      packages =
        all_deps
        |> Enum.filter(fn {name, _path} ->
          to_string(name) in provided_packages
        end)
        |> Enum.flat_map(fn {name, path} ->
          usage_rules_path = Path.join(path, "usage-rules.md")

          if Igniter.exists?(igniter, usage_rules_path) do
            [{name, path}]
          else
            []
          end
        end)

      igniter
      |> maybe_add_builtin_notices(builtins)
      |> generate_usage_rules_file(packages, link_to_folder, link_style, builtins, builtins_link)
    end

    defp handle_remove_packages(igniter, provided_packages, link_to_folder) do
      file_path = igniter.args.positional[:file]

      if Igniter.exists?(igniter, file_path) do
        remove_packages_from_file(igniter, file_path, provided_packages, link_to_folder)
      else
        Igniter.add_issue(igniter, "File #{file_path} does not exist")
      end
    end

    defp get_packages_with_usage_rules(igniter, all_deps) do
      all_deps
      |> Enum.filter(fn {_name, path} ->
        usage_rules_path = Path.join(path, "usage-rules.md")
        Igniter.exists?(igniter, usage_rules_path)
      end)
    end

    defp list_packages_with_file_comparison(
           igniter,
           packages_with_rules,
           file_path,
           link_to_folder
         ) do
      current_file_content = read_current_file_content(igniter, file_path)

      Enum.reduce(packages_with_rules, igniter, fn {name, path}, acc ->
        usage_rules_path = Path.join(path, "usage-rules.md")

        package_rules_content =
          case Rewrite.source(acc.rewrite, usage_rules_path) do
            {:ok, source} -> Rewrite.Source.get(source, :content)
            {:error, _} -> File.read!(usage_rules_path)
          end

        status =
          get_package_status_in_file(
            acc,
            name,
            package_rules_content,
            current_file_content,
            link_to_folder
          )

        Igniter.add_notice(acc, "#{name}: #{colorize_status(status)}")
      end)
    end

    defp list_packages_without_comparison(igniter, packages_with_rules) do
      Enum.reduce(packages_with_rules, igniter, fn {name, _path}, acc ->
        Igniter.add_notice(acc, "#{name}: #{IO.ANSI.green()}has usage rules#{IO.ANSI.reset()}")
      end)
    end

    defp read_current_file_content(igniter, file_path) do
      if Igniter.exists?(igniter, file_path) do
        case Rewrite.source(igniter.rewrite, file_path) do
          {:ok, source} ->
            Rewrite.Source.get(source, :content)

          {:error, _} ->
            case File.read(file_path) do
              {:ok, content} -> content
              {:error, _} -> ""
            end
        end
      else
        ""
      end
    end

    defp generate_usage_rules_file(
           igniter,
           packages,
           link_to_folder,
           link_style,
           builtins,
           builtins_link
         ) do
      if link_to_folder do
        generate_usage_rules_with_folder_links(
          igniter,
          packages,
          link_to_folder,
          link_style,
          builtins,
          builtins_link
        )
      else
        generate_usage_rules_inline(igniter, packages, builtins)
      end
    end

    defp generate_usage_rules_inline(igniter, packages, builtins) do
      package_contents =
        packages
        |> Enum.map(fn {name, path} ->
          usage_rules_path = Path.join(path, "usage-rules.md")

          content =
            case Rewrite.source(igniter.rewrite, usage_rules_path) do
              {:ok, source} -> Rewrite.Source.get(source, :content)
              {:error, _} -> File.read!(usage_rules_path)
            end

          description = get_package_description(name)
          description_part = if description == "", do: "", else: "_#{description}_\n\n"

          {name,
           "<!-- #{name}-start -->\n" <>
             "## #{name} usage\n" <>
             description_part <>
             content <>
             "\n<!-- #{name}-end -->"}
        end)

      builtin_contents = get_builtin_contents(builtins)

      all_contents = package_contents ++ builtin_contents
      all_rules_content = Enum.map_join(all_contents, "\n", &elem(&1, 1))

      full_contents_for_new_file =
        "<!-- usage-rules-start -->\n" <>
          usage_rules_header() <>
          "\n" <>
          all_rules_content <>
          "\n<!-- usage-rules-end -->"

      Igniter.create_or_update_file(
        igniter,
        igniter.args.positional[:file],
        full_contents_for_new_file,
        fn source ->
          current_contents = Rewrite.Source.get(source, :content)

          new_content =
            case String.split(current_contents, [
                   "<!-- usage-rules-start -->\n",
                   "\n<!-- usage-rules-end -->"
                 ]) do
              [prelude, current_packages_contents, postlude] ->
                Enum.reduce(all_contents, current_packages_contents, fn {name, package_content},
                                                                        acc ->
                  case String.split(acc, [
                         "<!-- #{name}-start -->\n",
                         "\n<!-- #{name}-end -->"
                       ]) do
                    [prelude, _, postlude] ->
                      prelude <> package_content <> postlude

                    _ ->
                      acc <> "\n" <> package_content
                  end
                end)
                |> then(fn content ->
                  # Ensure header is present
                  content_with_header =
                    if String.contains?(content, "<!-- usage-rules-header -->") do
                      content
                    else
                      usage_rules_header() <> "\n" <> content
                    end

                  prelude <>
                    "<!-- usage-rules-start -->\n" <>
                    content_with_header <>
                    "\n<!-- usage-rules-end -->" <>
                    postlude
                end)

              _ ->
                current_contents <>
                  "\n<!-- usage-rules-start -->\n" <>
                  usage_rules_header() <>
                  "\n" <>
                  all_rules_content <>
                  "\n<!-- usage-rules-end -->\n"
            end

          Rewrite.Source.update(source, :content, new_content)
        end
      )
    end

    defp generate_usage_rules_with_folder_links(
           igniter,
           packages,
           folder_name,
           link_style,
           builtins,
           builtins_link
         ) do
      # Create individual files for each package in the folder (unless folder is "deps")
      igniter =
        if folder_name == "deps" do
          igniter
        else
          # Create builtin files in the target folder only if builtins_link is true
          igniter =
            if builtins_link do
              Enum.reduce(builtins, igniter, fn builtin, acc ->
                builtin_source_path =
                  Path.join([:code.priv_dir(:usage_rules), "builtins", "#{builtin}.md"])

                builtin_file_path = Path.join(folder_name, "#{builtin}.md")
                content = File.read!(builtin_source_path)

                Igniter.create_or_update_file(
                  acc,
                  builtin_file_path,
                  content,
                  fn source ->
                    Rewrite.Source.update(source, :content, content)
                  end
                )
              end)
            else
              igniter
            end

          Enum.reduce(packages, igniter, fn {name, path}, acc ->
            usage_rules_path = Path.join(path, "usage-rules.md")

            content =
              case Rewrite.source(acc.rewrite, usage_rules_path) do
                {:ok, source} -> Rewrite.Source.get(source, :content)
                {:error, _} -> File.read!(usage_rules_path)
              end

            package_file_path = Path.join(folder_name, "#{name}.md")

            Igniter.create_or_update_file(
              acc,
              package_file_path,
              content,
              fn source ->
                Rewrite.Source.update(source, :content, content)
              end
            )
          end)
        end

      # Then, create the main file with links
      package_contents =
        packages
        |> Enum.map(fn {name, _path} ->
          link_content =
            case {link_style, folder_name} do
              {"at", "deps"} -> "@deps/#{name}/usage-rules.md"
              {"at", _} -> "@#{folder_name}/#{name}.md"
              {_, "deps"} -> "[#{name} usage rules](deps/#{name}/usage-rules.md)"
              _ -> "[#{name} usage rules](#{folder_name}/#{name}.md)"
            end

          description = get_package_description(name)
          description_part = if description == "", do: "", else: "_#{description}_\n\n"

          {name,
           "<!-- #{name}-start -->\n" <>
             "## #{name} usage\n" <>
             description_part <>
             link_content <>
             "\n<!-- #{name}-end -->"}
        end)

      builtin_contents =
        if builtins_link do
          # If builtins_link is true, create links
          builtins
          |> Enum.map(fn builtin ->
            link_content =
              case {link_style, folder_name} do
                {"at", "deps"} ->
                  "@deps/usage_rules/priv/builtins/#{builtin}.md"

                {"at", _} ->
                  "@#{folder_name}/#{builtin}.md"

                {_, "deps"} ->
                  "[#{builtin} usage rules](deps/usage_rules/priv/builtins/#{builtin}.md)"

                _ ->
                  "[#{builtin} usage rules](#{folder_name}/#{builtin}.md)"
              end

            description =
              case builtin do
                "elixir" -> "Core Elixir language features and standard library"
                "otp" -> "OTP (Open Telecom Platform) behaviors and patterns"
                _ -> ""
              end

            description_part = if description == "", do: "", else: "_#{description}_\n\n"

            {String.to_atom(builtin),
             "<!-- #{builtin}-start -->\n" <>
               "## #{builtin} usage\n" <>
               description_part <>
               link_content <>
               "\n<!-- #{builtin}-end -->"}
          end)
        else
          # If builtins_link is false (default), inline the content
          get_builtin_contents(builtins)
        end

      all_contents = package_contents ++ builtin_contents
      all_rules_content = Enum.map_join(all_contents, "\n", &elem(&1, 1))

      full_contents_for_new_file =
        "<!-- usage-rules-start -->\n" <>
          usage_rules_header() <>
          "\n" <>
          all_rules_content <>
          "\n<!-- usage-rules-end -->"

      Igniter.create_or_update_file(
        igniter,
        igniter.args.positional[:file],
        full_contents_for_new_file,
        fn source ->
          current_contents = Rewrite.Source.get(source, :content)

          new_content =
            case String.split(current_contents, [
                   "<!-- usage-rules-start -->\n",
                   "\n<!-- usage-rules-end -->"
                 ]) do
              [prelude, current_packages_contents, postlude] ->
                Enum.reduce(all_contents, current_packages_contents, fn {name, package_content},
                                                                        acc ->
                  case String.split(acc, [
                         "<!-- #{name}-start -->\n",
                         "\n<!-- #{name}-end -->"
                       ]) do
                    [prelude, _, postlude] ->
                      prelude <> package_content <> postlude

                    _ ->
                      acc <> "\n" <> package_content
                  end
                end)
                |> then(fn content ->
                  # Ensure header is present
                  content_with_header =
                    if String.contains?(content, "<!-- usage-rules-header -->") do
                      content
                    else
                      usage_rules_header() <> "\n" <> content
                    end

                  prelude <>
                    "<!-- usage-rules-start -->\n" <>
                    content_with_header <>
                    "\n<!-- usage-rules-end -->" <>
                    postlude
                end)

              _ ->
                current_contents <>
                  "\n<!-- usage-rules-start -->\n" <>
                  usage_rules_header() <>
                  "\n" <>
                  all_rules_content <>
                  "\n<!-- usage-rules-end -->\n"
            end

          Rewrite.Source.update(source, :content, new_content)
        end
      )
    end

    defp remove_packages_from_file(igniter, file_path, packages_to_remove, link_to_folder) do
      # If using link-to-folder, also remove the individual package files
      igniter =
        if link_to_folder do
          Enum.reduce(packages_to_remove, igniter, fn package_name, acc ->
            package_file_path = Path.join(link_to_folder, "#{package_name}.md")

            if Igniter.exists?(acc, package_file_path) do
              Igniter.rm(acc, package_file_path)
            else
              acc
            end
          end)
        else
          igniter
        end

      Igniter.update_file(igniter, file_path, fn source ->
        current_contents = Rewrite.Source.get(source, :content)

        new_content =
          Enum.reduce(packages_to_remove, current_contents, fn package_name, acc ->
            remove_package_from_content(acc, package_name)
          end)
          |> clean_empty_package_rules_section()

        Rewrite.Source.update(source, :content, new_content)
      end)
    end

    defp remove_package_from_content(content, package_name) do
      package_start_marker = "<!-- #{package_name}-start -->\n"
      package_end_marker = "\n<!-- #{package_name}-end -->"

      case String.split(content, [package_start_marker, package_end_marker]) do
        [prelude, _package_content, postlude] ->
          # Remove the package section completely, handling newlines properly
          cleaned_prelude = String.trim_trailing(prelude)
          cleaned_postlude = String.trim_leading(postlude)

          if cleaned_postlude == "" do
            cleaned_prelude
          else
            cleaned_prelude <> "\n" <> cleaned_postlude
          end

        _ ->
          # Package not found, return content unchanged
          content
      end
    end

    defp clean_empty_package_rules_section(content) do
      # Handle both cases: empty section and section with only whitespace
      case String.split(content, "<!-- usage-rules-start -->") do
        [prelude, remainder] ->
          case String.split(remainder, "<!-- usage-rules-end -->") do
            [package_section, postlude] ->
              # Check if package section is empty or only contains whitespace
              if String.trim(package_section) == "" do
                # Remove the entire usage-rules section if empty
                cleaned_prelude = String.trim_trailing(prelude)
                cleaned_postlude = String.trim_leading(postlude)

                if cleaned_postlude == "" do
                  cleaned_prelude
                else
                  cleaned_prelude <> "\n\n" <> cleaned_postlude
                end
              else
                # Keep the usage-rules section
                prelude <>
                  "<!-- usage-rules-start -->" <>
                  package_section <> "<!-- usage-rules-end -->" <> postlude
              end

            _ ->
              # No end marker found
              content
          end

        _ ->
          # No usage-rules section found
          content
      end
    end

    defp get_package_status_in_file(
           igniter,
           name,
           package_rules_content,
           file_content,
           link_to_folder
         ) do
      package_start_marker = "<!-- #{name}-start -->"
      package_end_marker = "<!-- #{name}-end -->"

      case String.split(file_content, [package_start_marker, package_end_marker]) do
        [_, current_package_content, _] ->
          # Package is present in file, check if content matches
          expected_content =
            if link_to_folder do
              "\n## #{name} usage\n@#{link_to_folder}/#{name}.md\n"
            else
              "\n## #{name} usage\n" <> package_rules_content <> "\n"
            end

          if String.trim(current_package_content) == String.trim(expected_content) do
            # If using link-to-folder, also check the linked file exists and matches
            if link_to_folder do
              check_linked_file_status(igniter, name, package_rules_content, link_to_folder)
            else
              "present"
            end
          else
            "stale"
          end

        _ ->
          # Package not found in file
          "missing"
      end
    end

    defp check_linked_file_status(igniter, name, expected_content, link_to_folder) do
      linked_file_path = Path.join(link_to_folder, "#{name}.md")

      if Igniter.exists?(igniter, linked_file_path) do
        actual_content =
          case Rewrite.source(igniter.rewrite, linked_file_path) do
            {:ok, source} ->
              Rewrite.Source.get(source, :content)

            {:error, _} ->
              if File.exists?(linked_file_path) do
                File.read!(linked_file_path)
              else
                ""
              end
          end

        if String.trim(actual_content) == String.trim(expected_content) do
          "present"
        else
          "stale"
        end
      else
        "stale"
      end
    end

    defp colorize_status("present"), do: "#{IO.ANSI.green()}present#{IO.ANSI.reset()}"
    defp colorize_status("stale"), do: "#{IO.ANSI.yellow()}stale#{IO.ANSI.reset()}"
    defp colorize_status("missing"), do: "#{IO.ANSI.red()}missing#{IO.ANSI.reset()}"
  end
else
  defmodule Mix.Tasks.UsageRules.Sync do
    @shortdoc "#{__MODULE__.Docs.short_doc()} | Install `igniter` to use"

    @moduledoc __MODULE__.Docs.long_doc()

    use Mix.Task

    @impl Mix.Task
    def run(_argv) do
      Mix.shell().error("""
      The task 'usage_rules.sync' requires igniter. Please install igniter and try again.

      For more information, see: https://hexdocs.pm/igniter/readme.html#installation
      """)

      exit({:shutdown, 1})
    end
  end
end