zilverline/sequent

# frozen_string_literal: true

require 'fileutils'
require 'active_support'
require 'active_support/core_ext/string'
require 'erb'
require 'parser/current'

class NoAggregateFound < StandardError; end

module Sequent
  module Generator
    class Command
      attr_reader :command, :attrs

      def initialize(name, command, attrs)
        @name = name
        @command = command
        @attrs = attrs.map { |a| a.split(':') }
      end

      def execute
        ensure_existing_aggregate!
        add_command_to_aggregate
      end

      def name
        @name ||= File.basename(path)
      end

      private

      def append_command_handler
        ast = Parser::CurrentRuby.parse(File.read("#{path_to_dir}/#{name_underscored}_command_handler.rb"))
        target_cursor_position = find_target_cursor_position(ast)

        File.open("#{path_to_dir}/#{name_underscored}_command_handler.rb", 'r+') do |f|
          f.seek(target_cursor_position, IO::SEEK_SET)
          lines_to_be_overwritten = f.read
          f.seek(target_cursor_position, IO::SEEK_SET)
          f << command_handler_template.result(binding).gsub(/^.+(\s)$/) { |x| x.gsub!(Regexp.last_match(1), '') }
          f << lines_to_be_overwritten
        end
      end

      def find_target_cursor_position(ast)
        return unless ast.children.any?
        return if ast.children.any? { |c| c.class.to_s != 'Parser::AST::Node' }
        if (child = ast.children.find { |c| c.type.to_s == 'block' })
          return child.loc.expression.end_pos
        end

        ast.children.map do |c|
          find_target_cursor_position(c)
        end&.flatten&.compact&.max
      end

      def append_command
        File.open("#{path_to_dir}/commands.rb", 'a') { |f| f << command_template.result(binding) }
      end

      def add_command_to_aggregate
        append_command
        append_command_handler
      end

      def path
        @path ||= File.expand_path('lib')
      end

      def name_underscored
        @name_underscored ||= name.underscore
      end

      def path_to_dir
        @path_to_dir ||= "#{path}/#{name_underscored}"
      end

      def ensure_existing_aggregate!
        if !File.directory?(path_to_dir) ||
           !File.exist?("#{path_to_dir}/#{name_underscored}_command_handler.rb") ||
           !File.exist?("#{path_to_dir}/commands.rb")
          fail NoAggregateFound
        end
      end

      def command_template
        ERB.new(File.read(File.join(File.dirname(__FILE__), 'template_command.erb')))
      end

      def command_handler_template
        ERB.new(File.read(File.join(File.dirname(__FILE__), 'template_command_handler.erb')))
      end
    end
  end
end