# encoding: utf-8

module Synvert
  class Rewriter::Action
    def initialize(code)
      @code = code
    end

    def rewrite(source, node)
      raise NotImplementedError.new 'rewrite method is not implemented'
    end
  end

  class Rewriter::ReplaceWithAction < Rewriter::Action
    def rewrite(source, node)
      begin_pos = node.loc.expression.begin_pos
      end_pos = node.loc.expression.end_pos
      source[begin_pos...end_pos] = node.to_source(@code)
      source
    end
  end

  class Rewriter::InsertAction < Rewriter::Action
    def rewrite(source, node)
      source[insert_position(node), 0] = "\n" + insert_indent(node) + node.to_source(@code)
      source
    end

    def insert_position(node)
      case node.type
      when :block
        node.children[1].loc.expression.end_pos
      when :class
        node.children[0].loc.expression.end_pos
      else
        node.children.last.loc.expression.end_pos
      end
    end

    def insert_indent(node)
      if [:block, :class].include? node.type
        ' ' * (node.indent + 2)
      else
        ' ' * node.indent
      end
    end
  end

  class Rewriter::InsertAfterAction < Rewriter::Action
    def rewrite(source, node)
      source[node.loc.expression.end_pos, 0] = "\n" + insert_indent(node) + node.to_source(@code)
      source
    end

    def insert_indent(node)
      ' ' * node.indent
    end
  end

  class Rewriter::RemoveAction < Rewriter::Action
    def initialize
    end

    def rewrite(source, node)
      begin_pos = node.loc.expression.begin_pos
      end_pos = node.loc.expression.end_pos
      line = node.loc.expression.line
      source[begin_pos...end_pos] = ''
      remove_code_or_whole_line(source, line)
    end

  private
    def remove_code_or_whole_line(source, line)
      newline_at_end_of_line = source[-1] == "\n"
      source_arr = source.split("\n")
      if source_arr[line - 1] && source_arr[line - 1].strip.empty?
        source_arr.delete_at(line - 1)
        source_arr.join("\n") + (newline_at_end_of_line ? "\n" : '')
      else
        source
      end
    end
  end
end