class Sass::Tree::Visitors::Convert

def self.visit(root, options, format)
  new(options, format).send(:visit, root)
end

def dasherize(s)
  if @options[:dasherize]
    s.gsub('_', '-')
  else
    s
  end
end

def initialize(options, format)
  @options = options
  @format = format
  @tabs = 0
end

def selector_to_sass(sel)
  sel.map do |r|
    if r.is_a?(String)
      r.gsub(/(,[ \t]*)?\n\s*/) {$1 ? $1 + "\n" : " "}
    else
      "\#{#{r.to_sass(@options)}}"
    end
  end.join
end

def selector_to_scss(sel)
  sel.map {|r| r.is_a?(String) ? r : "\#{#{r.to_sass(@options)}}"}.
    join.gsub(/^[ \t]*/, tab_str)
end

def selector_to_src(sel)
  @format == :sass ? selector_to_sass(sel) : selector_to_scss(sel)
end

def semi
  @format == :sass ? "" : ";"
end

def tab_str
  '  ' * @tabs
end

def visit_charset(node)
  "#{tab_str}@charset \"#{node.name}\"#{semi}\n"
end

def visit_children(parent)
  @tabs += 1
  return @format == :sass ? "\n" : " {}\n" if parent.children.empty?
  (@format == :sass ? "\n" : " {\n") + super.join.rstrip + (@format == :sass ? "\n" : " }\n")
ensure
  @tabs -= 1
end

def visit_comment(node)
  content = if @format == :sass
    content = node.value.gsub(/\*\/$/, '').rstrip
    if content =~ /\A[ \t]/
      # Re-indent SCSS comments like this:
      #     /* foo
      #   bar
      #       baz */
      content.gsub!(/^/, '   ')
      content.sub!(/\A([ \t]*)\/\*/, '/*\1')
    end
    content =
      unless content.include?("\n")
        content
      else
        content.gsub!(/\n( \*|\/\/)/, "\n  ")
        spaces = content.scan(/\n( *)/).map {|s| s.first.size}.min
        sep = node.silent ? "\n//" : "\n *"
        if spaces >= 2
          content.gsub(/\n  /, sep)
        else
          content.gsub(/\n#{' ' * spaces}/, sep)
        end
      end
    content.gsub!(/\A\/\*/, '//') if node.silent
    content.gsub!(/^/, tab_str)
    content.rstrip + "\n"
  else
    spaces = ('  ' * [@tabs - node.value[/^ */].size, 0].max)
    content = if node.silent
      node.value.gsub(/^[\/ ]\*/, '//').gsub(/ *\*\/$/, '')
    else
      node.value
    end.gsub(/^/, spaces) + "\n"
    content
  end
  if node.loud
    if node.silent
      content.gsub!(%r{^\s*(//!?)}, '//!')
    else
      content.sub!(%r{^\s*(/\*)}, '/*!')
    end
  end
  content
end

def visit_debug(node)
  "#{tab_str}@debug #{node.expr.to_sass(@options)}#{semi}\n"
end

def visit_directive(node)
  res = "#{tab_str}#{node.value}"
  return res + "#{semi}\n" unless node.has_children
  res + yield + "\n"
end

def visit_each(node)
  "#{tab_str}@each $#{dasherize(node.var)} in #{node.list.to_sass(@options)}#{yield}"
end

def visit_extend(node)
  "#{tab_str}@extend #{selector_to_src(node.selector).lstrip}#{semi}\n"
end

def visit_for(node)
  "#{tab_str}@for $#{dasherize(node.var)} from #{node.from.to_sass(@options)} " +
    "#{node.exclusive ? "to" : "through"} #{node.to.to_sass(@options)}#{yield}"
end

def visit_function(node)
  args = node.args.map do |v, d|
    d ? "#{v.to_sass(@options)}: #{d.to_sass(@options)}" : v.to_sass(@options)
  end.join(", ")
  "#{tab_str}@function #{dasherize(node.name)}(#{args})#{yield}"
end

def visit_if(node)
  name =
    if !@is_else; "if"
    elsif node.expr; "else if"
    else; "else"
    end
  str = "#{tab_str}@#{name}"
  str << " #{node.expr.to_sass(@options)}" if node.expr
  str << yield
  @is_else = true
  str << visit(node.else) if node.else
  str
ensure
  @is_else = false
end

def visit_import(node)
  quote = @format == :scss ? '"' : ''
  "#{tab_str}@import #{quote}#{node.imported_filename}#{quote}#{semi}\n"
end

def visit_media(node)
  "#{tab_str}@media #{node.query}#{yield}"
end

def visit_mixin(node)
  unless node.args.empty? && node.keywords.empty?
    args = node.args.map {|a| a.to_sass(@options)}.join(", ")
    keywords = node.keywords.map {|k, v| "$#{dasherize(k)}: #{v.to_sass(@options)}"}.join(', ')
    arglist = "(#{args}#{', ' unless args.empty? || keywords.empty?}#{keywords})"
  end
  "#{tab_str}#{@format == :sass ? '+' : '@include '}#{dasherize(node.name)}#{arglist}#{semi}\n"
end

def visit_mixindef(node)
  args =
    if node.args.empty?
      ""
    else
      '(' + node.args.map do |v, d|
        if d
          "#{v.to_sass(@options)}: #{d.to_sass(@options)}"
        else
          v.to_sass(@options)
        end
      end.join(", ") + ')'
    end
        
  "#{tab_str}#{@format == :sass ? '=' : '@mixin '}#{dasherize(node.name)}#{args}#{yield}"
end

def visit_prop(node)
  res = tab_str + node.declaration(@options, @format)
  return res + semi + "\n" if node.children.empty?
  res + yield.rstrip + semi + "\n"
end

def visit_return(node)
  "#{tab_str}@return #{node.expr.to_sass(@options)}#{semi}\n"
end

def visit_root(node)
  Sass::Util.enum_cons(node.children + [nil], 2).map do |child, nxt|
    visit(child) +
      if nxt &&
          (child.is_a?(Sass::Tree::CommentNode) &&
            child.line + child.value.count("\n") + 1 == nxt.line) ||
          (child.is_a?(Sass::Tree::ImportNode) && nxt.is_a?(Sass::Tree::ImportNode) &&
            child.line + 1 == nxt.line) ||
          (child.is_a?(Sass::Tree::VariableNode) && nxt.is_a?(Sass::Tree::VariableNode) &&
            child.line + 1 == nxt.line)
        ""
      else
        "\n"
      end
  end.join.rstrip + "\n"
end

def visit_rule(node)
  if @format == :sass
    name = selector_to_sass(node.rule)
    name = "\\" + name if name[0] == ?:
    name.gsub(/^/, tab_str) + yield
  elsif @format == :scss
    name = selector_to_scss(node.rule)
    res = name + yield
    if node.children.last.is_a?(Sass::Tree::CommentNode) && node.children.last.silent
      res.slice!(-3..-1)
      res << "\n" << tab_str << "}\n"
    end
    res
  end
end

def visit_variable(node)
  "#{tab_str}$#{dasherize(node.name)}: #{node.expr.to_sass(@options)}#{' !default' if node.guarded}#{semi}\n"
end

def visit_warn(node)
  "#{tab_str}@warn #{node.expr.to_sass(@options)}#{semi}\n"
end

def visit_while(node)
  "#{tab_str}@while #{node.expr.to_sass(@options)}#{yield}"
end