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
  # 2 spaces by default
  @tab_chars = @options[:indent] || "  "
end

def interp_to_src(interp)
  interp.map do |r|
    next r if r.is_a?(String)
    "\#{#{r.to_sass(@options)}}"
  end.join
end

def query_interp_to_src(interp)
  interp = interp.map do |e|
    next e unless e.is_a?(Sass::Script::Tree::Literal)
    next e unless e.value.is_a?(Sass::Script::Value::String)
    e.value.value
  end
  Sass::Util.enum_with_index(interp).map do |r, i|
    next r if r.is_a?(String)
    before, after = interp[i - 1], interp[i + 1]
    if before.is_a?(String) && after.is_a?(String) &&
        ((before[-1] == ?( && after[0] == ?:) ||
         (before =~ /:\s*/ && after[0] == ?)))
      r.to_sass(@options)
    else
      "\#{#{r.to_sass(@options)}}"
    end
  end.join
end

def selector_to_sass(sel)
  sel.map do |r|
    if r.is_a?(String)
      r.gsub(/(,)?([ \t]*)\n\s*/) {$1 ? "#{$1}#{$2}\n" : " "}
    else
      "\#{#{r.to_sass(@options)}}"
    end
  end.join
end

def selector_to_scss(sel)
  interp_to_src(sel).gsub(/^[ \t]*/, tab_str).gsub(/[ \t]*$/, '')
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
  @tab_chars * @tabs
end

def visit_atroot(node)
  if node.query
    "#{tab_str}@at-root #{query_interp_to_src(node.query)}#{yield}"
  elsif node.children.length == 1 && node.children.first.is_a?(Sass::Tree::RuleNode)
    rule = node.children.first
    "#{tab_str}@at-root #{selector_to_src(rule.rule)}#{visit_children(rule)}"
  else
    "#{tab_str}@at-root#{yield}"
  end
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?
  if @format == :sass
    "\n"  + super.join.rstrip + "\n"
  else
    " {\n" + super.join.rstrip + "\n#{ @tab_chars * (@tabs - 1)}}\n"
  end
ensure
  @tabs -= 1
end

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

def visit_content(node)
  "#{tab_str}@content#{semi}\n"
end

def visit_cssimport(node)
  if node.uri.is_a?(Sass::Script::Tree::Node)
    str = "#{tab_str}@import #{node.uri.to_sass(@options)}"
  else
    str = "#{tab_str}@import #{node.uri}"
  end
  str << " #{interp_to_src(node.query)}" unless node.query.empty?
  "#{str}#{semi}\n"
end

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

def visit_directive(node)
  res = "#{tab_str}#{interp_to_src(node.value)}"
  res.gsub!(/^@import \#\{(.*)\}([^}]*)$/, '@import \1\2')
  return res + "#{semi}\n" unless node.has_children
  res + yield + "\n"
end

def visit_each(node)
  vars = node.vars.map {|var| "$#{dasherize(var)}"}.join(", ")
  "#{tab_str}@each #{vars} in #{node.list.to_sass(@options)}#{yield}"
end

def visit_extend(node)
  "#{tab_str}@extend #{selector_to_src(node.selector).lstrip}#{semi}" +
    "#{" !optional" if node.optional?}\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(", ")
  if node.splat
    args << ", " unless node.args.empty?
    args << node.splat.to_sass(@options) << "..."
  end
  "#{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
  @is_else = false
  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 #{query_interp_to_src(node.query)}#{yield}"
end

def visit_mixin(node)
  arg_to_sass = lambda do |arg|
    sass = arg.to_sass(@options)
    sass = "(#{sass})" if arg.is_a?(Sass::Script::Tree::ListLiteral) && arg.separator == :comma
    sass
  end
  unless node.args.empty? && node.keywords.empty? && node.splat.nil?
    args = node.args.map(&arg_to_sass)
    keywords = Sass::Util.hash_to_a(node.keywords.as_stored).
      map {|k, v| "$#{dasherize(k)}: #{arg_to_sass[v]}"}
    if node.splat
      splat = "#{arg_to_sass[node.splat]}..."
      kwarg_splat = "#{arg_to_sass[node.kwarg_splat]}..." if node.kwarg_splat
    end
    arglist = "(#{[args, splat, keywords, kwarg_splat].flatten.compact.join(', ')})"
  end
  "#{tab_str}#{@format == :sass ? '+' : '@include '}" +
    "#{dasherize(node.name)}#{arglist}#{node.has_children ? yield : semi}\n"
end

def visit_mixindef(node)
  args =
    if node.args.empty? && node.splat.nil?
      ""
    else
      str = '('
      str << node.args.map do |v, d|
        if d
          "#{v.to_sass(@options)}: #{d.to_sass(@options)}"
        else
          v.to_sass(@options)
        end
      end.join(", ")
      if node.splat
        str << ", " unless node.args.empty?
        str << node.splat.to_sass(@options) << '...'
      end
      str << ')'
    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.lines + 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.type == :silent
      res.slice!(-3..-1)
      res << "\n" << tab_str << "}\n"
    end
    res
  end
end

def visit_supports(node)
  "#{tab_str}@#{node.name} #{node.condition.to_src(@options)}#{yield}"
end

def visit_variable(node)
  "#{tab_str}$#{dasherize(node.name)}: #{node.expr.to_sass(@options)}" +
    "#{' !global' if node.global}#{' !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