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 media_interp_to_src(interp)
  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_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#{ @tab_chars * (@tabs-1)}}\n")
ensure
  @tabs -= 1
end

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

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

def visit_cssimport(node)
  if node.uri.is_a?(Sass::Script::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)
  "#{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}#{" !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 #{media_interp_to_src(node.query)}#{yield}"
end

def visit_mixin(node)
  unless node.args.empty? && node.keywords.empty? && node.splat.nil?
    args = node.args.map {|a| a.to_sass(@options)}.join(", ")
    keywords = Sass::Util.hash_to_a(node.keywords).
      map {|k, v| "$#{dasherize(k)}: #{v.to_sass(@options)}"}.join(', ')
    if node.splat
      splat = (args.empty? && keywords.empty?) ? "" : ", "
      splat = "#{splat}#{node.splat.to_sass(@options)}..."
    end
    arglist = "(#{args}#{', ' unless args.empty? || keywords.empty?}#{keywords}#{splat})"
  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)}#{' !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