module Haml::AttributeBuilder

def build(escape_attrs, quote, format, object_ref, *hashes)
  hashes << Haml::ObjectRef.parse(object_ref) if object_ref
  buf  = []
  hash = merge_all_attrs(hashes)
  keys = hash.keys.sort!
  keys.each do |key|
    case key
    when 'id'
      buf << " id=#{quote}#{build_id(escape_attrs, *hash[key])}#{quote}"
    when 'class'
      buf << " class=#{quote}#{build_class(escape_attrs, *hash[key])}#{quote}"
    when 'data'
      buf << build_data(escape_attrs, quote, *hash[key])
    when 'aria'
      buf << build_aria(escape_attrs, quote, *hash[key])
    when *Haml::BOOLEAN_ATTRIBUTES, /\Adata-/, /\Aaria-/
      build_boolean!(escape_attrs, quote, format, buf, key, hash[key])
    else
      buf << " #{key}=#{quote}#{escape_html(escape_attrs, hash[key].to_s)}#{quote}"
    end
  end
  buf.join
end

def build_aria(escape_attrs, quote, *hashes)
  build_data_attribute(:aria, escape_attrs, quote, *hashes)
end

def build_boolean!(escape_attrs, quote, format, buf, key, value)
  case value
  when true
    case format
    when :xhtml
      buf << " #{key}=#{quote}#{key}#{quote}"
    else
      buf << " #{key}"
    end
  when false, nil
    # omitted
  else
    buf << " #{key}=#{quote}#{escape_html(escape_attrs, value)}#{quote}"
  end
end

def build_class(escape_attrs, *values)
  if values.size == 1
    value = values.first
    case
    when value.is_a?(String)
      # noop
    when value.is_a?(Array)
      value = value.flatten.select { |v| v }.map(&:to_s).uniq.join(' ')
    when value
      value = value.to_s
    else
      return ''
    end
    return escape_html(escape_attrs, value)
  end
  classes = []
  values.each do |value|
    case
    when value.is_a?(String)
      classes += value.split(' ')
    when value.is_a?(Array)
      classes += value.select { |v| v }
    when value
      classes << value.to_s
    end
  end
  escape_html(escape_attrs, classes.map(&:to_s).uniq.join(' '))
end

def build_data(escape_attrs, quote, *hashes)
  build_data_attribute(:data, escape_attrs, quote, *hashes)
end

def build_data_attribute(key, escape_attrs, quote, *hashes)
  attrs = []
  if hashes.size > 1 && hashes.all? { |h| h.is_a?(Hash) }
    data_value = merge_all_attrs(hashes)
  else
    data_value = hashes.last
  end
  hash = flatten_attributes(key => data_value)
  hash.sort_by(&:first).each do |key, value|
    case value
    when true
      attrs << " #{key}"
    when nil, false
      # noop
    else
      attrs << " #{key}=#{quote}#{escape_html(escape_attrs, value.to_s)}#{quote}"
    end
  end
  attrs.join
end

def build_id(escape_attrs, *values)
  escape_html(escape_attrs, values.flatten.select { |v| v }.join('_'))
end

def escape_html(escape_attrs, str)
  if escape_attrs
    Haml::Util.escape_html(str)
  else
    str
  end
end

def flatten_attributes(attributes)
  flattened = {}
  attributes.each do |key, value|
    case value
    when attributes
    when Hash
      flatten_attributes(value).each do |k, v|
        if k.nil?
          flattened[key] = v
        else
          flattened["#{key}-#{k.to_s.gsub(/_/, '-')}"] = v
        end
      end
    else
      flattened[key] = value if value
    end
  end
  flattened
end

def merge_all_attrs(hashes)
  merged = {}
  hashes.each do |hash|
    unless hash.is_a?(Hash)
      raise ArgumentError, "Non-hash object is given to attributes!"
    end
    hash.each do |key, value|
      key = key.to_s
      case key
      when 'id', 'class', 'data', 'aria'
        merged[key] ||= []
        merged[key] << value
      else
        merged[key] = value
      end
    end
  end
  merged
end