class Jekyll::URL

def self.escape_path(path)
  return path if path.empty? || %r!^[a-zA-Z0-9./-]+$!.match?(path)
  # Because URI.escape doesn't escape "?", "[" and "]" by default,
  # specify unsafe string (except unreserved, sub-delims, ":", "@" and "/").
  #
  # URI path segment is defined in RFC 3986 as follows:
  #   segment       = *pchar
  #   pchar         = unreserved / pct-encoded / sub-delims / ":" / "@"
  #   unreserved    = ALPHA / DIGIT / "-" / "." / "_" / "~"
  #   pct-encoded   = "%" HEXDIG HEXDIG
  #   sub-delims    = "!" / "$" / "&" / "'" / "(" / ")"
  #                 / "*" / "+" / "," / ";" / "="
  Addressable::URI.encode(path).encode("utf-8").sub("#", "%23")
end

def self.unescape_path(path)
  path = path.encode("utf-8")
  return path unless path.include?("%")
  Addressable::URI.unencode(path)
end

def generate_url(template)
  if @placeholders.is_a? Drops::UrlDrop
    generate_url_from_drop(template)
  else
    generate_url_from_hash(template)
  end
end

def generate_url_from_drop(template)
  template.gsub(%r!:([a-z_]+)!) do |match|
    name = Regexp.last_match(1)
    pool = name.end_with?("_") ? [name, name.chomp!("_")] : [name]
    winner = pool.find { |key| @placeholders.key?(key) }
    if winner.nil?
      raise NoMethodError,
            "The URL template doesn't have #{pool.join(" or ")} keys. " \
            "Check your permalink template!"
    end
    value = @placeholders[winner]
    value = "" if value.nil?
    replacement = self.class.escape_path(value)
    match.sub!(":#{winner}", replacement)
  end
end

def generate_url_from_hash(template)
  @placeholders.inject(template) do |result, token|
    break result if result.index(":").nil?
    if token.last.nil?
      # Remove leading "/" to avoid generating urls with `//`
      result.gsub("/:#{token.first}", "")
    else
      result.gsub(":#{token.first}", self.class.escape_path(token.last))
    end
  end
end

def generated_permalink
  (@generated_permalink ||= generate_url(@permalink)) if @permalink
end

def generated_url
  @generated_url ||= generate_url(@template)
end

def initialize(options)
  @template     = options[:template]
  @placeholders = options[:placeholders] || {}
  @permalink    = options[:permalink]
  if (@template || @permalink).nil?
    raise ArgumentError, "One of :template or :permalink must be supplied."
  end
end

def possible_keys(key)
  if key.end_with?("_")
    [key, key.chomp("_")]
  else
    [key]
  end
end

def sanitize_url(str)
  "/#{str}".gsub("..", "/").tap do |result|
    result.gsub!("./", "")
    result.squeeze!("/")
  end
end

def to_s
  sanitize_url(generated_permalink || generated_url)
end