class Asciidoctor::PathResolver

def absolute_path? path
  (path.start_with? SLASH) || (@file_separator == BACKSLASH && (WindowsRootRx.match? path))
end

def descends_from? path, base
  if base == path
    0
  elsif base == SLASH
    (path.start_with? SLASH) && 1
  else
    (path.start_with? base + SLASH) && (base.length + 1)
  end
end

def expand_path path
  path_segments, path_root = partition_path path
  if path.include? DOT_DOT
    resolved_segments = []
    path_segments.each do |segment|
      segment == DOT_DOT ? resolved_segments.pop : resolved_segments << segment
    end
    join_path resolved_segments, path_root
  else
    join_path path_segments, path_root
  end
end

def extract_uri_prefix str
  if (str.include? ':') && UriSniffRx =~ str
    [(str.slice $&.length, str.length), $&]
  else
    str
  end
end

def initialize file_separator = nil, working_dir = nil
  @file_separator = file_separator || ::File::ALT_SEPARATOR || ::File::SEPARATOR
  @working_dir = working_dir ? ((root? working_dir) ? (posixify working_dir) : (::File.expand_path working_dir)) : ::Dir.pwd
  @_partition_path_sys = {}
  @_partition_path_web = {}
end

def join_path segments, root = nil
  root ? %(#{root}#{segments.join SLASH}) : (segments.join SLASH)
end

def partition_path path, web = nil
  if (result = (cache = web ? @_partition_path_web : @_partition_path_sys)[path])
    return result
  end
  posix_path = posixify path
  if web
    # ex. /sample/path
    if web_root? posix_path
      root = SLASH
    # ex. ./sample/path
    elsif posix_path.start_with? DOT_SLASH
      root = DOT_SLASH
    end
    # otherwise ex. sample/path
  elsif root? posix_path
    # ex. //sample/path
    if unc? posix_path
      root = DOUBLE_SLASH
    # ex. /sample/path
    elsif posix_path.start_with? SLASH
      root = SLASH
    # ex. C:/sample/path (or file:///sample/path in browser environment)
    else
      root = posix_path.slice 0, (posix_path.index SLASH) + 1
    end
  # ex. ./sample/path
  elsif posix_path.start_with? DOT_SLASH
    root = DOT_SLASH
  end
  # otherwise ex. sample/path
  path_segments = (root ? (posix_path.slice root.length, posix_path.length) : posix_path).split SLASH
  # strip out all dot entries
  path_segments.delete DOT
  cache[path] = [path_segments, root]
end

def posixify path
  if path
    @file_separator == BACKSLASH && (path.include? BACKSLASH) ? (path.tr BACKSLASH, SLASH) : path
  else
    ''
  end
end

def relative_path path, base
  if root? path
    if (offset = descends_from? path, base)
      path.slice offset, path.length
    else
      begin
        (Pathname.new path).relative_path_from(Pathname.new base).to_s
      rescue
        path
      end
    end
  else
    path
  end
end

def root? path
  (absolute_path? path) || (path.start_with? 'file://', 'http://', 'https://')
end

def system_path target, start = nil, jail = nil, opts = {}
  if jail
    raise ::SecurityError, %(Jail is not an absolute path: #{jail}) unless root? jail
    #raise ::SecurityError, %(Jail is not a canonical path: #{jail}) if jail.include? DOT_DOT
    jail = posixify jail
  end
  if target
    if root? target
      target_path = expand_path target
      if jail && !(descends_from? target_path, jail)
        if opts.fetch :recover, true
          logger.warn %(#{opts[:target_name] || 'path'} is outside of jail; recovering automatically)
          target_segments, = partition_path target_path
          jail_segments, jail_root = partition_path jail
          return join_path jail_segments + target_segments, jail_root
        else
          raise ::SecurityError, %(#{opts[:target_name] || 'path'} #{target} is outside of jail: #{jail} (disallowed in safe mode))
        end
      end
      return target_path
    else
      target_segments, = partition_path target
    end
  else
    target_segments = []
  end
  if target_segments.empty?
    if start.nil_or_empty?
      return jail || @working_dir
    elsif root? start
      if jail
        start = posixify start
      else
        return expand_path start
      end
    else
      target_segments, = partition_path start
      start = jail || @working_dir
    end
  elsif start.nil_or_empty?
    start = jail || @working_dir
  elsif root? start
    start = posixify start if jail
  else
    #start = system_path start, jail, jail, opts
    start = %(#{(jail || @working_dir).chomp '/'}/#{start})
  end
  # both jail and start have been posixified at this point if jail is set
  if jail && (recheck = !(descends_from? start, jail)) && @file_separator == BACKSLASH
    start_segments, start_root = partition_path start
    jail_segments, jail_root = partition_path jail
    if start_root != jail_root
      if opts.fetch :recover, true
        logger.warn %(start path for #{opts[:target_name] || 'path'} is outside of jail root; recovering automatically)
        start_segments = jail_segments
        recheck = false
      else
        raise ::SecurityError, %(start path for #{opts[:target_name] || 'path'} #{start} refers to location outside jail root: #{jail} (disallowed in safe mode))
      end
    end
  else
    start_segments, jail_root = partition_path start
  end
  if (resolved_segments = start_segments + target_segments).include? DOT_DOT
    unresolved_segments, resolved_segments = resolved_segments, []
    if jail
      jail_segments, = partition_path jail unless jail_segments
      warned = false
      unresolved_segments.each do |segment|
        if segment == DOT_DOT
          if resolved_segments.size > jail_segments.size
            resolved_segments.pop
          elsif opts.fetch :recover, true
            unless warned
              logger.warn %(#{opts[:target_name] || 'path'} has illegal reference to ancestor of jail; recovering automatically)
              warned = true
            end
          else
            raise ::SecurityError, %(#{opts[:target_name] || 'path'} #{target} refers to location outside jail: #{jail} (disallowed in safe mode))
          end
        else
          resolved_segments << segment
        end
      end
    else
      unresolved_segments.each do |segment|
        segment == DOT_DOT ? resolved_segments.pop : resolved_segments << segment
      end
    end
  end
  if recheck
    target_path = join_path resolved_segments, jail_root
    if descends_from? target_path, jail
      target_path
    elsif opts.fetch :recover, true
      logger.warn %(#{opts[:target_name] || 'path'} is outside of jail; recovering automatically)
      jail_segments, = partition_path jail unless jail_segments
      join_path jail_segments + target_segments, jail_root
    else
      raise ::SecurityError, %(#{opts[:target_name] || 'path'} #{target} is outside of jail: #{jail} (disallowed in safe mode))
    end
  else
    join_path resolved_segments, jail_root
  end
end

def unc? path
  path.start_with? DOUBLE_SLASH
end

def web_path target, start = nil
  target = posixify target
  start = posixify start
  unless start.nil_or_empty? || (web_root? target)
    target, uri_prefix = extract_uri_prefix %(#{start}#{(start.end_with? SLASH) ? '' : SLASH}#{target})
  end
  # use this logic instead if we want to normalize target if it contains a URI
  #unless web_root? target
  #  target, uri_prefix = extract_uri_prefix target if preserve_uri_target
  #  target, uri_prefix = extract_uri_prefix %(#{start}#{SLASH}#{target}) unless uri_prefix || start.nil_or_empty?
  #end
  target_segments, target_root = partition_path target, true
  resolved_segments = []
  target_segments.each do |segment|
    if segment == DOT_DOT
      if resolved_segments.empty?
        resolved_segments << segment unless target_root && target_root != DOT_SLASH
      elsif resolved_segments[-1] == DOT_DOT
        resolved_segments << segment
      else
        resolved_segments.pop
      end
    else
      resolved_segments << segment
      # checking for empty would eliminate repeating forward slashes
      #resolved_segments << segment unless segment.empty?
    end
  end
  if (resolved_path = join_path resolved_segments, target_root).include? ' '
    resolved_path = resolved_path.gsub ' ', '%20'
  end
  uri_prefix ? %(#{uri_prefix}#{resolved_path}) : resolved_path
end

def web_root? path
  path.start_with? SLASH
end