class Bootsnap::LoadPathCache::Cache

def dir_changed?
  @prev_dir ||= Dir.pwd
  if @prev_dir == Dir.pwd
    false
  else
    @prev_dir = Dir.pwd
    true
  end
end

def expand_path(feature)
  maybe_append_extension(File.expand_path(feature))
end

def find(feature, try_extensions: true)
  reinitialize if (@has_relative_paths && dir_changed?) || stale?
  feature = feature.to_s.freeze
  return feature if Bootsnap.absolute_path?(feature)
  if feature.start_with?("./", "../")
    return try_extensions ? expand_path(feature) : File.expand_path(feature).freeze
  end
  @mutex.synchronize do
    x = search_index(feature, try_extensions: try_extensions)
    return x if x
    return unless try_extensions
    # Ruby has some built-in features that require lies about.
    # For example, 'enumerator' is built in. If you require it, ruby
    # returns false as if it were already loaded; however, there is no
    # file to find on disk. We've pre-built a list of these, and we
    # return false if any of them is loaded.
    return false if BUILTIN_FEATURES.key?(feature)
    # The feature wasn't found on our preliminary search through the index.
    # We resolve this differently depending on what the extension was.
    case File.extname(feature)
    # If the extension was one of the ones we explicitly cache (.rb and the
    # native dynamic extension, e.g. .bundle or .so), we know it was a
    # failure and there's nothing more we can do to find the file.
    # no extension, .rb, (.bundle or .so)
    when "", *CACHED_EXTENSIONS
      nil
    # Ruby allows specifying native extensions as '.so' even when DLEXT
    # is '.bundle'. This is where we handle that case.
    when DOT_SO
      x = search_index(feature[0..-4] + DLEXT)
      return x if x
      if DLEXT2
        x = search_index(feature[0..-4] + DLEXT2)
        return x if x
      end
    else
      # other, unknown extension. For example, `.rake`. Since we haven't
      # cached these, we legitimately need to run the load path search.
      return FALLBACK_SCAN
    end
  end
  # In development mode, we don't want to confidently return failures for
  # cases where the file doesn't appear to be on the load path. We should
  # be able to detect newly-created files without rebooting the
  # application.
  return FALLBACK_SCAN if @development_mode
end

def initialize(store, path_obj, development_mode: false)
  @development_mode = development_mode
  @store = store
  @mutex = Mutex.new
  @path_obj = path_obj.map! { |f| PathScanner.os_path(File.exist?(f) ? File.realpath(f) : f.dup) }
  @has_relative_paths = nil
  reinitialize
end

def load_dir(dir)
  reinitialize if stale?
  @mutex.synchronize { @dirs[dir] }
end

def maybe_append_extension(feature)
  try_ext(feature + DOT_RB) ||
    try_ext(feature + DLEXT) ||
    try_ext(feature + DLEXT2) ||
    feature
end

def maybe_append_extension(feature)
  try_ext(feature + DOT_RB) || try_ext(feature + DLEXT) || feature
end

def now: () -> Integer

def now
  Process.clock_gettime(Process::CLOCK_MONOTONIC).to_i
end

def push_paths(sender, *paths)
  return unless sender == @path_obj
  @mutex.synchronize { push_paths_locked(*paths) }
end

def push_paths_locked(*paths)
  @store.transaction do
    paths.map(&:to_s).each do |path|
      p = Path.new(path)
      @has_relative_paths = true if p.relative?
      next if p.non_directory?
      p = p.to_realpath
      expanded_path = p.expanded_path
      entries, dirs = p.entries_and_dirs(@store)
      # push -> low precedence -> set only if unset
      dirs.each    { |dir| @dirs[dir] ||= path }
      entries.each { |rel| @index[rel] ||= expanded_path }
    end
  end
end

def reinitialize(path_obj = @path_obj)
  @mutex.synchronize do
    @path_obj = path_obj
    ChangeObserver.register(self, @path_obj)
    @index = {}
    @dirs = {}
    @generated_at = now
    push_paths_locked(*@path_obj)
  end
end

def search_index: (String feature, try_extensions: true) -> String

def search_index(feature, try_extensions: true)
  if try_extensions
    try_index(feature + DOT_RB) ||
      try_index(feature + DLEXT) ||
      try_index(feature + DLEXT2) ||
      try_index(feature)
  else
    try_index(feature)
  end
end

def search_index: (String feature, try_extensions: true) -> String

def search_index(feature, try_extensions: true)
  if try_extensions
    try_index(feature + DOT_RB) || try_index(feature + DLEXT) || try_index(feature)
  else
    try_index(feature)
  end
end

def stale?
  @development_mode && @generated_at + AGE_THRESHOLD < now
end

def try_ext(feature)
  feature if File.exist?(feature)
end

def try_index(feature)
  if (path = @index[feature])
    -File.join(path, feature).freeze
  end
end

def try_index(feature)
  if (path = @index[feature])
    -File.join(path, feature).untaint
  end
end

def try_index(feature)
  if (path = @index[feature])
    File.join(path, feature)
  end
end

def unshift_paths(sender, *paths)
  return unless sender == @path_obj
  @mutex.synchronize { unshift_paths_locked(*paths) }
end

def unshift_paths_locked(*paths)
  @store.transaction do
    paths.map(&:to_s).reverse_each do |path|
      p = Path.new(path)
      next if p.non_directory?
      p = p.to_realpath
      expanded_path = p.expanded_path
      entries, dirs = p.entries_and_dirs(@store)
      # unshift -> high precedence -> unconditional set
      dirs.each    { |dir| @dirs[dir]  = path }
      entries.each { |rel| @index[rel] = expanded_path }
    end
  end
end