class RBS::EnvironmentLoader

def self.gem_sig_path(name, version)
  spec = Gem::Specification.find_by_name(name, version)
  path = Pathname(spec.gem_dir) + "sig"
  if path.directory?
    [spec, path]
  end
rescue Gem::MissingSpecError
  nil
end

def add(path: nil, library: nil, version: nil)
  case
  when path
    dirs << path
  when library
    libs << Library.new(name: library, version: version)
  end
end

def add_collection(collection_config)
  collection_config.check_rbs_availability!
  repository.add(collection_config.repo_path)
  collection_config.gems.each do |gem|
    add(library: gem['name'], version: gem['version'])
  end
end

def each_decl
  files = Set[]
  each_dir do |source, dir|
    skip_hidden = !source.is_a?(Pathname)
    each_file(dir, skip_hidden: skip_hidden, immediate: true) do |path|
      next if files.include?(path)
      files << path
      buffer = Buffer.new(name: path.to_s, content: path.read(encoding: "UTF-8"))
      Parser.parse_signature(buffer).each do |decl|
        yield decl, buffer, source, path
      end
    end
  end
end

def each_dir
  if root = core_root
    yield :core, root
  end
  libs.each do |lib|
    unless has_library?(version: lib.version, library: lib.name)
      raise UnknownLibraryError.new(lib: lib)
    end
    case
    when from_gem = self.class.gem_sig_path(lib.name, lib.version)
      yield lib, from_gem[1]
    when from_repo = repository.lookup(lib.name, lib.version)
      yield lib, from_repo
    end
  end
  dirs.each do |dir|
    yield dir, dir
  end
end

def each_file(path, immediate:, skip_hidden:, &block)
  case
  when path.file?
    if path.extname == ".rbs" || immediate
      yield path
    end
  when path.directory?
    if path.basename.to_s.start_with?("_")
      if skip_hidden
        unless immediate
          return
        end
      end
    end
    path.children.sort.each do |child|
      each_file(child, immediate: false, skip_hidden: skip_hidden, &block)
    end
  end
end

def has_library?(library:, version:)
  if self.class.gem_sig_path(library, version) || repository.lookup(library, version)
    true
  else
    false
  end
end

def initialize(core_root: DEFAULT_CORE_ROOT, repository: Repository.new)
  @core_root = core_root
  @repository = repository
  @libs = []
  @dirs = []
end

def load(env:)
  # @type var loaded: Array[[AST::Declarations::t, Pathname, source]]
  loaded = []
  each_decl do |decl, buf, source, path|
    env << decl
    loaded << [decl, path, source]
  end
  loaded
end