class Dependabot::Python::FileUpdater

def self.updated_files_regex
  [
    /^.*Pipfile$/,             # Match Pipfile at any level
    /^.*Pipfile\.lock$/,       # Match Pipfile.lock at any level
    /^.*\.txt$/,               # Match any .txt files (e.g., requirements.txt) at any level
    /^.*\.in$/,                # Match any .in files at any level
    /^.*setup\.py$/,           # Match setup.py at any level
    /^.*setup\.cfg$/,          # Match setup.cfg at any level
    /^.*pyproject\.toml$/,     # Match pyproject.toml at any level
    /^.*pyproject\.lock$/,     # Match pyproject.lock at any level
    /^.*poetry\.lock$/ # Match poetry.lock at any level
  ]
end

def check_required_files
  filenames = dependency_files.map(&:name)
  return if filenames.any? { |name| name.end_with?(".txt", ".in") }
  return if pipfile
  return if pyproject
  return if get_original_file("setup.py")
  return if get_original_file("setup.cfg")
  raise "Missing required files!"
end

def pip_compile_files
  @pip_compile_files ||= T.let(
    dependency_files.select { |f| f.name.end_with?(".in") },
    T.nilable(T::Array[DependencyFile])
  )
end

def pip_compile_index_urls
  if credentials.any?(&:replaces_base?)
    credentials.select(&:replaces_base?).map { |cred| AuthedUrlBuilder.authed_url(credential: cred) }
  else
    urls = credentials.map { |cred| AuthedUrlBuilder.authed_url(credential: cred) }
    # If there are no credentials that replace the base, we need to
    # ensure that the base URL is included in the list of extra-index-urls.
    [nil, *urls]
  end
end

def pipfile
  @pipfile ||= T.let(get_original_file("Pipfile"), T.nilable(Dependabot::DependencyFile))
end

def pipfile_lock
  @pipfile_lock ||= T.let(get_original_file("Pipfile.lock"), T.nilable(Dependabot::DependencyFile))
end

def poetry_based?
  return false unless pyproject
  !TomlRB.parse(pyproject&.content).dig("tool", "poetry").nil?
end

def poetry_lock
  @poetry_lock ||= T.let(get_original_file("poetry.lock"), T.nilable(Dependabot::DependencyFile))
end

def pyproject
  @pyproject ||= T.let(get_original_file("pyproject.toml"), T.nilable(Dependabot::DependencyFile))
end

def resolver_type
  reqs = dependencies.flat_map(&:requirements)
  changed_reqs = reqs.zip(dependencies.flat_map(&:previous_requirements))
                     .reject { |(new_req, old_req)| new_req == old_req }
                     .map(&:first)
  changed_req_files = changed_reqs.map { |r| r.fetch(:file) }
  # If there are no requirements then this is a sub-dependency. It
  # must come from one of Pipenv, Poetry or pip-tools, and can't come
  # from the first two unless they have a lockfile.
  return subdependency_resolver if changed_reqs.none?
  # Otherwise, this is a top-level dependency, and we can figure out
  # which resolver to use based on the filename of its requirements
  return :pipfile if changed_req_files.any?("Pipfile")
  if changed_req_files.any?("pyproject.toml")
    return :poetry if poetry_based?
    return :requirements
  end
  return :pip_compile if changed_req_files.any? { |f| f.end_with?(".in") }
  :requirements
end

def subdependency_resolver
  return :pipfile if pipfile_lock
  return :poetry if poetry_lock
  return :pip_compile if pip_compile_files.any?
  raise "Claimed to be a sub-dependency, but no lockfile exists!"
end

def updated_dependency_files
  updated_files =
    case resolver_type
    when :pipfile then updated_pipfile_based_files
    when :poetry then updated_poetry_based_files
    when :pip_compile then updated_pip_compile_based_files
    when :requirements then updated_requirement_based_files
    else raise "Unexpected resolver type: #{resolver_type}"
    end
  if updated_files.none? ||
     updated_files.sort_by(&:name) == dependency_files.sort_by(&:name)
    raise "No files have changed!"
  end
  updated_files
end

def updated_pip_compile_based_files
  T.must(PipCompileFileUpdater.new(
    dependencies: dependencies,
    dependency_files: dependency_files,
    credentials: credentials,
    index_urls: pip_compile_index_urls
  ).updated_dependency_files)
end

def updated_pipfile_based_files
  PipfileFileUpdater.new(
    dependencies: dependencies,
    dependency_files: dependency_files,
    credentials: credentials,
    repo_contents_path: repo_contents_path
  ).updated_dependency_files
end

def updated_poetry_based_files
  PoetryFileUpdater.new(
    dependencies: dependencies,
    dependency_files: dependency_files,
    credentials: credentials
  ).updated_dependency_files
end

def updated_requirement_based_files
  RequirementFileUpdater.new(
    dependencies: dependencies,
    dependency_files: dependency_files,
    credentials: credentials,
    index_urls: pip_compile_index_urls
  ).updated_dependency_files
end