import type { BigIntStats } from "node:fs";
import { lstat } from "node:fs/promises";
import type { FileHandle } from "node:fs/promises";

import { ArtifactReaderFailure } from "./ArtifactReader.js";

export type DirectoryIdentity = Pick<BigIntStats, "dev" | "ino">;
export type FileIdentity = DirectoryIdentity;

export const readDirectoryIdentity = async (
  path: string,
): Promise<DirectoryIdentity> => {
  const metadata = await lstat(path, { bigint: true });
  if (!metadata.isDirectory()) throw replacedDirectory(path);
  return { dev: metadata.dev, ino: metadata.ino };
};

export const assertPathIdentity = async (
  path: string,
  expected: DirectoryIdentity,
): Promise<void> => {
  const metadata = await lstat(path, { bigint: true });
  if (
    !metadata.isDirectory() ||
    metadata.dev !== expected.dev ||
    metadata.ino !== expected.ino
  )
    throw replacedDirectory(path);
};

export const assertHandleIdentity = async (
  handle: FileHandle,
  expected: DirectoryIdentity,
  path: string,
): Promise<void> => {
  const metadata = await handle.stat({ bigint: true });
  if (
    !metadata.isDirectory() ||
    metadata.dev !== expected.dev ||
    metadata.ino !== expected.ino
  )
    throw replacedDirectory(path);
};

export const readFileIdentity = async (
  handle: FileHandle,
  path: string,
): Promise<FileIdentity> => {
  const metadata = await handle.stat({ bigint: true });
  if (!metadata.isFile())
    throw new ArtifactReaderFailure(
      "path",
      `Extraction file identity changed: ${path}`,
    );
  return { dev: metadata.dev, ino: metadata.ino };
};

export const assertFilePathIdentity = async (
  path: string,
  expected: FileIdentity,
): Promise<void> => {
  const metadata = await lstat(path, { bigint: true });
  if (
    !metadata.isFile() ||
    metadata.dev !== expected.dev ||
    metadata.ino !== expected.ino
  )
    throw new ArtifactReaderFailure(
      "path",
      `Extraction file identity changed: ${path}`,
    );
};

export const isAbsent = async (path: string): Promise<boolean> =>
  lstat(path).then(
    () => false,
    (cause: unknown) => {
      if (isNotFound(cause)) return true;
      throw cause;
    },
  );

export const replacedDirectory = (path: string): ArtifactReaderFailure =>
  new ArtifactReaderFailure(
    "path",
    `Extraction directory identity changed: ${path}`,
  );

const isNotFound = (cause: unknown): boolean =>
  cause instanceof Error && "code" in cause && cause.code === "ENOENT";