import {
  chmod,
  chown,
  copyFile,
  mkdir,
  opendir,
  symlink,
  writeFile,
} from "node:fs/promises";
import path from "node:path";
import { cwd } from "node:process";
import { Fstab } from "./fstab.js";
import { execFile, exists } from "./helpers/better-api.js";
import { PasswdEntry, readPasswd } from "./helpers/passwd.js";
import { logDebug } from "./helpers/logger.js";
import assert from "node:assert";
import { Persist } from "./persist.js";
import { writePasswd } from "./passwd.js";

export class Alpine {
  dir: string;
  private constructor({ dir }: { dir: string }) {
    this.dir = dir;
  }
  fstab: Fstab = new Fstab(this);
  persist: Persist = new Persist(this);
  packages: string[] = [];

  async mkdirP(dir: string): Promise<void> {
    await mkdir(this.path(dir), { recursive: true });
  }
  async writeFile(
    filePath: string,
    content: string,
    permissions?: { uid: number; gid: number }
  ): Promise<void> {
    const p = path.join(this.dir, filePath);
    await this.mkdirP(path.dirname(filePath));
    await writeFile(p, content);
    if (permissions) {
      await chown(p, permissions.uid, permissions.gid);
      await chmod(p, 0o600);
    }
  }
  async writeExecutable(filePath: string, content: string): Promise<void> {
    await this.writeFile(filePath, content);
    await chmod(this.path(filePath), 0o700);
  }
  async assertExists(path: string) {
    assert(await exists(this.path(path)));
  }
  path(p: string): string {
    return path.join(this.dir, p);
  }
  private getRelativeSymlink(
    target: string,
    filePath: string
  ): { target: string; filePath: string } {
    const realFilePath = path.join(this.dir, filePath);
    return {
      target: path.relative(
        path.dirname(realFilePath),
        path.join(this.dir, target)
      ),
      filePath: realFilePath,
    };
  }
  async symlink(_target: string, _filePath: string): Promise<void> {
    const { target, filePath } = this.getRelativeSymlink(_target, _filePath);
    await symlink(target, filePath);
  }

  readPasswd(): Promise<PasswdEntry[]> {
    return readPasswd(this.path("/etc/passwd"));
  }
  async userAdd(
    user: string,
    {
      system,
      homeDir,
      createHome,
    }: { system: boolean; homeDir?: string; createHome: boolean } = {
      system: false,
      homeDir: "",
      createHome: true,
    }
  ): Promise<PasswdEntry> {
    await execFile("useradd", [
      "--user-group",
      ...(system ? ["--system"] : []),
      ...(homeDir ? ["--home-dir", homeDir] : []),
      ...(createHome ? ["--create-home"] : []),
      "--root",
      this.dir,
      user,
    ]);
    const passwd = await this.readPasswd();
    const entry = passwd.find((e) => e.name === user);
    if (!entry) {
      throw new Error("fatal(userAdd): no encontré el usuario " + user);
    }
    return entry;
  }

  async actuallyInstallPackages(): Promise<void> {
    await this.installPackages(this.packages);
  }

  async installPackages(packages: string[]): Promise<void> {
    logDebug(
      "installPackages",
      await execFile("apk", [
        "add",
        "--clean-protected",
        "--root",
        this.dir,
        ...packages,
      ])
    );
  }
  async addPackages(packages: string[]): Promise<void> {
    this.packages = this.packages.concat(packages);
  }

  static async makeWorld({
    dir,
    packages,
  }: {
    dir: string;
    packages?: string[];
  }): Promise<Alpine> {
    const apkDir = path.join(dir, "/etc/apk");
    await mkdir(apkDir, { recursive: true });

    // hack
    {
      const cacheDir = path.join(cwd(), "cache");
      await mkdir("cache", { recursive: true });
      await symlink(cacheDir, path.join(apkDir, "cache"));
    }

    {
      const apkKeysDir = path.join(apkDir, "keys");
      const keysSrcDir = "alpine/keys";
      await mkdir(apkKeysDir, { recursive: true });
      for await (const { name } of await opendir(keysSrcDir))
        await copyFile(
          path.join(keysSrcDir, name),
          path.join(apkKeysDir, name)
        );
    }

    await writeFile(
      path.join(apkDir, "repositories"),
      [
        "https://dl-cdn.alpinelinux.org/alpine/v3.17/main",
        "https://dl-cdn.alpinelinux.org/alpine/v3.17/community",
      ].join("\n")
    );
    logDebug(
      "makeWorld",
      await execFile("apk", [
        "add",
        "--initdb",
        "--clean-protected",
        "--root",
        dir,
        ...["alpine-baselayout", "busybox", "libc-utils", "alpine-keys"],
        ...(packages || []),
      ])
    );

    const alpine = new Alpine({ dir });
    await alpine.fstab.write();
    await alpine.persist.write();
    await writePasswd(alpine);
    return alpine;
  }
}