import type { ProcessInfo } from "@nibling/kernel";
import type { Files } from "./files.ts";
import { PROJECT_ROOT } from "./sandbox.ts";

/** A process and the processes it spawned that are still running. */
export interface ProcessNode {
  readonly process: ProcessInfo;
  readonly children: readonly ProcessNode[];
}

/** Nests the table by ppid, oldest first. A process whose parent has exited is a root. */
export function processTree(table: readonly ProcessInfo[]): ProcessNode[] {
  const live = new Set(table.map((p) => p.pid));
  const childrenOf = (ppid: number | null): ProcessNode[] =>
    table
      .filter((p) => (ppid === null ? p.ppid === null || !live.has(p.ppid) : p.ppid === ppid))
      .map((process) => ({ process, children: childrenOf(process.pid) }));
  return childrenOf(null);
}

const NPM_BIN = /^(?:\/usr\/local\/bin\/(npm|npx)|\/usr\/local\/lib\/node_modules\/npm\/bin\/(npm|npx)-cli\.js)$/;

/** A process's command line as it was typed: `npm run dev`, `node server.js`, with project paths relative. */
export function commandLine(argv: readonly string[]): string {
  const [, entry = "", ...args] = argv;
  const npm = NPM_BIN.exec(entry);
  const words = npm ? [npm[1] ?? npm[2]!, ...args] : ["node", entry.startsWith(`${PROJECT_ROOT}/`) ? entry.slice(PROJECT_ROOT.length + 1) : entry, ...args];
  return words.map((word) => (/^[\w./:@=+-]+$/.test(word) ? word : `'${word.replaceAll("'", `'\\''`)}'`)).join(" ");
}

/** The project's npm scripts, by name, from its package.json. A missing or unreadable one has none. */
export function projectScripts(files: Files): string[] {
  try {
    const scripts: unknown = (JSON.parse(files.read("package.json") ?? "{}") as { scripts?: unknown }).scripts;
    if (typeof scripts !== "object" || scripts === null) return [];
    return Object.entries(scripts).filter(([, command]) => typeof command === "string").map(([name]) => name);
  } catch {
    return [];
  }
}

/** The address a browser panel shows for a port the sandbox listens on. */
export const localUrl = (port: number) => `http://localhost:${port}/`;

/** The sandbox port a browser panel's address names, when it names one: `http://localhost:<port>/…`. */
export function sandboxPort(url: string): number | undefined {
  const parsed = URL.parse(url);
  if (!parsed || parsed.protocol !== "http:" || !["localhost", "127.0.0.1"].includes(parsed.hostname)) return;
  return Number(parsed.port || 80);
}