// zsh's tools — the module's own, and its implementation of the login-shell seat's one verb
// (novox/hq ADR 0176). Served by the node tools runtime (ADR 0175); nothing here runs a process.
//
// `execute` runs as the operator account. The runtime runs as the node's account — root when the
// host started it — so the command is handed to the account through `runuser` when we are not
// already that account. Root is the module's concern (ADR 0175 §4): a command that needs it uses
// sudo inside the shell like a person would.

import { spawn } from "node:child_process";
import { readFile } from "node:fs/promises";
import { homedir, userInfo } from "node:os";
import { registerModuleTools, type ToolDefinition } from "@novox/mesh-sdk/tools";

/** The operator account on this machine, as the mesh told the runtime; the current user otherwise. */
function account(env: NodeJS.ProcessEnv): string {
  return env.MESH_OPERATOR_ACCOUNT?.trim() || userInfo().username;
}

interface Executed {
  command: string;
  account: string;
  status: number | null;
  signal: string | null;
  stdout: string;
  stderr: string;
  timed_out: boolean;
}

/** Run one command line in a zsh login shell as the account, capturing everything. */
export async function execute(command: string, who: string, timeoutSeconds: number): Promise<Executed> {
  const self = userInfo().username;
  const argv = who === self
    ? ["zsh", "-lc", command]
    : ["runuser", "-u", who, "--", "zsh", "-lc", command];
  return new Promise((resolve) => {
    const child = spawn(argv[0], argv.slice(1), { stdio: ["ignore", "pipe", "pipe"] });
    let stdout = "";
    let stderr = "";
    let timedOut = false;
    child.stdout.on("data", (d: Buffer) => { stdout += d.toString(); });
    child.stderr.on("data", (d: Buffer) => { stderr += d.toString(); });
    const timer = setTimeout(() => { timedOut = true; child.kill("SIGKILL"); }, timeoutSeconds * 1000);
    child.on("error", (err) => {
      clearTimeout(timer);
      resolve({ command, account: who, status: null, signal: null, stdout, stderr: stderr + err.message, timed_out: false });
    });
    child.on("close", (status, signal) => {
      clearTimeout(timer);
      resolve({ command, account: who, status, signal, stdout, stderr, timed_out: timedOut });
    });
  });
}

function seatVerbs(env: NodeJS.ProcessEnv): ToolDefinition[] {
  return [
    {
      name: "execute",
      description: "Run one command on this machine as the operator account, in a login shell; answers with what it printed and how it exited.",
      input: {
        type: "object",
        properties: {
          command: { type: "string", description: "the command line, as you would type it" },
          timeout_seconds: { type: "number", description: "give up after this long (default 60)" },
        },
        required: ["command"],
      },
      run: async (args) => {
        const command = String(args.command ?? "").trim();
        if (!command) throw new Error("execute: a command is required");
        const timeout = Number(args.timeout_seconds ?? 60);
        return execute(command, account(env), Number.isFinite(timeout) && timeout > 0 ? timeout : 60);
      },
    },
  ];
}

function ownTools(env: NodeJS.ProcessEnv): ToolDefinition[] {
  return [
    {
      name: "zsh_config",
      description: "The operator account's ~/.zshrc on this machine as it is now: the mesh's block and the lines around it.",
      input: { type: "object", properties: {} },
      run: async () => {
        const who = account(env);
        const home = env.MESH_OPERATOR_HOME?.trim() || (who === userInfo().username ? homedir() : `/home/${who}`);
        const path = `${home}/.zshrc`;
        const text = await readFile(path, "utf8").catch(() => "");
        const inBlock = /# BEGIN mesh [^\n]*\n([\s\S]*?)# END mesh/.exec(text);
        return { account: who, path, lines: text.split("\n").length, mesh_block_lines: inBlock ? inBlock[1].split("\n").length - 1 : 0, content: text };
      },
    },
  ];
}

// The seat's verb is registered under the seat's name (what the runtime serves on the seat's
// subject when this module holds it) and the module's own tools under the module's.
registerModuleTools("login-shell", seatVerbs);
registerModuleTools("zsh", ownTools);