import * as fs from "node:fs";
import * as path from "node:path";
import { execSync } from "node:child_process";
import * as os from "node:os";

const BASE_DIR = path.resolve(process.env.GCA_WORKSPACE ?? process.cwd());

function safePath(p: string): string {
  const r = path.resolve(BASE_DIR, p);
  if (!r.startsWith(BASE_DIR)) throw new Error(`Path traversal blocked: ${p}`);
  return r;
}

// ── C-002: file_list ────────────────────────────────────────
export async function file_list(args: { path: string; recursive?: boolean }): Promise<any> {
  const dir = safePath(args.path || ".");
  const entries = fs.readdirSync(dir, { withFileTypes: true });
  const result = entries.map(e => ({
    name: e.name,
    type: e.isDirectory() ? "dir" : e.isFile() ? "file" : "other",
    size: e.isFile() ? fs.statSync(path.join(dir, e.name)).size : undefined,
  }));
  return { path: dir, entries: result, count: result.length };
}

// ── C-003: file_read ────────────────────────────────────────
export async function file_read(args: { path: string; encoding?: string; offset?: number; limit?: number }): Promise<any> {
  const filePath = safePath(args.path);
  const enc = (args.encoding === "base64" ? "base64" : "utf8") as BufferEncoding;
  let content = fs.readFileSync(filePath, enc);
  if (enc === "utf8") {
    const lines = (content as string).split("\n");
    content = lines.slice(args.offset ?? 0, args.limit ? (args.offset ?? 0) + args.limit : undefined).join("\n");
  }
  return { path: filePath, content, size: fs.statSync(filePath).size };
}

// ── C-004: file_write ───────────────────────────────────────
export async function file_write(args: { path: string; content: string; encoding?: string }): Promise<any> {
  const filePath = safePath(args.path);
  fs.mkdirSync(path.dirname(filePath), { recursive: true });
  fs.writeFileSync(filePath, args.content, (args.encoding === "base64" ? "base64" : "utf8") as BufferEncoding);
  return { ok: true, path: filePath, size: fs.statSync(filePath).size };
}

// ── C-005: file_move ────────────────────────────────────────
export async function file_move(args: { from: string; to: string }): Promise<any> {
  const fromPath = safePath(args.from);
  const toPath = safePath(args.to);
  fs.mkdirSync(path.dirname(toPath), { recursive: true });
  fs.renameSync(fromPath, toPath);
  return { ok: true, from: fromPath, to: toPath };
}

// ── C-008: exec ─────────────────────────────────────────────
function sanitizeCommand(cmd: string): string {
  // Allow: alphanumeric, dash, slash, dot, colon, underscore, space, equals, comma
  if (/[^a-zA-Z0-9_./\-: =,]/.test(cmd)) throw new Error(`Dangerous chars: ${cmd.slice(0,50)}`);
  return cmd;
}

export async function exec(args: { command: string; cwd?: string; timeout?: number }): Promise<any> {
  const command = sanitizeCommand(args.command);
  const cwd = safePath(args.cwd ?? ".");
  try {
    const stdout = execSync(command, { cwd, timeout: args.timeout ?? 30000, encoding: "utf8", maxBuffer: 10*1024*1024, stdio: ["pipe","pipe","pipe"] });
    return { ok: true, stdout: stdout.toString(), stderr: "" };
  } catch (err: any) {
    return { ok: false, stdout: err.stdout?.toString() ?? "", stderr: err.stderr?.toString() ?? "", exitCode: err.status ?? -1, signal: err.signal };
  }
}

// ── C-010: process_list ─────────────────────────────────────
export async function process_list(args: { filter?: string }): Promise<any> {
  let stdout: string;
  try {
    if (process.platform === "win32") {
      stdout = execSync("tasklist /FO CSV /NH", { encoding: "utf8" }).toString();
    } else {
      stdout = execSync("ps aux --no-headers", { encoding: "utf8" }).toString();
    }
  } catch { return { error: "Failed to list processes" }; }
  const processes = stdout.trim().split("\n").map(line => {
    if (process.platform === "win32") {
      const [name, pid, , mem] = line.replace(/"/g, "").split(",");
      return { name: name?.trim(), pid: Number(pid), mem: mem?.trim() };
    }
    const parts = line.trim().split(/\s+/);
    return { user: parts[0], pid: Number(parts[1]), cpu: parts[2], mem: parts[3], name: parts[10] };
  });
  const filtered = args.filter ? processes.filter(p => p.name?.toLowerCase().includes(args.filter!.toLowerCase())) : processes.slice(0, 50);
  return { count: filtered.length, processes: filtered };
}

// ── C-011: sysinfo ──────────────────────────────────────────
export async function sysinfo(_args: {}): Promise<any> {
  const tm = os.totalmem(); const fm = os.freemem();
  return { hostname: os.hostname(), platform: os.platform(), arch: os.arch(), cpus: os.cpus().length, loadavg: os.loadavg(), memory: { total: tm, free: fm, used: tm - fm, percent: Math.round(((tm-fm)/tm)*100) }, uptime: os.uptime(), node: process.version };
}