import { execSync, execFileSync } from "node:child_process";
import { basename } from "node:path";

const commandAvailability = new Map<string, boolean>();

export function hasCommand(command: string): boolean {
  if (commandAvailability.has(command)) {
    return commandAvailability.get(command)!;
  }

  let available: boolean;
  if (process.platform === "win32") {
    // `command -v` is not available in Windows shells, so prefer `where.exe`.
    try {
      execFileSync("where.exe", [command], { stdio: "ignore" });
      available = true;
    } catch {
      try {
        execSync(`command -v ${command}`, { stdio: "ignore" });
        available = true;
      } catch {
        available = false;
      }
    }
  } else {
    try {
      execSync(`command -v ${command}`, { stdio: "ignore" });
      available = true;
    } catch {
      available = false;
    }
  }

  commandAvailability.set(command, available);
  return available;
}

export function isFishShell(): boolean {
  const shell = process.env.SHELL ?? "";
  return basename(shell) === "fish";
}

export function exitStatusVar(): string {
  return isFishShell() ? "$status" : "$?";
}

export function shellEscape(s: string): string {
  return "'" + s.replace(/'/g, "'\\''") + "'";
}

export function tailLines(text: string, lines: number): string {
  const split = text.split("\n");
  if (split.length <= lines) return text;
  return split.slice(-lines).join("\n");
}

export const __test__ = {
  clearCommandAvailability(): void {
    commandAvailability.clear();
  },
};