import { BACKGROUND_CONTEXT } from "@earendil-works/chord/context";
import type { Environment } from "@berry/api";

/** An interactive shell on the target, preferring PowerShell 7 to Windows PowerShell. */
export async function shell(env: Environment): Promise<string[]> {
  if (env.platform !== "win32") return [env.variables.SHELL || "/bin/sh", "-l"];

  const variables = Object.fromEntries(
    Object.entries(env.variables).map(([key, value]) => [key.toUpperCase(), value]),
  );
  const onPath = (name: string) =>
    (variables.PATH ?? "").split(";").filter(Boolean).flatMap((dir) =>
      (variables.PATHEXT ?? ".EXE").split(";").filter(Boolean).map((ext) => [
        dir.replace(/^"(.*)"$/, "$1"),
        name + ext,
      ])
    );
  const candidates = [
    ...onPath("pwsh"),
    ...[variables.PROGRAMFILES, variables.PROGRAMW6432].filter(Boolean).map((dir) => [
      dir,
      "PowerShell",
      "7",
      "pwsh.exe",
    ]),
    ...onPath("powershell"),
    ...(variables.SYSTEMROOT
      ? [[variables.SYSTEMROOT, "System32", "WindowsPowerShell", "v1.0", "powershell.exe"]]
      : []),
  ];
  for (const parts of candidates) {
    const path = await env.joinPath(parts, BACKGROUND_CONTEXT);
    if (!path.ok) continue;
    const info = await env.fileInfo(path.value, BACKGROUND_CONTEXT);
    if (info.ok && info.value.kind !== "directory") return [path.value, "-NoLogo"];
  }
  throw new Error("PowerShell not found. Install PowerShell 7 or add it to PATH.");
}