import {
  ObjectFreeze,
  TypedArrayPrototypeGetByteLength as length,
  TypedArrayPrototypeGetTag as tag,
  TypeError,
  Uint8Array,
  Uint8ArrayPrototypeSet as setBytes,
} from "ext:core/primordials";
import { op_stdio_read_sync, op_stdio_write_sync } from "ext:core/ops";
import { array } from "ext:web/idl.js";
import { result } from "ext:file/errors.js";

const empty = new Uint8Array();

export const stdin = ObjectFreeze({
  read(buffer: Uint8Array<ArrayBufferLike>): number | null {
    if (tag(buffer) !== "Uint8Array") {
      throw new TypeError("Stdin reads require a Uint8Array");
    }
    setBytes(buffer, empty);
    const chunk = result(op_stdio_read_sync(length(buffer)));
    setBytes(buffer, empty);
    if (chunk === null) return null;
    setBytes(buffer, chunk);
    return length(chunk);
  },
});

function write(stderr: boolean, bytes: Uint8Array<ArrayBufferLike>): number {
  if (tag(bytes) !== "Uint8Array") {
    throw new TypeError("Stdio writes require a Uint8Array");
  }
  const args = array() as [boolean, Uint8Array<ArrayBuffer>];
  args[0] = stderr;
  args[1] = new Uint8Array(bytes);
  return result(op_stdio_write_sync(args));
}

export const stdout = ObjectFreeze({
  write(bytes: Uint8Array<ArrayBufferLike>) {
    return write(false, bytes);
  },
});

export const stderr = ObjectFreeze({
  write(bytes: Uint8Array<ArrayBufferLike>) {
    return write(true, bytes);
  },
});