use std::mem;
use std::ptr;

use super::Value;
use crate::error::check_status;
use crate::{sys, Env, Error, JsObject, JsUnknown, NapiValue, Result, Status};

#[derive(Clone, Copy, Debug)]
pub struct JsFunction(pub(crate) Value);

impl JsFunction {
  pub fn call(&self, this: Option<&JsObject>, args: &[JsUnknown]) -> Result<JsUnknown> {
    let raw_this = this
      .map(|v| v.into_raw())
      .or_else(|| {
        Env::from_raw(self.0.env)
          .get_undefined()
          .ok()
          .map(|u| u.into_raw())
      })
      .ok_or(Error::new(
        Status::Unknown,
        "Get raw this failed".to_owned(),
      ))?;
    let mut raw_args = unsafe { mem::MaybeUninit::<[sys::napi_value; 8]>::uninit().assume_init() };
    for (i, arg) in args.into_iter().enumerate() {
      raw_args[i] = arg.0.value;
    }
    let mut return_value = ptr::null_mut();
    let status = unsafe {
      sys::napi_call_function(
        self.0.env,
        raw_this,
        self.0.value,
        args.len() as u64,
        &raw_args[0],
        &mut return_value,
      )
    };
    check_status(status)?;

    JsUnknown::from_raw(self.0.env, return_value)
  }
}