use std::any::TypeId;
use std::convert::TryInto;
use std::ffi::CString;
use std::mem;
use std::os::raw::{c_char, c_void};
use std::ptr;

use crate::async_work::AsyncWork;
use crate::error::check_status;
use crate::js_values::*;
use crate::task::Task;
use crate::{sys, Error, NodeVersion, Result, Status};

#[cfg(all(any(feature = "libuv", feature = "tokio_rt"), napi4))]
use crate::promise;
#[cfg(all(feature = "tokio_rt", napi4))]
use crate::tokio_rt::{get_tokio_sender, Message};
#[cfg(all(feature = "libuv", napi4))]
use crate::uv;
#[cfg(all(feature = "libuv", napi4))]
use std::future::Future;
#[cfg(all(feature = "tokio_rt", napi4))]
use tokio::sync::mpsc::error::TrySendError;

pub type Callback = extern "C" fn(sys::napi_env, sys::napi_callback_info) -> sys::napi_value;

#[derive(Clone, Copy, Debug)]
pub struct Env(pub(crate) sys::napi_env);

impl Env {
  #[inline]
  pub fn from_raw(env: sys::napi_env) -> Self {
    Env(env)
  }

  #[inline]
  pub fn get_undefined(&self) -> Result<JsUndefined> {
    let mut raw_value = ptr::null_mut();
    let status = unsafe { sys::napi_get_undefined(self.0, &mut raw_value) };
    check_status(status)?;
    Ok(JsUndefined::from_raw_unchecked(self.0, raw_value))
  }

  #[inline]
  pub fn get_null(&self) -> Result<JsNull> {
    let mut raw_value = ptr::null_mut();
    let status = unsafe { sys::napi_get_null(self.0, &mut raw_value) };
    check_status(status)?;
    Ok(JsNull::from_raw_unchecked(self.0, raw_value))
  }

  #[inline]
  pub fn get_boolean(&self, value: bool) -> Result<JsBoolean> {
    let mut raw_value = ptr::null_mut();
    let status = unsafe { sys::napi_get_boolean(self.0, value, &mut raw_value) };
    check_status(status)?;
    Ok(JsBoolean::from_raw_unchecked(self.0, raw_value))
  }

  #[inline]
  pub fn create_int32(&self, int: i32) -> Result<JsNumber> {
    let mut raw_value = ptr::null_mut();
    let status =
      unsafe { sys::napi_create_int32(self.0, int, (&mut raw_value) as *mut sys::napi_value) };
    check_status(status)?;
    Ok(JsNumber::from_raw_unchecked(self.0, raw_value))
  }

  #[inline]
  pub fn create_int64(&self, int: i64) -> Result<JsNumber> {
    let mut raw_value = ptr::null_mut();
    let status =
      unsafe { sys::napi_create_int64(self.0, int, (&mut raw_value) as *mut sys::napi_value) };
    check_status(status)?;
    Ok(JsNumber::from_raw_unchecked(self.0, raw_value))
  }

  #[inline]
  pub fn create_uint32(&self, number: u32) -> Result<JsNumber> {
    let mut raw_value = ptr::null_mut();
    let status = unsafe { sys::napi_create_uint32(self.0, number, &mut raw_value) };
    check_status(status)?;
    Ok(JsNumber::from_raw_unchecked(self.0, raw_value))
  }

  #[inline]
  pub fn create_double(&self, double: f64) -> Result<JsNumber> {
    let mut raw_value = ptr::null_mut();
    let status =
      unsafe { sys::napi_create_double(self.0, double, (&mut raw_value) as *mut sys::napi_value) };
    check_status(status)?;
    Ok(JsNumber::from_raw_unchecked(self.0, raw_value))
  }

  #[inline]
  pub fn create_string(&self, s: &str) -> Result<JsString> {
    self.create_string_from_chars(s.as_ptr() as *const _, s.len() as u64)
  }

  #[inline]
  pub fn create_string_from_std(&self, s: String) -> Result<JsString> {
    self.create_string_from_chars(s.as_ptr() as *const _, s.len() as u64)
  }

  #[inline]
  pub fn create_string_from_vec_u8(&self, bytes: Vec<u8>) -> Result<JsString> {
    self.create_string_from_chars(bytes.as_ptr() as *const _, bytes.len() as u64)
  }

  #[inline]
  pub fn create_string_from_vec_i8(&self, bytes: Vec<i8>) -> Result<JsString> {
    self.create_string_from_chars(bytes.as_ptr(), bytes.len() as u64)
  }

  #[inline]
  fn create_string_from_chars(&self, data_ptr: *const c_char, len: u64) -> Result<JsString> {
    let mut raw_value = ptr::null_mut();
    let status = unsafe { sys::napi_create_string_utf8(self.0, data_ptr, len, &mut raw_value) };
    check_status(status)?;
    Ok(JsString::from_raw_unchecked(self.0, raw_value))
  }

  #[inline]
  pub fn create_string_utf16(&self, chars: &[u16]) -> Result<JsString> {
    let mut raw_value = ptr::null_mut();
    let status = unsafe {
      sys::napi_create_string_utf16(self.0, chars.as_ptr(), chars.len() as u64, &mut raw_value)
    };
    check_status(status)?;
    Ok(JsString::from_raw_unchecked(self.0, raw_value))
  }

  #[inline]
  pub fn create_symbol_from_js_string(&self, description: JsString) -> Result<JsSymbol> {
    let mut result = ptr::null_mut();
    check_status(unsafe { sys::napi_create_symbol(self.0, description.0.value, &mut result) })?;
    Ok(JsSymbol::from_raw_unchecked(self.0, result))
  }

  #[inline]
  pub fn create_symbol(&self, description: Option<&str>) -> Result<JsSymbol> {
    let mut result = ptr::null_mut();
    check_status(unsafe {
      sys::napi_create_symbol(
        self.0,
        description
          .and_then(|desc| self.create_string(desc).ok())
          .map(|string| string.0.value)
          .unwrap_or(ptr::null_mut()),
        &mut result,
      )
    })?;
    Ok(JsSymbol::from_raw_unchecked(self.0, result))
  }

  #[inline]
  pub fn create_object(&self) -> Result<JsObject> {
    let mut raw_value = ptr::null_mut();
    let status = unsafe { sys::napi_create_object(self.0, &mut raw_value) };
    check_status(status)?;
    Ok(JsObject::from_raw_unchecked(self.0, raw_value))
  }

  #[inline]
  pub fn create_array_with_length(&self, length: usize) -> Result<JsObject> {
    let mut raw_value = ptr::null_mut();
    let status =
      unsafe { sys::napi_create_array_with_length(self.0, length as u64, &mut raw_value) };
    check_status(status)?;
    Ok(JsObject::from_raw_unchecked(self.0, raw_value))
  }

  #[inline]
  pub fn create_buffer(&self, length: u64) -> Result<JsBuffer> {
    let mut raw_value = ptr::null_mut();
    let mut data = Vec::with_capacity(length as usize);
    let mut data_ptr = data.as_mut_ptr();
    let status = unsafe { sys::napi_create_buffer(self.0, length, &mut data_ptr, &mut raw_value) };
    check_status(status)?;
    mem::forget(data);

    let mut buffer = JsBuffer::from_raw_unchecked(self.0, raw_value);
    buffer.data = data_ptr as *const u8;
    buffer.len = length;
    Ok(buffer)
  }

  #[inline]
  pub fn create_buffer_with_data(&self, data: Vec<u8>) -> Result<JsBuffer> {
    let length = data.len() as u64;
    let mut raw_value = ptr::null_mut();
    let data_ptr = data.as_ptr();
    let status = unsafe {
      sys::napi_create_external_buffer(
        self.0,
        length,
        data_ptr as *mut c_void,
        Some(drop_buffer),
        Box::leak(Box::new(length)) as *mut u64 as *mut _,
        &mut raw_value,
      )
    };
    check_status(status)?;
    let mut changed = 0;
    let adjust_external_memory_status =
      unsafe { sys::napi_adjust_external_memory(self.0, length as i64, &mut changed) };
    check_status(adjust_external_memory_status)?;
    mem::forget(data);
    let mut buffer = JsBuffer::from_raw_unchecked(self.0, raw_value);
    buffer.data = data_ptr as *const u8;
    buffer.len = length;
    Ok(buffer)
  }

  #[inline]
  pub fn create_arraybuffer(&self, length: u64) -> Result<JsArrayBuffer> {
    let mut raw_value = ptr::null_mut();
    let mut data = Vec::with_capacity(length as usize);
    let mut data_ptr = data.as_mut_ptr();
    let status =
      unsafe { sys::napi_create_arraybuffer(self.0, length, &mut data_ptr, &mut raw_value) };
    check_status(status)?;
    mem::forget(data);
    let mut array_buffer = JsArrayBuffer::from_raw_unchecked(self.0, raw_value);
    array_buffer.data = data_ptr as *const u8;
    array_buffer.len = length;
    Ok(array_buffer)
  }

  #[inline]
  pub fn create_arraybuffer_with_data(&self, data: Vec<u8>) -> Result<JsArrayBuffer> {
    let length = data.len() as u64;
    let mut raw_value = ptr::null_mut();
    let data_ptr = data.as_ptr();
    let status = unsafe {
      sys::napi_create_external_arraybuffer(
        self.0,
        data_ptr as *mut c_void,
        length,
        Some(drop_buffer),
        &length as *const _ as *mut c_void,
        &mut raw_value,
      )
    };
    check_status(status)?;
    let mut changed = 0;
    let adjust_external_memory_status =
      unsafe { sys::napi_adjust_external_memory(self.0, length as i64, &mut changed) };
    check_status(adjust_external_memory_status)?;
    mem::forget(data);
    let mut array_buffer = JsArrayBuffer::from_raw_unchecked(self.0, raw_value);
    array_buffer.data = data_ptr as *const u8;
    array_buffer.len = length;
    Ok(array_buffer)
  }

  #[inline]
  pub fn create_function(&self, name: &str, callback: Callback) -> Result<JsFunction> {
    let mut raw_result = ptr::null_mut();
    let status = unsafe {
      sys::napi_create_function(
        self.0,
        name.as_ptr() as *const c_char,
        name.len() as u64,
        Some(callback),
        callback as *mut c_void,
        &mut raw_result,
      )
    };

    check_status(status)?;

    Ok(JsFunction::from_raw_unchecked(self.0, raw_result))
  }

  #[inline]
  pub fn throw(&self, error: Error) -> Result<()> {
    let err_value = self.create_error(error)?.0.value;
    check_status(unsafe { sys::napi_throw(self.0, err_value) })?;
    Ok(())
  }

  #[inline]
  pub fn throw_error(&self, msg: &str) -> Result<()> {
    check_status(unsafe {
      sys::napi_throw_error(
        self.0,
        ptr::null(),
        CString::from_vec_unchecked(msg.into()).as_ptr() as *const _,
      )
    })
  }

  #[inline]
  pub fn create_reference<T: NapiValue>(&self, value: T) -> Result<Ref<T>> {
    let mut raw_ref = ptr::null_mut();
    let initial_ref_count = 1;
    unsafe {
      let status =
        sys::napi_create_reference(self.0, value.raw_value(), initial_ref_count, &mut raw_ref);
      check_status(status)?;
    };

    Ok(Ref::new(self.0, raw_ref))
  }

  #[inline]
  pub fn get_reference_value<T: NapiValue>(&self, reference: &Ref<T>) -> Result<T> {
    let mut raw_value = ptr::null_mut();
    unsafe {
      let status = sys::napi_get_reference_value(self.0, reference.ref_value, &mut raw_value);
      check_status(status)?;
    };

    T::from_raw(self.0, raw_value)
  }

  #[inline]
  pub fn define_class(
    &self,
    name: &str,
    constructor_cb: Callback,
    properties: Vec<Property>,
  ) -> Result<JsFunction> {
    let mut raw_result = ptr::null_mut();
    let raw_properties = properties
      .into_iter()
      .map(|prop| prop.into_raw(self))
      .collect::<Result<Vec<sys::napi_property_descriptor>>>()?;

    let status = unsafe {
      sys::napi_define_class(
        self.0,
        name.as_ptr() as *const c_char,
        name.len() as u64,
        Some(constructor_cb),
        ptr::null_mut(),
        raw_properties.len() as u64,
        raw_properties.as_ptr(),
        &mut raw_result,
      )
    };

    check_status(status)?;

    Ok(JsFunction::from_raw_unchecked(self.0, raw_result))
  }

  #[inline]
  pub fn wrap<T: 'static>(&self, js_object: &mut JsObject, native_object: T) -> Result<()> {
    let status = unsafe {
      sys::napi_wrap(
        self.0,
        js_object.0.value,
        Box::into_raw(Box::new(TaggedObject::new(native_object))) as *mut c_void,
        Some(raw_finalize::<T>),
        ptr::null_mut(),
        ptr::null_mut(),
      )
    };

    check_status(status).or(Ok(()))
  }

  #[inline]
  pub fn unwrap<T: 'static>(&self, js_object: &JsObject) -> Result<&mut T> {
    unsafe {
      let mut unknown_tagged_object: *mut c_void = ptr::null_mut();
      let status = sys::napi_unwrap(self.0, js_object.0.value, &mut unknown_tagged_object);
      check_status(status)?;

      let type_id: *const TypeId = mem::transmute(unknown_tagged_object);
      if *type_id == TypeId::of::<T>() {
        let tagged_object: *mut TaggedObject<T> = mem::transmute(unknown_tagged_object);
        (*tagged_object).object.as_mut().ok_or(Error {
          status: Status::InvalidArg,
          reason: "Invalid argument, nothing attach to js_object".to_owned(),
        })
      } else {
        Err(Error {
          status: Status::InvalidArg,
          reason: "Invalid argument, T on unrwap is not the type of wrapped object".to_owned(),
        })
      }
    }
  }

  #[inline]
  pub fn drop_wrapped<T: 'static>(&self, js_object: JsObject) -> Result<()> {
    unsafe {
      let mut unknown_tagged_object: *mut c_void = ptr::null_mut();
      let status = sys::napi_unwrap(self.0, js_object.0.value, &mut unknown_tagged_object);
      check_status(status)?;

      let type_id: *const TypeId = mem::transmute(unknown_tagged_object);
      if *type_id == TypeId::of::<T>() {
        let tagged_object: *mut TaggedObject<T> = mem::transmute(unknown_tagged_object);
        (*tagged_object).object = None;
        Ok(())
      } else {
        Err(Error {
          status: Status::InvalidArg,
          reason: "Invalid argument, T on drop_wrapped is not the type of wrapped object"
            .to_owned(),
        })
      }
    }
  }

  #[inline]
  pub fn create_external<T: 'static>(&self, native_object: T) -> Result<JsExternal> {
    let mut object_value = ptr::null_mut();
    let status = unsafe {
      sys::napi_create_external(
        self.0,
        Box::into_raw(Box::new(TaggedObject::new(native_object))) as *mut c_void,
        Some(raw_finalize::<T>),
        ptr::null_mut(),
        &mut object_value,
      )
    };

    check_status(status)?;
    Ok(JsExternal::from_raw_unchecked(self.0, object_value))
  }

  #[inline]
  pub fn get_value_external<T: 'static>(&self, js_external: &JsExternal) -> Result<&mut T> {
    unsafe {
      let mut unknown_tagged_object = ptr::null_mut();
      let status =
        sys::napi_get_value_external(self.0, js_external.0.value, &mut unknown_tagged_object);
      check_status(status)?;

      let type_id: *const TypeId = mem::transmute(unknown_tagged_object);
      if *type_id == TypeId::of::<T>() {
        let tagged_object: *mut TaggedObject<T> = mem::transmute(unknown_tagged_object);
        (*tagged_object).object.as_mut().ok_or(Error {
          status: Status::InvalidArg,
          reason: "Invalid argument, nothing attach to js_external".to_owned(),
        })
      } else {
        Err(Error {
          status: Status::InvalidArg,
          reason: "Invalid argument, T on get_value_external is not the type of wrapped object"
            .to_owned(),
        })
      }
    }
  }

  #[inline]
  pub fn create_error(&self, e: Error) -> Result<JsObject> {
    let reason = e.reason;
    let reason_string = self.create_string(reason.as_str())?;
    let mut result = ptr::null_mut();
    let status = unsafe {
      sys::napi_create_error(self.0, ptr::null_mut(), reason_string.0.value, &mut result)
    };
    check_status(status)?;
    Ok(JsObject::from_raw_unchecked(self.0, result))
  }

  #[inline]
  pub fn spawn<T: 'static + Task>(&self, task: T) -> Result<JsObject> {
    let mut raw_promise = ptr::null_mut();
    let mut raw_deferred = ptr::null_mut();

    check_status(unsafe { sys::napi_create_promise(self.0, &mut raw_deferred, &mut raw_promise) })?;
    AsyncWork::run(self.0, task, raw_deferred)?;
    Ok(JsObject::from_raw_unchecked(self.0, raw_promise))
  }

  #[inline]
  pub fn get_global(&self) -> Result<JsObject> {
    let mut raw_global = ptr::null_mut();
    check_status(unsafe { sys::napi_get_global(self.0, &mut raw_global) })?;
    Ok(JsObject::from_raw_unchecked(self.0, raw_global))
  }

  #[inline]
  pub fn get_napi_version(&self) -> Result<u32> {
    let global = self.get_global()?;
    let process = global.get_named_property::<JsObject>("process")?;
    let versions = process.get_named_property::<JsObject>("versions")?;
    let napi_version = versions.get_named_property::<JsString>("napi")?;
    napi_version
      .as_str()?
      .parse()
      .map_err(|e| Error::new(Status::InvalidArg, format!("{}", e)))
  }

  #[cfg(all(feature = "libuv", napi4))]
  #[inline]
  pub fn execute<
    T: 'static + Send,
    V: 'static + NapiValue,
    F: 'static + Future<Output = Result<T>>,
    R: 'static + Send + Sync + FnOnce(&mut Env, T) -> Result<V>,
  >(
    &self,
    deferred: F,
    resolver: R,
  ) -> Result<JsObject> {
    let mut raw_promise = ptr::null_mut();
    let mut raw_deferred = ptr::null_mut();

    unsafe {
      let status = sys::napi_create_promise(self.0, &mut raw_deferred, &mut raw_promise);
      check_status(status)?;
    }

    let event_loop = unsafe { sys::uv_default_loop() };
    let future_promise = promise::FuturePromise::create(self.0, raw_deferred, Box::from(resolver))?;
    let future_to_execute = promise::resolve_from_future(future_promise.start()?, deferred);
    uv::execute(event_loop, Box::pin(future_to_execute))?;

    Ok(JsObject::from_raw_unchecked(self.0, raw_promise))
  }

  #[cfg(all(feature = "tokio_rt", napi4))]
  #[inline]
  pub fn execute_tokio_future<
    T: 'static + Send,
    V: 'static + NapiValue,
    F: 'static + Send + Future<Output = Result<T>>,
    R: 'static + Send + Sync + FnOnce(&mut Env, T) -> Result<V>,
  >(
    &self,
    fut: F,
    resolver: R,
  ) -> Result<JsObject> {
    let mut raw_promise = ptr::null_mut();
    let mut raw_deferred = ptr::null_mut();
    check_status(unsafe { sys::napi_create_promise(self.0, &mut raw_deferred, &mut raw_promise) })?;

    let raw_env = self.0;
    let future_promise =
      promise::FuturePromise::create(raw_env, raw_deferred, Box::from(resolver))?;
    let future_to_resolve = promise::resolve_from_future(future_promise.start()?, fut);
    let mut sender = get_tokio_sender().clone();
    sender
      .try_send(Message::Task(Box::pin(future_to_resolve)))
      .map_err(|e| match e {
        TrySendError::Full(_) => Error::new(
          Status::QueueFull,
          format!("Failed to run future: no available capacity"),
        ),
        TrySendError::Closed(_) => Error::new(
          Status::Closing,
          format!("Failed to run future: receiver closed"),
        ),
      })?;
    Ok(JsObject::from_raw_unchecked(self.0, raw_promise))
  }

  #[inline]
  pub fn get_node_version(&self) -> Result<NodeVersion> {
    let mut result = ptr::null();
    check_status(unsafe { sys::napi_get_node_version(self.0, &mut result) })?;
    let version = unsafe { *result };
    version.try_into()
  }
}

unsafe extern "C" fn drop_buffer(env: sys::napi_env, finalize_data: *mut c_void, len: *mut c_void) {
  let length = Box::from_raw(len as *mut u64);
  let length = *length as usize;
  let _ = Vec::from_raw_parts(finalize_data as *mut u8, length, length);
  let mut changed = 0;
  let adjust_external_memory_status =
    sys::napi_adjust_external_memory(env, -(length as i64), &mut changed);
  debug_assert!(Status::from(adjust_external_memory_status) == Status::Ok);
}

unsafe extern "C" fn raw_finalize<T>(
  _raw_env: sys::napi_env,
  finalize_data: *mut c_void,
  _finalize_hint: *mut c_void,
) {
  let tagged_object: *mut TaggedObject<T> = mem::transmute(finalize_data);
  Box::from_raw(tagged_object);
}