// Copyright 2018-2022 the Deno authors. All rights reserved. MIT license.

use crate::check_unstable;
use crate::FfiPermissions;
use deno_core::error::range_error;
use deno_core::error::type_error;
use deno_core::error::AnyError;
use deno_core::op;
use deno_core::serde_v8;
use deno_core::v8;
use std::ffi::c_char;
use std::ffi::c_void;
use std::ffi::CStr;
use std::ptr;

#[op(fast)]
pub fn op_ffi_ptr_of<FP>(
  state: &mut deno_core::OpState,
  buf: *const u8,
  out: &mut [u32],
) -> Result<(), AnyError>
where
  FP: FfiPermissions + 'static,
{
  check_unstable(state, "Deno.UnsafePointer#of");
  let permissions = state.borrow_mut::<FP>();
  permissions.check(None)?;

  let outptr = out.as_ptr() as *mut usize;
  let length = out.len();
  assert!(
    length >= (std::mem::size_of::<usize>() / std::mem::size_of::<u32>())
  );
  assert_eq!(outptr as usize % std::mem::size_of::<usize>(), 0);

  // SAFETY: Out buffer was asserted to be at least large enough to hold a usize, and properly aligned.
  let out = unsafe { &mut *outptr };
  *out = buf as usize;

  Ok(())
}

unsafe extern "C" fn noop_deleter_callback(
  _data: *mut c_void,
  _byte_length: usize,
  _deleter_data: *mut c_void,
) {
}

#[op(v8)]
pub fn op_ffi_get_buf<FP, 'scope>(
  scope: &mut v8::HandleScope<'scope>,
  state: &mut deno_core::OpState,
  ptr: usize,
  offset: usize,
  len: usize,
) -> Result<serde_v8::Value<'scope>, AnyError>
where
  FP: FfiPermissions + 'static,
{
  check_unstable(state, "Deno.UnsafePointerView#arrayBuffer");

  let permissions = state.borrow_mut::<FP>();
  permissions.check(None)?;

  let ptr = ptr as *mut c_void;

  if ptr.is_null() {
    return Err(type_error("Invalid FFI pointer value, got nullptr"));
  }

  // SAFETY: Offset is user defined.
  let ptr = unsafe { ptr.add(offset) };

  // SAFETY: Trust the user to have provided a real pointer, and a valid matching size to it. Since this is a foreign pointer, we should not do any deletion.
  let backing_store = unsafe {
    v8::ArrayBuffer::new_backing_store_from_ptr(
      ptr,
      len,
      noop_deleter_callback,
      std::ptr::null_mut(),
    )
  }
  .make_shared();
  let array_buffer: v8::Local<v8::Value> =
    v8::ArrayBuffer::with_backing_store(scope, &backing_store).into();
  Ok(array_buffer.into())
}

#[op(fast)]
pub fn op_ffi_buf_copy_into<FP>(
  state: &mut deno_core::OpState,
  src: usize,
  offset: usize,
  dst: &mut [u8],
  len: usize,
) -> Result<(), AnyError>
where
  FP: FfiPermissions + 'static,
{
  check_unstable(state, "Deno.UnsafePointerView#copyInto");

  let permissions = state.borrow_mut::<FP>();
  permissions.check(None)?;

  if dst.len() < len {
    Err(range_error(
      "Destination length is smaller than source length",
    ))
  } else {
    let src = src as *const c_void;

    // SAFETY: Offset is user defined.
    let src = unsafe { src.add(offset) as *const u8 };

    // SAFETY: src is user defined.
    // dest is properly aligned and is valid for writes of len * size_of::<T>() bytes.
    unsafe { ptr::copy::<u8>(src, dst.as_mut_ptr(), len) };
    Ok(())
  }
}

#[op(v8)]
pub fn op_ffi_cstr_read<FP, 'scope>(
  scope: &mut v8::HandleScope<'scope>,
  state: &mut deno_core::OpState,
  ptr: usize,
  offset: usize,
) -> Result<serde_v8::Value<'scope>, AnyError>
where
  FP: FfiPermissions + 'static,
{
  check_unstable(state, "Deno.UnsafePointerView#getCString");

  let permissions = state.borrow_mut::<FP>();
  permissions.check(None)?;

  let ptr = ptr as *const c_void;

  if ptr.is_null() {
    return Err(type_error("Invalid CString pointer, pointer is null"));
  }

  // SAFETY: Offset is user defined.
  let ptr = unsafe { ptr.add(offset) };

  // SAFETY: Pointer is user provided.
  let cstr = unsafe { CStr::from_ptr(ptr as *const c_char) }
    .to_str()
    .map_err(|_| type_error("Invalid CString pointer, not valid UTF-8"))?;
  let value: v8::Local<v8::Value> = v8::String::new(scope, cstr)
    .ok_or_else(|| {
      type_error("Invalid CString pointer, string exceeds max length")
    })?
    .into();
  Ok(value.into())
}

#[op(fast)]
pub fn op_ffi_read_bool<FP>(
  state: &mut deno_core::OpState,
  ptr: usize,
  offset: usize,
) -> Result<bool, AnyError>
where
  FP: FfiPermissions + 'static,
{
  check_unstable(state, "Deno.UnsafePointerView#getBool");

  let permissions = state.borrow_mut::<FP>();
  permissions.check(None)?;

  let ptr = ptr as *const c_void;

  if ptr.is_null() {
    return Err(type_error("Invalid bool pointer, pointer is null"));
  }

  // SAFETY: ptr and offset are user provided.
  Ok(unsafe { ptr::read_unaligned::<bool>(ptr.add(offset) as *const bool) })
}

#[op(fast)]
pub fn op_ffi_read_u8<FP>(
  state: &mut deno_core::OpState,
  ptr: usize,
  offset: usize,
) -> Result<u32, AnyError>
where
  FP: FfiPermissions + 'static,
{
  check_unstable(state, "Deno.UnsafePointerView#getUint8");

  let permissions = state.borrow_mut::<FP>();
  permissions.check(None)?;

  let ptr = ptr as *const c_void;

  if ptr.is_null() {
    return Err(type_error("Invalid u8 pointer, pointer is null"));
  }

  // SAFETY: ptr and offset are user provided.
  Ok(unsafe { ptr::read_unaligned::<u8>(ptr.add(offset) as *const u8) as u32 })
}

#[op(fast)]
pub fn op_ffi_read_i8<FP>(
  state: &mut deno_core::OpState,
  ptr: usize,
  offset: usize,
) -> Result<i32, AnyError>
where
  FP: FfiPermissions + 'static,
{
  check_unstable(state, "Deno.UnsafePointerView#getInt8");

  let permissions = state.borrow_mut::<FP>();
  permissions.check(None)?;

  let ptr = ptr as *const c_void;

  if ptr.is_null() {
    return Err(type_error("Invalid i8 pointer, pointer is null"));
  }

  // SAFETY: ptr and offset are user provided.
  Ok(unsafe { ptr::read_unaligned::<i8>(ptr.add(offset) as *const i8) as i32 })
}

#[op(fast)]
pub fn op_ffi_read_u16<FP>(
  state: &mut deno_core::OpState,
  ptr: usize,
  offset: usize,
) -> Result<u32, AnyError>
where
  FP: FfiPermissions + 'static,
{
  check_unstable(state, "Deno.UnsafePointerView#getUint16");

  let permissions = state.borrow_mut::<FP>();
  permissions.check(None)?;

  let ptr = ptr as *const c_void;

  if ptr.is_null() {
    return Err(type_error("Invalid u16 pointer, pointer is null"));
  }

  // SAFETY: ptr and offset are user provided.
  Ok(unsafe {
    ptr::read_unaligned::<u16>(ptr.add(offset) as *const u16) as u32
  })
}

#[op(fast)]
pub fn op_ffi_read_i16<FP>(
  state: &mut deno_core::OpState,
  ptr: usize,
  offset: usize,
) -> Result<i32, AnyError>
where
  FP: FfiPermissions + 'static,
{
  check_unstable(state, "Deno.UnsafePointerView#getInt16");

  let permissions = state.borrow_mut::<FP>();
  permissions.check(None)?;

  let ptr = ptr as *const c_void;

  if ptr.is_null() {
    return Err(type_error("Invalid i16 pointer, pointer is null"));
  }

  // SAFETY: ptr and offset are user provided.
  Ok(unsafe {
    ptr::read_unaligned::<i16>(ptr.add(offset) as *const i16) as i32
  })
}

#[op(fast)]
pub fn op_ffi_read_u32<FP>(
  state: &mut deno_core::OpState,
  ptr: usize,
  offset: usize,
) -> Result<u32, AnyError>
where
  FP: FfiPermissions + 'static,
{
  check_unstable(state, "Deno.UnsafePointerView#getUint32");

  let permissions = state.borrow_mut::<FP>();
  permissions.check(None)?;

  let ptr = ptr as *const c_void;

  if ptr.is_null() {
    return Err(type_error("Invalid u32 pointer, pointer is null"));
  }

  // SAFETY: ptr and offset are user provided.
  Ok(unsafe {
    ptr::read_unaligned::<u32>(ptr.add(offset) as *const u32) as u32
  })
}

#[op(fast)]
pub fn op_ffi_read_i32<FP>(
  state: &mut deno_core::OpState,
  ptr: usize,
  offset: usize,
) -> Result<i32, AnyError>
where
  FP: FfiPermissions + 'static,
{
  check_unstable(state, "Deno.UnsafePointerView#getInt32");

  let permissions = state.borrow_mut::<FP>();
  permissions.check(None)?;

  let ptr = ptr as *const c_void;

  if ptr.is_null() {
    return Err(type_error("Invalid i32 pointer, pointer is null"));
  }

  // SAFETY: ptr and offset are user provided.
  Ok(unsafe {
    ptr::read_unaligned::<i32>(ptr.add(offset) as *const i32) as i32
  })
}

#[op]
pub fn op_ffi_read_u64<FP>(
  state: &mut deno_core::OpState,
  ptr: usize,
  offset: usize,
  out: &mut [u32],
) -> Result<(), AnyError>
where
  FP: FfiPermissions + 'static,
{
  check_unstable(state, "Deno.UnsafePointerView#getBigUint64");

  let permissions = state.borrow_mut::<FP>();
  permissions.check(None)?;

  let outptr = out.as_mut_ptr() as *mut u64;

  assert!(
    out.len() >= (std::mem::size_of::<u64>() / std::mem::size_of::<u32>())
  );
  assert_eq!((outptr as usize % std::mem::size_of::<u64>()), 0);

  let ptr = ptr as *const c_void;

  if ptr.is_null() {
    return Err(type_error("Invalid u64 pointer, pointer is null"));
  }

  let value =
  // SAFETY: ptr and offset are user provided.
    unsafe { ptr::read_unaligned::<u64>(ptr.add(offset) as *const u64) };

  // SAFETY: Length and alignment of out slice were asserted to be correct.
  unsafe { *outptr = value };
  Ok(())
}

#[op(fast)]
pub fn op_ffi_read_i64<FP>(
  state: &mut deno_core::OpState,
  ptr: usize,
  offset: usize,
  out: &mut [u32],
) -> Result<(), AnyError>
where
  FP: FfiPermissions + 'static,
{
  check_unstable(state, "Deno.UnsafePointerView#getBigUint64");

  let permissions = state.borrow_mut::<FP>();
  permissions.check(None)?;

  let outptr = out.as_mut_ptr() as *mut i64;

  assert!(
    out.len() >= (std::mem::size_of::<i64>() / std::mem::size_of::<u32>())
  );
  assert_eq!((outptr as usize % std::mem::size_of::<i64>()), 0);

  let ptr = ptr as *const c_void;

  if ptr.is_null() {
    return Err(type_error("Invalid i64 pointer, pointer is null"));
  }

  let value =
  // SAFETY: ptr and offset are user provided.
    unsafe { ptr::read_unaligned::<i64>(ptr.add(offset) as *const i64) };
  // SAFETY: Length and alignment of out slice were asserted to be correct.
  unsafe { *outptr = value };
  Ok(())
}

#[op(fast)]
pub fn op_ffi_read_f32<FP>(
  state: &mut deno_core::OpState,
  ptr: usize,
  offset: usize,
) -> Result<f32, AnyError>
where
  FP: FfiPermissions + 'static,
{
  check_unstable(state, "Deno.UnsafePointerView#getFloat32");

  let permissions = state.borrow_mut::<FP>();
  permissions.check(None)?;

  let ptr = ptr as *const c_void;

  if ptr.is_null() {
    return Err(type_error("Invalid f32 pointer, pointer is null"));
  }

  // SAFETY: ptr and offset are user provided.
  Ok(unsafe { ptr::read_unaligned::<f32>(ptr.add(offset) as *const f32) })
}

#[op(fast)]
pub fn op_ffi_read_f64<FP>(
  state: &mut deno_core::OpState,
  ptr: usize,
  offset: usize,
) -> Result<f64, AnyError>
where
  FP: FfiPermissions + 'static,
{
  check_unstable(state, "Deno.UnsafePointerView#getFloat64");

  let permissions = state.borrow_mut::<FP>();
  permissions.check(None)?;

  let ptr = ptr as *const c_void;

  if ptr.is_null() {
    return Err(type_error("Invalid f64 pointer, pointer is null"));
  }

  // SAFETY: ptr and offset are user provided.
  Ok(unsafe { ptr::read_unaligned::<f64>(ptr.add(offset) as *const f64) })
}