// Copyright 2018-2023 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::op2;
use deno_core::v8;
use deno_core::OpState;
use std::ffi::c_char;
use std::ffi::c_void;
use std::ffi::CStr;
use std::ptr;

#[op2(fast)]
pub fn op_ffi_ptr_create<FP>(
  state: &mut OpState,
  #[bigint] ptr_number: usize,
) -> Result<*mut c_void, AnyError>
where
  FP: FfiPermissions + 'static,
{
  check_unstable(state, "Deno.UnsafePointer#create");
  let permissions = state.borrow_mut::<FP>();
  permissions.check_partial(None)?;

  Ok(ptr_number as *mut c_void)
}

#[op2(fast)]
pub fn op_ffi_ptr_equals<FP>(
  state: &mut OpState,
  a: *const c_void,
  b: *const c_void,
) -> Result<bool, AnyError>
where
  FP: FfiPermissions + 'static,
{
  check_unstable(state, "Deno.UnsafePointer#equals");
  let permissions = state.borrow_mut::<FP>();
  permissions.check_partial(None)?;

  Ok(a == b)
}

#[op2(fast)]
pub fn op_ffi_ptr_of<FP>(
  state: &mut OpState,
  #[anybuffer] buf: *const u8,
) -> Result<*mut c_void, AnyError>
where
  FP: FfiPermissions + 'static,
{
  check_unstable(state, "Deno.UnsafePointer#of");
  let permissions = state.borrow_mut::<FP>();
  permissions.check_partial(None)?;

  Ok(buf as *mut c_void)
}

#[op2(fast)]
pub fn op_ffi_ptr_of_exact<FP>(
  state: &mut OpState,
  buf: v8::Local<v8::ArrayBufferView>,
) -> Result<*mut c_void, AnyError>
where
  FP: FfiPermissions + 'static,
{
  check_unstable(state, "Deno.UnsafePointer#of");
  let permissions = state.borrow_mut::<FP>();
  permissions.check_partial(None)?;

  let Some(buf) = buf.get_backing_store() else {
    return Ok(0 as _);
  };
  let Some(buf) = buf.data() else {
    return Ok(0 as _);
  };
  Ok(buf.as_ptr() as _)
}

#[op2(fast)]
pub fn op_ffi_ptr_offset<FP>(
  state: &mut OpState,
  ptr: *mut c_void,
  #[number] offset: isize,
) -> Result<*mut c_void, AnyError>
where
  FP: FfiPermissions + 'static,
{
  check_unstable(state, "Deno.UnsafePointer#offset");
  let permissions = state.borrow_mut::<FP>();
  permissions.check_partial(None)?;

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

  // TODO(mmastrac): Create a RawPointer that can safely do pointer math.

  // SAFETY: Using `ptr.offset` is *actually unsafe* and has generated UB, but our FFI code relies on this working so we're going to
  // try and ask the compiler to be less undefined here by using `ptr.wrapping_offset`.
  Ok(ptr.wrapping_offset(offset))
}

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

#[op2(fast)]
pub fn op_ffi_ptr_value<FP>(
  state: &mut OpState,
  ptr: *mut c_void,
  #[buffer] out: &mut [u32],
) -> Result<(), AnyError>
where
  FP: FfiPermissions + 'static,
{
  check_unstable(state, "Deno.UnsafePointer#value");
  let permissions = state.borrow_mut::<FP>();
  permissions.check_partial(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 = ptr as usize;

  Ok(())
}

#[op2]
pub fn op_ffi_get_buf<FP, 'scope>(
  scope: &mut v8::HandleScope<'scope>,
  state: &mut OpState,
  ptr: *mut c_void,
  #[number] offset: isize,
  #[number] len: usize,
) -> Result<v8::Local<'scope, v8::ArrayBuffer>, AnyError>
where
  FP: FfiPermissions + 'static,
{
  check_unstable(state, "Deno.UnsafePointerView#getArrayBuffer");

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

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

  // SAFETY: Trust the user to have provided a real pointer, offset, 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.offset(offset),
      len,
      noop_deleter_callback,
      std::ptr::null_mut(),
    )
  }
  .make_shared();
  let array_buffer = v8::ArrayBuffer::with_backing_store(scope, &backing_store);
  Ok(array_buffer)
}

#[op2(fast)]
pub fn op_ffi_buf_copy_into<FP>(
  state: &mut OpState,
  src: *mut c_void,
  #[number] offset: isize,
  #[anybuffer] dst: &mut [u8],
  #[number] len: usize,
) -> Result<(), AnyError>
where
  FP: FfiPermissions + 'static,
{
  check_unstable(state, "Deno.UnsafePointerView#copyInto");

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

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

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

#[op2]
pub fn op_ffi_cstr_read<FP, 'scope>(
  scope: &mut v8::HandleScope<'scope>,
  state: &mut OpState,
  ptr: *mut c_void,
  #[number] offset: isize,
) -> Result<v8::Local<'scope, v8::String>, AnyError>
where
  FP: FfiPermissions + 'static,
{
  check_unstable(state, "Deno.UnsafePointerView#getCString");

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

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

  let cstr =
  // SAFETY: Pointer and offset are user provided.
    unsafe { CStr::from_ptr(ptr.offset(offset) as *const c_char) }.to_bytes();
  let value = v8::String::new_from_utf8(scope, cstr, v8::NewStringType::Normal)
    .ok_or_else(|| {
      type_error("Invalid CString pointer, string exceeds max length")
    })?;
  Ok(value)
}

#[op2(fast)]
pub fn op_ffi_read_bool<FP>(
  state: &mut OpState,
  ptr: *mut c_void,
  #[number] offset: isize,
) -> Result<bool, AnyError>
where
  FP: FfiPermissions + 'static,
{
  check_unstable(state, "Deno.UnsafePointerView#getBool");

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

  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.offset(offset) as *const bool) })
}

#[op2(fast)]
pub fn op_ffi_read_u8<FP>(
  state: &mut OpState,
  ptr: *mut c_void,
  #[number] offset: isize,
) -> Result<u32, AnyError>
where
  FP: FfiPermissions + 'static,
{
  check_unstable(state, "Deno.UnsafePointerView#getUint8");

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

  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.offset(offset) as *const u8) as u32
  })
}

#[op2(fast)]
pub fn op_ffi_read_i8<FP>(
  state: &mut OpState,
  ptr: *mut c_void,
  #[number] offset: isize,
) -> Result<i32, AnyError>
where
  FP: FfiPermissions + 'static,
{
  check_unstable(state, "Deno.UnsafePointerView#getInt8");

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

  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.offset(offset) as *const i8) as i32
  })
}

#[op2(fast)]
pub fn op_ffi_read_u16<FP>(
  state: &mut OpState,
  ptr: *mut c_void,
  #[number] offset: isize,
) -> Result<u32, AnyError>
where
  FP: FfiPermissions + 'static,
{
  check_unstable(state, "Deno.UnsafePointerView#getUint16");

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

  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.offset(offset) as *const u16) as u32
  })
}

#[op2(fast)]
pub fn op_ffi_read_i16<FP>(
  state: &mut OpState,
  ptr: *mut c_void,
  #[number] offset: isize,
) -> Result<i32, AnyError>
where
  FP: FfiPermissions + 'static,
{
  check_unstable(state, "Deno.UnsafePointerView#getInt16");

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

  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.offset(offset) as *const i16) as i32
  })
}

#[op2(fast)]
pub fn op_ffi_read_u32<FP>(
  state: &mut OpState,
  ptr: *mut c_void,
  #[number] offset: isize,
) -> Result<u32, AnyError>
where
  FP: FfiPermissions + 'static,
{
  check_unstable(state, "Deno.UnsafePointerView#getUint32");

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

  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.offset(offset) as *const u32) })
}

#[op2(fast)]
pub fn op_ffi_read_i32<FP>(
  state: &mut OpState,
  ptr: *mut c_void,
  #[number] offset: isize,
) -> Result<i32, AnyError>
where
  FP: FfiPermissions + 'static,
{
  check_unstable(state, "Deno.UnsafePointerView#getInt32");

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

  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.offset(offset) as *const i32) })
}

#[op2(fast)]
pub fn op_ffi_read_u64<FP>(
  state: &mut OpState,
  ptr: *mut c_void,
  #[number] offset: isize,
  #[buffer] out: &mut [u32],
) -> Result<(), AnyError>
where
  FP: FfiPermissions + 'static,
{
  check_unstable(state, "Deno.UnsafePointerView#getBigUint64");

  let permissions = state.borrow_mut::<FP>();
  permissions.check_partial(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);

  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.offset(offset) as *const u64) };

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

#[op2(fast)]
pub fn op_ffi_read_i64<FP>(
  state: &mut OpState,
  ptr: *mut c_void,
  #[number] offset: isize,
  #[buffer] out: &mut [u32],
) -> Result<(), AnyError>
where
  FP: FfiPermissions + 'static,
{
  check_unstable(state, "Deno.UnsafePointerView#getBigUint64");

  let permissions = state.borrow_mut::<FP>();
  permissions.check_partial(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);

  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.offset(offset) as *const i64) };
  // SAFETY: Length and alignment of out slice were asserted to be correct.
  unsafe { *outptr = value };
  Ok(())
}

#[op2(fast)]
pub fn op_ffi_read_f32<FP>(
  state: &mut OpState,
  ptr: *mut c_void,
  #[number] offset: isize,
) -> Result<f32, AnyError>
where
  FP: FfiPermissions + 'static,
{
  check_unstable(state, "Deno.UnsafePointerView#getFloat32");

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

  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.offset(offset) as *const f32) })
}

#[op2(fast)]
pub fn op_ffi_read_f64<FP>(
  state: &mut OpState,
  ptr: *mut c_void,
  #[number] offset: isize,
) -> Result<f64, AnyError>
where
  FP: FfiPermissions + 'static,
{
  check_unstable(state, "Deno.UnsafePointerView#getFloat64");

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

  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.offset(offset) as *const f64) })
}

#[op2(fast)]
pub fn op_ffi_read_ptr<FP>(
  state: &mut OpState,
  ptr: *mut c_void,
  #[number] offset: isize,
) -> Result<*mut c_void, AnyError>
where
  FP: FfiPermissions + 'static,
{
  check_unstable(state, "Deno.UnsafePointerView#getPointer");

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

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

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