use core::ops::Deref;

use bitflags::bitflags;
use windows_kernel_sys::{
  base::{
    IO_NO_INCREMENT,
    IO_STACK_LOCATION,
    IRP,
    STATUS_SUCCESS,
    _MM_PAGE_PRIORITY as MM_PAGE_PRIORITY,
  },
  ntoskrnl::{
    IoCompleteRequest,
    IoGetCurrentIrpStackLocation,
    MmGetMdlByteCount,
    MmGetMdlByteOffset,
    MmGetSystemAddressForMdlSafe,
  },
};

use crate::{
  error::Error,
  ioctl::{ControlCode, RequiredAccess, TransferMethod},
  user_ptr::UserPtr,
};

bitflags! {
    pub struct IrpFlags: u32 {
        const NOCACHE = windows_kernel_sys::base::IRP_NOCACHE;
        const PAGING_IO = windows_kernel_sys::base::IRP_PAGING_IO;
        const MOUNT_COMPLETION =  windows_kernel_sys::base::IRP_MOUNT_COMPLETION;
        const SYNCHRONOUS_API = windows_kernel_sys::base::IRP_SYNCHRONOUS_API;
        const ASSOCIATED_IRP = windows_kernel_sys::base::IRP_ASSOCIATED_IRP;
        const BUFFERED_IO = windows_kernel_sys::base::IRP_BUFFERED_IO;
        const DEALLOCATE_BUFFER = windows_kernel_sys::base::IRP_DEALLOCATE_BUFFER;
        const INPUT_OPERATION = windows_kernel_sys::base::IRP_INPUT_OPERATION;
        const SYNCHRONOUS_PAGING_IO = windows_kernel_sys::base::IRP_SYNCHRONOUS_PAGING_IO;
        const CREATE_OPERATION = windows_kernel_sys::base::IRP_CREATE_OPERATION;
        const READ_OPERATION = windows_kernel_sys::base::IRP_READ_OPERATION;
        const WRITE_OPERATION = windows_kernel_sys::base::IRP_WRITE_OPERATION;
        const CLOSE_OPERATION = windows_kernel_sys::base::IRP_CLOSE_OPERATION;
        const DEFER_IO_COMPLETION = windows_kernel_sys::base::IRP_DEFER_IO_COMPLETION;
        const OB_QUERY_NAME = windows_kernel_sys::base::IRP_OB_QUERY_NAME;
        const HOLD_DEVICE_QUEUE = windows_kernel_sys::base::IRP_HOLD_DEVICE_QUEUE;
        const UM_DRIVER_INITIATED_IO = windows_kernel_sys::base::IRP_UM_DRIVER_INITIATED_IO;
    }
}

pub struct IoRequest {
  irp: *mut IRP,
}

impl IoRequest {
  /// # Safety
  /// `unsafe`
  pub unsafe fn from_raw(irp: *mut IRP) -> Self {
    Self {
      irp,
    }
  }

  pub fn irp(&self) -> &IRP { unsafe { &*self.irp } }

  pub fn irp_mut(&self) -> &mut IRP { unsafe { &mut *self.irp } }

  pub fn flags(&self) -> IrpFlags {
    IrpFlags::from_bits(self.irp().Flags).unwrap_or_else(IrpFlags::empty)
  }

  pub fn stack_location(&self) -> &IO_STACK_LOCATION {
    unsafe { &*IoGetCurrentIrpStackLocation(self.irp_mut()) }
  }

  pub fn major(&self) -> u8 { self.stack_location().MajorFunction }

  pub(crate) fn complete(&self, value: Result<u32, Error>) {
    let irp = self.irp_mut();

    match value {
      Ok(value) => {
        irp.IoStatus.Information = value as _;
        irp.IoStatus.__bindgen_anon_1.Status = STATUS_SUCCESS;
      }
      Err(error) => {
        irp.IoStatus.Information = 0;
        irp.IoStatus.__bindgen_anon_1.Status = error.to_ntstatus();
      }
    }

    unsafe {
      IoCompleteRequest(irp, IO_NO_INCREMENT as _);
    }
  }
}

pub struct ReadRequest {
  pub(crate) inner: IoRequest,
}

impl Deref for ReadRequest {
  type Target = IoRequest;

  fn deref(&self) -> &Self::Target { &self.inner }
}

impl ReadRequest {
  pub fn user_ptr(&self) -> UserPtr {
    let stack_location = self.stack_location();
    let irp = self.irp();

    let (ptr, size) = if !irp.MdlAddress.is_null() {
      let ptr = unsafe {
        MmGetSystemAddressForMdlSafe(irp.MdlAddress, MM_PAGE_PRIORITY::HighPagePriority as _)
      };

      let size = unsafe { MmGetMdlByteCount(irp.MdlAddress) } as usize;

      (ptr, size)
    } else if !unsafe { irp.AssociatedIrp.SystemBuffer }.is_null() {
      let ptr = unsafe { irp.AssociatedIrp.SystemBuffer };
      let size = unsafe { stack_location.Parameters.Read }.Length as usize;

      (ptr, size)
    } else {
      (core::ptr::null_mut(), 0)
    };

    unsafe { UserPtr::new_buffered(ptr, 0, size) }
  }

  pub fn offset(&self) -> i64 {
    let stack_location = self.stack_location();
    let irp = self.irp();

    if !irp.MdlAddress.is_null() {
      (unsafe { MmGetMdlByteOffset(irp.MdlAddress) }) as i64
    } else if !unsafe { irp.AssociatedIrp.SystemBuffer }.is_null() {
      unsafe { stack_location.Parameters.Read.ByteOffset.QuadPart }
    } else {
      0
    }
  }
}

// impl Into<IoRequest> for ReadRequest {
//   fn into(self) -> IoRequest { self.inner }
// }
impl From<ReadRequest> for IoRequest {
  fn from(r: ReadRequest) -> Self { r.inner }
}

pub struct WriteRequest {
  pub(crate) inner: IoRequest,
}

impl Deref for WriteRequest {
  type Target = IoRequest;

  fn deref(&self) -> &Self::Target { &self.inner }
}

impl WriteRequest {
  pub fn user_ptr(&self) -> UserPtr {
    let stack_location = self.stack_location();
    let irp = self.irp();

    let (ptr, size) = if !irp.MdlAddress.is_null() {
      let ptr = unsafe {
        MmGetSystemAddressForMdlSafe(irp.MdlAddress, MM_PAGE_PRIORITY::HighPagePriority as _)
      };

      let size = unsafe { MmGetMdlByteCount(irp.MdlAddress) } as usize;

      (ptr, size)
    } else if !unsafe { irp.AssociatedIrp.SystemBuffer }.is_null() {
      let ptr = unsafe { irp.AssociatedIrp.SystemBuffer };
      let size = unsafe { stack_location.Parameters.Write }.Length as usize;

      (ptr, size)
    } else {
      (core::ptr::null_mut(), 0)
    };

    unsafe { UserPtr::new_buffered(ptr, size, 0) }
  }

  pub fn offset(&self) -> i64 {
    let stack_location = self.stack_location();
    let irp = self.irp();

    if !irp.MdlAddress.is_null() {
      (unsafe { MmGetMdlByteOffset(irp.MdlAddress) }) as i64
    } else if !unsafe { irp.AssociatedIrp.SystemBuffer }.is_null() {
      unsafe { stack_location.Parameters.Write.ByteOffset.QuadPart }
    } else {
      0
    }
  }
}

// impl Into<IoRequest> for WriteRequest {
//   fn into(self) -> IoRequest { self.inner }
// }
impl From<WriteRequest> for IoRequest {
  fn from(w: WriteRequest) -> Self { w.inner }
}

pub struct IoControlRequest {
  pub(crate) inner: IoRequest,
}

impl Deref for IoControlRequest {
  type Target = IoRequest;

  fn deref(&self) -> &Self::Target { &self.inner }
}

impl IoControlRequest {
  pub fn control_code(&self) -> ControlCode {
    let stack_location = self.stack_location();

    unsafe {
      stack_location
        .Parameters
        .DeviceIoControl
        .IoControlCode
        .into()
    }
  }

  pub fn function(&self) -> (RequiredAccess, u32) {
    let code = self.control_code();

    (code.required_access(), code.number())
  }

  pub fn user_ptr(&self) -> UserPtr {
    let stack_location = self.stack_location();
    let irp = self.irp();

    let system_buffer = unsafe { irp.AssociatedIrp.SystemBuffer };

    let mdl_address = if !irp.MdlAddress.is_null() {
      unsafe {
        MmGetSystemAddressForMdlSafe(irp.MdlAddress, MM_PAGE_PRIORITY::HighPagePriority as _)
      }
    } else {
      core::ptr::null_mut()
    };

    let input_size =
      unsafe { stack_location.Parameters.DeviceIoControl.InputBufferLength } as usize;
    let output_size =
      unsafe { stack_location.Parameters.DeviceIoControl.OutputBufferLength } as usize;

    match self.control_code().transfer_method() {
      TransferMethod::Buffered => unsafe {
        UserPtr::new_buffered(system_buffer, input_size, output_size)
      },
      TransferMethod::InputDirect => unsafe {
        UserPtr::new_direct(mdl_address, system_buffer, output_size, input_size)
      },
      TransferMethod::OutputDirect => unsafe {
        UserPtr::new_direct(system_buffer, mdl_address, input_size, output_size)
      },
      TransferMethod::Neither => unsafe { UserPtr::new_neither() },
    }
  }
}

// impl Into<IoRequest> for IoControlRequest {
//   fn into(self) -> IoRequest { self.inner }
// }
impl From<IoControlRequest> for IoRequest {
  fn from(i: IoControlRequest) -> Self { i.inner }
}