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use std::{
    fmt::{self, Debug},
    mem,
    ptr::NonNull,
};

use libusb1_sys::*;

use crate::{
    config_descriptor::{self, ConfigDescriptor},
    device_descriptor::{self, DeviceDescriptor},
    device_handle::{self, DeviceHandle},
    fields::{self, Speed},
    UsbContext,
};

/// A reference to a USB device.
#[derive(Eq, PartialEq)]
pub struct Device<T: UsbContext> {
    context: T,
    device: NonNull<libusb_device>,
}

impl<T: UsbContext> Drop for Device<T> {
    /// Releases the device reference.
    fn drop(&mut self) {
        unsafe {
            libusb_unref_device(self.device.as_ptr());
        }
    }
}

unsafe impl<T: UsbContext> Send for Device<T> {}
unsafe impl<T: UsbContext> Sync for Device<T> {}

impl<T: UsbContext> Debug for Device<T> {
    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
        let descriptor = match self.device_descriptor() {
            Ok(descriptor) => descriptor,
            Err(e) => {
                return write!(f, "Can't read device descriptor {:?}", e);
            }
        };
        write!(
            f,
            "Bus {:03} Device {:03}: ID {:04x}:{:04x}",
            self.bus_number(),
            self.address(),
            descriptor.vendor_id(),
            descriptor.product_id(),
        )
    }
}

impl<T: UsbContext> Device<T> {
    /// Get the raw libusb_device pointer, for advanced use in unsafe code
    pub fn as_raw(&self) -> *mut libusb_device {
        self.device.as_ptr()
    }

    /// Reads the device descriptor.
    pub fn device_descriptor(&self) -> crate::Result<DeviceDescriptor> {
        let mut descriptor = mem::MaybeUninit::<libusb_device_descriptor>::uninit();

        // since libusb 1.0.16, this function always succeeds
        try_unsafe!(libusb_get_device_descriptor(
            self.device.as_ptr(),
            descriptor.as_mut_ptr()
        ));

        Ok(device_descriptor::from_libusb(unsafe {
            descriptor.assume_init()
        }))
    }

    /// Reads a configuration descriptor.
    pub fn config_descriptor(&self, config_index: u8) -> crate::Result<ConfigDescriptor> {
        let mut config = mem::MaybeUninit::<*const libusb_config_descriptor>::uninit();

        try_unsafe!(libusb_get_config_descriptor(
            self.device.as_ptr(),
            config_index,
            config.as_mut_ptr()
        ));

        Ok(unsafe { config_descriptor::from_libusb(config.assume_init()) })
    }

    /// Reads the configuration descriptor for the current configuration.
    pub fn active_config_descriptor(&self) -> crate::Result<ConfigDescriptor> {
        let mut config = mem::MaybeUninit::<*const libusb_config_descriptor>::uninit();

        try_unsafe!(libusb_get_active_config_descriptor(
            self.device.as_ptr(),
            config.as_mut_ptr()
        ));

        Ok(unsafe { config_descriptor::from_libusb(config.assume_init()) })
    }

    /// Returns the number of the bus that the device is connected to.
    pub fn bus_number(&self) -> u8 {
        unsafe { libusb_get_bus_number(self.device.as_ptr()) }
    }

    /// Returns the device's address on the bus that it's connected to.
    pub fn address(&self) -> u8 {
        unsafe { libusb_get_device_address(self.device.as_ptr()) }
    }

    /// Returns the device's connection speed.
    pub fn speed(&self) -> Speed {
        fields::speed_from_libusb(unsafe { libusb_get_device_speed(self.device.as_ptr()) })
    }

    /// Opens the device.
    pub fn open(&self) -> crate::Result<DeviceHandle<T>> {
        let mut handle = mem::MaybeUninit::<*mut libusb_device_handle>::uninit();

        try_unsafe!(libusb_open(self.device.as_ptr(), handle.as_mut_ptr()));

        Ok(unsafe { device_handle::from_libusb(self.context.clone(), handle.assume_init()) })
    }

    /// Returns the device's port number
    pub fn port_number(&self) -> u8 {
        unsafe { libusb_get_port_number(self.device.as_ptr()) }
    }
}

#[doc(hidden)]
pub(crate) unsafe fn from_libusb<T: UsbContext>(
    context: T,
    device: *mut libusb_device,
) -> Device<T> {
    libusb_ref_device(device);

    Device {
        context,
        device: NonNull::new_unchecked(device),
    }
}