use std::fmt;

use libusb1_sys::*;

use crate::fields::Version;

/// Describes a device.
pub struct DeviceDescriptor {
    descriptor: libusb_device_descriptor,
}

impl DeviceDescriptor {
    /// Returns the size of the descriptor in bytes
    pub fn length(&self) -> u8 {
        self.descriptor.bLength
    }

    /// Returns the descriptor type
    pub fn descriptor_type(&self) -> u8 {
        self.descriptor.bDescriptorType
    }

    /// Returns the device's maximum supported USB version.
    pub fn usb_version(&self) -> Version {
        Version::from_bcd(self.descriptor.bcdUSB)
    }

    /// Returns the manufacturer's version of the device.
    pub fn device_version(&self) -> Version {
        Version::from_bcd(self.descriptor.bcdDevice)
    }

    /// Returns the index of the string descriptor that contains the manufacturer name.
    pub fn manufacturer_string_index(&self) -> Option<u8> {
        match self.descriptor.iManufacturer {
            0 => None,
            n => Some(n),
        }
    }

    /// Returns the index of the string descriptor that contains the product name.
    pub fn product_string_index(&self) -> Option<u8> {
        match self.descriptor.iProduct {
            0 => None,
            n => Some(n),
        }
    }

    /// Returns the index of the string descriptor that contains the device's serial number.
    pub fn serial_number_string_index(&self) -> Option<u8> {
        match self.descriptor.iSerialNumber {
            0 => None,
            n => Some(n),
        }
    }

    /// Returns the device's class code.
    pub fn class_code(&self) -> u8 {
        self.descriptor.bDeviceClass
    }

    /// Returns the device's sub class code.
    pub fn sub_class_code(&self) -> u8 {
        self.descriptor.bDeviceSubClass
    }

    /// Returns the device's protocol code.
    pub fn protocol_code(&self) -> u8 {
        self.descriptor.bDeviceProtocol
    }

    /// Returns the device's vendor ID.
    pub fn vendor_id(&self) -> u16 {
        self.descriptor.idVendor
    }

    /// Returns the device's product ID.
    pub fn product_id(&self) -> u16 {
        self.descriptor.idProduct
    }

    /// Returns the maximum packet size of the device's first endpoint.
    pub fn max_packet_size(&self) -> u8 {
        self.descriptor.bMaxPacketSize0
    }

    /// Returns the number of config descriptors available for the device.
    pub fn num_configurations(&self) -> u8 {
        self.descriptor.bNumConfigurations
    }
}

impl fmt::Debug for DeviceDescriptor {
    fn fmt(&self, fmt: &mut fmt::Formatter) -> Result<(), fmt::Error> {
        let mut debug = fmt.debug_struct("DeviceDescriptor");

        debug.field("bLength", &self.descriptor.bLength);
        debug.field("bDescriptorType", &self.descriptor.bDescriptorType);
        debug.field("bcdUSB", &self.descriptor.bcdUSB);
        debug.field("bDeviceClass", &self.descriptor.bDeviceClass);
        debug.field("bDeviceSubClass", &self.descriptor.bDeviceSubClass);
        debug.field("bDeviceProtocol", &self.descriptor.bDeviceProtocol);
        debug.field("bMaxPacketSize", &self.descriptor.bMaxPacketSize0);
        debug.field("idVendor", &self.descriptor.idVendor);
        debug.field("idProduct", &self.descriptor.idProduct);
        debug.field("bcdDevice", &self.descriptor.bcdDevice);
        debug.field("iManufacturer", &self.descriptor.iManufacturer);
        debug.field("iProduct", &self.descriptor.iProduct);
        debug.field("iSerialNumber", &self.descriptor.iSerialNumber);
        debug.field("bNumConfigurations", &self.descriptor.bNumConfigurations);

        debug.finish()
    }
}

#[doc(hidden)]
pub fn from_libusb(device: libusb_device_descriptor) -> DeviceDescriptor {
    DeviceDescriptor { descriptor: device }
}

#[cfg(test)]
mod test {
    use crate::fields::Version;

    #[test]
    fn it_has_usb_version() {
        assert_eq!(
            Version::from_bcd(0x1234),
            super::from_libusb(device_descriptor!(bcdUSB: 0x1234)).usb_version()
        );
    }

    #[test]
    fn it_has_device_version() {
        assert_eq!(
            Version::from_bcd(0x1234),
            super::from_libusb(device_descriptor!(bcdDevice: 0x1234)).device_version()
        );
    }

    #[test]
    fn it_has_manufacturer_string_index() {
        assert_eq!(
            Some(42),
            super::from_libusb(device_descriptor!(iManufacturer: 42)).manufacturer_string_index()
        );
    }

    #[test]
    fn it_handles_missing_manufacturer_string_index() {
        assert_eq!(
            None,
            super::from_libusb(device_descriptor!(iManufacturer: 0)).manufacturer_string_index()
        );
    }

    #[test]
    fn it_has_product_string_index() {
        assert_eq!(
            Some(42),
            super::from_libusb(device_descriptor!(iProduct: 42)).product_string_index()
        );
    }

    #[test]
    fn it_handles_missing_product_string_index() {
        assert_eq!(
            None,
            super::from_libusb(device_descriptor!(iProduct: 0)).product_string_index()
        );
    }

    #[test]
    fn it_has_serial_number_string_index() {
        assert_eq!(
            Some(42),
            super::from_libusb(device_descriptor!(iSerialNumber: 42)).serial_number_string_index()
        );
    }

    #[test]
    fn it_handles_missing_serial_number_string_index() {
        assert_eq!(
            None,
            super::from_libusb(device_descriptor!(iSerialNumber: 0)).serial_number_string_index()
        );
    }

    #[test]
    fn it_has_class_code() {
        assert_eq!(
            42,
            super::from_libusb(device_descriptor!(bDeviceClass: 42)).class_code()
        );
    }

    #[test]
    fn it_has_sub_class_code() {
        assert_eq!(
            42,
            super::from_libusb(device_descriptor!(bDeviceSubClass: 42)).sub_class_code()
        );
    }

    #[test]
    fn it_has_protocol_code() {
        assert_eq!(
            42,
            super::from_libusb(device_descriptor!(bDeviceProtocol: 42)).protocol_code()
        );
    }

    #[test]
    fn it_has_vendor_id() {
        assert_eq!(
            42,
            super::from_libusb(device_descriptor!(idVendor: 42)).vendor_id()
        );
    }

    #[test]
    fn it_has_product_id() {
        assert_eq!(
            42,
            super::from_libusb(device_descriptor!(idProduct: 42)).product_id()
        );
    }

    #[test]
    fn it_has_max_packet_size() {
        assert_eq!(
            42,
            super::from_libusb(device_descriptor!(bMaxPacketSize0: 42)).max_packet_size()
        );
    }

    #[test]
    fn it_has_num_configurations() {
        assert_eq!(
            3,
            super::from_libusb(device_descriptor!(bNumConfigurations: 3)).num_configurations()
        );
    }
}