/// USB Protocol level types and functions.
///
/// Everything in here is defined by the USB specification, and
/// hardware independent.

// TODO: Put protocol section references in for types and
// documentation.

#[derive(Copy, Clone, Debug, Default)]
#[repr(C, packed)]
pub struct USBDeviceDescriptor {
    pub b_length: u8,
    pub b_descriptor_type: u8,
    pub bcd_usb: u16,
    pub b_device_class: u8,
    pub b_device_sub_class: u8,
    pub b_device_protocol: u8,
    pub b_max_packet_size: u8,
    pub id_vendor: u16,
    pub id_product: u16,
    pub bcd_device: u16,
    pub i_manufacturer: u8,
    pub i_product: u8,
    pub i_serial_number: u8,
    pub b_num_configurations: u8,
}

#[derive(Copy, Clone, Debug, Default)]
#[repr(C, packed)]
pub struct USBConfigurationDescriptor {
    pub b_length: u8,
    pub b_descriptor_type: u8,
    pub w_total_length: u16,
    pub b_num_interfaces: u8,
    pub b_configuration_value: u8,
    pub i_configuration: u8,
    pub bm_attributes: u8,
    pub b_max_power: u8,
}

#[derive(Copy, Clone, Debug, Default)]
#[repr(C, packed)]
pub struct USBInterfaceDescriptor {
    pub b_length: u8,
    pub b_descriptor_type: u8,
    pub b_interface_number: u8,
    pub b_alternate_setting: u8,
    pub b_num_endpoints: u8,
    pub b_interface_class: u8,
    pub b_interface_sub_class: u8,
    pub b_interface_protocol: u8,
    pub i_interface: u8,
}

#[derive(Copy, Clone, Debug, Default)]
#[repr(C, packed)]
pub struct USBEndpointDescriptor {
    pub b_length: u8,
    pub b_descriptor_type: u8,
    pub b_endpoint_address: u8,
    pub bm_attributes: u8,
    pub w_max_packet_size: u16,
    pub b_interval: u8,
}

#[derive(Copy, Clone, Debug)]
#[repr(C, packed)]
pub struct USBSetupPacket {
    pub bm_request_type: BMRequestType,
    pub b_request: USBRequest,
    pub w_value: WValue,
    pub w_index: u16,
    pub w_length: u16,
}
// TODO: shortcuts for standard device requests §9.4 of USB standard.

#[derive(Copy, Clone, Debug, PartialEq)]
pub enum USBSetupDirection {
    HostToDevice = 0x00,
    DeviceToHost = 0x80,
}
impl<T> From<T> for USBSetupDirection
where
    T: Into<u8>,
{
    fn from(v: T) -> Self {
        match v.into() {
            0x00 => Self::HostToDevice,
            0x80 => Self::DeviceToHost,
            _ => panic!("direction can only be 0x00 or 0x80"),
        }
    }
}

#[derive(Copy, Clone, Debug, PartialEq)]
pub enum USBSetupType {
    Standard = 0x00,
    Class = 0x20,
    Vendor = 0x40,
}
impl<T> From<T> for USBSetupType
where
    T: Into<u8>,
{
    fn from(v: T) -> Self {
        match v.into() {
            0x00 => Self::Standard,
            0x20 => Self::Class,
            0x40 => Self::Vendor,
            _ => panic!("type can only be 0x00, 0x20, or 0x40"),
        }
    }
}

#[derive(Copy, Clone, Debug, PartialEq)]
pub enum USBSetupRecipient {
    Device = 0x00,
    Interface = 0x01,
    Endpoint = 0x02,
    Other = 0x03,
}
impl<T> From<T> for USBSetupRecipient
where
    T: Into<u8>,
{
    fn from(v: T) -> Self {
        match v.into() {
            0x00 => Self::Device,
            0x01 => Self::Interface,
            0x02 => Self::Endpoint,
            0x03 => Self::Other,
            _ => panic!("recipient can only be between 0 and 3"),
        }
    }
}

#[derive(Clone, Copy, Debug, Default, PartialEq)]
#[repr(C)]
pub struct BMRequestType(u8);
impl BMRequestType {
    // Get descriptor request type.
    pub fn get_descr() -> Self {
        Self::from((
            USBSetupDirection::DeviceToHost,
            USBSetupType::Standard,
            USBSetupRecipient::Device,
        ))
    }

    // Set request type for all but 'set feature' and 'set interface'.
    pub fn set() -> Self {
        Self::from((
            USBSetupDirection::HostToDevice,
            USBSetupType::Standard,
            USBSetupRecipient::Device,
        ))
    }

    // Get interface request type.
    pub fn cl_get_intf() -> Self {
        Self::from((
            USBSetupDirection::DeviceToHost,
            USBSetupType::Class,
            USBSetupRecipient::Interface,
        ))
    }

    pub fn recipient(&self) -> USBSetupRecipient {
        const POS: u8 = 0;
        const MASK: u8 = 0x1f;
        (self.0 & (MASK << POS)).into()
    }

    pub fn set_recipient(&mut self, v: USBSetupRecipient) {
        const POS: u8 = 0;
        const MASK: u8 = 0x1f;
        self.0 &= !(MASK << POS);
        self.0 |= v as u8 & MASK;
    }

    pub fn typ(&self) -> USBSetupType {
        const POS: u8 = 5;
        const MASK: u8 = 0x3;
        (self.0 & (MASK << POS)).into()
    }

    pub fn set_typ(&mut self, v: USBSetupType) {
        const POS: u8 = 5;
        const MASK: u8 = 0x3;
        self.0 &= !(MASK << POS);
        self.0 |= v as u8 & MASK;
    }

    pub fn direction(&self) -> USBSetupDirection {
        const POS: u8 = 7;
        const MASK: u8 = 0x1;
        (self.0 & (MASK << POS)).into()
    }

    pub fn set_direction(&mut self, v: USBSetupDirection) {
        const POS: u8 = 7;
        const MASK: u8 = 0x1;
        self.0 &= !(MASK << POS);
        self.0 |= v as u8 & MASK;
    }
}
impl From<u8> for BMRequestType {
    fn from(v: u8) -> Self {
        Self(v)
    }
}
impl From<(USBSetupDirection, USBSetupType, USBSetupRecipient)> for BMRequestType {
    fn from(v: (USBSetupDirection, USBSetupType, USBSetupRecipient)) -> Self {
        Self(v.0 as u8 | v.1 as u8 | v.2 as u8)
    }
}

#[derive(Clone, Copy, Debug, Default, PartialEq)]
#[repr(C)]
pub struct WValue(u16);
impl WValue {
    pub fn w_value_lo(&self) -> u8 {
        const POS: u8 = 0;
        const MASK: u16 = 0xff;
        ((self.0 >> POS) & MASK) as u8
    }

    pub fn set_w_value_lo(&mut self, v: u8) {
        const POS: u8 = 0;
        const MASK: u8 = 0xff;
        self.0 &= !((MASK as u16) << POS);
        self.0 |= ((v & MASK) as u16) << POS;
    }

    pub fn w_value_hi(&self) -> u8 {
        const POS: u8 = 8;
        const MASK: u16 = 0xff;
        ((self.0 >> POS) & MASK) as u8
    }

    pub fn set_w_value_hi(&mut self, v: u8) {
        const POS: u8 = 8;
        const MASK: u8 = 0xff;
        self.0 &= !((MASK as u16) << POS);
        self.0 |= ((v & MASK) as u16) << POS;
    }
}
impl From<(u8, u8)> for WValue {
    fn from(v: (u8, u8)) -> Self {
        let mut rc = Self(0);
        rc.set_w_value_lo(v.0);
        rc.set_w_value_hi(v.1);
        rc
    }
}

#[derive(Clone, Copy, Debug, PartialEq)]
pub enum USBRequest {
    GetStatus = 0,
    ClearFeature = 1,
    SetFeature = 3,
    SetAddress = 5,
    GetDescriptor = 6,
    SetDescriptor = 7,
    GetConfiguration = 8,
    SetConfiguration = 9,
    GetInterface = 10,
    SetInterface = 11,
    SynchFrame = 12,
}
impl<T> From<T> for USBRequest
where
    T: Into<u8>,
{
    fn from(v: T) -> Self {
        match v.into() {
            0 => Self::GetStatus,
            1 => Self::ClearFeature,
            3 => Self::SetFeature,
            5 => Self::SetAddress,
            6 => Self::GetDescriptor,
            7 => Self::SetDescriptor,
            8 => Self::GetConfiguration,
            9 => Self::SetConfiguration,
            10 => Self::GetInterface,
            11 => Self::SetInterface,
            12 => Self::SynchFrame,
            _ => panic!("invalid request value"),
        }
    }
}

#[derive(Clone, Copy, Debug, PartialEq)]
pub enum USBFeature {
    EndpointHalt = 0,
    DeviceRemoteWakeup = 1,
    TestMode = 2,
}

#[derive(Clone, Copy, Debug, PartialEq)]
pub enum USBDescriptor {
    Device = 0x01,
    Configuration = 0x02,
    String = 0x03,
    Interface = 0x04,
    Endpoint = 0x05,
    DeviceQualifier = 0x06,
    OtherSpeed = 0x07,
    InterfacePower = 0x08,
    OTG = 0x09,
}

#[derive(Clone, Copy, Debug, PartialEq)]
pub enum HIDDescriptor {
    HID = 0x21,
}

#[derive(Clone, Copy, Debug, PartialEq)]
pub enum OTGFeature {
    BHNPEnable = 3,
    AHNPSupport = 4,
    AAltHNPSupport = 5,
}

#[derive(Clone, Copy, Debug, PartialEq)]
pub enum USBTransferType {
    Control = 0x00,
    Isochronous = 0x01,
    Bulk = 0x02,
    Interrupt = 0x03,
}