// Copyright 2019 Robin Krahl <robin.krahl@ireas.org>
// SPDX-License-Identifier: GPL-3.0-or-later

use serde::Serialize;
use serde_big_array::big_array;
use usb_device::bus::{UsbBus, UsbBusAllocator};
use usb_device::device::{UsbDevice, UsbDeviceBuilder, UsbVidPid};

use crate::commands::{CommandId, COMMAND_LEN};
use crate::hid::{HidDevice, Protocol, ReportType, Subclass};
use crate::util::TryFrom;

const VID_CLAY_LOGIC: u16 = 0x20a0;
const PID_NITROKEY_PRO: u16 = 0x4108;

const REPORT_LEN: usize = 64;
const REPORT_DESCRIPTOR: &[u8] = &[
    0x05, 0x01, 0x09, 0x06, 0xA1, 0x01, 0x05, 0x07, 0x19, 0xE0, 0x29, 0xE7, 0x15, 0x00, 0x25, 0x01,
    0x75, 0x01, 0x95, 0x08, 0x81, 0x02, 0x95, 0x01, 0x75, 0x08, 0x81, 0x03, 0x95, 0x05, 0x75, 0x01,
    0x05, 0x08, 0x19, 0x01, 0x29, 0x05, 0x91, 0x02, 0x95, 0x01, 0x75, 0x03, 0x91, 0x03, 0x95, 0x06,
    0x75, 0x08, 0x15, 0x00, 0x25, 0x65, 0x05, 0x07, 0x19, 0x00, 0x29, 0x65, 0x81, 0x00, 0x09, 0x03,
    0x75, 0x08, 0x95, 0x40, 0xB1, 0x02, 0xC0,
];

big_array! { BigArray; COMMAND_LEN, }

enum_u8! {
    #[derive(Clone, Copy, Debug, PartialEq)]
    pub enum DeviceStatus {
        Ok = 0,
        Busy = 1,
        Error = 2,
        ReceivedReport = 3,
    }
}

enum_u8! {
    #[derive(Clone, Copy, Debug, PartialEq)]
    pub enum CommandStatus {
        Ok = 0,
        WrongCrc = 1,
        WrongSlot = 2,
        SlotNotProgrammed = 3,
        WrongPassword = 4,
        NotAuthorized = 5,
        TimestampWarning = 6,
        NoNameError = 7,
        NotSupported = 8,
        UnknownCommand = 9,
        AesDecryptionFailed = 10,
    }
}

#[derive(Serialize)]
struct Response {
    pub device_status: DeviceStatus,
    pub command_id: u8,
    pub last_crc: [u8; 4],
    pub command_status: CommandStatus,
    #[serde(with = "BigArray")]
    pub data: [u8; COMMAND_LEN],
    pub crc: u32,
}

impl Response {
    fn new(device_status: DeviceStatus, command_id: u8) -> Response {
        Response {
            device_status,
            command_id,
            last_crc: [0; 4],
            command_status: CommandStatus::NotSupported,
            data: [0; COMMAND_LEN],
            crc: 0,
        }
    }
}

pub struct Nitrokey {
    buf: [u8; REPORT_LEN],
}

impl Nitrokey {
    pub fn new() -> Self {
        Nitrokey {
            buf: [0; REPORT_LEN],
        }
    }
}

impl HidDevice for Nitrokey {
    fn subclass(&self) -> Subclass {
        Subclass::BootInterface
    }

    fn protocol(&self) -> Protocol {
        Protocol::Keyboard
    }

    fn report_descriptor(&self) -> &[u8] {
        REPORT_DESCRIPTOR
    }

    fn get_report(&mut self, report_type: ReportType, report_id: u8) -> Result<&[u8], ()> {
        if report_type != ReportType::Feature || report_id != 0 {
            return Err(());
        }

        let mut response = Response::new(DeviceStatus::Ok, self.buf[0]);
        response.last_crc = [self.buf[60], self.buf[61], self.buf[62], self.buf[63]];
        response.command_status = if let Ok(command_id) = CommandId::try_from(response.command_id) {
            command_id.execute(&self.buf[1..60], &mut response.data)
        } else {
            CommandStatus::UnknownCommand
        };
        // TODO: calculate actual CRC
        response.crc = 1; // libnitrokey accepts any non-zero value

        let len = ssmarshal::serialize(&mut self.buf, &response).map_err(|_| ())?;
        assert!(len == REPORT_LEN);
        Ok(&self.buf)
    }

    fn set_report(
        &mut self,
        report_type: ReportType,
        report_id: u8,
        data: &[u8],
    ) -> Result<(), ()> {
        if report_type != ReportType::Feature || report_id != 0 || data.len() != REPORT_LEN {
            Err(())
        } else {
            self.buf.copy_from_slice(data);
            Ok(())
        }
    }
}

pub fn create_usb_device<B: UsbBus>(alloc: &UsbBusAllocator<B>) -> UsbDevice<'_, B> {
    UsbDeviceBuilder::new(alloc, UsbVidPid(VID_CLAY_LOGIC, PID_NITROKEY_PRO))
        .manufacturer("Nitrokey/ntw")
        .product("Nitrokey Pro/ntw")
        .serial_number("?")
        .build()
}