extern crate rusb;

use rusb::{DeviceHandle, Direction, GlobalContext, Recipient, RequestType};
use std::time::Duration;

// const BLOCK_DEMODB: u16 = 0;
const BLOCK_USBB: u16 = 1;
const BLOCK_SYSB: u16 = 2;
// const BLOCK_TUNB: u16 = 3;
const BLOCK_IICB: u8 = 6;

const ADDR_USB_SYSCTL: u16 = 0x2000;
// const ADDR_USB_CTRL: u16 = 0x2010;
// const ADDR_USB_STAT: u16 = 0x2014;
// const ADDR_USB_EPA_CFG: u16 = 0x2144;
const ADDR_USB_EPA_CTL: u16 = 0x2148;
const ADDR_USB_EPA_MAXPKT: u16 = 0x2158;
// const ADDR_USB_EPA_MAXPKT_2: u16 = 0x215a;
// const ADDR_USB_EPA_FIFO_CFG: u16 = 0x2160;

const ADDR_SYS_DEMOD_CTL: u16 = 0x3000;
const ADDR_SYS_DEMOD_CTL_1: u16 = 0x300b;

const FIR_LENGTH: usize = 20;
const FIR_DEFAULT: [u8; FIR_LENGTH] = [
    0xca, 0xdc, 0xd7, 0xd8, 0xe0, 0xf2, 0x0e, 0x35, 0x06, 0x50, 0x9c, 0x0d, 0x71, 0x11, 0x14, 0x71,
    0x74, 0x19, 0x41, 0xa5,
];

const DEF_RTL_XTAL_FREQ: u32 = 28800000;
// const MIN_RTL_XTAL_FREQ: u32 = DEF_RTL_XTAL_FREQ - 1000;
// const MAX_RTL_XTAL_FREQ: u32 = DEF_RTL_XTAL_FREQ + 1000;

const CTRL_TIMEOUT: Duration = Duration::from_millis(300);

pub struct RtlSdrDeviceHandle {
    handle: DeviceHandle<GlobalContext>,
    iface_id: u8,
    kernel_driver_active: bool,
}

/// A wrapper around libusb's DeviceHandle that implements
/// various rtl-sdr specific methods
impl RtlSdrDeviceHandle {
    pub fn new(handle: DeviceHandle<GlobalContext>, iface_id: u8) -> RtlSdrDeviceHandle {
        let mut handle = RtlSdrDeviceHandle {
            handle,
            iface_id,
            kernel_driver_active: false,
        };
        handle.detach_kernel_driver();
        handle
    }

    pub fn detach_kernel_driver(&mut self) {
        let active = match self.handle.kernel_driver_active(self.iface_id) {
            Ok(true) => {
                self.handle.detach_kernel_driver(self.iface_id).ok();
                true
            }
            _ => false,
        };
        self.kernel_driver_active = active;
    }

    pub fn attach_kernel_driver(&mut self) {
        if self.kernel_driver_active {
            self.handle.attach_kernel_driver(self.iface_id).ok();
        }
    }

    pub fn claim_interface(&mut self) {
        self.handle.claim_interface(self.iface_id).unwrap()
    }

    pub fn write_reg(&self, block: u16, addr: u16, val: u16, len: u8) -> usize {
        let type_vendor_out =
            rusb::request_type(Direction::Out, RequestType::Vendor, Recipient::Device);
        let mut data: [u8; 2] = [0, 0];
        let index: u16 = (block << 8) | 0x10;

        // switching endianness???
        data[0] = if len == 1 {
            (val & 0xff) as u8
        } else {
            (val >> 8) as u8
        };
        data[1] = (val & 0xff) as u8;

        match self
            .handle
            .write_control(type_vendor_out, 0, addr, index, &data, CTRL_TIMEOUT)
        {
            Ok(n) => n,
            Err(_) => 0,
        }
    }

    pub fn demod_read_reg(&self, page: u8, addr: u16, _len: u8) -> u16 {
        let type_vendor_in =
            rusb::request_type(Direction::In, RequestType::Vendor, Recipient::Device);
        let data: [u8; 2] = [0, 0];
        let index: u16 = page.into();
        let addr = (addr << 8) | 0x20;
        let _res = self
            .handle
            .write_control(type_vendor_in, 0, addr, index, &data, CTRL_TIMEOUT);
        let reg: u16 = ((data[1] as u16) << 8) | (data[0] as u16);
        return reg;
    }

    pub fn demod_write_reg(&self, page: u8, addr: u16, val: u16, len: u8) -> u16 {
        let type_vendor_out =
            rusb::request_type(Direction::Out, RequestType::Vendor, Recipient::Device);
        let mut data: [u8; 2] = [0, 0];
        let index: u16 = (0x10 | page).into();
        let addr = (addr << 8) | 0x20;

        data[0] = if len == 1 {
            (val & 0xff) as u8
        } else {
            (val >> 8) as u8
        };
        data[1] = (val & 0xff) as u8;

        let _res = self
            .handle
            .write_control(type_vendor_out, 0, addr, index, &data, CTRL_TIMEOUT);
        self.demod_read_reg(0x0a, 0x01, 1)
    }

    pub fn read_array(&self, block: u8, addr: u16, arr: &mut [u8], _len: u8) -> usize {
        let type_vendor_in =
            rusb::request_type(Direction::In, RequestType::Vendor, Recipient::Device);
        let index: u16 = (block as u16) << 8;
        self.handle
            .read_control(type_vendor_in, 0, addr, index, arr, CTRL_TIMEOUT)
            .unwrap()
    }

    pub fn write_array(
        &self,
        block: u8,
        addr: u16,
        arr: &[u8],
        _len: u8,
    ) -> Result<usize, rusb::Error> {
        let type_vendor_out =
            rusb::request_type(Direction::Out, RequestType::Vendor, Recipient::Device);
        let index: u16 = ((block as u16) << 8) | 0x10;
        self.handle
            .write_control(type_vendor_out, 0, addr, index, arr, CTRL_TIMEOUT)
    }

    pub fn i2c_read_reg(&self, i2c_addr: u8, reg: u8) -> Result<u8, &str> {
        let addr: u16 = i2c_addr.into();
        let reg: [u8; 1] = [reg];
        let mut data: [u8; 1] = [0];

        match self.write_array(BLOCK_IICB, addr, &reg, 1) {
            Ok(_res) => {
                self.read_array(BLOCK_IICB, addr, &mut data, 1);
                Ok(data[0])
            }
            Err(_) => Err("Error"),
        }
    }

    pub fn set_i2c_repeater(&self, on: bool) {
        let val = match on {
            true => 0x18,
            false => 0x10,
        };
        self.demod_write_reg(1, 0x01, val, 1);
    }

    pub fn test_write(&self) {
        self.write_reg(BLOCK_USBB, ADDR_USB_SYSCTL, 0x09, 1);
    }

    pub fn init_baseband(&self) {
        // init USB
        self.write_reg(BLOCK_USBB, ADDR_USB_SYSCTL, 0x09, 1);
        self.write_reg(BLOCK_USBB, ADDR_USB_EPA_MAXPKT, 0x0002, 2);
        self.write_reg(BLOCK_USBB, ADDR_USB_EPA_CTL, 0x1002, 2);

        // power on demod
        self.write_reg(BLOCK_SYSB, ADDR_SYS_DEMOD_CTL_1, 0x22, 1);
        self.write_reg(BLOCK_SYSB, ADDR_SYS_DEMOD_CTL, 0xe8, 1);

        // reset demod (bit 3, soft_rst)
        self.demod_write_reg(1, 0x01, 0x14, 1);
        self.demod_write_reg(1, 0x01, 0x10, 1);

        // disable spectrum inversion and adjacent channel rejection
        self.demod_write_reg(1, 0x15, 0x00, 1);
        self.demod_write_reg(1, 0x16, 0x0000, 2);

        // clear both DDC shift and IF frequency registers
        for i in 0..6 {
            self.demod_write_reg(1, 0x16 + i, 0x00, 1);
        }

        // set the FIR coefficients
        for i in 0..FIR_LENGTH {
            self.demod_write_reg(1, (0x1c + i) as u16, FIR_DEFAULT[i].into(), 1);
        }

        // enable SDR mode, disable DAGC (bit 5)
        self.demod_write_reg(0, 0x19, 0x05, 1);

        // init FSM state-holding register
        self.demod_write_reg(1, 0x93, 0xf0, 1);
        self.demod_write_reg(1, 0x94, 0x0f, 1);

        // disable AGC (en_dagc, bit 0) (this seems to have no effect)
        self.demod_write_reg(1, 0x11, 0x00, 1);

        // disable RF and IF AGC loop
        self.demod_write_reg(1, 0x04, 0x00, 1);

        // disable PID filter (enable_PID = 0)
        self.demod_write_reg(0, 0x61, 0x60, 1);

        // opt_adc_iq = 0, default ADC_I/ADC_Q datapath
        self.demod_write_reg(0, 0x06, 0x80, 1);

        // Enable Zero-IF mode (en_bbin bit), DC cancellation (en_dc_est),
        // IQ estimation/compensation (en_iq_comp, en_iq_est)
        self.demod_write_reg(1, 0xb1, 0x1b, 1);

        // disable 4.096 MHz clock output on pin TP_CK0
        self.demod_write_reg(0, 0x0d, 0x83, 1);
    }

    pub fn set_if_freq(&self, freq: u32) {
        let rtl_xtal: u32 = DEF_RTL_XTAL_FREQ; // need to apply PPM correction
        let base = 1u32 << 22;
        let if_freq: i32 = (freq as f64 * base as f64 / rtl_xtal as f64 * -1f64) as i32;

        let tmp = ((if_freq >> 16) as u16) & 0x3f;
        self.demod_write_reg(1, 0x19, tmp, 1);
        let tmp = ((if_freq >> 8) as u16) & 0xff;
        self.demod_write_reg(1, 0x1a, tmp, 1);
        let tmp = if_freq as u16 & 0xff;
        self.demod_write_reg(1, 0x1b, tmp, 1);
    }

    pub fn deinit_baseband(&self) {
        // power off demod and ADCs
        self.write_reg(BLOCK_SYSB, ADDR_SYS_DEMOD_CTL, 0x20, 1);
    }
}

impl Drop for RtlSdrDeviceHandle {
    fn drop(&mut self) {
        self.deinit_baseband();
        self.attach_kernel_driver();
    }
}