// Copyright lowRISC contributors (OpenTitan project).
// Licensed under the Apache License, Version 2.0, see LICENSE for details.
// SPDX-License-Identifier: Apache-2.0

use std::cell::RefCell;
use std::rc::Rc;

use anyhow::{bail, ensure, Context, Result};

use crate::io::gpio::GpioPin;
use crate::io::spi::Target;
use crate::io::uart::Uart;
use crate::transport::{
    Capabilities, Capability, Transport, TransportError, TransportInterfaceType,
};

pub mod gpio;
pub mod mpsse;
pub mod spi;
pub mod uart;

#[derive(Default)]
pub struct Ultradebug {
    pub usb_vid: Option<u16>,
    pub usb_pid: Option<u16>,
    pub usb_serial: Option<String>,
    // A ref-counted pointer to an MPSSE context for FTDI interface B.  This is needed because
    // interface B contains both the SPI and GPIO functions on ultradebug.
    mpsse_b: RefCell<Option<Rc<RefCell<mpsse::Context>>>>,
    inner: RefCell<Inner>,
}

#[derive(Default)]
struct Inner {
    gpio: Option<Rc<gpio::UltradebugGpio>>,
    spi: Option<Rc<dyn Target>>,
    uart: Option<Rc<dyn Uart>>,
}

impl Ultradebug {
    pub const VID_GOOGLE: u16 = 0x18d1;
    pub const PID_ULTRADEBUG: u16 = 0x0304;

    /// Create a new `Ultradebug` struct, optionally specifying the USB vid/pid/serial number.
    pub fn new(usb_vid: Option<u16>, usb_pid: Option<u16>, usb_serial: Option<String>) -> Self {
        Ultradebug {
            usb_vid,
            usb_pid,
            usb_serial,
            ..Default::default()
        }
    }

    /// Construct an `ftdi::Device` for the specified `interface` on the Ultradebug device.
    pub fn from_interface(&self, interface: ftdi::Interface) -> Result<ftdi::Device> {
        let vid = self.usb_vid.unwrap_or(Ultradebug::VID_GOOGLE);
        let pid = self.usb_pid.unwrap_or(Ultradebug::PID_ULTRADEBUG);

        let mut opener = ftdi::find_by_vid_pid(vid, pid).interface(interface);
        if let Some(serial) = &self.usb_serial {
            opener = opener.serial(serial);
        }

        opener.open().context("FTDI error")
    }

    // Create an instance of an MPSSE context bound to Ultradebug interface B.
    // This is both the SPI and GPIO block on ultradebug.
    fn mpsse_interface_b(&self) -> Result<Rc<RefCell<mpsse::Context>>> {
        let mut mpsse_b = self.mpsse_b.borrow_mut();
        if mpsse_b.is_none() {
            let device = self.from_interface(ftdi::Interface::B)?;

            // Create a new MPSSE context and configure it
            let mut mpdev = mpsse::Context::new(device).context("FTDI error")?;
            mpdev.gpio_direction.insert(
                mpsse::GpioDirection::OUT_0 |   // Clock out
                mpsse::GpioDirection::OUT_1 |   // Master out
                                                // Pin 2 is Master In
                mpsse::GpioDirection::OUT_3 |   // Chip select
                mpsse::GpioDirection::OUT_4 |   // SPI_ZB
                mpsse::GpioDirection::OUT_5 |   // RESET_B
                mpsse::GpioDirection::OUT_6 |   // BOOTSTRAP
                mpsse::GpioDirection::OUT_7, // TGT_RESET
            );

            let _ = mpdev.gpio_get().context("FTDI error")?;
            // Clear the low 3 bits as they are mapped to the SPI pins.
            // The SPI chip select is managed like a normal GPIO.
            // We don't need to change the GPIOs immediately; it is sufficient
            // to cache the value before the next GPIO operation.
            mpdev.gpio_value &= 0xF8;
            *mpsse_b = Some(Rc::new(RefCell::new(mpdev)));
        }
        Ok(Rc::clone(mpsse_b.as_ref().unwrap()))
    }

    /// Construct an `mpsse::Context` for the requested interface.
    pub fn mpsse(&self, interface: ftdi::Interface) -> Result<Rc<RefCell<mpsse::Context>>> {
        match interface {
            // Note: we may want to be able to create an MPSSE for interface A in the future.
            // There are enough IOs for a second SPI bus or for JTAG or I2C busses.
            // For now, only interface B is supported.
            ftdi::Interface::B => self.mpsse_interface_b(),
            _ => {
                bail!(TransportError::UsbOpenError(format!(
                    "I don't know how to create an MPSSE context for interface {:?}",
                    interface
                )));
            }
        }
    }
}

impl Transport for Ultradebug {
    fn capabilities(&self) -> Result<Capabilities> {
        Ok(Capabilities::new(
            Capability::UART | Capability::GPIO | Capability::SPI,
        ))
    }

    fn uart(&self, instance: &str) -> Result<Rc<dyn Uart>> {
        ensure!(
            instance == "0",
            TransportError::InvalidInstance(TransportInterfaceType::Uart, instance.to_string())
        );
        let mut inner = self.inner.borrow_mut();
        if inner.uart.is_none() {
            inner.uart = Some(Rc::new(uart::UltradebugUart::open(self)?));
        }
        Ok(Rc::clone(inner.uart.as_ref().unwrap()))
    }

    fn gpio_pin(&self, instance: &str) -> Result<Rc<dyn GpioPin>> {
        let mut inner = self.inner.borrow_mut();
        if inner.gpio.is_none() {
            inner.gpio = Some(Rc::new(gpio::UltradebugGpio::open(self)?));
        }
        Ok(Rc::new(inner.gpio.as_ref().unwrap().pin(instance)?))
    }

    fn spi(&self, instance: &str) -> Result<Rc<dyn Target>> {
        ensure!(
            instance == "0",
            TransportError::InvalidInstance(TransportInterfaceType::Spi, instance.to_string())
        );
        let mut inner = self.inner.borrow_mut();
        if inner.spi.is_none() {
            inner.spi = Some(Rc::new(spi::UltradebugSpi::open(self)?));
        }
        Ok(Rc::clone(inner.spi.as_ref().unwrap()))
    }
}