#![cfg_attr(test, allow(unused_imports))]
#![cfg_attr(not(test), no_std)]
#![cfg_attr(not(test), no_main)]
#![feature(half_open_range_patterns)]
#![feature(exclusive_range_pattern)]
#![allow(dead_code)]

// custom panic handler
#[cfg(not(test))]
use core::panic::PanicInfo;

use core::{cell::RefCell, ops::DerefMut};
use cortex_m::{interrupt::free, interrupt::Mutex, peripheral::NVIC};
use cortex_m_rt::entry;
use stm32l4xx_hal::{delay::Delay, device::{I2C1, TIM2, TIM7}, gpio::{
        Alternate, Edge, Floating, Input, OpenDrain, Output, PullUp, PushPull, AF4, PA3, PB5, PC15,
    }, gpio::{State, PA10, PA9}, i2c::I2c, interrupt, pac, prelude::*, rcc, stm32::Interrupt, timer::{Timer, Event},
};

mod ds3231;
mod nixie;
mod pca9685;
mod tusb322;

use nixie::*;

// Local peripheral mappings
type RtcInt = PB5<Input<Floating>>;
type FaultInt = PA3<Input<PullUp>>;
type FaultLed = PC15<Output<PushPull>>;
type I2c1 = I2c<I2C1, (PA9<Alternate<AF4, Output<OpenDrain>>>,PA10<Alternate<AF4,Output<OpenDrain>>>)>;
type FpsTimer = Timer<TIM2>;
type CycleTimer = Timer<TIM7>;

// Global peripheral singletons
static RTC_INT: Mutex<RefCell<Option<RtcInt>>> = Mutex::new(RefCell::new(None));
static FAULT_INT: Mutex<RefCell<Option<FaultInt>>> = Mutex::new(RefCell::new(None));
static FAULT_LED: Mutex<RefCell<Option<FaultLed>>> = Mutex::new(RefCell::new(None));
static I2C: Mutex<RefCell<Option<I2c1>>> = Mutex::new(RefCell::new(None));
static REFRESH_TIMER: Mutex<RefCell<Option<FpsTimer>>> = Mutex::new(RefCell::new(None));
static CYCLE_TIMER: Mutex<RefCell<Option<CycleTimer>>> = Mutex::new(RefCell::new(None));
static CLOCK: Mutex<RefCell<Clock>> = Mutex::new(RefCell::new(Clock::default()));

#[cfg(not(test))]
#[entry]
fn main() -> ! {
    // Acquire a singleton instance for the chip's peripherals
    let mut dp = pac::Peripherals::take().unwrap();
    let cp = pac::CorePeripherals::take().unwrap();

    // Consume the raw peripheral and return a new object that implements a higher level API
    let mut flash = dp.FLASH.constrain();
    let mut rcc = dp.RCC.constrain();
    let mut pwr = dp.PWR.constrain(&mut rcc.apb1r1);

    // Configure clocks to run at maximum frequency off internal oscillator
    let clocks = rcc
        .cfgr
        .pll_source(rcc::PllSource::HSI16)
        .sysclk(64.mhz())
        .hclk(64.mhz())
        .pclk1(64.mhz())
        .pclk2(64.mhz())
        .hsi48(true)
        .freeze(&mut flash.acr, &mut pwr);

    // Configure delay timer that operates off systick timer
    let mut delay_timer = Delay::new(cp.SYST, clocks);

    // Split GPIO peripheral into independent pins and registers
    let mut gpioa = dp.GPIOA.split(&mut rcc.ahb2);
    let mut gpiob = dp.GPIOB.split(&mut rcc.ahb2);
    let mut gpioc = dp.GPIOC.split(&mut rcc.ahb2);

    // Configure high voltage PSU enable pin on PA2
    let mut hv_enable = gpioa.pa2.into_push_pull_output_with_state(&mut gpioa.moder, &mut gpioa.otyper, State::Low);

    // Configure serial port
    // let tx = gpiob.pb6.into_af7(&mut gpiob.moder, &mut gpiob.afrl);
    // let rx = gpiob.pb7.into_af7(&mut gpiob.moder, &mut gpiob.afrl);
    // let _serial = Serial::usart1(
    //     dp.USART1,
    //     (tx, rx),
    //     Config::default().baudrate(115_200.bps()),
    //     clocks,
    //     &mut rcc.apb2,
    // );

    // Configure fault LED output on PC15
    let fault_led = gpioc.pc15.into_push_pull_output_with_state(&mut gpioc.moder, &mut gpioc.otyper, State::Low);

    // Store fault LED in static singleton so that it's accessible from anywhere
    free(|cs| {
        FAULT_LED.borrow(cs).replace(Some(fault_led));
    });

    // Configure fault input interrupt on PA3
    let mut fault_int = gpioa.pa3.into_pull_up_input(&mut gpioa.moder, &mut gpioa.pupdr);
    fault_int.make_interrupt_source(&mut dp.SYSCFG, &mut rcc.apb2);
    fault_int.enable_interrupt(&mut dp.EXTI);
    fault_int.trigger_on_edge(&mut dp.EXTI, Edge::FALLING);

    // Sanity check that fault pin isn't already set (active low) before enabling interrupt
    if fault_int.is_high().unwrap() {
        // Configure NVIC mask to enable interrupt source
        unsafe {
            NVIC::unmask(Interrupt::EXTI3);
        }

        // Store fault interrupt in static singleton so that interrupt has access to it
        free(|cs| {
            FAULT_INT.borrow(cs).replace(Some(fault_int));
        });
    } else {
        panic!();
    }

    // Enable RNG peripheral
    let rng = dp.RNG.enable(&mut rcc.ahb2, clocks);

    // Configure I2C SCL pin
    let scl = gpioa.pa9.into_open_drain_output(&mut gpioa.moder, &mut gpioa.otyper);
    let scl = scl.into_af4(&mut gpioa.moder, &mut gpioa.afrh);

    // Configure I2C SDA pin
    let sda = gpioa.pa10.into_open_drain_output(&mut gpioa.moder, &mut gpioa.otyper);
    let sda = sda.into_af4(&mut gpioa.moder, &mut gpioa.afrh);

    // Initialize I2C (configured for 1Mhz, but actually runs at 600kHz)
    let mut i2c = I2c::i2c1(dp.I2C1, (scl, sda), 1.mhz(), clocks, &mut rcc.apb1r1);

    // Initialize TUSB322 (USB Type-C configuration chip)
    tusb322::init(TUSB322_ADDR, &mut i2c);

    // Initialize DS3231 (RTC)
    ds3231::init(DS3231_ADDR, &mut i2c);

    // ds3231::set_date(DS3231_ADDR, &mut i2c, ds3231::Weekday::Wednesday, 15, 9, 21, 20);
    // ds3231::set_time(DS3231_ADDR, &mut i2c, 00, 37, 12);

    // Configure input interrupt pin from DS3231 on PB5
    // Interrupt is pulled high, with open drain on DS3231 
    let mut rtc_int = gpiob.pb5.into_floating_input(&mut gpiob.moder, &mut gpiob.pupdr);
    rtc_int.make_interrupt_source(&mut dp.SYSCFG, &mut rcc.apb2);
    rtc_int.enable_interrupt(&mut dp.EXTI);
    rtc_int.trigger_on_edge(&mut dp.EXTI, Edge::FALLING);

    // Configure NVIC mask to enable interrupt from DS3231
    unsafe { NVIC::unmask(Interrupt::EXTI9_5); }

    // Store RTC interrupt in static singleton so that interrupt has access to it
    free(|cs| {
        RTC_INT.borrow(cs).replace(Some(rtc_int));
    });

    // Configure DAC AMP enable pin for AD8591 on PB1
    let mut _dac_enable = gpiob.pb1.into_push_pull_output_with_state(&mut gpiob.moder, &mut gpiob.otyper, State::High);

    // Configure DAC VIN for AD8591 on PA5
    // Note that this pin should actually be configured as analog output (for DAC)
    // but stm32l4xx_hal doesn't have support for the DAC as of now. We also currently
    // set the output to only the highest possible voltage, so the same functionality
    // can be achieved by configuring the pin as a digital output set to high.
    let mut _dac_output = gpioa.pa5.into_push_pull_output_with_state(&mut gpioa.moder, &mut gpioa.otyper, State::High);

    // Configure PWM enable pin (active low) for PCA9685 on PA7
    let mut pwm_enable = gpioa.pa7.into_push_pull_output_with_state(&mut gpioa.moder, &mut gpioa.otyper, State::High);

    // Initialize the PCA9685 display refresh timer
    let refresh_timer = Timer::tim2(dp.TIM2, nixie::DISPLAY_REFRESH_FPS.hz(), clocks, &mut rcc.apb1r1);

    // Configure NVIC mask to enable interrupt for the display refresh timer
    unsafe { NVIC::unmask(Interrupt::TIM2) };

    // Save display refresh timer in static singleton so that interrupt has access to it
    free(|cs| {
        REFRESH_TIMER.borrow(cs).replace(Some(refresh_timer));
    });

    // Initiaize display cycle timer
    let cycle_timer = Timer::tim7(dp.TIM7, (1000 / nixie::CYCLE_FADE_DURATION_MS).hz(), clocks, &mut rcc.apb1r1);

    // Configure NVIC mask to enable interrupt for display cycle timer
    unsafe { NVIC::unmask(Interrupt::TIM7) };

    // Save display cycle timer in static singleton so that interrupt has access to it
    free(|cs| {
        CYCLE_TIMER.borrow(cs).replace(Some(cycle_timer));
    });

    // Small delay to ensure that PCA9685 is fully powered on before writing to it
    delay_timer.delay_us(10_u32);

    // Initialize PCA9685 (PWM driver)
    pca9685::init(PCA9685_ALL_CALL, &mut i2c);

    // Enable PWM output after PCA9685 has been initialized
    pwm_enable.set_low().unwrap();

    // Store I2C peripheral in global static variable as it is used in interrupt
    free(|cs| {
        I2C.borrow(cs).replace(Some(i2c));
    });

    // Enable the high voltage power supply last
    hv_enable.set_high().unwrap();

    // Cycle through all tubes on powerup
    start_cycle(0);
    start_cycle(1);
    start_cycle(2);
    start_cycle(3);

    loop {
        // Delay before cycling digits to prevent cathode poisoning
        delay_timer.delay_ms(CYCLE_REFRESH_INTERVAL * 1000);

        // Choose a random tube to cycle
        let tube = (rng.get_random_data() % 4) as usize;
        start_cycle(tube);
    }
}

// Trigger the start of a new cycle sequence
fn start_cycle(tube: usize) {
    free(|cs| {
        let mut cycle_timer_ref = CYCLE_TIMER.borrow(cs).borrow_mut();
        let mut clock_ref = CLOCK.borrow(cs).borrow_mut();
        if let Some(ref mut cycle_timer) = cycle_timer_ref.deref_mut() {
            // Trigger the start of a cycling sequence
            clock_ref.deref_mut().cycle_start(tube);

            // Start the timer to cycle through individual digits
            cycle_timer.listen(Event::TimeOut);
        }
    });
}

// Interrupt handler for 1HZ signal from offchip RTC (DS3231)
#[interrupt]
fn EXTI9_5() {
    free(|cs| {
        let mut rtc_int_ref = RTC_INT.borrow(cs).borrow_mut();
        let mut i2c_int_ref = I2C.borrow(cs).borrow_mut();
        let mut refresh_timer_ref = REFRESH_TIMER.borrow(cs).borrow_mut();
        let mut clock_ref = CLOCK.borrow(cs).borrow_mut();
        if let Some(ref mut rtc_int) = rtc_int_ref.deref_mut() {
            if let Some(ref mut i2c) = i2c_int_ref.deref_mut() {
                if let Some(ref mut refresh_timer) = refresh_timer_ref.deref_mut() {
                    // Read new time from DS3231
                    let (second, minute, hour) = ds3231::get_time(DS3231_ADDR, i2c);
                    let (weekday, day, month, _, _) = ds3231::get_date(DS3231_ADDR, i2c);

                    // Calculate new values and account for DST
                    let hour = if ds3231::in_dst(weekday, day, month, hour) { (hour + 1) % 12 } else { hour % 12 };
                    let hour = if hour == 0 { 12 } else { hour };

                    // Trigger the processing of a new time value
                    clock_ref.deref_mut().rtc_tick(second, minute, hour);

                    // Start the refresh timer to update the display
                    refresh_timer.listen(Event::TimeOut);
                    
                    // Clear the interrupt flag for the timer
                    rtc_int.clear_interrupt_pending_bit();
                }
            }
        }
    });
}

// Interrupt handler for fault interrupt from USB monitor (TUSB322)
#[interrupt]
fn EXTI3() {
    free(|cs| {
        let mut nfault_ref = FAULT_INT.borrow(cs).borrow_mut();
        if let Some(ref mut nfault) = nfault_ref.deref_mut() {
            if nfault.check_interrupt() {
                nfault.clear_interrupt_pending_bit();
                panic!();
            }
        }
    });
}

// Interrupt handler for internal timer that drives display refresh rate
#[interrupt]
fn TIM2() {
    free(|cs| {
        let mut i2c_int_ref = I2C.borrow(cs).borrow_mut();
        let mut refresh_timer_ref = REFRESH_TIMER.borrow(cs).borrow_mut();
        let mut clock_ref = CLOCK.borrow(cs).borrow_mut();
        if let Some(ref mut i2c) = i2c_int_ref.deref_mut() {
            if let Some(ref mut refresh_timer) = refresh_timer_ref.deref_mut() {
                // Write new values if values have changed, otherwise disable the refresh timer
                if clock_ref.deref_mut().fps_tick() {
                    clock_ref.deref_mut().write_i2c(i2c);
                    refresh_timer.clear_interrupt(Event::TimeOut);
                } else {
                    refresh_timer.unlisten(Event::TimeOut);
                }
            }
        }
    });
}

// Interrupt handler for internal timer that drives individual digits within a cycle sequence
#[interrupt]
fn TIM7() {
    free(|cs| {
        let mut cycle_timer_ref = CYCLE_TIMER.borrow(cs).borrow_mut();
        let mut refresh_timer_ref = REFRESH_TIMER.borrow(cs).borrow_mut();
        let mut clock_ref = CLOCK.borrow(cs).borrow_mut();
        if let Some(ref mut cycle_timer) = cycle_timer_ref.deref_mut() {
            if let Some(ref mut refresh_timer) = refresh_timer_ref.deref_mut() {
                // Trigger the next step in the cycling sequence
                if clock_ref.deref_mut().cycle_tick() {
                    cycle_timer.unlisten(Event::TimeOut);
                } else {
                    cycle_timer.clear_interrupt(Event::TimeOut);
                }

                // Start the refresh timer to update the display
                refresh_timer.listen(Event::TimeOut);
            }
        }
    });
}

// Helper function to set onboard LED state
fn set_fault_led(state: State) {
    free(|cs| {
        let mut led_ref = FAULT_LED.borrow(cs).borrow_mut();
        if let Some(ref mut led) = led_ref.deref_mut() {
            match state {
                State::High => led.set_high().unwrap(),
                State::Low => led.set_low().unwrap(),
            };
        }
    });
}

// Custom panic handler
#[panic_handler]
#[cfg(not(test))]
fn panic(_info: &PanicInfo) -> ! {
    set_fault_led(State::High);
    loop {
        continue;
    }
}