use core::{mem::MaybeUninit, ptr::addr_of_mut};

use stm32f4xx_hal::pac;

fn jump_to_bootloader() {
    unsafe {
        cortex_m::interrupt::disable();

        let address: u32 = 0x1FFF0000;

        let device = pac::Peripherals::steal();
        device.SYSCFG.memrm.modify(|_, w| w.bits(0x01));

        let mut p = cortex_m::Peripherals::steal();
        p.SCB.invalidate_icache();
        p.SCB.vtor.write(address as u32);

        cortex_m::interrupt::enable();

        cortex_m::asm::bootload(address as *const u32);
    }
}

const BOOTLOADER_REQUESTED: u32 = 0xdecafbad;

#[link_section = ".uninit.DFU_FLAG"]
static mut DFU_FLAG: MaybeUninit<u32> = MaybeUninit::uninit();

fn get_bootloader_flag() -> u32 {
    unsafe { DFU_FLAG.assume_init() }
}

fn set_bootloader_flag() {
    unsafe { DFU_FLAG.write(BOOTLOADER_REQUESTED) };
}

fn clear_bootloader_flag() {
    unsafe { DFU_FLAG.write(0) };
}

pub fn init() {
    let requested = get_bootloader_flag() == BOOTLOADER_REQUESTED;
    if requested {
        jump_to_bootloader();
    }

    clear_bootloader_flag();
}

pub fn reboot_to_bootloader() -> ! {
    defmt::info!("Rebooting into the bootloader");
    set_bootloader_flag();
    cortex_m::peripheral::SCB::sys_reset();
}