#include <libopencm3/cm3/nvic.h>
#include <libopencm3/cm3/systick.h>
#include <libopencm3/stm32/rcc.h>
#include <stddef.h>
#include <stdio.h>

#include "adc.h"
#include "usb.h"
#include "ringbuffer.h"
#include "uart.h"

volatile uint32_t tick = 0;
RINGBUFFER_STORAGE(usb_to_uart_buf, 64)
RINGBUFFER_STORAGE(uart_to_usb_buf, 64)
RINGBUFFER_STORAGE(comm_in_buf, 64)
RINGBUFFER_STORAGE(comm_out_buf, 64)

static void sys_tick_setup(void);

static void sys_tick_setup() {
  systick_set_reload(168000);
  systick_set_clocksource(STK_CSR_CLKSOURCE_AHB);
  systick_counter_enable();
  systick_interrupt_enable();
}

void sys_tick_handler() {
  tick++;
}

int main(void) {
#if 0
  rcc_clock_setup_pll(&rcc_hse_25mhz_3v3[RCC_CLOCK_3V3_84MHZ]);
#else
  rcc_clock_setup_pll(&rcc_hse_12mhz_3v3[RCC_CLOCK_3V3_168MHZ]);
#endif

  RINGBUFFER_INIT(uart_to_usb_buf, 64);
  RINGBUFFER_INIT(usb_to_uart_buf, 64);
  RINGBUFFER_INIT(comm_in_buf, 64);
  RINGBUFFER_INIT(comm_out_buf, 64);

  usb_setup();
  adc_setup();
  uart_setup();
  sys_tick_setup();

  nvic_enable_irq(NVIC_USART3_IRQ);

  while (1) {
    /* Handle control messages through the comms CDC */
    char buf[64];
    unsigned buf_len = 0;
    for (char c; ringbuffer_get(comm_in_buf, (void*)&c, 1); ) {
      switch (c) {
      case 'B':
        buf_len =
            snprintf(buf, sizeof(buf), "%lu\r\n",
                     (unsigned long)adc_bat_voltage());
        ringbuffer_add(comm_out_buf, buf, buf_len);
        break;
      }
    }

    /* Send replies */
    if ((buf_len = ringbuffer_peek(comm_out_buf, &buf[0], sizeof buf))) {
      if (usb_write_cdcacm(ACM_COMM, (void*)buf, buf_len, 1)) {
        ringbuffer_skip(comm_out_buf, buf_len);
      }
    }

    /* Send any available data to the NFC CDC */
    if (!ringbuffer_empty(uart_to_usb_buf)) {
      unsigned len = ringbuffer_peek(uart_to_usb_buf, &buf[0], sizeof buf);
      if(usb_write_cdcacm(ACM_NFC, buf, len, 1)) {
        ringbuffer_skip(uart_to_usb_buf, len);
      }
    }
    if (!ringbuffer_empty(usb_to_uart_buf)) {
      usart_enable_tx_interrupt(USART3);
    }

    usbd_poll(g_usbd_dev);
    __asm__("wfi");
  }
}

void usart3_isr() {
  while (USART_SR(USART3) & USART_SR_RXNE) {
    uint8_t c = usart_recv(USART3);
    ringbuffer_add(uart_to_usb_buf, (void *)&c, 1);
  }
  while (USART_SR(USART3) & USART_SR_TXE) {
    if (ringbuffer_empty(usb_to_uart_buf)) {
      usart_disable_tx_interrupt(USART3);
      break;
    } else {
      uint8_t c;
      ringbuffer_get(usb_to_uart_buf, &c, 1);
      usart_send(USART3, c);
    }
  }
}