#include <Arduino.h>
#include "crypto_aead.h"
#include "api.h"
#include "uartp.h"

#define MAX_BYTES 172
#define CMDBUF_LEN 200
static uint8_t cmdbuf[CMDBUF_LEN];

#define CRYPTO_BUSY PA7
#define noInterrupts() eclic_global_interrupt_disable()
#define interrupts() eclic_global_interrupt_disable()
#define yield() do {} while(0)

uint8_t npub[CRYPTO_NPUBBYTES];
uint8_t nsec[CRYPTO_NSECBYTES];
uint8_t k[CRYPTO_KEYBYTES];
uint8_t ad[MAX_BYTES];
uint8_t m[MAX_BYTES];
uint8_t c[MAX_BYTES];
unsigned long long int adlen = 0;
unsigned long long int mlen = 0;
unsigned long long int clen = 0;
int res = 0;

void setup();
void loop();

#ifdef __cplusplus
extern "C" {
#endif

static void init_uart0(void)
{
    // enable GPIO clock 
    rcu_periph_clock_enable(RCU_GPIOA);
    // enable USART0 clock 
    rcu_periph_clock_enable(RCU_USART0);  
    // configure USART0
    usart_deinit(USART0);
    usart_baudrate_set(USART0, 4*115200);
    usart_word_length_set(USART0, USART_WL_8BIT);
    usart_stop_bit_set(USART0, USART_STB_1BIT);
    usart_parity_config(USART0, USART_PM_NONE);
    usart_hardware_flow_rts_config(USART0, USART_RTS_DISABLE);
    usart_hardware_flow_cts_config(USART0, USART_CTS_DISABLE);
    usart_receive_config(USART0, USART_RECEIVE_ENABLE);
    usart_transmit_config(USART0, USART_TRANSMIT_ENABLE);
    usart_enable(USART0);
}

void uart_wbyte(uint8_t x) {
    while (usart_flag_get(USART0, USART_FLAG_TBE) == RESET);
    usart_data_transmit(USART0, x);
    while (usart_flag_get(USART0, USART_FLAG_TBE) == RESET);
}

uint8_t uart_rbyte() {
    while (usart_flag_get(USART0, USART_FLAG_RBNE) == RESET);
    return (uint8_t) usart_data_receive(USART0);
}

void uart_wstr(const char *str) {
    char x;
    while ((x = *(str++)) != 0) {
        uart_wbyte((uint8_t) x);
    }
}

#ifdef __cplusplus
}
#endif

void my_assert(bool b) {
    if (b)
        return;
    for(;;)
        yield();
}

void setup() {
    init_uart0();
    pinMode(CRYPTO_BUSY, OUTPUT);
    digitalWrite(CRYPTO_BUSY, HIGH);
    delay(100);
    memset(npub, 0, CRYPTO_NPUBBYTES);
    memset(nsec, 0, CRYPTO_NSECBYTES);
    memset(k, 0, CRYPTO_KEYBYTES);
    memset(ad, 0, MAX_BYTES);
    memset(m, 0, MAX_BYTES);
    memset(c, 0, MAX_BYTES);
    uart_wstr("Hello, World!");
}

void loop() {
    int res;
    uint16_t len = uartp_recv(cmdbuf, CMDBUF_LEN - 1);
    uint8_t action = cmdbuf[0];
    if (len == 0 || len > CMDBUF_LEN - 1)
        return;

    uint16_t l = len - 1;
    uint16_t rl = 0;
    uint8_t *var = cmdbuf+1;
    switch (action) {
        case 'm': my_assert(l <= MAX_BYTES);        memcpy(m,    var, l); mlen = l; break;
        case 'c': my_assert(l <= MAX_BYTES);        memcpy(c,    var, l); clen = l; break;
        case 'a': my_assert(l <= MAX_BYTES);        memcpy(ad,   var, l); adlen = l; break;
        case 'k': my_assert(l == CRYPTO_KEYBYTES);  memcpy(k,    var, l); break;
        case 'p': my_assert(l == CRYPTO_NPUBBYTES); memcpy(npub, var, l); break;
        case 's': my_assert(l == CRYPTO_NSECBYTES); memcpy(nsec, var, l); break;
        case 'e':
			noInterrupts();
			asm("nop");
            digitalWrite(CRYPTO_BUSY, LOW);
            res = crypto_aead_encrypt(c, &clen, m, mlen, ad, adlen, nsec, npub, k);
            digitalWrite(CRYPTO_BUSY, HIGH);
			asm("nop");
			interrupts();
            break;
        case 'd':
			noInterrupts();
			asm("nop");
            digitalWrite(CRYPTO_BUSY, LOW);
            res = crypto_aead_decrypt(m, &mlen, nsec, c, clen, ad, adlen, npub, k);
            digitalWrite(CRYPTO_BUSY, HIGH);
			asm("nop");
			interrupts();
            break;
        case'M': var = m;    rl = mlen; break;
        case'C': var = c;    rl = clen; break;
        case'A': var = ad;   rl = adlen; break;
        case'K': var = k;    rl = CRYPTO_KEYBYTES; break;
        case'P': var = npub; rl = CRYPTO_NPUBBYTES; break;
        case'S': var = nsec; rl = CRYPTO_NSECBYTES; break;
        case'R': var = (uint8_t *) &res; rl = sizeof(res); break;
        default:
            my_assert(false);
    }
    cmdbuf[0] = action;
    memcpy(cmdbuf+1, var, rl);
    uartp_send(cmdbuf, rl+1);
}