/*-
 * Copyright 2021 John-Mark Gurney.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
 */

#include <usbd_cdc_if.h>

#include <string.h>

/* LoRaMac headers */
#include <board.h>
#include <adc.h>
#include <radio.h>
#include <delay.h>

/* lora-irr headers */
#include <misc.h>
#include <strobe_rng_init.h>


char *
findeol(char *pos, size_t len)
{

	while (len) {
		if (*pos == '\r' || *pos == '\n')
			return pos;
		pos++;
		len--;
	}

	return NULL;
}

void
hexdump(const uint8_t *ptr, size_t len)
{
	int i;

	for (i = 0; i < len; i++)
		usb_printf("%02x", ptr[i]);
}

void
txdone(void)
{

	usb_printf("txdone\r\n");
}

void
txtimeout(void)
{

	usb_printf("txtimeout\r\n");
}

void
rxdone(uint8_t *payload, uint16_t size, int16_t rssi, int8_t snr)
{

	usb_printf("rxdone: size: %hu, rssi: %hd, snr: %d\r\ndata: ", size, rssi, snr);
	hexdump(payload, size);
	usb_printf("\r\n");
}

void
rxtimeout(void)
{

	usb_printf("rxtimeout\r\n");
}

void
rxerr(void)
{
	usb_printf("rxerr\r\n");
}

RadioEvents_t revents = {
	.TxDone = txdone,
	.TxTimeout = txtimeout,
	.RxDone = rxdone,
	.RxTimeout = rxtimeout,
	.RxError = rxerr,
};

static uint8_t
hexchartonib(char s)
{

	switch (s) {
	case '0'...'9':
		return s - '0';
	case 'a'...'f':
		return s - 'a' + 10;
	case 'A'...'F':
		return s - 'A' + 10;
	default:
		return -1;
	}
}

static bool
hexdecode(char *buf, size_t len, uint8_t *out)
{
	uint8_t topchr, botchr;

	if (len % 2)
		return false;

	/* NB: only needed to silence a bad gcc warning */
	topchr = -1;

	while (len) {
		if (len % 2) {
			/* bottom nibble */
			botchr = hexchartonib(*buf);
			if (topchr == -1 || botchr == -1)
				return false;

			*out = topchr << 4 | botchr;
			out++;
		} else {
			/* top nibble */
			topchr = hexchartonib(*buf);
		}
		len--;
		buf++;
	}

	return true;
}

static const char pktstart[] = "pkt:";
static const size_t pktstartlen = sizeof pktstart - 1;
static uint8_t pktbuf[128];

static void
process_line(char *start, char *end)
{
	size_t len;

	/* trim off leading CR/NL */
	while (start < end && (*start == '\r' || *start == '\n'))
		start++;

	len = end - start;

	if (len >= pktstartlen && memcmp(start, pktstart, sizeof pktstart - 1) == 0) {
		start += pktstartlen;
		len -= pktstartlen;

		if (len % 2) {
			usb_printf("invalid pkt len\r\n");
			return;
		}
		if (!hexdecode(start, len, pktbuf)) {
			usb_printf("invalid pkt\r\n");
			return;
		}
		Radio.Send(pktbuf, len / 2);
		return;
	}
	usb_printf("line: %.*s", end - start, start);
}

/*
 * Seed the randomness from the radio.  This is not a great
 * seed, and is hard to gauge how much randomness is really
 * there.  Assuming about 1 bit per 8 bits looks pretty safe,
 * so add 256 * 8 / 32 words.
 */
static void
radio_seed_rng(void)
{
#if 1
	uint32_t v;
	int i;

	for (i = 0; i < 256 * 8 / 32; i++) {
		v = Radio.Random();
		strobe_seed_prng((uint8_t *)&v, sizeof v);
	}
#endif
}

static void
analog_seed_rng(void)
{
#if 1
	uint16_t v;
	int i;

	for (i = 0; i < 256 / 2; i++) {
		/*
		 * Capture some ADC data.  If pin is floating, 0xfff
		 * happens frequently, if pin is grounded, 0 happens
		 * frequently, filter these values out.
		 */
		do {
			v = AdcReadChannel(&Adc, ADC_CHANNEL_21);
		} while (v == 0 || v == 0xfff);
		strobe_seed_prng((uint8_t *)&v, sizeof v);
	}
#endif
}

int
main(void)
{
	uint8_t bytes[8];

	strobe_rng_init();

	BoardInitMcu();

	Radio.Init(&revents);

	analog_seed_rng();

	radio_seed_rng();

	strobe_rng_save();

	/* turn on LED */
	HAL_GPIO_WritePin(GPIOB, GPIO_PIN_8, GPIO_PIN_SET);

#if 1
	wait_for_vcp();

	usb_printf("starting...\r\n");

	bare_strobe_randomize(bytes, sizeof bytes);
	hexdump(bytes, sizeof bytes);
	usb_printf("\r\n");
#endif

	uint32_t v;

	usb_printf("gs: %#x\r\n", Radio.GetStatus());

	usb_printf("set modem\r\n");
	Radio.SetModem(MODEM_LORA);

	usb_printf("check rffreq: %d\r\n", (int)Radio.CheckRfFrequency(914350 * 1000));
	usb_printf("set channel\r\n");
	Radio.SetChannel(914350 * 1000);

	v = Radio.Random();
	usb_printf("rr: %#x\r\n", v);

	usb_printf("rssi: %#hx\r\n", Radio.Rssi(MODEM_LORA));

	/* RX/TX parameters */
	const uint8_t modem = MODEM_LORA;
	const uint8_t bandwidth = 0 /* 128 kHz */;
	const uint8_t datarate = 7 /* 128 chips */;
	const uint8_t coderate = 1 /* 4/5 */;
	const uint8_t preambleLen = 4 /* symbols */;
	const uint8_t fixLen = 0 /* variable */;
	const uint8_t crcOn = 1 /* on */;
	const uint8_t freqHopOn = 0 /* off */;
	const bool iqInverted = false /* not inverted */;

	Radio.SetRxConfig(modem, bandwidth, datarate, coderate, 0/*afc*/,
	    preambleLen, 5/*symTimeout*/, fixLen, 0/*payloadlen*/, crcOn,
	    freqHopOn, 0/*hopPeriod*/, iqInverted, true/*rxcont*/);
	Radio.SetTxConfig(modem, 11/*power*/, 0/*fdev*/, bandwidth, datarate,
	    coderate, preambleLen, fixLen, crcOn, freqHopOn, 0/*hopPeriod*/,
	    iqInverted, 1000/*timeout*/);

	uint8_t sendmsg[] = "testing lora123";

	usb_printf("sending...\r\n");
	Radio.Send(sendmsg, sizeof sendmsg);
	DelayMs(200);
	Radio.Send(sendmsg, sizeof sendmsg);
	DelayMs(200);
	Radio.Send(sendmsg, sizeof sendmsg);
	DelayMs(200);

	usb_printf("rx(0)...\r\n");
	Radio.Rx(0);

	char inpbuf[1024];
	char *lastcheck;
	char *endchr;
	int inpbufpos = 0;
	int cpylen;

loop:
	BoardLowPowerHandler();
	if (Radio.IrqProcess != NULL)
		Radio.IrqProcess();

	/* while we have data */
	while (CDC_RX_LEN) {
		/* store last position */
		lastcheck = &inpbuf[inpbufpos];

		/* calculate how much space left */
		cpylen = MIN(sizeof inpbuf - inpbufpos, CDC_RX_LEN);

		/* copy into buffer */
		memcpy(&inpbuf[inpbufpos], CDC_RX_BUFFER, cpylen);

		/* and point to end of buffer */
		inpbufpos += cpylen;

		do {
			/* find first end of line characters */
			endchr = findeol(lastcheck, cpylen);

			if (endchr != NULL) {
				/* if so, process it */
				process_line(inpbuf, endchr);

				/* skip end of line char */
				endchr++;

				/* move remaining buffer to the beginning */
				memmove(inpbuf, endchr, inpbufpos - (endchr - inpbuf));

				/* and store new length */
				inpbufpos = inpbufpos - (endchr - inpbuf);

				/* mark begining of stream as last checked */
				lastcheck = inpbuf;

				/* and try to process another line */
				continue;
			} else if (inpbufpos == sizeof inpbuf) {
				/* we overflowed the buffer */
				/* XXX - best way is to throw away this line */
				inpbufpos = 0;
			}
		} while (0);

		/* if we copied all the data */
		if (cpylen == CDC_RX_LEN) {
			/* declare that we are ready to receive more data */
			CDC_RX_LEN = 0;
			USBD_CDC_ReceivePacket(&hUsbDeviceFS);
		} else {
			/* if not, move the remaining to the begining and try again */
			memmove(CDC_RX_BUFFER, &CDC_RX_BUFFER[cpylen], CDC_RX_LEN - cpylen);
			CDC_RX_LEN -= cpylen;
		}
	}
	goto loop;
}