#include <linux/if.h>
#include <stdio.h>
#include <string.h>
#include <assert.h>
#include <math.h>
#include <liquid/liquid.h>

#include <unistd.h>

#include "utils.h"
#include "layer1/tx.h"
#include "layer1/rx.h"

#include "layer2/tundev.h"

#define RESULT_CHECK(stmt) { \
	result_t res = stmt; \
	if(res != OK) { \
		fprintf(stderr, "Error %d in %s:%d!", res, __FILE__, __LINE__); \
		exit(1); \
	} \
}

static int  m_tunfd = -1;
static bool m_running = true;

void print_complex_array(const char *varname, float complex const *array, size_t len)
{
	fprintf(stderr, "%s=np.array([%f%+fj", varname, crealf(array[0]), cimagf(array[0]));
	for(size_t k = 1; k < len; k++) {
		fprintf(stderr, ", %f%+fj", crealf(array[k]), cimagf(array[k]));
	}
	fprintf(stderr, "])\n");
}


void cb_rx(rx_evt_t evt, uint8_t *packet_data, size_t packet_len)
{
	int ret;

	switch(evt)
	{
		case RX_EVT_CHECKSUM_ERROR:
			fprintf(stderr, "Received a message of %zu bytes, but decoding failed.\n", packet_len);
			//fprintf(stderr, "=== FAILED PAYLOAD ===\n");
			//fprintf(stderr, "%s\n", packet_data);
			//fprintf(stderr, "=======================\n");
			break;

		case RX_EVT_PACKET_RECEIVED:
			fprintf(stderr, "=== DECODED PAYLOAD (%4zu bytes) ===\n", packet_len);
			fprintf(stderr, "%s\n", packet_data);
			fprintf(stderr, "====================================\n");

			ret = write(m_tunfd, packet_data, packet_len);
			if(ret < 0) {
				perror("write");
			}
			break;

		case RX_EVT_PREAMBLE_FOUND:
			fprintf(stderr, "Found preamble!\n");
			break;
	}
}


int main(void)
{
	layer1_tx_t tx;
	layer1_rx_t rx;

	// ** Initialize **

	char devname[IFNAMSIZ] = "hamnet70";
	m_tunfd = tundev_open(devname);

	if(m_tunfd < 0) {
		return 1;
	}

	RESULT_CHECK(layer1_tx_init(&tx));
	RESULT_CHECK(layer1_rx_init(&rx, cb_rx));

	// channel emulation
	channel_cccf channel = channel_cccf_create();

	float snr = 15.0f;
	channel_cccf_add_awgn(channel, -snr, snr);
	channel_cccf_add_carrier_offset(channel, 0.20f, 1.00f);
	//channel_cccf_add_shadowing(channel, 1.00f, 0.1f);

	// ** Process packets **

	uint8_t packetbuf[2048];
	while(m_running) {
		int ret = read(m_tunfd, packetbuf, sizeof(packetbuf));
		if(ret < 0) {
			perror("read");
			break;
		} else if(ret == 0) {
			// no more data
			break;
		}

		fprintf(stderr, "Transmitting packet with %d bytes.\n", ret);

		RESULT_CHECK(layer1_tx_reset(&tx));

		// ** Modulate packet **

		RESULT_CHECK(layer1_tx_add_packet_to_burst(&tx, packetbuf, ret));
		RESULT_CHECK(layer1_tx_finalize_burst(&tx));

		size_t burst_len = layer1_tx_get_sample_count(&tx);
		const float complex *whole_burst = layer1_tx_get_sample_data(&tx);

		dump_array_cf(whole_burst, burst_len, 1.0f, "/tmp/tx.cpx");

		// ** Apply channel distortions **

		float complex msg_received[burst_len];

		channel_cccf_execute_block(channel, whole_burst, burst_len, msg_received);

		// scale the entire signal to give the AGC something to do
		for(size_t i = 0; i < burst_len; i++) {
			msg_received[i] *= 0.02f;
		}

		dump_array_cf(msg_received, burst_len, 1.0f, "/tmp/rx.cpx");

		// ** Receive signal **

		RESULT_CHECK(layer1_rx_process(&rx, msg_received, burst_len));
	}

	// ** Cleanup **

	channel_cccf_destroy(channel);

	layer1_tx_shutdown(&tx);
	layer1_rx_shutdown(&rx);

	fprintf(stderr, "Done.\n");
}