#include <libusb-1.0/libusb.h>
#include <stdio.h>
#include <stdlib.h>
#include <signal.h>
#include <unistd.h>

// arduino ID vendor and product
#define ID_VENDOR 0x2341
#define ID_PRODUCT 0x01
#define ENDPOINTS_NUMBER 4
#define TIMEOUT 50
#define MAX_DATA 50

void init(libusb_context **context, libusb_device ***devices, ssize_t *devices_count){
	int status = libusb_init(context);
	if(status != 0){perror("libusb_init"); exit(-1);}

	*devices_count = libusb_get_device_list(*context, devices);
	if(*devices_count < 0){perror("libusb_get_device_list"); exit(-1);}
}

libusb_device* searchArduino(libusb_device **devices, ssize_t devices_count){
	for(int i=0; i<devices_count; i++){
		libusb_device *device = devices[i];

		// device description
		struct libusb_device_descriptor desc;
		int status = libusb_get_device_descriptor(device, &desc);
		if(status != 0) continue;
		
		// search for device
		if(desc.idVendor == ID_VENDOR
				&& desc.idProduct == ID_PRODUCT)
			return device;
	}
	return NULL;
}

void openConnection(libusb_device *arduino, libusb_device_handle **handle, struct libusb_config_descriptor **config_desc){
	// open connection
	int status = libusb_open(arduino, handle);
	if(status != 0){ perror("libusb_open"); exit(-1); }
	
	// prepare config
	status = libusb_get_config_descriptor(arduino, 0, config_desc);
	if(status != 0){ perror("libusb_get_config_descriptor"); exit(-1); }
	int configuration = (*config_desc)->bConfigurationValue;

	// detach kernel
	for(int j=0; j<(*config_desc)->bNumInterfaces; j++){
		int interface = (*config_desc)->interface[j].altsetting[0].bInterfaceNumber;
		if(libusb_kernel_driver_active(*handle, interface)){
			status = libusb_detach_kernel_driver(*handle, interface);
			if(status != 0){ perror("libusb_detach_kernel_driver"); exit(-1); }
		}
	}
	
	// use config
	status = libusb_set_configuration(*handle, configuration);
	if(status != 0){ perror("libusb_set_configuration"); exit(-1); }
	
	// claim interfaces
	for(int j=0; j<(*config_desc)->bNumInterfaces; j++){
		struct libusb_interface_descriptor interface_desc = (*config_desc)->interface[j].altsetting[0];
		int interface = interface_desc.bInterfaceNumber;

		status = libusb_claim_interface(*handle, interface);
		if(status != 0){ perror("libusb_claim_interface"); exit(-1); }
	}
}

void getEndpoints(struct libusb_config_descriptor *config_desc, struct libusb_endpoint_descriptor *endpoint_desc_list){
	int count = 0;
	// in interfaces
	for(int j=0; j<config_desc->bNumInterfaces; j++){
		// find endpoints
		for(int k=0; k<config_desc->interface[j].altsetting[0].bNumEndpoints; k++){
			if(count > ENDPOINTS_NUMBER){ printf("getEndpoints: Array out of bound :%d:", count); exit(-1); }
			*(endpoint_desc_list + count) = config_desc->interface[j].altsetting[0].endpoint[k];
			count++;
		}
	}
	//if(count != ENDPOINTS_NUMBER){ printf("Wrong number of endpoints.\nIs this the good device ?\n"); exit(-1); }
}

void start(libusb_context **context, libusb_device ***devices, libusb_device_handle **handle, struct libusb_config_descriptor **config_desc, struct libusb_endpoint_descriptor *endpoint_desc_list){
	// init
	ssize_t devices_count;
	init(context, devices, &devices_count);

	// get arduino device
	libusb_device *arduino = searchArduino(*devices, devices_count);
	if(arduino == NULL){ printf("Arduino device not found\n"); exit(-1); }

	// open connection, use config, detach kernel and claim interfaces
	openConnection(arduino, handle, config_desc);

	// get enpoints
	getEndpoints(*config_desc, endpoint_desc_list);
}

void stop(struct libusb_config_descriptor *config_desc, libusb_device_handle *handle, libusb_device **devices, libusb_context *context){
	// release interfaces
	for(int j=0; j<config_desc->bNumInterfaces; j++){
		struct libusb_interface_descriptor interface_desc = config_desc->interface[j].altsetting[0];
		int interface = interface_desc.bInterfaceNumber;

		int status = libusb_release_interface(handle, interface);
		if(status != 0){ perror("libusb_release_interface"); exit(-1); }
	}
	
	// free config
	libusb_free_config_descriptor(config_desc);

	// close connection
	libusb_close(handle);

	// free device list
	libusb_free_device_list(devices, 1);

	// libusb exit
	libusb_exit(context);
}

void sendData(int endpoint_id, uint8_t data, libusb_device_handle *handle, struct libusb_endpoint_descriptor *endpoint_desc_list){
	if(endpoint_id < 0 || endpoint_id > 1){ printf("(sendData) Wrong endpoint !\nMust be 0 or 1\n"); return; }
	int status = libusb_interrupt_transfer(handle, endpoint_desc_list[endpoint_id].bEndpointAddress, (unsigned char *) &data, 1, NULL, TIMEOUT);
	if(status!=0 && status!=LIBUSB_ERROR_TIMEOUT){ perror("libusb_interrupt_transfer"); exit(-1); }
}

int receiveData(int endpoint_id, uint8_t *data, libusb_device_handle *handle, struct libusb_endpoint_descriptor *endpoint_desc_list){
	if(endpoint_id < 2 || endpoint_id > 3){ printf("(sendData) Wrong endpoint !\nMust be 2 or 3\n"); return -1; }
	int status = libusb_interrupt_transfer(handle, endpoint_desc_list[endpoint_id].bEndpointAddress, (unsigned char *) data, 1, NULL, TIMEOUT);
	if(status!=0 && status!=LIBUSB_ERROR_TIMEOUT){ perror("libusb_interrupt_transfer"); exit(-1); }
	return status;
}

int go = 1;
void signalINT(int sig){
	if(sig == SIGINT){
		go = 0;
	}
}
int main(){
	libusb_context *context;
	libusb_device **devices;
	libusb_device_handle *handle;
	struct libusb_config_descriptor *config_desc;
	struct libusb_endpoint_descriptor endpoint_desc_list[ENDPOINTS_NUMBER];

	// start
	printf("Starting...\n");
	start(&context, &devices, &handle, &config_desc, endpoint_desc_list);
	printf("Start complete\n");

	// singals
	struct sigaction action;
	action.sa_handler = signalINT;
	sigaction(SIGINT, &action, NULL);

	uint8_t data;
	while(go){
		int status = receiveData(2, &data, handle, endpoint_desc_list);
		if(status == 0)
			sendData(0, data, handle, endpoint_desc_list);
	}

	// stop
	printf("\nStopping...\n");
	stop(config_desc, handle, devices, context);
	printf("Stop complete...\n");
}