#include "ergodox.hpp"



Ergodox::Ergodox(
	unsigned short vendor_id,
	unsigned short product_id,
	unsigned short usage,
	unsigned short usage_page
) :
	vendor_id(vendor_id),
	product_id(product_id),
	usage(usage),
	usage_page(usage_page),
	handle(NULL)
{
	hid_init();
	open();
}



/*
Initialize Ergodox interface.

Should be called once at start of execution. Arguments are the USB parameters of the keyboard.

Returns instance of singleton.
*/
Ergodox& Ergodox::init(
	unsigned short vendor_id,
	unsigned short product_id,
	unsigned short usage,
	unsigned short usage_page
) {
	static bool has_been_initialized = false;
	static Ergodox Instance(
		vendor_id,
		product_id,
		usage,
		usage_page
	);

	// This isn't strictly necessary, but there is no reason
	// to call init() twice.
	if (has_been_initialized) {
		has_been_initialized = true;
		throw std::runtime_error("Ergodox has already been initialized!");
	}

	return Instance;
}


// Instance is a static function variable,
// and will be deleted at end of program.
Ergodox::~Ergodox() {
	close();
	hid_exit();
}


/*
Try to open this keyboard's hid device.
Throws a runtime error if device is already open,
or if we can't find a device with the given params.
*/
void Ergodox::open() {
	if (handle != NULL) {
		throw std::runtime_error("Device already open");
	}

	struct hid_device_info *devs, *cur_dev;
	const char *path_to_open = NULL;

	devs = hid_enumerate(vendor_id, product_id);
	cur_dev = devs;
	while (cur_dev) {
		if (cur_dev->vendor_id == vendor_id &&
			cur_dev->product_id == product_id &&
			cur_dev->usage == usage &&
			cur_dev->usage_page == usage_page
		) {
			path_to_open = cur_dev->path;
			break;
		}
		cur_dev = cur_dev->next;
	}

	if (path_to_open) {
		handle = hid_open_path(path_to_open);
		hid_free_enumeration(devs);
	} else {
		hid_free_enumeration(devs);
		throw std::runtime_error("Could not open hid device");
	}
}


// Close hid device if it is open.
void Ergodox::close() {
	if (handle != NULL) {
		hid_close(handle);
	}
}


/*
Send data to Ergodox.

@param data Data to send
@param length How many bytes to send
@returns Actual number of bytes written, or -1 on error.
*/
int Ergodox::write(uint8_t* data, size_t length) const {
	if (handle == NULL) {
		throw std::runtime_error("Cannot write, device is not open!");
	}

	return hid_write(handle, data, length);
}