#include <cstring>
#include "frame.h"

unsigned char hex_byte_to_byte(unsigned char byte) {
	if (byte >= 'a' && byte <= 'f') return byte - 'a' + 10;
	if (byte >= 'A' && byte <= 'F') return byte - 'A' + 10;
	if (byte >= '0' && byte <= '9') return byte - '0';
	throw std::invalid_argument("Character isn't a hex value!");
}

unsigned char hex_value_to_byte(const unsigned char* hex) {
	// Could've been done with sprintf, however this is faster
	return (hex_byte_to_byte(hex[0]) << 4) | hex_byte_to_byte(hex[1]);
}

unsigned char next_hex_byte(const unsigned char*& iso_tp_frame) {
	if (*iso_tp_frame == '\0')
		throw "Bad";

	char byte = hex_value_to_byte(iso_tp_frame);
	iso_tp_frame += 2;
	return byte;
}

/* Private */

void Frame::parse_frame_str(const unsigned char* iso_tp_frame) {
	// Every two characters in a frame represent the hex value of a single byte
	// Example (spaces added for visual clarity):
	// b0 b1 b2 b3 b4 b5 b6 b7
	// 02 10 C0 00 00 00 00 00

	unsigned char byte0 = next_hex_byte(iso_tp_frame);

	this->type =(FrameType)((byte0 & 0b11110000) >> 4);
	this->size =             byte0 & 0b00001111;

	switch (this->type) {
		// Single frame
		case SF: this->data_size = size;
		         break;

		// First frame
		case FF: {
		         	unsigned char byte1 = next_hex_byte(iso_tp_frame);
		         	this->size = (this->size << 8) | byte1;
		         	this->data_size = 6;
		         }
		         break;

		// Consecutive frame
		case CF: this->index = this->size;
		         this->data_size = 7; // Message objects track total amount of data
		                              // from multipart messages
		         this->size = data_size;
		         break;

		// Flow control frame
		case FC: this->data_size = 2; // The FC flag takes less than a byte, so I'm
		                              // not considering it data. Maybe I should?
		         this->size = 2;
		         break;
	}

	this->data = new unsigned char[this->data_size];
	for (int i = 0; i < this->data_size; ++i) {
		this->data[i] = next_hex_byte(iso_tp_frame);
	}
}

void Frame::free() {
	delete[] this->data;
}

void Frame::copyFrom(const Frame& other) {
	this->type = other.type;
	this->index = other.index;
	this->size = other.size;
	this->data_size = other.data_size;

	this->data = new unsigned char[this->data_size];
	std::memcpy(this->data, other.data, this->data_size);
}

/* Public */

Frame::Frame(const char* iso_tp_frame) : index(0) {
	this->parse_frame_str((const unsigned char*)iso_tp_frame);
}

Frame::~Frame() {
	free();
}

Frame::Frame(const Frame& other) {
	copyFrom(other);
}

Frame& Frame::operator=(const Frame& other) {
	if (this != &other) {
		free();
		copyFrom(other);
	}
	return *this;
}

FrameType Frame::get_type() const {
	return this->type;
}

unsigned char Frame::get_index() const {
	return this->index;
}

unsigned int Frame::get_size() const {
	return this->size;
}

unsigned int Frame::get_data_size() const {
	return this->data_size;
}

const unsigned char* Frame::get_data() const {
	return this->data;
}

std::ostream& operator<<(std::ostream& os, const Frame& f) {
	for (int i = 0; i < f.data_size; ++i) {
		os << (unsigned)f.data[i];
	}
	return os;
}