Decompress.cpp

#include "Decompress.H"

#include <fstream>
#include <iostream>
#include <string>
#include <math.h>
#include <string.h>

using namespace std;

void Decompress::parseText(){
	ifstream inpFile(_fname);
	
	if (!inpFile.is_open()){
		throw("[Error] Could not open file " + _fname + " in parseText()\n");
	}

	_header = make_shared<Header>(Header());

	char c;
	string val;

	//Retrieve header Size
	while(inpFile.get(c) && c != '/'){
		val += string(1,c);	
	}
	_header->preorderSize = stoi(val);

	//Retrieve Body Size
	val = "";
	while (inpFile.get(c) && c != '/'){
		val += string(1,c);		
	}
	_header->bodySize = stoi(val);

	//Getting PreOrder String
	val = "";
	for (int i = 0; i < ceil((_header->preorderSize)/8.0);i++){
		val += inpFile.get();
	}

	_header->preorderStr = convertToString(val);
	_header->preorderStr = string(_header->preorderStr.begin(),_header->preorderStr.begin()+_header->preorderSize);
	
	//Getting Letters for each leaf in Tree
	int counter = 0;
	for (char c : _header->preorderStr){
		if(c == '1') counter++;
	}

	for (int i = 0; i < counter;i++){
		_header->letters.push(inpFile.get());	
	}
	
	//Getting the body of compressed file and then converting it into string form
	val = "";
	while (inpFile.get(c)){
		val += string(1,c);	
	}
	inpFile.close();
	_header->body = convertToString(val);
	_header->body = string(_header->body.begin(),_header->body.begin()+_header->bodySize);	
}

void Decompress::generateTree(){
	_tree = generateTreeHelper(_header->preorderStr);
}

shared_ptr<Node> Decompress::generateTreeHelper(string& bin){
	if (bin.size() < 1){
		return NULL;
	}

	string bit = string(bin.begin(),bin.begin()+1); // First element in string
	bin = string(bin.begin()+1,bin.end()); //The rest of the string
	shared_ptr<Node> curr;

	if (!bit.compare("1")){
		curr = make_shared<Node>(Node(0,_header->letters.front(),NULL,NULL));
		_header->letters.pop();
	}
	else if (!bit.compare("0")){
		curr = make_shared<Node>(Node(0,'\0',generateTreeHelper(bin),generateTreeHelper(bin)));
	}
	return curr;
}

void Decompress::decompressFile(string output){
	parseText();
	generateTree();
	generateBitMap();

	shared_ptr<Node> curr = _tree;
	string uncompress = "";
	for (char c : _header->body){
		curr = (c == '1') ? curr->right : curr->left;

		if (curr->isLeaf()){
			uncompress += string(1,curr->letter);
			curr = _tree;
		}	
	}

	ofstream outFile(output);
	
	if (!outFile.is_open()) throw("[Error] Could not open filename " + output + "in decompressFile()\n");
	
	outFile << uncompress;
	outFile.close();
	cout << "Decompressed " + _fname + " and saved to " + output << endl;	
}

/*
int main(int argc, char *argv[]){
	using namespace std;
	try{
		Decompress tst = Decompress(argv[1]);
		
		tst.decompressFile();
		tst.printPreorder();
	}
	catch(string &e){cout << e;}
	return 0;
}
*/