#include <fstream>
#include <iostream>
#include <sstream>

#include "FileUtils.hpp"
#include "HCNode.hpp"
#include "HCTree.hpp"
#include "cxxopts.hpp"

#define SECOND_ARG 2
#define NUM_CHARS 256

/**
 * Pseudo-decompression method that decompresses files based on ASCII and naive
 * header.
 * Params: infileName - input file, outFileName - output file
 * Returns: void
 */
void pseudoDecompression(string inFileName, string outFileName) {
    ifstream readFile;
    unsigned int nextFreq;
    string num;
    vector<unsigned int> freqs(NUM_CHARS, 0);
    readFile.open(inFileName, ios::binary);
    int i = 0;
    // while file still has bytes to read
    while (std::getline(readFile, num) && i < NUM_CHARS) {
        istringstream freq(num);
        freq >> nextFreq;
        freqs[i] = nextFreq;
        i++;
    }

    // build HCTree
    HCTree tree;
    tree.build(freqs);

    // write to output file
    ofstream writeFile;
    writeFile.open(outFileName);
    // decoded bits
    readFile.clear();
    readFile.seekg(0, readFile.beg);
    int y = 0;
    while (y < NUM_CHARS) {
        readFile.seekg(1, readFile.cur);
        if (readFile.peek() == '\n') {
            y++;
        }
    }
    readFile.seekg(1, readFile.cur);
    while (true) {
        char c = tree.decode(readFile);
        if (readFile.eof()) {
            break;
        }
        writeFile << c;
    }
    readFile.close();
    writeFile.close();
}

/**
 * True decompression method that decompresses files based on bitwise i/o and
 * small header.
 * Params: infileName - input file, outFileName - output file
 * Returns: void
 */
void trueDecompression(string inFileName, string outFileName) {
    ifstream readFile;
    unsigned int nextFreq;
    string num;
    vector<unsigned int> freqs(NUM_CHARS, 0);
    readFile.open(inFileName, ios::binary);
    int i = 0;
    // while file still has bytes to read
    while (std::getline(readFile, num) && i < NUM_CHARS) {
        istringstream freq(num);
        freq >> nextFreq;
        freqs[i] = nextFreq;
        i++;
    }

    // build HCTree
    HCTree tree;
    tree.build(freqs);

    // write to output file
    ofstream writeFile;
    writeFile.open(outFileName, ios::binary);
    // decoded bits
    readFile.clear();
    readFile.seekg(0, readFile.beg);
    int y = 0;
    while (y < NUM_CHARS) {
        readFile.seekg(1, readFile.cur);
        if (readFile.peek() == '\n') {
            y++;
        }
    }
    readFile.seekg(1, readFile.cur);

    string fsizeStr;
    std::getline(readFile, fsizeStr);
    istringstream fsizess(fsizeStr);
    int fsize;
    fsizess >> fsize;

    readFile.clear();
    readFile.seekg(0, readFile.beg);
    y = 0;
    while (y < NUM_CHARS + 1) {
        readFile.seekg(1, readFile.cur);
        if (readFile.peek() == '\n') {
            y++;
        }
    }
    readFile.seekg(1, readFile.cur);

    BitInputStream bis(readFile);
    int decodeCount = 0;
    while (decodeCount < fsize) {
        char c = tree.decode(bis);
        if (readFile.eof()) {
            break;
        }
        writeFile << c;
        decodeCount++;
    }
    readFile.close();
    writeFile.close();
}

/**
 * Main program for running decompression, handles parsing and checking files.
 * Params: argc - # of args, argv - command-line args
 * Returns: 0 if successful exit, 1 otherwise
 */
int main(int argc, char* argv[]) {
    cxxopts::Options options("./uncompress",
                             "Uncompresses files using Huffman Encoding");
    options.positional_help("./path_to_input_file ./path_to_output_file");

    bool isAsciiOutput = false;
    string inFileName, outFileName;
    options.allow_unrecognised_options().add_options()(
        "ascii", "Write output in ascii mode instead of bit stream",
        cxxopts::value<bool>(isAsciiOutput))(
        "input", "", cxxopts::value<string>(inFileName))(
        "output", "", cxxopts::value<string>(outFileName))(
        "h,help", "Print help and exit");

    options.parse_positional({"input", "output"});
    auto userOptions = options.parse(argc, argv);

    if (userOptions.count("help") || !FileUtils::isValidFile(inFileName) ||
        outFileName.empty()) {
        cout << options.help({""}) << std::endl;
        exit(0);
    }

    // check empty input
    if (FileUtils::isEmptyFile(inFileName)) {
        ofstream output(outFileName);
    } else {  // handle decompressing
        if (isAsciiOutput) {
            pseudoDecompression(inFileName, outFileName);
        } else {
            trueDecompression(inFileName, outFileName);
        }
    }
    return 0;
}