#include <iostream>
#include <fstream>
#include <string>
#include <unistd.h>
#include <time.h>
#include <stdlib.h>
#include <sys/stat.h>
#include <errno.h>
#include <vector>
#include <thread>
#include <dirent.h>
#include <filesystem>

#include <opencv4/opencv2/opencv.hpp>
#include <opencv4/opencv2/videoio.hpp>

using namespace cv;
using namespace std;
using namespace std::filesystem;

#define BUF_SZ 10

struct shared_t
{
    string recordUrl;
    string outDir;
    string postCmd;
    string conf;
    string buffDir;
    string concatTxtTmp;
    string concatShTmp;
    string createShTmp;
    string vidEtx;
    bool   init;
    int    tmpId;
    int    colorThresh;
    int    secs;
    int    blockThresh;
    int    blockX;
    int    blockY;
    int    maxDays;
    int    retCode;

} sharedRes;

string cleanDir(const string &path)
{
    if (path[path.size() - 1] == '/')
    {
        return path.substr(0, path.size() - 1);
    }
    else
    {
        return path;
    }
}

bool createDir(const string &dir)
{
    auto ret = mkdir(dir.c_str(), 0777);

    if (ret == -1)
    {
        return errno == EEXIST;
    }
    else
    {
        return true;
    }
}

bool createDirTree(const string &full_path)
{
    size_t pos = 0;
    auto   ret = true;

    while (ret == true && pos != string::npos)
    {
        pos = full_path.find('/', pos + 1);
        ret = createDir(full_path.substr(0, pos));
    }

    return ret;
}

bool fileExists(const string& name)
{
    return access(name.c_str(), F_OK) != -1;
}

void replaceAll(string &str, const string &from, const string &to)
{
    if(from.empty())
        return;

    size_t startPos = 0;

    while((startPos = str.find(from, startPos)) != string::npos)
    {
        str.replace(startPos, from.length(), to);

        startPos += to.length();
    }
}

vector<string> lsFilesInDir(const string &path, const string &ext)
{
    DIR           *dir;
    struct dirent *ent;
    vector<string> names;

    if ((dir = opendir(path.c_str())) != NULL)
    {
        while ((ent = readdir(dir)) != NULL)
        {
            auto name = string(ent->d_name);

            if ((name.size() >= 4) && (ent->d_type & DT_REG))
            {
                if (name.substr(name.size() - 4) == ext)
                {
                    names.push_back(name);
                }
            }
        }

        closedir(dir);
    }

    sort(names.begin(), names.end());

    return names;
}

void enforceMaxDays(shared_t *share)
{
    auto names = lsFilesInDir(share->outDir, ".m3u");

    while (names.size() > share->maxDays)
    {
        auto name    = names[0];
        auto plsFile = cleanDir(share->outDir) + "/" + name;
        auto vidFold = cleanDir(share->outDir) + "/." + name.substr(0, name.size() - 4);

        remove(plsFile.c_str());
        remove_all(vidFold.c_str());

        names.erase(names.begin());
    }
}

string genTimeStr(const char *fmt)
{
    time_t rawtime;

    time(&rawtime);

    auto timeinfo = localtime(&rawtime);

    char ret[50];

    strftime(ret, 50, fmt, timeinfo);

    return string(ret);
}

string genDstFile(const string &dirOut, const char *fmt, const string &ext)
{
    createDirTree(cleanDir(dirOut));

    return cleanDir(dirOut) + string("/") + genTimeStr(fmt) + ext;
}

string genTmpFile(const string &dirOut, const string &ext, shared_t *share)
{
    createDirTree(cleanDir(dirOut));

    if (share->tmpId == 9999999)
    {
        share->tmpId = 0;
    }

    return cleanDir(dirOut) + string("/") + to_string(share->tmpId++) + ext;
}

Mat toGray(const Mat &src)
{
    Mat ret;

    cvtColor(src, ret, COLOR_BGR2GRAY);

    return ret;
}

bool pixDiff(const uchar &pixA, const uchar &pixB, shared_t *share)
{
    auto diff = 0;

    if (pixA > pixB) diff = pixA - pixB;
    if (pixB > pixA) diff = pixB - pixA;

    if (diff < share->colorThresh)
    {
        diff = 0;
    }

    return diff != 0;
}

void secDiff(Mat imgA, Mat imgB, int rows, int cols, int rowOffs, int colOffs, bool *mod, shared_t *share)
{
    auto pnts = 0;

    for (auto y = rowOffs; y < rows; y++)
    {
        for (auto x = colOffs; x < cols; x++)
        {
            auto pixA = imgA.at<uchar>(Point(x, y));
            auto pixB = imgB.at<uchar>(Point(x, y));

            if (pixDiff(pixA, pixB, share))
            {
                pnts += 1;

                if (pnts >= share->blockThresh)
                {
                    *mod = true; return;
                }
            }
        }
    }
}

bool imgDiff(Mat prev, Mat next, shared_t *share)
{
    auto numOfXBlocks = prev.cols / share->blockX;
    auto numOfYBlocks = prev.rows / share->blockY;
    auto moInBlock    = false;

    vector<thread> threads;

    for (auto x = 0; (x < numOfXBlocks) && !moInBlock; x += share->blockX)
    {
        for (auto y = 0; (y < numOfYBlocks) && !moInBlock; y += share->blockY)
        {
            threads.push_back(thread(secDiff, prev, next, share->blockY, share->blockX, y, x, &moInBlock, share));
        }
    }

    for (auto &&thr : threads)
    {
        thr.join();
    }

    return moInBlock;
}

string parseForParam(const string &arg, int argc, char** argv, bool argOnly)
{
    for (int i = 0; i < argc; ++i)
    {
        auto argInParams = string(argv[i]);

        if (arg.compare(argInParams) == 0)
        {
            if (!argOnly)
            {
                // check ahead, make sure i + 1 won't cause out-of-range exception
                if ((i + 1) <= (argc - 1))
                {
                    return string(argv[i + 1]);
                }
            }
            else
            {
                return string("true");
            }
        }
    }

    return string();
}

void rdLine(const string &param, const string &line, string *value)
{
    if (line.rfind(param.c_str(), 0) == 0)
    {
        *value = line.substr(param.size());

        //cout << param << *value << endl;
    }
}

void rdLine(const string &param, const string &line, int *value)
{
    if (line.rfind(param.c_str(), 0) == 0)
    {
        *value = strtol(line.substr(param.size()).c_str(), NULL, 10);

        //cout << param << *value << endl;
    }
}

bool rdConf(shared_t *share)
{
    ifstream varFile(share->conf.c_str());

    if (!varFile.is_open())
    {
        share->retCode = ENOENT;

        cerr << "err: Failed to open the config file: " << share->conf << " for reading. please check file permissions or if it exists." << endl;
    }
    else
    {
        string line;

        share->recordUrl.clear();
        share->outDir.clear();
        share->postCmd.clear();
        share->buffDir.clear();

        share->colorThresh  = 5;
        share->secs         = 60;
        share->blockX       = 32;
        share->blockY       = 32;
        share->blockThresh  = 900;
        share->maxDays      = 5;
        share->vidEtx       = "mp4";

        do
        {
            getline(varFile, line);

            if (line.rfind("#", 0) != 0)
            {
                rdLine("recording_stream = ", line, &share->recordUrl);
                rdLine("output_dir = ",       line, &share->outDir);
                rdLine("post_cmd = ",         line, &share->postCmd);
                rdLine("color_threshold = ",  line, &share->colorThresh);
                rdLine("duration = ",         line, &share->secs);
                rdLine("buff_dir = ",         line, &share->buffDir);
                rdLine("block_x = ",          line, &share->blockX);
                rdLine("block_y = ",          line, &share->blockY);
                rdLine("block_threshold = ",  line, &share->blockThresh);
                rdLine("max_days = ",         line, &share->maxDays);
                rdLine("vid_container = ",    line, &share->vidEtx);
            }

        } while(!line.empty());

        if (share->init)
        {
            remove_all(share->buffDir.c_str());

            share->init = false;
        }

        new thread(enforceMaxDays, share);

        share->retCode = 0;
    }

    varFile.close();

    return share->retCode == 0;
}

bool capPair(Mat &prev, Mat &next, VideoCapture &capture, shared_t *share)
{
    capture >> prev;
    capture >> next;

    return !prev.empty() && !next.empty();
}

void wrOut(const string &buffFile, shared_t *share)
{
    auto clnDir = cleanDir(share->outDir);
    auto vidOut = genDstFile(clnDir + "/." + genTimeStr("%Y-%m-%d"), "%H%M%S", "." + share->vidEtx);
    auto m3uOut = vidOut.substr(clnDir.size() + 1);
    auto lisOut = genDstFile(share->outDir, "%Y-%m-%d", ".m3u");

    copy_file(buffFile.c_str(), vidOut.c_str());
    remove(buffFile.c_str());

    ofstream file;

    if (fileExists(lisOut))
    {
        file.open(lisOut.c_str(), ios_base::app);
    }
    else
    {
        file.open(lisOut.c_str());
    }

    file << m3uOut << endl;

    file.close();
}

bool moDetect(const string &buffFile, shared_t *share)
{
    auto mod = false;

    VideoCapture capture(buffFile.c_str(), CAP_FFMPEG);

    if (capture.isOpened())
    {
        Mat prev;
        Mat next;

        while (capPair(prev, next, capture, share))
        {
            if (imgDiff(toGray(prev), toGray(next), share))
            {
                mod = true; break;
            }
        }

        if (mod)
        {
            new thread(wrOut, buffFile, share);
        }
    }
    else
    {
        cerr << "err: Could not open buff file: " << buffFile << " for reading. check formatting/permissions." << endl;
        cerr << "     Also check if opencv was compiled with FFMPEG encoding enabled." << endl;
    }

    if (!mod)
    {
        remove(buffFile.c_str());
    }

    return mod;
}

void recLoop(shared_t *share)
{
    while (rdConf(share))
    {
        auto mod = false;

        for (auto ind = 0; ind < share->secs; ind += BUF_SZ)
        {
            auto bufPath = genTmpFile(share->buffDir, "." + share->vidEtx, share);
            auto secs    = to_string(BUF_SZ);
            auto limSecs = to_string(BUF_SZ + 3);
            auto cmd     = "timeout -k 1 " + limSecs + " ffmpeg -hide_banner -i " + share->recordUrl + " -y -vcodec copy -t " + secs + " " + bufPath;

            if (system(cmd.c_str()) == 0)
            {
                if (mod)
                {
                    new thread(wrOut, bufPath, share);

                    mod = false;
                }
                else if (moDetect(bufPath, share))
                {
                    mod = true;
                    ind = 0;
                }
            }
            else if (fileExists(bufPath))
            {
                remove(bufPath.c_str());
                sleep(BUF_SZ);
            }
        }

        system(share->postCmd.c_str());
    }
}

void showHelp()
{
    cout << "Motion Watch v1.1" << endl << endl;
    cout << "Usage: mow <argument>" << endl << endl;
    cout << "-h : display usage information about this application." << endl;
    cout << "-c : path to the config file." << endl;
}

int main(int argc, char** argv)
{
    sharedRes.conf = parseForParam("-c", argc, argv, false);

    if (parseForParam("-h", argc, argv, true) == "true")
    {
        showHelp();
    }
    else if (sharedRes.conf.empty())
    {
        cerr << "err: A config file was not given in -c" << endl;
    }
    else
    {
        sharedRes.retCode = 0;
        sharedRes.tmpId   = 0;
        sharedRes.init    = true;

        thread th1(recLoop, &sharedRes);

        th1.join();

        return sharedRes.retCode;
    }

    return EINVAL;
}