#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 <mutex>

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

using namespace cv;
using namespace std;

#define BUF_SZ 3

struct shared_t
{
    string recordUrl;
    string outDir;
    string postCmd;
    string conf;
    string buffDir;
    string concatTxtTmp;
    string concatShTmp;
    string createShTmp;
    mutex  thrMutex;
    bool   init;
    int    tmpId;
    int    colorThresh;
    int    secs;
    int    blockThresh;
    int    blockX;
    int    blockY;
    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();
    }
}

string genDstFile(const string &dirOut, const string &ext)
{
    time_t rawtime;

    time(&rawtime);

    auto timeinfo = localtime(&rawtime);

    char dateC[20];

    strftime(dateC, 20, "%Y-%m-%d", timeinfo);

    createDirTree(cleanDir(dirOut));

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

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

    share->tmpId += 1;

    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));

            //cout << "pnts: " << pnts << endl;

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

                if (pnts >= share->blockThresh)
                {
                    lock_guard<mutex> guard(share->thrMutex);

                    *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;

        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);
            }

        } while(!line.empty());

        if (share->init)
        {
            system(string("rm -r " + share->buffDir).c_str());

            share->init = false;
        }

        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, const string &dstPath, shared_t *share)
{
    ofstream file;

    auto scriptFile = genTmpFile(share->buffDir, ".sh", share);
    auto scriptData = string();

    if (fileExists(dstPath))
    {
        auto concatFile = genTmpFile(share->buffDir, ".txt", share);
        auto existsFile = genTmpFile(share->outDir, ".ts", share);
        auto concatData = share->concatTxtTmp;

        scriptData = share->concatShTmp;

        replaceAll(concatData, "%existsFile%", existsFile);
        replaceAll(concatData, "%buffFile%", buffFile);

        replaceAll(scriptData, "%existsFile%", existsFile);
        replaceAll(scriptData, "%concatFile%", concatFile);

        file.open(concatFile.c_str());
        file << concatData;
        file.close();
    }
    else
    {
        scriptData = share->createShTmp;
    }

    replaceAll(scriptData, "%buffFile%", buffFile);
    replaceAll(scriptData, "%dstPath%", dstPath);
    replaceAll(scriptData, "%scriptFile%", scriptFile);

    file.open(scriptFile.c_str());
    file << scriptData;
    file.close();

    system(string("sh " + scriptFile + " &").c_str());
}

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)
        {
            auto dstPath = genDstFile(share->outDir, ".ts");

            wrOut(buffFile, dstPath, share);
        }
    }
    else
    {
        cerr << "err: Could not open buff file: " << buffFile << " for reading. check formatting/permissions." << endl;
    }

    if (!mod)
    {
        system(string("rm " + buffFile + " &").c_str());
    }

    return mod;
}

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

        for (auto i = 0; i < share->secs; i += BUF_SZ)
        {
            auto dstPath = genTmpFile(share->buffDir, ".ts", share);
            auto cmd     = "ffmpeg -hide_banner -loglevel error -i " + share->recordUrl + " -y -vcodec copy -t " + to_string(BUF_SZ) + " " + dstPath;

            system(cmd.c_str());

            mod = moDetect(dstPath, share);
        }

        if (!mod)
        {
            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;

        sharedRes.concatTxtTmp += "file '%existsFile%'\n";
        sharedRes.concatTxtTmp += "file '%buffFile%'\n";

        sharedRes.concatShTmp += "#!/bin/sh\n";
        sharedRes.concatShTmp += "cp '%dstPath%' '%existsFile%'\n";
        sharedRes.concatShTmp += "ffmpeg -hide_banner -loglevel error -y -f concat -safe 0 -i '%concatFile%' -c copy '%dstPath%'\n";
        sharedRes.concatShTmp += "rm '%concatFile%'\n";
        sharedRes.concatShTmp += "rm '%existsFile%'\n";
        sharedRes.concatShTmp += "rm '%buffFile%'\n";
        sharedRes.concatShTmp += "rm '%scriptFile%'\n";

        sharedRes.createShTmp += "#!/bin/sh\n";
        sharedRes.createShTmp += "cp '%buffFile%' '%dstPath%'\n";
        sharedRes.createShTmp += "rm '%buffFile%'\n";
        sharedRes.createShTmp += "rm '%scriptFile%'\n";

        thread th1(recLoop, &sharedRes);

        th1.join();

        return sharedRes.retCode;
    }

    return EINVAL;
}