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

#include <opencv4/opencv2/opencv.hpp>
#include <opencv4/opencv2/video/tracking.hpp>
#include <opencv4/opencv2/core/ocl.hpp>
#include <opencv4/opencv2/videoio.hpp>

using namespace cv;
using namespace std;

struct shared_t
{
    vector<Mat> buff;
    string      detectUrl;
    string      recordUrl;
    string      outDir;
    string      postCmd;
    string      conf;
    bool        wrRunning;
    bool        ffRunning;
    int         motion;
    int         secs;
    int         thrWithMotion;
    int         thresh;
    int         pixSize;
    int         postMoIncr;
    int         minRecFrames;
    int         sectionSize;
    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;
}

void vidCap(shared_t *share)
{
    if (share->buff.size() >= share->minRecFrames)
    {
        share->wrRunning = true;

        time_t rawtime;

        time(&rawtime);

        auto timeinfo = localtime(&rawtime);

        char dirName[20];
        char fileName[20];

        strftime(dirName, 20, "%Y%m%d", timeinfo);
        strftime(fileName, 20, "%H%M%S.avi", timeinfo);

        createDirTree(cleanDir(share->outDir) + string("/") + string(dirName));

        auto dstPath = cleanDir(share->outDir) + string("/") + string(dirName) + string("/") + string(fileName);
        auto codec   = VideoWriter::fourcc('M', 'J', 'P', 'G');

        VideoWriter writer;

        writer.open(dstPath, codec, 30.0, share->buff[0].size(), true);

        if (!writer.isOpened())
        {
            cerr << "could not open the output video file for writing: " << dstPath;
        }
        else
        {
            for (; !share->buff.empty(); share->buff.erase(share->buff.begin()))
            {
                writer.write(share->buff[0]);
            }
        }

        share->wrRunning = false;
    }
}

uchar valDiff(uchar valA, uchar valB)
{
    auto diff = 0;

    if (valA > valB) diff = valA - valB;
    if (valA < valB) diff = valB - valA;

    return diff;
}

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

    for (auto y = rowOffs; (y < rows) && share->thrWithMotion == 0; y++)
    {
        for (auto x = colOffs; (x < cols) && share->thrWithMotion == 0; x++)
        {
            auto pixA = imgA.at<uchar>(Point(x, y));
            auto pixB = imgB.at<uchar>(Point(x, y));

            if (valDiff(pixA, pixB) > share->thresh)
            {
                xCnt += 1;

                if (xCnt >= share->pixSize) break;
            }
            else
            {
                xCnt = 0;
            }
        }

        if (xCnt >= share->pixSize)
        {
            yCnt += 1;

            if (yCnt >= share->pixSize)
            {
                share->thrWithMotion += 1;
            }
        }
        else
        {
            xCnt = 0;
            yCnt = 0;
        }
    }
}

bool grayDiff(Mat imgA, Mat imgB, shared_t *share)
{
    share->thrWithMotion = 0;

    auto colBuff  = share->sectionSize;
    auto allRows  = imgA.rows;
    auto allCols  = imgA.cols;
    auto colsOffs = 0;

    vector<thread> thrs;

    while (allCols != 0)
    {
        if (colBuff > allCols)
        {
            colBuff -= (colBuff - allCols);
        }

        thrs.push_back(thread(secDiff, imgA, imgB, allRows, colBuff, 0, colsOffs, share));

        colsOffs += colBuff;
        allCols  -= colBuff;
    }

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

    return share->thrWithMotion != 0;
}

void timer(shared_t *share)
{
    sleep(share->secs);

    if (share->motion == 0)
    {
        share->ffRunning = false;
    }

    if (!share->wrRunning)
    {
        new thread(vidCap, share);
    }
}

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

    cvtColor(src, ret, COLOR_BGR2GRAY);

    return ret;
}

void moDetect(shared_t *share)
{
    auto dCap = VideoCapture(share->detectUrl, CAP_FFMPEG);
    auto rCap = VideoCapture(share->recordUrl, CAP_FFMPEG);

    Mat dFrame, rFrame, dPrev, rPrev;

    while (share->ffRunning)
    {
        if (share->motion == 0) dCap >> dFrame;

        rCap >> rFrame;

        if (dFrame.empty() && (share->motion == 0))
        {
            // broken frames returned from the cameras i've tested this with would cause
            // the entire capture connection to drop, hence why this bit of code is here
            // to detect empty frames (signs of a dropped connection) and attempt
            // re-connect to the cammera.
            dCap.open(share->detectUrl, CAP_FFMPEG);
        }
        else if (rFrame.empty())
        {
            rCap.open(share->recordUrl, CAP_FFMPEG);
        }
        else if (share->motion > 0)
        {
            share->buff.push_back(rFrame.clone());

            share->motion -= 1;
        }
        else if (dPrev.empty() || rPrev.empty())
        {
            dPrev = toGray(dFrame);
            rPrev = rFrame.clone();
        }
        else if (grayDiff(dPrev, toGray(dFrame), share))
        {
            share->buff.push_back(rPrev);
            share->buff.push_back(rFrame.clone());

            share->motion += share->postMoIncr;

            rPrev.release();
            dPrev.release();
        }
        else
        {
            rPrev.release();
            dPrev.release();
        }
    }

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

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();
}

bool rdConf(shared_t *share)
{
    // recording_stream
    // detection_stream
    // output_dir
    // diff_threshold
    // post_cmd
    // duration
    // pixel_size
    // frames_post_motion
    // minimum_recording_frames
    // section_size

    auto ret = false;

    share->retCode = ENOENT;

    ifstream varFile(share->conf.c_str());

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

        do
        {
            getline(varFile, line);

            if (line.rfind("#", 0) != 0)
            {
                if (line.rfind("recording_stream = ", 0) == 0)
                {
                    share->recordUrl = line.substr(19);

                    cout << "recording_stream = " << share->recordUrl << endl;
                }
                else if (line.rfind("detection_stream = ", 0) == 0)
                {
                    share->detectUrl = line.substr(19);

                    cout << "detection_stream = " << share->detectUrl << endl;
                }
                else if (line.rfind("output_dir = ", 0) == 0)
                {
                    share->outDir = line.substr(13);

                    cout << "output_dir = " << share->outDir << endl;
                }
                else if (line.rfind("post_cmd = ", 0) == 0)
                {
                    share->postCmd = line.substr(11);

                    cout << "post_cmd = " << share->postCmd << endl;
                }
                else if (line.rfind("diff_threshold = ", 0) == 0)
                {
                    share->thresh = strtol(line.substr(17).c_str(), NULL, 10);

                    cout << "diff_threshold = " << share->thresh << endl;
                }
                else if (line.rfind("duration = ", 0) == 0)
                {
                    share->secs = strtol(line.substr(11).c_str(), NULL, 10);

                    cout << "duration = " << share->secs << endl;
                }
                else if (line.rfind("pixel_size = ", 0) == 0)
                {
                    share->pixSize = strtol(line.substr(13).c_str(), NULL, 10);

                    cout << "pixel_size = " << share->pixSize << endl;
                }
                else if (line.rfind("frames_post_motion = ", 0) == 0)
                {
                    share->postMoIncr = strtol(line.substr(21).c_str(), NULL, 10);

                    cout << "frames_post_motion = " << share->postMoIncr << endl;
                }
                else if (line.rfind("minimum_recording_frames = ", 0) == 0)
                {
                    share->minRecFrames = strtol(line.substr(27).c_str(), NULL, 10);

                    cout << "minimum_recording_frames = " << share->minRecFrames << endl;
                }
                else if (line.rfind("section_size = ", 0) == 0)
                {
                    share->sectionSize = strtol(line.substr(15).c_str(), NULL, 10);

                    cout << "section_size = " << share->sectionSize << endl;
                }
            }

        } while(!line.empty());

        ret = true;

        share->retCode = 0;
    }

    varFile.close();

    return ret;
}

void showHelp()
{
    cout << "Motion Watch v1.0" << 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.motion    = 0;
        sharedRes.wrRunning = false;

        while (rdConf(&sharedRes))
        {
            sharedRes.ffRunning = true;

            thread th1(timer, &sharedRes);
            thread th2(moDetect, &sharedRes);

            // Wait for the threads to finish
            // Wait for thread t1 to finish
            th1.join();
            // Wait for thread t2 to finish
            th2.join();
        }

        return sharedRes.retCode;
    }

    return EINVAL;
}