/**
* This file is part of ORB-SLAM3
*
* Copyright (C) 2017-2020 Carlos Campos, Richard Elvira, Juan J. Gómez Rodríguez, José M.M. Montiel and Juan D. Tardós, University of Zaragoza.
* Copyright (C) 2014-2016 Raúl Mur-Artal, José M.M. Montiel and Juan D. Tardós, University of Zaragoza.
*
* ORB-SLAM3 is free software: you can redistribute it and/or modify it under the terms of the GNU General Public
* License as published by the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* ORB-SLAM3 is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even
* the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License along with ORB-SLAM3.
* If not, see <http://www.gnu.org/licenses/>.
*/


#include<iostream>
#include<algorithm>
#include<fstream>
#include<iomanip>
#include<chrono>
#include <unistd.h>

#include<opencv2/core/core.hpp>

#include<System.h>

using namespace std;

void LoadImages(const string &strPathLeft, const string &strPathRight, const string &strPathTimes,
                vector<string> &vstrImageLeft, vector<string> &vstrImageRight, vector<double> &vTimeStamps);

double ttrack_tot = 0;
int main(int argc, char **argv)
{
    const int num_seq = (argc-3)/3;
    cout << "num_seq = " << num_seq << endl;
    bool bFileName= (((argc-3) % 3) == 1);
    string file_name;
    if (bFileName)
        file_name = string(argv[argc-1]);

    if(argc < 6)
    {
        cerr << endl << "Usage: ./stereo_tum_vi path_to_vocabulary path_to_settings path_to_image_folder1_1 path_to_image_folder2_1 path_to_times_file_1 (path_to_image_folder1_2 path_to_image_folder2_2 path_to_times_file_2 ... path_to_image_folder1_N path_to_image_folder2_N path_to_times_file_N) (trajectory_file_name)" << endl;
        return 1;
    }

    // Load all sequences:
    int seq;
    vector< vector<string> > vstrImageLeftFilenames;
    vector< vector<string> > vstrImageRightFilenames;
    vector< vector<double> > vTimestampsCam;
    vector<int> nImages;

    vstrImageLeftFilenames.resize(num_seq);
    vstrImageRightFilenames.resize(num_seq);
    vTimestampsCam.resize(num_seq);
    nImages.resize(num_seq);

    int tot_images = 0;
    for (seq = 0; seq<num_seq; seq++)
    {
        cout << "Loading images for sequence " << seq << "...";
        LoadImages(string(argv[(3*seq)+3]), string(argv[(2*seq)+4]), string(argv[(2*seq)+5]), vstrImageLeftFilenames[seq], vstrImageRightFilenames[seq], vTimestampsCam[seq]);
        cout << "Total images: " << vstrImageLeftFilenames[seq].size() << endl;
        cout << "Total cam ts: " << vTimestampsCam[seq].size() << endl;
        cout << "first cam ts: " << vTimestampsCam[seq][0] << endl;

        cout << "LOADED!" << endl;

        nImages[seq] = vstrImageLeftFilenames[seq].size();
        tot_images += nImages[seq];

        if((nImages[seq]<=0))
        {
            cerr << "ERROR: Failed to load images for sequence" << seq << endl;
            return 1;
        }

    }

    // Vector for tracking time statistics
    vector<float> vTimesTrack;
    vTimesTrack.resize(tot_images);

    cout << endl << "-------" << endl;
    cout.precision(17);


    // Create SLAM system. It initializes all system threads and gets ready to process frames.
    ORB_SLAM3::System SLAM(argv[1],argv[2],ORB_SLAM3::System::STEREO,true);

    cout << endl << "-------" << endl;
    cout.precision(17);

    cv::Mat imLeft, imRight;

    int proccIm = 0;
    for (seq = 0; seq<num_seq; seq++)
    {
        // Main loop
        proccIm = 0;
        for(int ni=0; ni<nImages[seq]; ni++, proccIm++)
        {

            // Read image from file
            imLeft = cv::imread(vstrImageLeftFilenames[seq][ni],cv::IMREAD_GRAYSCALE);
            imRight = cv::imread(vstrImageRightFilenames[seq][ni],cv::IMREAD_GRAYSCALE);

            double tframe = vTimestampsCam[seq][ni];

            if(imLeft.empty() || imRight.empty())
            {
                cerr << endl << "Failed to load image at: "
                     <<  vstrImageLeftFilenames[seq][ni] << endl;
                return 1;
            }

    #ifdef COMPILEDWITHC11
            std::chrono::steady_clock::time_point t1 = std::chrono::steady_clock::now();
    #else
            std::chrono::monotonic_clock::time_point t1 = std::chrono::monotonic_clock::now();
    #endif

            // Pass the image to the SLAM system
            SLAM.TrackStereo(imLeft,imRight,tframe);

    #ifdef COMPILEDWITHC11
            std::chrono::steady_clock::time_point t2 = std::chrono::steady_clock::now();
    #else
            std::chrono::monotonic_clock::time_point t2 = std::chrono::monotonic_clock::now();
    #endif

            double ttrack= std::chrono::duration_cast<std::chrono::duration<double> >(t2 - t1).count();
            ttrack_tot += ttrack;
            // std::cout << "ttrack: " << ttrack << std::endl;

            vTimesTrack[ni]=ttrack;

            // Wait to load the next frame
            double T=0;
            if(ni<nImages[seq]-1)
                T = vTimestampsCam[seq][ni+1]-tframe;
            else if(ni>0)
                T = tframe-vTimestampsCam[seq][ni-1];

            if(ttrack<T)
                usleep((T-ttrack)*1e6); // 1e6
        }
        if(seq < num_seq - 1)
        {
            cout << "Changing the dataset" << endl;

            SLAM.ChangeDataset();
        }
    }


    // Stop all threads
    SLAM.Shutdown();

    // Tracking time statistics

    // Save camera trajectory
    std::chrono::system_clock::time_point scNow = std::chrono::system_clock::now();
    std::time_t now = std::chrono::system_clock::to_time_t(scNow);
    std::stringstream ss;
    ss << now;

    if (bFileName)
    {
        const string kf_file =  "kf_" + string(argv[argc-1]) + ".txt";
        const string f_file =  "f_" + string(argv[argc-1]) + ".txt";
        SLAM.SaveTrajectoryEuRoC(f_file);
        SLAM.SaveKeyFrameTrajectoryEuRoC(kf_file);
    }
    else
    {
        SLAM.SaveTrajectoryEuRoC("CameraTrajectory.txt");
        SLAM.SaveKeyFrameTrajectoryEuRoC("KeyFrameTrajectory.txt");
    }

    sort(vTimesTrack.begin(),vTimesTrack.end());
    float totaltime = 0;
    for(int ni=0; ni<nImages[0]; ni++)
    {
        totaltime+=vTimesTrack[ni];
    }
    cout << "-------" << endl << endl;
    cout << "median tracking time: " << vTimesTrack[nImages[0]/2] << endl;
    cout << "mean tracking time: " << totaltime/proccIm << endl;

    return 0;
}

void LoadImages(const string &strPathLeft, const string &strPathRight, const string &strPathTimes,
                vector<string> &vstrImageLeft, vector<string> &vstrImageRight, vector<double> &vTimeStamps)
{
    ifstream fTimes;
    cout << strPathLeft << endl;
    cout << strPathRight << endl;
    cout << strPathTimes << endl;
    fTimes.open(strPathTimes.c_str());
    vTimeStamps.reserve(5000);
    vstrImageLeft.reserve(5000);
    vstrImageRight.reserve(5000);
    while(!fTimes.eof())
    {
        string s;
        getline(fTimes,s);
        if(!s.empty())
        {
            stringstream ss;
            ss << s;
            vstrImageLeft.push_back(strPathLeft + "/" + ss.str() + ".png");
            vstrImageRight.push_back(strPathRight + "/" + ss.str() + ".png");
            double t;
            ss >> t;
            vTimeStamps.push_back(t/1e9);
        }
    }
}