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 * OpenSpace                                                                             *
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 * Copyright (c) 2014-2019                                                               *
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#include <modules/fieldlinessequence/util/webfieldlinesworker.h>

#include <ghoul/logging/logmanager.h>
#include <modules/sync/syncs/httpsynchronization.h>
#include <ghoul/filesystem/filesystem.h>
#include <ghoul/filesystem/file.h>
#include <openspace/util/timemanager.h>
#include <openspace/engine/globals.h>
#include <openspace/json.h>


namespace {
    constexpr const char* _loggerCat = "FieldlinesSequence[ Web FLs Worker ]";
    using json = nlohmann::json;
} // namespace

namespace openspace{
    // CONSTRUCTOR
    WebFieldlinesWorker::WebFieldlinesWorker(std::string syncDir, std::string serverUrl)
    : _syncDir(syncDir), _serverUrl(serverUrl) {
        // Maybe to be used
        _endpointSingleDownload = _serverUrl; // should be set by argument to be more general [DEPRICATED FOR NOW, DO WE NEED THIS?]
    }

    // Destructor, deleting all files that were downloaded during the run.
    WebFieldlinesWorker::~WebFieldlinesWorker() {
        // Cancel any potential download
        if (_downloading && _downloading->hasStarted())
            _downloading->wait();
        // Remove all files
        std::vector<std::string> temp = ghoul::filesystem::Directory(_syncDir).readFiles();
        // Sneaky check, just want to make sure it is only deleting fieldlines for now
        if (temp.back().substr(temp.back().size() - 5) == "osfls" && temp.front().substr(temp.front().size() - 5) == "osfls") {
            std::for_each(temp.begin(), temp.end(), [&](auto it) {
                FileSys.deleteFile(it);
            });
        }
    }
    
    // PUBLIC FUNCTIONS
    void WebFieldlinesWorker::getRangeOfAvailableTriggerTimes(double startTime, double endTime, std::vector<std::pair<double, std::string>> &_triggerTimesWeb){

        // We don't want to keep sending request, if we just get empty responses.
        if (!_noMoreRequests) {
            auto time = global::timeManager.time().ISO8601();
            Time maxTime;
            Time minTime;
            const int timeSpann = 2*86400; // The timespann we would like to request (in seconds) [ 1 day = 86400, 1 week = 604800 ]
            const std::string dataID = "dataID";
            const std::string files = "files";
            std::string stringResult;
            std::vector<std::string> urlList;
            std::vector<std::string> timeList;

            maxTime.setTime(time);
            minTime.setTime(time);
            maxTime.advanceTime(timeSpann);
            minTime.advanceTime(-timeSpann);

            std::string url = _serverUrl + "&time.min=" + minTime.ISO8601() + "&time.max=" + maxTime.ISO8601();
            SyncHttpMemoryDownload mmryDld = SyncHttpMemoryDownload(url);
            HttpRequest::RequestOptions opt = {};
            opt.requestTimeoutSeconds = 0;
            mmryDld.download(opt);

            std::transform(mmryDld.downloadedData().begin(), mmryDld.downloadedData().end(), std::back_inserter(stringResult),
                [](char c) {
                return c;
            });

            auto res = json::parse(stringResult);
            auto temp = std::move(_triggerTimesWeb);
            _triggerTimesWeb.clear(); // Clear old big window

            for (auto& elem : res[files]) {
                timeList.push_back(elem["timestamp"]);
                urlList.push_back(elem["url"]);
            }

            // Just want to make sure there is no error in the parsing, so taking the smallest dimension, but should be the same
            for (int i = 0; i < std::min(timeList.size(), urlList.size()); i++) {
                _triggerTimesWeb.push_back(std::make_pair(triggerTimeString2Double(timeList[i]), urlList[i]));
            }

            std::sort(_triggerTimesWeb.begin(), _triggerTimesWeb.end()); // If by any chance it would not sort in properly

            if (_triggerTimesWeb.size() == 0 || std::equal(temp.begin(),temp.end(),_triggerTimesWeb.begin(), _triggerTimesWeb.end())) // We got an empty response or the same response twice, stahp it
                _strikes++;

            if (_strikes % 2 == 0){ // We have got 2 strikes, no more requests for you, Mr.Sir.
                _bigWindowHasData = (_triggerTimesWeb.size() > 0);
                _noMoreRequests = true;
                acceptableToStartRequestingAgain = std::make_pair(minTime.j2000Seconds(), maxTime.j2000Seconds());
            }     
        }
    }

    // Download all files in the current window
    // This function starts usually in the middle of the window and proceeds to download all future timesteps, 
    // then steps backwards from the startingpoint
    //TODO(Axel): Different behaviour depending on direction the user is moving in, might be wanted?
    void WebFieldlinesWorker::downloadWindow(std::vector<std::pair<double, std::string>> triggerTimes) {
        
        // Helper variables
        int startingPoint = triggerTimes.size() / 2;
        bool downloaded = false;
        bool oneUpdate = false;
        bool fastDownload = global::timeManager.deltaTime() > 1800.0;

        if (fastDownload) startingPoint = triggerTimes.size() - 1;

        // Is there a download thread to be joined and added to the list?
        if (_downloading && _downloading->hasSucceeded() && _newWindow) {
            _downloading->wait();
            addToDownloadedList(_latestDownload);
            _readyToDownload = true;
            // This is to trigger one update of the fieldline timestamp that the user is currently on,
            // while the rest of them will be downloaded in the background, and updated once ready
            if (_latestDownload.second == triggerTimes[startingPoint].second)
                oneUpdate = true;
        }

        if (_readyToDownload) {
            // Forwards
            std::vector<std::pair<double, std::string>>::iterator forwardIt = triggerTimes.begin();
            std::advance(forwardIt, startingPoint);
            std::for_each(forwardIt, triggerTimes.end(), [this, &downloaded](auto it) {
                if (!downloaded && !fileIsOnDisk(it.first)) {
                    downloadOsfls(it);
                    downloaded = true;
                    _doneUpdating = false;
                }
            });

            // Backwards
            if (!downloaded) {
                std::for_each(triggerTimes.rbegin(), triggerTimes.rend(), [this, &downloaded](auto it) {
                    if (!downloaded && !fileIsOnDisk(it.first)) {
                        downloadOsfls(it);
                        downloaded = true;
                        _doneUpdating = false;
                    }
                });
            }
        }

        if ((!downloaded && !_doneUpdating && _newWindow && _readyToDownload && _downloadedSomething) || oneUpdate && _downloadedSomething) {
            // If reach this point, we now know that we have downloaded all the sets
            _readyToUpdateSourceFiles = true;
            if(!oneUpdate)
                _newWindow = false;
            oneUpdate = false;
        }
    }

    // Updates the list of available sourcefiles, owned by renderablefieldlinessequence.
    void WebFieldlinesWorker::updateRFSSourceFiles(std::vector<std::string>& _sourceFiles) {
        if (_readyToUpdateSourceFiles) {
            std::vector<std::string> toInsert;
            std::transform(_downloadedTriggerTimes.begin(), _downloadedTriggerTimes.end(), std::back_inserter(toInsert), [this](auto const& pair) { return _syncDir + FileSys.PathSeparator + pair.second; });
            auto sourcePtr = _sourceFiles.begin();
            std::for_each(toInsert.begin(), toInsert.end(), [&sourcePtr, &_sourceFiles](auto insertableElement) {

                for (sourcePtr; sourcePtr != _sourceFiles.end(); sourcePtr++) {

                    if (sourcePtr != (--_sourceFiles.end())) {
                        if (insertableElement > *sourcePtr && insertableElement < *sourcePtr++) {
                            _sourceFiles.insert(sourcePtr++, insertableElement);
                            break;
                        }
                    }
                    if (insertableElement < *sourcePtr) {
                        sourcePtr = _sourceFiles.insert(sourcePtr, insertableElement);
                        break;
                    }
                    if (insertableElement == *sourcePtr) {
                        break;
                    }
                }
                if (sourcePtr == _sourceFiles.end()) {
                    sourcePtr = _sourceFiles.insert(sourcePtr, insertableElement);
                }
            });

            // Set flags to let anyone interested know that this has been done.
            _readyToUpdateSourceFiles = false;
            _doneUpdating = true;
        }
 
    }

    bool WebFieldlinesWorker::windowIsComplete(){
        return _doneUpdating;
    }

    void WebFieldlinesWorker::flagUpdated() {
        _doneUpdating = false;
    }

    void WebFieldlinesWorker::newWindowToDownload(){
        _newWindow = true;
        _downloadedSomething = false;
    }

    bool WebFieldlinesWorker::edgeMode(){
        if (global::timeManager.time().j2000Seconds() < acceptableToStartRequestingAgain.first || global::timeManager.time().j2000Seconds() > acceptableToStartRequestingAgain.second) {
            _noMoreRequests = false;
            _bigWindowHasData = false;
        }
        return _noMoreRequests && _bigWindowHasData;
    }
    
    std::string WebFieldlinesWorker::downloadOsfls(std::pair<double,std::string> downloadKey){
        _downloadedSomething = true;
        _latestDownload = downloadKey;
        // YYYY-MM-DDTHH-MM-SS.sss.osfls - Might change
        const int fileNameLength = 29;
        const std::string fileName = downloadKey.second.substr(downloadKey.second.size()-fileNameLength);
        std::string url = downloadKey.second;
        std::string destinationpath = absPath(_syncDir + ghoul::filesystem::FileSystem::PathSeparator + fileName); // what the downloaded filename is to be
        _downloading = std::make_unique<AsyncHttpFileDownload>(url, destinationpath, HttpFileDownload::Overwrite::Yes);
        HttpRequest::RequestOptions opt = {};
        opt.requestTimeoutSeconds = 0;
        _downloading->start(opt);
        _readyToDownload = false;
        return destinationpath;
    }

    // This function searches for triggerTime in _downloadedTriggerTimes, 
    // to see weather a file has already been downloaded or not
    bool WebFieldlinesWorker::fileIsOnDisk(double triggerTime){
        if(std::find_if(_downloadedTriggerTimes.begin(), _downloadedTriggerTimes.end(),
            [&triggerTime](std::pair<double, std::string> const &element){
            return element.first == triggerTime;
        }) != _downloadedTriggerTimes.end())
            return true;
        else
            return false;
    }
    
    void WebFieldlinesWorker::checkForExistingData(std::vector<std::tuple<double, std::string, int>>& _triggerTimesWeb,
                                                              std::vector<std::pair<double, std::string>>& _triggerTimesOnDisk){
        int indexWeb = 0;
        int indexDisk = 0;
        
        while(true){
            if(compareTimetriggersEqual(std::get<0>(_triggerTimesWeb[indexWeb]), _triggerTimesOnDisk[indexDisk].first)){
                std::get<1>(_triggerTimesWeb[indexWeb]) = _triggerTimesOnDisk[indexDisk].second;
            }
        }
    }
    
    // PRIVATE FUNCTIONS
    void WebFieldlinesWorker::parseTriggerTimesList(std::string s, std::vector<std::tuple<double, std::string, int>> &_triggerTimesWeb){
        // Turn into stringstream to parse the comma-delimited string into vector
        std::stringstream ss(s);
        char c;
        std::string sub;
        while(ss >> c)
        {
            if (c == '[' || c == ']' || c == '"' ) continue;
            else if (c == ','){
                _triggerTimesWeb.push_back(std::make_tuple(triggerTimeString2Double(sub), sub, -1));
                sub.clear();
            }
            else sub += c;
        }

        _triggerTimesWeb.push_back(std::make_tuple(triggerTimeString2Double(sub), sub, -1));
    }
    
    double WebFieldlinesWorker::triggerTimeString2Double(std::string s){
        s.replace(13, 1, ":");
        s.replace(16, 1, ":");
        Time time = Time();
        time.setTime(s);
        return (time.j2000Seconds() /*- 69.185013294*/); // openspace timeconverter gives an error. but we're gonna be consistent with the error
    }
    
    void WebFieldlinesWorker::triggerTimeDouble2String(double i, std::string& s){
        double temp = i /*+ 69.185013294*/;
        Time time = Time();
        time.setTime(temp);
        s = time.ISO8601();
        s.replace(13, 1, "-");
        s.replace(16, 1, "-");
    }
    
    // Inserts the pair in sorted order
    void WebFieldlinesWorker::addToDownloadedList(std::pair<double, std::string> pair){
        const std::string fileName = pair.second.substr(pair.second.size() - 29);
        _downloadedTriggerTimes.insert(std::upper_bound(_downloadedTriggerTimes.begin(),_downloadedTriggerTimes.end(),pair),std::make_pair(pair.first, fileName));
    }

    bool WebFieldlinesWorker::compareTimetriggersEqual(double first, double second){
        double eps = 100.0;
        if(first > second - eps && first < second + eps) return true;
        return false;
    }
    
} // namespace openspace