<?php
require __DIR__ . "/vendor/autoload.php";

use GuzzleHttp\Client;

use Monolog\Logger;
use Monolog\Level;
use Monolog\Handler\StreamHandler;

class sync{

    protected $db_host;
    protected $db_name;
    protected $db_user;
    protected $db_password;
    protected $server;

    protected $redis;
    protected $redis_port;
    protected $redis_host;
    protected $redis_ttl;
    protected $redis_timeout = 5;

    protected $db;
    protected $http;

    protected $endpoint;

    protected $logger;
    protected $log_file = __DIR__."/sync.log";

    private $payload;
    protected $server_status_url;

    function __construct(){
        # log service
        $this->logger = new Logger("data-sync");

        $stream_handler = new StreamHandler($this->log_file);
        $this->logger->pushHandler($stream_handler);

        $this->logger->info("initializing sync.");

        # database setup
        $this->db_name      = getenv('DB_DATABASE');
        $this->db_host      = getenv('DB_HOST');
        $this->db_user      = getenv('DB_USERNAME');
        $this->db_password  = getenv('DB_PASSWORD');

        $this->db = new PDO("mysql:host=". $this->db_host .";dbname=". $this->db_name, $this->db_user, $this->db_password);
        $this->db->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);

        if(!$this->db) $this->logger->error("failed to connect to database.");

        $this->logger->debug("Connected to database.");

        # redis 
        $this->redis_host = getenv("REDIS_HOST");
        $this->redis_port = getenv("REDIS_PORT");
        $this->redis_ttl  = getenv("REDIS_TTL");

        $this->redis = new Redis();
        $this->redis->connect($this->redis_host, $this->redis_port, $this->redis_timeout);
        if(!$this->redis) $this->logger->error('Failed to connect to redis server.');

        $this->logger->debug("Connected to redis server.");

        # remote server/endpoint
        $this->server   = getenv("SERVER");
        $this->server_status_url = getenv("SERVER_STATUS_URL");
        $this->endpoint = getenv('SERVER_ENDPOINT');

        $this->http = new Client([
            'base_uri' => $this->server,
            'timeout'  => 3.0,
        ]);

        # fetch data
        $db_data = $this->fetchData();
    }

    function startSync(){

        try{
            if(!$this->endpoint) throw new Exception("No remote server-endpoint specified. sync terminated.");

            $this->logger->info("Checking internet connection.", ["url"=> $this->endpoint ]);

            $response = $this->http->get($this->server_status_url, [
                'timeout'=> 10,
                'http_errors'=> true,
                'headers' => [
                    'Accept' => 'application/json',
                    'X-Requested-With' => 'XMLHttpRequest'
                ],
                'verify'=> true,
                'allow_redirects'=> false
            ]);

            $status_code    = $response->getStatusCode();
            $response_body  = $response->getBody()->getContents();

            if($status_code != 200) throw new Exception("Internet connection unavailable, saving to cache.");

            $this->logger->debug("Internet connection available.", ["status_code"=> $status_code, "response"=> $response_body]);

            $upload_cache = $this->uploadCache();
            if(!$upload_cache) throw new Exception("Upload failed. [". $upload_cache."]");

            $this->logger->info("Internet connection available. uploading data.", ["upload"=> $upload]);

            return true;
        }catch(Exception $ex){
            $this->logger->error($ex->getMessage());

            return false;
        }
    }

    public function fetchData(){
        $this->logger->info("Querying database. ", ["db"=> $this->db_name]);

	    try{
            $previous = $this->db->query("SELECT * FROM signalytic_data")->fetch(PDO::FETCH_ASSOC)['last_fetch_date'];

            if(!$previous) $this->logger->error("last fetch date not found. ");
    
            $hospitalInformation = $this->db->query("SELECT * FROM hospital_information")->fetch(PDO::FETCH_ASSOC);
    
            $episodes = $this->db->query("SELECT triage_id, consultation_id, gender, clinic_id, name, slug FROM patient_episodes 
                JOIN patients ON patient_episodes.patient_id = patients.id 
                LEFT JOIN clinics ON patient_episodes.clinic_id = clinics.id 
                WHERE patient_episodes.created_at > '{$previous}'");
    
            $episodes_created_male = 0;
            $episodes_created_female = 0;
            $episodes_completed_with_outcome = [];
            $episodes_per_clinic = [];
            $episodes_triaged = 0;
    
            while ($row = $episodes->fetch(PDO::FETCH_ASSOC)) {
                if ($row['gender'] == 1) {
                    $episodes_created_male++;
                } else if ($row['gender'] == 2) {
                    $episodes_created_female++;
                }
    
                if (!is_null($row['triage_id'])) {
                    $episodes_triaged++;
                }
    
                if (!is_null($row['clinic_id'])) {
                    $episodes_per_clinic[$row['clinic_id']] = [
                        'clinic_name' => $row['name'],
                        'clinic_type' => $row['slug'],
                        'clinic_count' => ($episodes_per_clinic[$row['clinic_id']]['clinic_count'] ?? 0) + 1,
                    ];
                }
    
                if (!is_null($row['consultation_id'])) {
                    $cons = $this->db->query("SELECT consultations.outcome_id, outcomes.name FROM consultations 
                        JOIN outcomes ON consultations.outcome_id = outcomes.id 
                        WHERE consultations.id = '{$row['consultation_id']}'")->fetch(PDO::FETCH_ASSOC);
                    $episodes_completed_with_outcome[$cons['outcome_id']] = [
                        'outcome_name' => $cons['name'],
                        'outcome_count' => ($episodes_completed_with_outcome[$cons['outcome_id']]['outcome_count'] ?? 0) + 1,
                    ];
                }
            }
    
            $users_seen      = $this->db->query("SELECT * FROM users WHERE last_seen > '{$previous}'")->rowCount();
            $male_patients   = $this->db->query("SELECT * FROM patients WHERE created_at > '{$previous}' AND gender = '1'")->rowCount();
            $female_patients = $this->db->query("SELECT * FROM patients WHERE created_at > '{$previous}' AND gender = '2'")->rowCount();
            $receipts        = $this->db->query("SELECT * FROM track_receipts WHERE created_at > '{$previous}'")->rowCount();
            $pharmacyRec     = $this->db->query("SELECT * FROM pharmacy_stock_reconciliations WHERE created_at > '{$previous}' AND completion_status = 1")->rowCount();
            $storeRec        = $this->db->query("SELECT * FROM store_stock_reconciliations WHERE created_at > '{$previous}' AND completion_status = 1")->rowCount();
            $quotations      = $this->db->query("SELECT * FROM quotations WHERE created_at > '{$previous}' AND receive_date IS NOT NULL")->rowCount();
    
            $inpatients      = $this->db->query("SELECT inpatient_info.discharged, inpatient_info.died_on, patients.gender FROM inpatient_info JOIN patients ON inpatient_info.patient_id = patients.id WHERE inpatient_info.created_at > '{$previous}'");
    
            $patients_admitted_male = 0;
            $patients_admitted_female = 0;
            $patients_discharged_male = 0;
            $patients_discharged_female = 0;
    
            while ($row = $inpatients->fetch(PDO::FETCH_ASSOC)) {
                if ($row['gender'] == 1) {
                    $patients_admitted_male++;
                } else if ($row['gender'] == 2) {
                    $patients_admitted_female++;
                }
    
                if ($row['discharged'] === 1 || !is_null($row['died_on'])) {
                    if ($row['gender'] == 1) {
                        $patients_discharged_male++;
                    } else if ($row['gender'] == 2) {
                        $patients_discharged_female++;
                    }
                }
            }
    
            $investigations = $this->db->query("SELECT * FROM ordered_investigations WHERE created_at > '{$previous}'");
    
            $investigation_requests = 0;
            $investigation_results = 0;
    
            while ($row = $investigations->fetch(PDO::FETCH_ASSOC)) {
                $investigation_requests++;
    
                // top_investigations
                if ($row['investigation_status'] === 1) {
                    $investigation_results++;
                }
            }
    
            $treatments = $this->db->query("SELECT * FROM treatments WHERE created_at > '{$previous}'");
    
            $prescriptions = 0;
            $prescriptions_dispensed = 0;
    
            while ($row = $treatments->fetch(PDO::FETCH_ASSOC)) {
                $prescriptions++;
    
                if ($row['dispense_status'] === 1) {
                    $prescriptions_dispensed++;
                }
            }
    
            $top_diagnosis = $this->db->query("SELECT primary_diagnosis, COUNT(*) AS freq, name FROM consultations JOIN diagnoses ON consultations.primary_diagnosis = diagnoses.id WHERE consultations.created_at > '{$previous}' GROUP BY primary_diagnosis ORDER BY freq DESC LIMIT 5")->fetchAll();
    
            $data = json_encode([
                'facility_name' => $hospitalInformation['name'],
                'facility_email' => $hospitalInformation['email'],
                'facility_address' => $hospitalInformation['address'],
                'facility_unique_identifier' => $hospitalInformation['unique_hospital_identifier'] ?? '',
                'time_period' => "{$previous} to " . date("Y-m-d H:i:s"),
                'episodes_created_male' => $episodes_created_male,
                'episodes_created_female' => $episodes_created_female,
                'episodes_completed_with_outcome' => $episodes_completed_with_outcome,
                'episodes_triaged' => $episodes_triaged,
                'patients_admitted_male' => $patients_admitted_male,
                'patients_admitted_female' => $patients_admitted_female,
                'patients_discharged_male' => $patients_discharged_male,
                'patients_discharged_female' => $patients_discharged_female,
                'number_of_prescriptions' => $prescriptions,
                'number_of_prescriptions_dispensed' => $prescriptions_dispensed,
                'payment_receipts_generated' => $receipts,
                'active_users' => $users_seen,
                'male_patients_registered' => $male_patients,
                'female_patients_registered' => $female_patients,
                'investigation_requests' => $investigation_requests,
                'investigation_requests_with_results' => $investigation_results,
                'times_inventory_stock_received' => $quotations,
                'times_stock_reconciled_pharmacy' => $pharmacyRec,
                'times_stock_reconciled_store' => $storeRec,
                'top_diagnosis' => $top_diagnosis,
                'top_investigations' => [],
                'top_prescribed_drugs_opd' => [],
                'top_prescribed_drugs_ipd' => [],
                'top_dispensed_drugs_opd' => [],
                'top_dispensed_drugs_ipd' => [],
                'episodes_per_clinic' => $episodes_per_clinic]);
    
            $this->logger->debug("Fetched: ". $data);
            $this->logger->info("Queries executed successfully. data saved.", ['size'=> strlen($data)]);

            return $this->saveToCache($data);
        }catch(Exception $ex){
            $this->logger->error($ex->getMessage());
            return false;
        }
    }

    public function uploadData($endpoint = null, $data = null)
    {
        $this->logger->info("Uploading payload.", ["url"=> $this->server. $this->endpoint ]);

        try{
            if(!$endpoint) throw new Exception("No endpoint specified.");

            if(empty($data)) throw new Exception("Payload is empty.");

            $options = [
                'json' => $data,
                'allow_redirects' => false,
                'timeout' => 5,
                'headers' => [
                    'Accept' => 'application/json',
                    'X-Requested-With' => 'XMLHttpRequest'
                ]
            ];

            $response = $this->http->post($endpoint, $options);
    
            $statusCode     = $response->getStatusCode();
            $response_body  = $response->getBody()->getContents();

	        if($statusCode != 200) throw new Exception("Unexpected http-response: ". $response_body);

            $this->logger->info("Data uploaded.", ["remote"=> $this->server. $endpoint, "status_code"=> $statusCode, "response"=> $response_body ]);

            $this->updateLastFetchDate();

            return true;
        }catch(Exception $ex){
		    $this->logger->error($ex->getMessage());

            return false;
        }
    }

    function updateLastFetchDate(){
        try {
            $update_date = $this->db->prepare("UPDATE signalytic_data SET last_fetch_date = ? WHERE id = ?");
            $update_date->execute([date("Y-m-d H:i:s"), 1]);

            $this->logger->info("Last fetch updated.");
            return true;
        }catch(Exception $ex){
            $this->logger->error("Last fetch failed. ", [ 'error_msg'=> $ex->getMessage()]);
            return false;
        }
    }

    function saveToCache($data = null){
        try{
            if(!$data) throw new Exception("No data fetched.");

            $cache_key = "data:". date("d_m_Y_H");

            $result = $this->redis->setex($cache_key, $this->redis_ttl, $data);
            if (!$result) $this->logger->error("cache: $cache_key failed", ["error"=> $result]);

            $this->logger->info("Cached: $cache_key");
            return true;
        }catch(Exception $ex){
            $this->logger->error($ex->getMessage());
            return false;
        }
    }

    function uploadCache(){
        $this->logger->info("Checking cache.");
        try{
            $cache_keys = $this->getCacheKeys();
            if(empty($cache_keys)) throw new Exception("Cache is empty. ");

            foreach($cache_keys as $cache_key)
            {
                $cached_data = $this->redis->get($cache_key);
                $this->logger->debug("[key] $cache_key found.", ["key"=>$cache_key, "data"=> $cached_data]);

                $result = $this->uploadData($this->endpoint, $cached_data);
                $this->logger->debug("[key] $cache_key uploaded", ["upload"=> $result]);

                $this->clearCache($cache_key); # clear cache
            }

        }catch(Exception $ex){
            $this->logger->warning($ex->getMessage());
            return false;
        }
    }

    private function getCacheKeys(){
        $keys = [];
        $iterator = null;

        do {
            //get all keys
            $result = $this->redis->scan($iterator, 'data:*');

            if ($result !== false) $keys = array_merge($keys, $result);

        } while ($iterator > 0);

        return $keys;
    }

    function clearCache($cache_key = null){
        if(!$cache_key){
            $this->logger->error("No cache key provided. exiting ...");
            return false;
        }

        try{
            $clear = $this->redis->del($cache_key);

            if($clear === 0) throw new Exception("Invalid cache key. [ $cache_key ]");

            $this->logger->info("Cache cleared", ["key"=> $cache_key, "result"=> $clear ]);

            return true;
        }catch(Exception $ex){
            $this->logger->error($ex->getMessage());
            return false;
        }
    }

    function resetCache(){
        try{
            $this->logger->warning("Flushing cache");
            $clear = $this->redis->flushDB();

            if(!$clear) throw new Exception("Clearing cache failed. ($clear) ");

            $this->logger->info("Cache cleared", ["result"=> $clear]);

            return true;
        }catch(Exception $ex){
            $this->logger->error($ex->getMessage());
            return false;
        }
    }
}

$sync = new Sync();
$sync->startSync();