<?php defined('BASEPATH') OR exit('No direct script access allowed');

/* ----------------------------------------------------------------------------
 * Easy!Appointments - Open Source Web Scheduler
 *
 * @package     EasyAppointments
 * @author      A.Tselegidis <alextselegidis@gmail.com>
 * @copyright   Copyright (c) 2013 - 2020, Alex Tselegidis
 * @license     http://opensource.org/licenses/GPL-3.0 - GPLv3
 * @link        http://easyappointments.org
 * @since       v1.4.0
 * ---------------------------------------------------------------------------- */

/**
 * Timezones Model
 *
 * @package Models
 */
class Timezones_Model extends CI_Model {
    /**
     * @var string
     */
    protected $default = 'UTC';

    /**
     * @var array
     */
    protected $timezones = [
        'America' => [
            'America/Adak' => 'Adak -10:00',
            'America/Atka' => 'Atka -10:00',
            'America/Anchorage' => 'Anchorage -9:00',
            'America/Juneau' => 'Juneau -9:00',
            'America/Nome' => 'Nome -9:00',
            'America/Yakutat' => 'Yakutat -9:00',
            'America/Dawson' => 'Dawson -8:00',
            'America/Ensenada' => 'Ensenada -8:00',
            'America/Los_Angeles' => 'Los_Angeles -8:00',
            'America/Tijuana' => 'Tijuana -8:00',
            'America/Vancouver' => 'Vancouver -8:00',
            'America/Whitehorse' => 'Whitehorse -8:00',
            'America/Boise' => 'Boise -7:00',
            'America/Cambridge_Bay' => 'Cambridge_Bay -7:00',
            'America/Chihuahua' => 'Chihuahua -7:00',
            'America/Dawson_Creek' => 'Dawson_Creek -7:00',
            'America/Denver' => 'Denver -7:00',
            'America/Edmonton' => 'Edmonton -7:00',
            'America/Hermosillo' => 'Hermosillo -7:00',
            'America/Inuvik' => 'Inuvik -7:00',
            'America/Mazatlan' => 'Mazatlan -7:00',
            'America/Phoenix' => 'Phoenix -7:00',
            'America/Shiprock' => 'Shiprock -7:00',
            'America/Yellowknife' => 'Yellowknife -7:00',
            'America/Belize' => 'Belize -6:00',
            'America/Cancun' => 'Cancun -6:00',
            'America/Chicago' => 'Chicago -6:00',
            'America/Costa_Rica' => 'Costa_Rica -6:00',
            'America/El_Salvador' => 'El_Salvador -6:00',
            'America/Guatemala' => 'Guatemala -6:00',
            'America/Knox_IN' => 'Knox_IN -6:00',
            'America/Managua' => 'Managua -6:00',
            'America/Menominee' => 'Menominee -6:00',
            'America/Merida' => 'Merida -6:00',
            'America/Mexico_City' => 'Mexico_City -6:00',
            'America/Monterrey' => 'Monterrey -6:00',
            'America/Rainy_River' => 'Rainy_River -6:00',
            'America/Rankin_Inlet' => 'Rankin_Inlet -6:00',
            'America/Regina' => 'Regina -6:00',
            'America/Swift_Current' => 'Swift_Current -6:00',
            'America/Tegucigalpa' => 'Tegucigalpa -6:00',
            'America/Winnipeg' => 'Winnipeg -6:00',
            'America/Atikokan' => 'Atikokan -5:00',
            'America/Bogota' => 'Bogota -5:00',
            'America/Cayman' => 'Cayman -5:00',
            'America/Coral_Harbour' => 'Coral_Harbour -5:00',
            'America/Detroit' => 'Detroit -5:00',
            'America/Fort_Wayne' => 'Fort_Wayne -5:00',
            'America/Grand_Turk' => 'Grand_Turk -5:00',
            'America/Guayaquil' => 'Guayaquil -5:00',
            'America/Havana' => 'Havana -5:00',
            'America/Indianapolis' => 'Indianapolis -5:00',
            'America/Iqaluit' => 'Iqaluit -5:00',
            'America/Jamaica' => 'Jamaica -5:00',
            'America/Lima' => 'Lima -5:00',
            'America/Louisville' => 'Louisville -5:00',
            'America/Montreal' => 'Montreal -5:00',
            'America/Nassau' => 'Nassau -5:00',
            'America/New_York' => 'New_York -5:00',
            'America/Nipigon' => 'Nipigon -5:00',
            'America/Panama' => 'Panama -5:00',
            'America/Pangnirtung' => 'Pangnirtung -5:00',
            'America/Port-au-Prince' => 'Port-au-Prince -5:00',
            'America/Resolute' => 'Resolute -5:00',
            'America/Thunder_Bay' => 'Thunder_Bay -5:00',
            'America/Toronto' => 'Toronto -5:00',
            'America/Caracas' => 'Caracas -4:-30',
            'America/Anguilla' => 'Anguilla -4:00',
            'America/Antigua' => 'Antigua -4:00',
            'America/Aruba' => 'Aruba -4:00',
            'America/Asuncion' => 'Asuncion -4:00',
            'America/Barbados' => 'Barbados -4:00',
            'America/Blanc-Sablon' => 'Blanc-Sablon -4:00',
            'America/Boa_Vista' => 'Boa_Vista -4:00',
            'America/Campo_Grande' => 'Campo_Grande -4:00',
            'America/Cuiaba' => 'Cuiaba -4:00',
            'America/Curacao' => 'Curacao -4:00',
            'America/Dominica' => 'Dominica -4:00',
            'America/Eirunepe' => 'Eirunepe -4:00',
            'America/Glace_Bay' => 'Glace_Bay -4:00',
            'America/Goose_Bay' => 'Goose_Bay -4:00',
            'America/Grenada' => 'Grenada -4:00',
            'America/Guadeloupe' => 'Guadeloupe -4:00',
            'America/Guyana' => 'Guyana -4:00',
            'America/Halifax' => 'Halifax -4:00',
            'America/La_Paz' => 'La_Paz -4:00',
            'America/Manaus' => 'Manaus -4:00',
            'America/Marigot' => 'Marigot -4:00',
            'America/Martinique' => 'Martinique -4:00',
            'America/Moncton' => 'Moncton -4:00',
            'America/Montserrat' => 'Montserrat -4:00',
            'America/Port_of_Spain' => 'Port_of_Spain -4:00',
            'America/Porto_Acre' => 'Porto_Acre -4:00',
            'America/Porto_Velho' => 'Porto_Velho -4:00',
            'America/Puerto_Rico' => 'Puerto_Rico -4:00',
            'America/Rio_Branco' => 'Rio_Branco -4:00',
            'America/Santiago' => 'Santiago -4:00',
            'America/Santo_Domingo' => 'Santo_Domingo -4:00',
            'America/St_Barthelemy' => 'St_Barthelemy -4:00',
            'America/St_Kitts' => 'St_Kitts -4:00',
            'America/St_Lucia' => 'St_Lucia -4:00',
            'America/St_Thomas' => 'St_Thomas -4:00',
            'America/St_Vincent' => 'St_Vincent -4:00',
            'America/Thule' => 'Thule -4:00',
            'America/Tortola' => 'Tortola -4:00',
            'America/Virgin' => 'Virgin -4:00',
            'America/St_Johns' => 'St_Johns -3:-30',
            'America/Araguaina' => 'Araguaina -3:00',
            'America/Bahia' => 'Bahia -3:00',
            'America/Belem' => 'Belem -3:00',
            'America/Buenos_Aires' => 'Buenos_Aires -3:00',
            'America/Catamarca' => 'Catamarca -3:00',
            'America/Cayenne' => 'Cayenne -3:00',
            'America/Cordoba' => 'Cordoba -3:00',
            'America/Fortaleza' => 'Fortaleza -3:00',
            'America/Godthab' => 'Godthab -3:00',
            'America/Jujuy' => 'Jujuy -3:00',
            'America/Maceio' => 'Maceio -3:00',
            'America/Mendoza' => 'Mendoza -3:00',
            'America/Miquelon' => 'Miquelon -3:00',
            'America/Montevideo' => 'Montevideo -3:00',
            'America/Paramaribo' => 'Paramaribo -3:00',
            'America/Recife' => 'Recife -3:00',
            'America/Rosario' => 'Rosario -3:00',
            'America/Santarem' => 'Santarem -3:00',
            'America/Sao_Paulo' => 'Sao_Paulo -3:00',
            'America/Noronha' => 'Noronha -2:00',
            'America/Scoresbysund' => 'Scoresbysund -1:00',
            'America/Danmarkshavn' => 'Danmarkshavn +0:00',
        ],
        'Canada' => [
            'Canada/Pacific' => 'Pacific -8:00',
            'Canada/Yukon' => 'Yukon -8:00',
            'Canada/Mountain' => 'Mountain -7:00',
            'Canada/Central' => 'Central -6:00',
            'Canada/East-Saskatchewan' => 'East-Saskatchewan -6:00',
            'Canada/Saskatchewan' => 'Saskatchewan -6:00',
            'Canada/Eastern' => 'Eastern -5:00',
            'Canada/Atlantic' => 'Atlantic -4:00',
            'Canada/Newfoundland' => 'Newfoundland -3:-30',
        ],
        'Mexico' => [
            'Mexico/BajaNorte' => 'BajaNorte -8:00',
            'Mexico/BajaSur' => 'BajaSur -7:00',
            'Mexico/General' => 'General -6:00',
        ],
        'Chile' => [
            'Chile/EasterIsland' => 'EasterIsland -6:00',
            'Chile/Continental' => 'Continental -4:00',
        ],
        'Antarctica' => [
            'Antarctica/Palmer' => 'Palmer -4:00',
            'Antarctica/Rothera' => 'Rothera -3:00',
            'Antarctica/Syowa' => 'Syowa +3:00',
            'Antarctica/Mawson' => 'Mawson +6:00',
            'Antarctica/Vostok' => 'Vostok +6:00',
            'Antarctica/Davis' => 'Davis +7:00',
            'Antarctica/Casey' => 'Casey +8:00',
            'Antarctica/DumontDUrville' => 'DumontDUrville +10:00',
            'Antarctica/McMurdo' => 'McMurdo +12:00',
            'Antarctica/South_Pole' => 'South_Pole +12:00',
        ],
        'Atlantic' => [
            'Atlantic/Bermuda' => 'Bermuda -4:00',
            'Atlantic/Stanley' => 'Stanley -4:00',
            'Atlantic/South_Georgia' => 'South_Georgia -2:00',
            'Atlantic/Azores' => 'Azores -1:00',
            'Atlantic/Cape_Verde' => 'Cape_Verde -1:00',
            'Atlantic/Canary' => 'Canary +0:00',
            'Atlantic/Faeroe' => 'Faeroe +0:00',
            'Atlantic/Faroe' => 'Faroe +0:00',
            'Atlantic/Madeira' => 'Madeira +0:00',
            'Atlantic/Reykjavik' => 'Reykjavik +0:00',
            'Atlantic/St_Helena' => 'St_Helena +0:00',
            'Atlantic/Jan_Mayen' => 'Jan_Mayen +1:00',
        ],
        'Brazil' => [
            'Brazil/Acre' => 'Acre -4:00',
            'Brazil/West' => 'West -4:00',
            'Brazil/East' => 'East -3:00',
            'Brazil/DeNoronha' => 'DeNoronha -2:00',
        ],
        'Africa' => [
            'Africa/Abidjan' => 'Abidjan +0:00',
            'Africa/Accra' => 'Accra +0:00',
            'Africa/Bamako' => 'Bamako +0:00',
            'Africa/Banjul' => 'Banjul +0:00',
            'Africa/Bissau' => 'Bissau +0:00',
            'Africa/Casablanca' => 'Casablanca +0:00',
            'Africa/Conakry' => 'Conakry +0:00',
            'Africa/Dakar' => 'Dakar +0:00',
            'Africa/El_Aaiun' => 'El_Aaiun +0:00',
            'Africa/Freetown' => 'Freetown +0:00',
            'Africa/Lome' => 'Lome +0:00',
            'Africa/Monrovia' => 'Monrovia +0:00',
            'Africa/Nouakchott' => 'Nouakchott +0:00',
            'Africa/Ouagadougou' => 'Ouagadougou +0:00',
            'Africa/Sao_Tome' => 'Sao_Tome +0:00',
            'Africa/Timbuktu' => 'Timbuktu +0:00',
            'Africa/Algiers' => 'Algiers +1:00',
            'Africa/Bangui' => 'Bangui +1:00',
            'Africa/Brazzaville' => 'Brazzaville +1:00',
            'Africa/Ceuta' => 'Ceuta +1:00',
            'Africa/Douala' => 'Douala +1:00',
            'Africa/Kinshasa' => 'Kinshasa +1:00',
            'Africa/Lagos' => 'Lagos +1:00',
            'Africa/Libreville' => 'Libreville +1:00',
            'Africa/Luanda' => 'Luanda +1:00',
            'Africa/Malabo' => 'Malabo +1:00',
            'Africa/Ndjamena' => 'Ndjamena +1:00',
            'Africa/Niamey' => 'Niamey +1:00',
            'Africa/Porto-Novo' => 'Porto-Novo +1:00',
            'Africa/Tunis' => 'Tunis +1:00',
            'Africa/Windhoek' => 'Windhoek +1:00',
            'Africa/Blantyre' => 'Blantyre +2:00',
            'Africa/Bujumbura' => 'Bujumbura +2:00',
            'Africa/Cairo' => 'Cairo +2:00',
            'Africa/Gaborone' => 'Gaborone +2:00',
            'Africa/Harare' => 'Harare +2:00',
            'Africa/Johannesburg' => 'Johannesburg +2:00',
            'Africa/Kigali' => 'Kigali +2:00',
            'Africa/Lubumbashi' => 'Lubumbashi +2:00',
            'Africa/Lusaka' => 'Lusaka +2:00',
            'Africa/Maputo' => 'Maputo +2:00',
            'Africa/Maseru' => 'Maseru +2:00',
            'Africa/Mbabane' => 'Mbabane +2:00',
            'Africa/Tripoli' => 'Tripoli +2:00',
            'Africa/Addis_Ababa' => 'Addis_Ababa +3:00',
            'Africa/Asmara' => 'Asmara +3:00',
            'Africa/Asmera' => 'Asmera +3:00',
            'Africa/Dar_es_Salaam' => 'Dar_es_Salaam +3:00',
            'Africa/Djibouti' => 'Djibouti +3:00',
            'Africa/Kampala' => 'Kampala +3:00',
            'Africa/Khartoum' => 'Khartoum +3:00',
            'Africa/Mogadishu' => 'Mogadishu +3:00',
            'Africa/Nairobi' => 'Nairobi +3:00',
        ],
        'Europe' => [
            'Europe/Belfast' => 'Belfast +0:00',
            'Europe/Dublin' => 'Dublin +0:00',
            'Europe/Guernsey' => 'Guernsey +0:00',
            'Europe/Isle_of_Man' => 'Isle_of_Man +0:00',
            'Europe/Jersey' => 'Jersey +0:00',
            'Europe/Lisbon' => 'Lisbon +0:00',
            'Europe/London' => 'London +0:00',
            'Europe/Amsterdam' => 'Amsterdam +1:00',
            'Europe/Andorra' => 'Andorra +1:00',
            'Europe/Belgrade' => 'Belgrade +1:00',
            'Europe/Berlin' => 'Berlin +1:00',
            'Europe/Bratislava' => 'Bratislava +1:00',
            'Europe/Brussels' => 'Brussels +1:00',
            'Europe/Budapest' => 'Budapest +1:00',
            'Europe/Copenhagen' => 'Copenhagen +1:00',
            'Europe/Gibraltar' => 'Gibraltar +1:00',
            'Europe/Ljubljana' => 'Ljubljana +1:00',
            'Europe/Luxembourg' => 'Luxembourg +1:00',
            'Europe/Madrid' => 'Madrid +1:00',
            'Europe/Malta' => 'Malta +1:00',
            'Europe/Monaco' => 'Monaco +1:00',
            'Europe/Oslo' => 'Oslo +1:00',
            'Europe/Paris' => 'Paris +1:00',
            'Europe/Podgorica' => 'Podgorica +1:00',
            'Europe/Prague' => 'Prague +1:00',
            'Europe/Rome' => 'Rome +1:00',
            'Europe/San_Marino' => 'San_Marino +1:00',
            'Europe/Sarajevo' => 'Sarajevo +1:00',
            'Europe/Skopje' => 'Skopje +1:00',
            'Europe/Stockholm' => 'Stockholm +1:00',
            'Europe/Tirane' => 'Tirane +1:00',
            'Europe/Vaduz' => 'Vaduz +1:00',
            'Europe/Vatican' => 'Vatican +1:00',
            'Europe/Vienna' => 'Vienna +1:00',
            'Europe/Warsaw' => 'Warsaw +1:00',
            'Europe/Zagreb' => 'Zagreb +1:00',
            'Europe/Zurich' => 'Zurich +1:00',
            'Europe/Athens' => 'Athens +2:00',
            'Europe/Bucharest' => 'Bucharest +2:00',
            'Europe/Chisinau' => 'Chisinau +2:00',
            'Europe/Helsinki' => 'Helsinki +2:00',
            'Europe/Istanbul' => 'Istanbul +2:00',
            'Europe/Kaliningrad' => 'Kaliningrad +2:00',
            'Europe/Kiev' => 'Kiev +2:00',
            'Europe/Mariehamn' => 'Mariehamn +2:00',
            'Europe/Minsk' => 'Minsk +2:00',
            'Europe/Nicosia' => 'Nicosia +2:00',
            'Europe/Riga' => 'Riga +2:00',
            'Europe/Simferopol' => 'Simferopol +2:00',
            'Europe/Sofia' => 'Sofia +2:00',
            'Europe/Tallinn' => 'Tallinn +2:00',
            'Europe/Tiraspol' => 'Tiraspol +2:00',
            'Europe/Uzhgorod' => 'Uzhgorod +2:00',
            'Europe/Vilnius' => 'Vilnius +2:00',
            'Europe/Zaporozhye' => 'Zaporozhye +2:00',
            'Europe/Moscow' => 'Moscow +3:00',
            'Europe/Volgograd' => 'Volgograd +3:00',
            'Europe/Samara' => 'Samara +4:00',
        ],
        'Arctic' => [
            'Arctic/Longyearbyen' => 'Longyearbyen +1:00',
        ],
        'Asia' => [
            'Asia/Amman' => 'Amman +2:00',
            'Asia/Beirut' => 'Beirut +2:00',
            'Asia/Damascus' => 'Damascus +2:00',
            'Asia/Gaza' => 'Gaza +2:00',
            'Asia/Istanbul' => 'Istanbul +2:00',
            'Asia/Jerusalem' => 'Jerusalem +2:00',
            'Asia/Nicosia' => 'Nicosia +2:00',
            'Asia/Tel_Aviv' => 'Tel_Aviv +2:00',
            'Asia/Aden' => 'Aden +3:00',
            'Asia/Baghdad' => 'Baghdad +3:00',
            'Asia/Bahrain' => 'Bahrain +3:00',
            'Asia/Kuwait' => 'Kuwait +3:00',
            'Asia/Qatar' => 'Qatar +3:00',
            'Asia/Tehran' => 'Tehran +3:30',
            'Asia/Baku' => 'Baku +4:00',
            'Asia/Dubai' => 'Dubai +4:00',
            'Asia/Muscat' => 'Muscat +4:00',
            'Asia/Tbilisi' => 'Tbilisi +4:00',
            'Asia/Yerevan' => 'Yerevan +4:00',
            'Asia/Kabul' => 'Kabul +4:30',
            'Asia/Aqtau' => 'Aqtau +5:00',
            'Asia/Aqtobe' => 'Aqtobe +5:00',
            'Asia/Ashgabat' => 'Ashgabat +5:00',
            'Asia/Ashkhabad' => 'Ashkhabad +5:00',
            'Asia/Dushanbe' => 'Dushanbe +5:00',
            'Asia/Karachi' => 'Karachi +5:00',
            'Asia/Oral' => 'Oral +5:00',
            'Asia/Samarkand' => 'Samarkand +5:00',
            'Asia/Tashkent' => 'Tashkent +5:00',
            'Asia/Yekaterinburg' => 'Yekaterinburg +5:00',
            'Asia/Calcutta' => 'Calcutta +5:30',
            'Asia/Colombo' => 'Colombo +5:30',
            'Asia/Kolkata' => 'Kolkata +5:30',
            'Asia/Katmandu' => 'Katmandu +5:45',
            'Asia/Almaty' => 'Almaty +6:00',
            'Asia/Bishkek' => 'Bishkek +6:00',
            'Asia/Dacca' => 'Dacca +6:00',
            'Asia/Dhaka' => 'Dhaka +6:00',
            'Asia/Novosibirsk' => 'Novosibirsk +6:00',
            'Asia/Omsk' => 'Omsk +6:00',
            'Asia/Qyzylorda' => 'Qyzylorda +6:00',
            'Asia/Thimbu' => 'Thimbu +6:00',
            'Asia/Thimphu' => 'Thimphu +6:00',
            'Asia/Rangoon' => 'Rangoon +6:30',
            'Asia/Bangkok' => 'Bangkok +7:00',
            'Asia/Ho_Chi_Minh' => 'Ho_Chi_Minh +7:00',
            'Asia/Hovd' => 'Hovd +7:00',
            'Asia/Jakarta' => 'Jakarta +7:00',
            'Asia/Krasnoyarsk' => 'Krasnoyarsk +7:00',
            'Asia/Phnom_Penh' => 'Phnom_Penh +7:00',
            'Asia/Pontianak' => 'Pontianak +7:00',
            'Asia/Saigon' => 'Saigon +7:00',
            'Asia/Vientiane' => 'Vientiane +7:00',
            'Asia/Brunei' => 'Brunei +8:00',
            'Asia/Choibalsan' => 'Choibalsan +8:00',
            'Asia/Chongqing' => 'Chongqing +8:00',
            'Asia/Chungking' => 'Chungking +8:00',
            'Asia/Harbin' => 'Harbin +8:00',
            'Asia/Hong_Kong' => 'Hong_Kong +8:00',
            'Asia/Irkutsk' => 'Irkutsk +8:00',
            'Asia/Kashgar' => 'Kashgar +8:00',
            'Asia/Kuala_Lumpur' => 'Kuala_Lumpur +8:00',
            'Asia/Kuching' => 'Kuching +8:00',
            'Asia/Macao' => 'Macao +8:00',
            'Asia/Macau' => 'Macau +8:00',
            'Asia/Makassar' => 'Makassar +8:00',
            'Asia/Manila' => 'Manila +8:00',
            'Asia/Shanghai' => 'Shanghai +8:00',
            'Asia/Singapore' => 'Singapore +8:00',
            'Asia/Taipei' => 'Taipei +8:00',
            'Asia/Ujung_Pandang' => 'Ujung_Pandang +8:00',
            'Asia/Ulaanbaatar' => 'Ulaanbaatar +8:00',
            'Asia/Ulan_Bator' => 'Ulan_Bator +8:00',
            'Asia/Urumqi' => 'Urumqi +8:00',
            'Asia/Dili' => 'Dili +9:00',
            'Asia/Jayapura' => 'Jayapura +9:00',
            'Asia/Pyongyang' => 'Pyongyang +9:00',
            'Asia/Seoul' => 'Seoul +9:00',
            'Asia/Tokyo' => 'Tokyo +9:00',
            'Asia/Yakutsk' => 'Yakutsk +9:00',
            'Asia/Sakhalin' => 'Sakhalin +10:00',
            'Asia/Vladivostok' => 'Vladivostok +10:00',
            'Asia/Magadan' => 'Magadan +11:00',
            'Asia/Anadyr' => 'Anadyr +12:00',
            'Asia/Kamchatka' => 'Kamchatka +12:00',
        ],
        'Indian' => [
            'Indian/Antananarivo' => 'Antananarivo +3:00',
            'Indian/Comoro' => 'Comoro +3:00',
            'Indian/Mayotte' => 'Mayotte +3:00',
            'Indian/Mahe' => 'Mahe +4:00',
            'Indian/Mauritius' => 'Mauritius +4:00',
            'Indian/Reunion' => 'Reunion +4:00',
            'Indian/Kerguelen' => 'Kerguelen +5:00',
            'Indian/Maldives' => 'Maldives +5:00',
            'Indian/Chagos' => 'Chagos +6:00',
            'Indian/Cocos' => 'Cocos +6:30',
            'Indian/Christmas' => 'Christmas +7:00',
        ],
        'Australia' => [
            'Australia/Perth' => 'Perth +8:00',
            'Australia/West' => 'West +8:00',
            'Australia/Eucla' => 'Eucla +8:45',
            'Australia/Adelaide' => 'Adelaide +9:30',
            'Australia/Broken_Hill' => 'Broken_Hill +9:30',
            'Australia/Darwin' => 'Darwin +9:30',
            'Australia/North' => 'North +9:30',
            'Australia/South' => 'South +9:30',
            'Australia/Yancowinna' => 'Yancowinna +9:30',
            'Australia/ACT' => 'ACT +10:00',
            'Australia/Brisbane' => 'Brisbane +10:00',
            'Australia/Canberra' => 'Canberra +10:00',
            'Australia/Currie' => 'Currie +10:00',
            'Australia/Hobart' => 'Hobart +10:00',
            'Australia/Lindeman' => 'Lindeman +10:00',
            'Australia/Melbourne' => 'Melbourne +10:00',
            'Australia/NSW' => 'NSW +10:00',
            'Australia/Queensland' => 'Queensland +10:00',
            'Australia/Sydney' => 'Sydney +10:00',
            'Australia/Tasmania' => 'Tasmania +10:00',
            'Australia/Victoria' => 'Victoria +10:00',
            'Australia/LHI' => 'LHI +10:30',
            'Australia/Lord_Howe' => 'Lord_Howe +10:30',
        ],
    ];

    /**
     * Get all timezones to a flat array.
     *
     * @return array
     */
    public function to_array()
    {
        $continents = [];

        foreach ($this->timezones as $continent => $timezones)
        {
            $continents[] = $timezones;
        }

        return array_merge($continents);
    }

    /**
     * Get all timezones to a grouped array (by continent).
     *
     * @return array
     */
    public function to_grouped_array()
    {
        return $this->timezones;
    }

    /**
     * Convert a date time value to a new timezone.
     *
     * @param string $value Provide a date time value as a string (format Y-m-d H:i:s).
     * @param string $from_timezone From timezone value.
     * @param string $to_timezone To timezone value.
     * @return string
     * @throws Exception
     */
    public function convert($value, $from_timezone, $to_timezone)
    {
        if ( ! $to_timezone)
        {
            return $value;
        }

        $from = new \DateTimeZone($from_timezone);

        $to = new \DateTimeZone($to_timezone);

        $result = new \DateTime($value, $from);

        $result->setTimezone($to);

        return $result->format('Y-m-d H:i:s');
    }

    /**
     * Convert the dates of an event to the timezone of the user.
     *
     * @param array $event Must contain the "start_datetime", "end_datetime" and "id_users_provider" properties.
     * @return array
     * @throws Exception
     */
    public function convert_event_datetime($event)
    {
        if ( ! isset($event['start_datetime'], $event['end_datetime'], $event['id_users_provider']))
        {
            throw new Exception('The provided event does not have the required properties: ' . print_r($event));
        }

        $user_timezone = $this->get_user_timezone($event['id_users_provider']);

        $session_timezone = $this->get_session_timezone();

        $event['start_datetime'] = $this->convert($event['start_datetime'],
            $user_timezone, $session_timezone);

        $event['end_datetime'] = $this->convert($event['end_datetime'],
            $user_timezone, $session_timezone);

        return $event;
    }

    /**
     * Get the timezone of a user.
     *
     * @param int $id Database ID of the user.
     * @return string|null
     */
    public function get_user_timezone($id)
    {
        $row = $this->db->get_where('ea_users', ['id' => $id])->row_array();

        return $row ? $row['timezone'] : NULL;
    }

    /**
     * Returns the session timezone or the default timezone as a fallback.
     *
     * @return string
     */
    public function get_session_timezone()
    {
        $this->load->library('session');

        $default_timezone = $this->get_default_timezone();

        return isset($this->session->timezone) ? $this->session->timezone : $default_timezone;
    }

    /**
     * Get the timezone name for the provided value.
     *
     * @param string $value
     * @return string|null
     */
    public function get_timezone_name($value)
    {
        $timezones = $this->to_array();

        return isset($timezones[$value]) ? $timezones[$value] : NULL;
    }


    /**
     * Get the default timezone value of the current system.
     *
     * @return string
     */
    public function get_default_timezone()
    {
        return 'UTC';
    }
}