86 lines
2.4 KiB
JavaScript
86 lines
2.4 KiB
JavaScript
/*
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File name : database.js
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Description : Communicates with the server to ensure that the data is up to date.
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*/
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const BASE_URL = "http://localhost/";
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let feData = JSON.parse(localStorage.getItem("feData"));
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function isOnline() {
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const networkState = (navigator.connection) ? navigator.connection.type : null;
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if (networkState != null && networkState != "none") {
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return true;
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}
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return false;
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}
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// Get the data from the server or update the data in the localstorage if needed
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function getOrUpdateData() {
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if (feData != null) {
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let body = new FormData();
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body.append('version', feData.version);
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fetch(BASE_URL + "update", {
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method: "POST",
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body: body,
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})
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.then(res => {
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if (res.ok) {
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return res.json();
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} else {
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console.log(res);
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}
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})
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.then(data => {
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updateData(data);
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})
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.catch(err => {
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console.log(err);
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});
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} else {
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// Import the data if none was found
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fetch(BASE_URL + "all")
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.then(res => {
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if (res.ok) {
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return res.json();
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} else {
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console.log(res);
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}
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})
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.then(data => {
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updateData(data);
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})
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.catch(err => {
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console.log(err);
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});
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}
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}
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// Update the data in the localstorage
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function updateData(data) {
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// If the data received from the server are not empty then we can save them in the local storage
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if (data != null && Object.keys(data).length > 0) {
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localStorage.setItem("feData", JSON.stringify(data));
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feData = data;
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}
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// End of the update process, we can now display the data
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displayCharacters();
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}
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// Doesn't try to get or update the data if the user is not connected to the internet
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if (isOnline()) {
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getOrUpdateData();
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} else {
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// If the user is not connected to internet but the data are already present in the app, then we display them
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if (feData != null) {
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displayCharacters();
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} else {
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alert("Please connect to the internet to download the data");
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}
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// Create an event to get/update the data when the user goes online
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document.addEventListener("online", getOrUpdateData, false);
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}
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