lang: navbar translation

frontend/static/js/api/LanguageManager.js

@@ -0,0 +1,45 @@
+export default class LanguageManager {
+	constructor() {
+		this.availableLanguages = ['en', 'fr'];
+
+		this.currentLang = 'en'
+		this.chosenLang = localStorage.getItem('preferedLanguage') || this.currentLang;
+		if (this.chosenLang !== this.currentLang && this.availableLanguages.includes(this.chosenLang)) {
+			this.translatePage();
+		}
+	}
+
+	async translatePage() {
+		if (this.currentLang === this.chosenLang)
+			return;
+
+		let dictUrl = `${location.origin}/static/js/lang/${this.chosenLang}.json`;
+		let translation = await fetch(dictUrl).then(response => {
+			if (response.status !== 200)
+				return null;
+			return response.json();
+		});
+		if (!translation) {
+			console.log(`No translation found for language ${this.chosenLang}`);
+			return 1;
+		}
+		document.querySelectorAll('[data-i18n]').forEach(el => {
+			let key = el.getAttribute('data-i18n');
+			el.innerHTML = translation[key];
+		})
+
+		this.currentLang = this.chosenLang;
+		return 0;
+	}
+
+	async changeLanguage(lang) {
+		if (lang === this.currentLang || !this.availableLanguages.includes(lang))
+			return;
+
+		this.chosenLang = lang;
+		if (await this.translatePage() !== 0)
+			return;
+
+		localStorage.setItem('preferedLanguage', lang);
+	}
+}