import type { i18n } from "i18next";
import { writable, type Readable, type Writable } from "svelte/store";


export interface TranslationService {
    i18n: Readable<i18n>;
}

export const isLoading = writable(true);

export class I18NextTranslationStore implements TranslationService {
    public i18n: Writable<i18n>;
    public isLoading: Writable<boolean>;

    constructor(i18n: i18n) {
        this.i18n = this.createInstance(i18n);
        this.isLoading = this.createLoadingInstance(i18n);
    }

    private createInstance(i18n: i18n): Writable<i18n> {
        const i18nWritable = writable(i18n)

        i18n.on('initialized', () => {
            i18nWritable.set(i18n)
        })
        i18n.on('loaded', () => {
            i18nWritable.set(i18n)
        })
        i18n.on('added', () => i18nWritable.set(i18n))
        i18n.on('languageChanged', () => {
            i18nWritable.set(i18n)
        })
        return i18nWritable;
    }

    private createLoadingInstance(i18n: i18n): Writable<boolean> {
        // if loaded resources are empty || {}, set loading to true
        i18n.on('loaded', (resources) => {
            Object.keys(resources).length !== 0 && isLoading.set(false)
        })

        // if resources failed loading, set loading to true
        i18n.on('failedLoading', () => {
            isLoading.set(true)
        })

        return isLoading;
    }
}