import { get } from '../objects/get';
import type { ObjectPathLike } from '../objects/parseObjectPath';
import { renderTemplate } from '../strings/renderTemplate';

export interface Translate<T extends object> {
	/** Get/Set the language key */
	locale(lang?: string): string;

	/** Define the dict of translations for a language */
	dict(lang: string, dict: T): void;

	/** Get the dict of translations for a language */
	dict(lang: string): T;

	/** Retrieve a translation segment for the current language */
	t<X extends Record<string, any> | any[]>(key: ObjectPathLike, params?: X, lang?: string): string;
}

export function createTranslate<T extends object>(obj?: Record<string, T>): Translate<T> {
	let locale = '';
	const tree = obj || {};
	// en-US -> en-US,en
	const keyOfDict = (s: string | string[]) => {
		if (Array.isArray(s)) {
			return s;
		}
		const sp = s.split(/[_-]/);
		if (sp.length > 1) {
			return [s, sp[0]];
		}
		return [s];
	};
	return {
		locale(lang) {
			return (locale = lang || locale);
		},

		dict: ((lang, dict?) => {
			if (dict) {
				tree[lang] = Object.assign(tree[lang] || {}, dict);
				return;
			}
			return tree[lang];
		}) as Translate<T>['dict'],

		t(key, params, lang) {
			let val: any;
			for (const k of keyOfDict(lang || locale)) {
				val = get(tree[k], key, '');
				if (val) {
					break;
				}
			}
			if (process.env.NODE_ENV === 'development') {
				if (val == null) {
					console.error(
						`[Translate] Missing the "${[].concat(key as any).join('.')}" key within the "${
							lang || locale
						}" dictionary`,
					);
					return;
				}
			}
			if (typeof val === 'function') return val(params);
			if (typeof val === 'string') return renderTemplate(val, params, 'common');
			return val;
		},
	};
}