import { getCollection, type CollectionEntry, type DataCollectionKey } from 'astro:content';
import config from 'virtual:starlight/user-config';
import project from 'virtual:starlight/project-context';
import pluginTranslations from 'virtual:starlight/plugin-translations';
import type { i18nSchemaOutput } from '../schemas/i18n';
import { createTranslationSystem } from './createTranslationSystem';
import type { RemoveIndexSignature } from './types';
import { getCollectionPathFromRoot } from './collection';
import { stripExtension, stripLeadingSlash } from './path';

// eslint-disable-next-line @typescript-eslint/ban-ts-comment
// @ts-ignore - This may be a type error in projects without an i18n collection and running
// `tsc --noEmit` in their project. Note that it is not possible to inline this type in
// `UserI18nSchema` because this would break types for users having multiple data collections.
type i18nCollection = CollectionEntry<'i18n'>;

const i18nCollectionPathFromRoot = getCollectionPathFromRoot('i18n', project);

export type UserI18nSchema = 'i18n' extends DataCollectionKey
	? i18nCollection extends { data: infer T }
		? i18nSchemaOutput & T
		: i18nSchemaOutput
	: i18nSchemaOutput;
export type UserI18nKeys = keyof RemoveIndexSignature<UserI18nSchema>;

/** Get all translation data from the i18n collection, keyed by `lang`, which are BCP-47 language tags. */
async function loadTranslations() {
	// Briefly override `console.warn()` to silence logging when a project has no i18n collection.
	const warn = console.warn;
	console.warn = () => {};
	const userTranslations: Record<string, UserI18nSchema> = Object.fromEntries(
		// eslint-disable-next-line @typescript-eslint/ban-ts-comment
		// @ts-ignore — may be a type error in projects without an i18n collection
		(await getCollection('i18n')).map(({ id, data, filePath }) => {
			const lang = !filePath
				? id
				: stripExtension(stripLeadingSlash(filePath.replace(i18nCollectionPathFromRoot, '')));
			return [lang, data] as const;
		})
	);
	// Restore the original warn implementation.
	console.warn = warn;
	return userTranslations;
}

/**
 * Generate a utility function that returns UI strings for the given language.
 * @param {string | undefined} [lang]
 * @example
 * const t = useTranslations('en');
 * const label = t('search.label'); // => 'Search'
 */
export const useTranslations = await createTranslationSystem(
	config,
	await loadTranslations(),
	pluginTranslations
);