const cache = new Map<string, any>();
const inflight = new Map<string, Promise<any>>();

const doFetchJsonCached = async (locale: string, filename: string) => {
    if (cache.has(filename)) { return cache.get(filename); }
    if (inflight.has(filename)) { return inflight.get(filename)!; }

    const p = (async () => {
        const data = await $fetch(`/api/docs/${filename}`, { query: { locale } });
        cache.set(filename, data);
        inflight.delete(filename);
        return data;
    })().catch((err) => {
        inflight.delete(filename);
        throw err;
    });

    inflight.set(filename, p);
    return p;
};

export const fetchJson = async (locale: string, filename: string, key: string) => {
    let c = await doFetchJsonCached(locale, filename);

    // terrible conventions, i know… i'm so tired…
    let explicitSign = false;
    let absolute = false;
    if (key.startsWith('@')) {
        explicitSign = true;
        key = key.substring(1);
    }
    if (key.startsWith('^')) {
        absolute = true;
        key = key.substring(1);
    }
    for (let part of key.replace(/\\\./g, '£').split('.')) {
        part = part.replace(/&#39;/g, '\'').replace(/£/g, '.');
        c = c[part];
        if (c === undefined) {
            throw `item "${part}" is undefined (file ${filename})`;
        }
    }
    if (typeof c === 'number') {
        if (absolute) {
            c = Math.abs(c);
        }
        if (explicitSign && c > 0) {
            c = `+${c}`;
        }
        // TODO make generic
        c = c.toString().replace('.', ',');
    }
    return c;
};