import {data} from "react-router-dom";

const ongoingRequests = new Map();


function _default_hash_function(url, method, body){
    const url_obj = new URL(url, window.location.origin);

    const query_params = [...url_obj.searchParams.entries()]
        .sort(([a], [b]) => a.localeCompare(b))
        .map(([key, value]) => `${key}=${value}`)
        .join("&");
    const normalized_url = `${url_obj.origin}${url_obj.pathname}${query_params ? "?" + query_params : ""}`;
    const normalized_body = body
        ? JSON.stringify(
            Object.keys(body)
                .sort()
                .reduce((acc, key) => {
                    acc[key] = body[key];
                    return acc;
                }, {})
        )
        : "";
    return `${method.toUpperCase()}:${normalized_url}:${normalized_body}`;
}


export async function fetch_(url, init = {}, init_options = {}){
    const default_options = {
        use_cache: true,
        cache_key: _default_hash_function(url, init.method || "GET", init.body || null),
        cache_expires: 60,
        use_token: true,
    };
    const options = { ...default_options, ...init_options };


    const token = options.use_token ? localStorage.getItem("accessToken") : null;

    const request_options = {
        ...init,
        headers: {
            ...(init.headers || {}),
            ...(token ? {Authorization: `Bearer ${token}`} : {}),
            ...(init.method && ['PUT', 'POST'].includes(init.method.toUpperCase())
                ? {'Content-Type': 'application/json'}
                : {}),
        }
    };

    if(options.use_cache && ongoingRequests.has(options.cache_key)){
        return ongoingRequests.get(options.cache_key);
    }
    const now = Date.now();
    const cached_data = localStorage.getItem(options.cache_key);
    if(options.use_cache && cached_data){
        const {data, timestamp} = JSON.parse(cached_data);
        if(now - timestamp < options.cache_expires * 1000)
            return data;
    }

    try {
        const fetchPromise = fetch(url, request_options)
            .then((response) => {
                if(!response.ok) {
                    throw new Error(`RESPONSE_ERROR: ${response.status}`);
                }
                return response.json();
            })
            .then((data) => {

                if (options.use_cache)
                {
                    localStorage.setItem(
                        options.cache_key,
                        JSON.stringify({ data, timestamp: now })
                    );
                    ongoingRequests.delete(options.cache_key);
                }
                return data;
            });
        if(options.use_cache){
            ongoingRequests.set(options.cache_key, fetchPromise);
        }
        return await fetchPromise;
    }catch(error){
        if(options.use_cache){
            ongoingRequests.delete(options.cache_key);
        }
        throw error;
    }
}