/**
 * part of Hachette
 * Getting available content for site from remote repositories.
 *
 * Copyright (C) 2021 Wojtek Kosior
 * Redistribution terms are gathered in the `copyright' file.
 */

/*
 * IMPORTS_START
 * IMPORT make_ajax_request
 * IMPORT observables
 * IMPORT TYPE_PREFIX
 * IMPORT parse_json_with_schema
 * IMPORT matchers
 * IMPORTS_END
 */

const paths = {
    [TYPE_PREFIX.PAGE]: "/pattern",
    [TYPE_PREFIX.BAG]: "/bag",
    [TYPE_PREFIX.SCRIPT]: "/script",
    [TYPE_PREFIX.URL]: "/query"
};

const queried_items = new Map();
const observable = observables.make();

function repo_query(prefix, item, repo_urls)
{
    const key = prefix + item;

    const results = queried_items.get(key) || {};
    queried_items.set(key, results);

    for (const repo_url of repo_urls)
	perform_query_against(key, repo_url, results);
}

const page_schema = {
    pattern: matchers.nonempty_string,
    payload: ["optional", matchers.component, "default", undefined]
};
const bag_schema = {
    name: matchers.nonempty_string,
    components: ["optional", [matchers.component, "repeat"], "default", []]
};
const script_schema = {
    name: matchers.nonempty_string,
    location: matchers.nonempty_string,
    sha256: matchers.sha256,
};
const search_result_schema = [page_schema, "repeat"];

const schemas = {
    [TYPE_PREFIX.PAGE]: page_schema,
    [TYPE_PREFIX.BAG]: bag_schema,
    [TYPE_PREFIX.SCRIPT]: script_schema,
    [TYPE_PREFIX.URL]: search_result_schema
}

async function perform_query_against(key, repo_url, results)
{
    if (results[repo_url] !== undefined)
	return;

    const prefix = key[0];
    const item = key.substring(1);
    const result = {state: "started"};
    results[repo_url] = result;

    const broadcast_msg = {prefix, item, results: {[repo_url]: result}};
    observables.broadcast(observable, broadcast_msg);

    let state = "connection_error";
    const query_url =
	  `${repo_url}${paths[prefix]}?n=${encodeURIComponent(item)}`;

    try {
	let xhttp = await make_ajax_request("GET", query_url);
	if (xhttp.status === 200) {
	    state = "parse_error";
	    result.response =
		parse_json_with_schema(schemas[prefix], xhttp.responseText);
	    state = "completed";
	}
    } catch (e) {
	console.log(e);
    }

    result.state = state;
    observables.broadcast(observable, broadcast_msg);
}

function subscribe_repo_query_results(cb)
{
    observables.subscribe(observable, cb);
    for (const [key, results] of queried_items.entries())
	cb({prefix: key[0], item: key.substring(1), results});
}

function unsubscribe_repo_query_results(cb)
{
    observables.unsubscribe(observable, cb);
}

/*
 * EXPORTS_START
 * EXPORT repo_query
 * EXPORT subscribe_repo_query_results
 * EXPORT unsubscribe_repo_query_results
 * EXPORTS_END
 */