// -*- mode: javascript; indent-tabs-mode: nil; c-basic-offset: 8 -*-

// Part of dump1090, a Mode-S message decoder for RTL-SDR devices.
//
// dbloader.js: load aircraft metadata from static json files
//
// Copyright (c) 2014,2015 Oliver Jowett <oliver@mutability.co.uk>
//
// This file is free software: you may copy, redistribute and/or modify it
// under the terms of the GNU General Public License as published by the
// Free Software Foundation, either version 2 of the License, or (at your
// option) any later version.
//
// This file is distributed in the hope that it will be useful, but
// WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
// General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with this program.  If not, see <http://www.gnu.org/licenses/>.

"use strict";

var _aircraft_cache = {};

function getAircraftData(icao) {
        var defer;

        icao = icao.toUpperCase();

        if (icao in _aircraft_cache) {
                defer = _aircraft_cache[icao];
        } else {
                // load from blocks:
                defer = _aircraft_cache[icao] = $.Deferred();
                request_from_db(icao, 1, defer);
        }

        return defer;
}

function request_from_db(icao, level, defer) {
        var bkey = icao.substring(0, level);
        var dkey = icao.substring(level);
        var req = db_ajax(bkey);

        req.done(function(data) {
                var subkey;

                if (dkey in data) {
                        defer.resolve(data[dkey]);
                        return;
                }

                if ("children" in data) {
                        subkey = bkey + dkey.substring(0,1);
                        if (data.children.indexOf(subkey) != -1) {
                                request_from_db(icao, level+1, defer);
                                return;
                        }
                }
                defer.reject();
       });

        req.fail(function(jqXHR,textStatus,errorThrown) {
                defer.reject();
        });
}

var _request_count = 0;
var _request_queue = [];
var _request_cache = {};

var MAX_REQUESTS = 2;

function db_ajax(bkey) {
        var defer;

        if (bkey in _request_cache) {
                return _request_cache[bkey];
        }

        if (_request_count < MAX_REQUESTS) {
                // just do ajax directly
                ++_request_count;
                defer = _request_cache[bkey] = $.ajax({ url: 'db/' + bkey + '.json',
                                                        cache: true,
                                                        timeout: 5000,
                                                        dataType : 'json' });
                defer.always(db_ajax_request_complete);
        } else {
                // put it in the queue
                defer = _request_cache[bkey] = $.Deferred();
                defer.bkey = bkey;
                _request_queue.push(defer);
        }

        return defer;
}

function db_ajax_request_complete() {
        var req;
        var ajaxreq;

        if (_request_queue.length == 0) {
                --_request_count;
        } else {
                req = _request_queue.shift();
                ajaxreq = $.ajax({ url: 'db/' + req.bkey + '.json',
                                   cache: true,
                                   timeout: 5000,
                                   dataType : 'json' });
                ajaxreq.done(function(data) { req.resolve(data); });
                ajaxreq.fail(function(jqxhr, status, error) { req.reject(jqxhr, status, error); });
                ajaxreq.always(db_ajax_request_complete);
        }
}
