// mr.js

MR = {};

MR.init = function() {
    $max = 0;
    $arr = [];
    emit = MR.emit;
    $numEmits = 0;
    $numReduces = 0;
    $numReducesToDB = 0;
    gc();  // this is just so that keep memory size sane
};

MR.cleanup = function() {
    MR.init();
    gc();
};

MR.emit = function(k, v) {
    $numEmits++;
    var num = nativeHelper.apply(get_num_, [k]);
    var data = $arr[num];
    if (!data) {
        data = {key: k, values: new Array(1000), count: 0};
        $arr[num] = data;
    }
    data.values[data.count++] = v;
    $max = Math.max($max, data.count);
};

MR.doReduce = function(useDB) {
    $numReduces++;
    if (useDB)
        $numReducesToDB++;
    $max = 0;
    for (var i = 0; i < $arr.length; i++) {
        var data = $arr[i];
        if (!data)
            continue;

        if (useDB) {
            var x = tempcoll.findOne({_id: data.key});
            if (x) {
                data.values[data.count++] = x.value;
            }
        }

        var r = $reduce(data.key, data.values.slice(0, data.count));
        if (r && r.length && r[0]) {
            data.values = r;
            data.count = r.length;
        } else {
            data.values[0] = r;
            data.count = 1;
        }

        $max = Math.max($max, data.count);

        if (useDB) {
            if (data.count == 1) {
                tempcoll.save({_id: data.key, value: data.values[0]});
            } else {
                tempcoll.save({_id: data.key, value: data.values.slice(0, data.count)});
            }
        }
    }
};

MR.check = function() {
    if ($max < 2000 && $arr.length < 1000) {
        return 0;
    }
    MR.doReduce();
    if ($max < 2000 && $arr.length < 1000) {
        return 1;
    }
    MR.doReduce(true);
    $arr = [];
    $max = 0;
    reset_num();
    gc();
    return 2;
};

MR.finalize = function() {
    tempcoll.find().forEach(function(z) {
        z.value = $finalize(z._id, z.value);
        tempcoll.save(z);
    });
};