// Confirms that the dbStats command returns expected content.
//
// @tags: [requires_dbstats]

(function() {
    "use strict";

    function serverIsMongos() {
        const res = db.runCommand("ismaster");
        assert.commandWorked(res);
        return res.msg === "isdbgrid";
    }

    function serverUsingPersistentStorage() {
        const res = db.runCommand("serverStatus");
        assert.commandWorked(res);
        return res.storageEngine.persistent === true;
    }

    const isMongoS = serverIsMongos();
    const isUsingPersistentStorage = !isMongoS && serverUsingPersistentStorage();

    let testDB = db.getSiblingDB("dbstats_js");
    assert.commandWorked(testDB.dropDatabase());

    let coll = testDB["testColl"];
    assert.commandWorked(coll.createIndex({x: 1}));
    const doc = {_id: 1, x: 1};
    assert.writeOK(coll.insert(doc));

    let dbStats = testDB.runCommand({dbStats: 1});
    assert.commandWorked(dbStats);

    assert.eq(1, dbStats.objects, tojson(dbStats));  // Includes testColl only
    const dataSize = Object.bsonsize(doc);
    assert.eq(dataSize, dbStats.avgObjSize, tojson(dbStats));
    assert.eq(dataSize, dbStats.dataSize, tojson(dbStats));

    // Index count will vary on mongoS if an additional index is needed to support sharding.
    if (isMongoS) {
        assert(dbStats.hasOwnProperty("indexes"), tojson(dbStats));
    } else {
        assert.eq(2, dbStats.indexes, tojson(dbStats));
    }

    assert(dbStats.hasOwnProperty("storageSize"), tojson(dbStats));
    assert(dbStats.hasOwnProperty("numExtents"), tojson(dbStats));
    assert(dbStats.hasOwnProperty("indexSize"), tojson(dbStats));

    if (isUsingPersistentStorage) {
        assert(dbStats.hasOwnProperty("fsUsedSize"), tojson(dbStats));
        assert(dbStats.hasOwnProperty("fsTotalSize"), tojson(dbStats));
    }

    // Confirm collection and view counts on mongoD
    if (!isMongoS) {
        assert.eq(testDB.getName(), dbStats.db, tojson(dbStats));

        // We wait to add a view until this point as it allows more exact testing of avgObjSize for
        // WiredTiger above. Having more than 1 document would require floating point comparison.
        assert.commandWorked(testDB.createView("testView", "testColl", []));

        dbStats = testDB.runCommand({dbStats: 1});
        assert.commandWorked(dbStats);

        assert.eq(2, dbStats.collections, tojson(dbStats));  // testColl + system.views
        assert.eq(1, dbStats.views, tojson(dbStats));
    }

})();