/*
 * Test that the explain command supports findAndModify when talking to a mongos
 * and the collection is sharded.
 */
(function() {
'use strict';

var collName = 'explain_find_and_modify';

// Create a cluster with 2 shards.
var st = new ShardingTest({shards: 2});

var testDB = st.s.getDB('test');
var shardKey = {a: 1};

// Create a collection with an index on the intended shard key.
var shardedColl = testDB.getCollection(collName);
shardedColl.drop();
assert.commandWorked(testDB.createCollection(collName));
assert.commandWorked(shardedColl.createIndex(shardKey));

// Enable sharding on the database and shard the collection.
// Use "st.shard0.shardName" as the primary shard.
assert.commandWorked(testDB.adminCommand({enableSharding: testDB.getName()}));
st.ensurePrimaryShard(testDB.toString(), st.shard0.shardName);
assert.commandWorked(
    testDB.adminCommand({shardCollection: shardedColl.getFullName(), key: shardKey}));

// Split and move the chunks so that
//   chunk { "a" : { "$minKey" : 1 } } -->> { "a" : 10 }                is on
//   st.shard0.shardName
//   chunk { "a" : 10 }                -->> { "a" : { "$maxKey" : 1 } } is on
//   st.shard1.shardName
assert.commandWorked(testDB.adminCommand({split: shardedColl.getFullName(), middle: {a: 10}}));
assert.commandWorked(testDB.adminCommand(
    {moveChunk: shardedColl.getFullName(), find: {a: 10}, to: st.shard1.shardName}));

var res;

// Queries that do not involve the shard key are invalid.
res = testDB.runCommand(
    {explain: {findAndModify: collName, query: {b: 1}, remove: true}, verbosity: 'queryPlanner'});
assert.commandFailed(res);

// Queries that have non-equality queries on the shard key are invalid.
res = testDB.runCommand({
    explain: {
        findAndModify: collName,
        query: {a: {$gt: 5}},
        update: {$inc: {b: 7}},
    },
    verbosity: 'allPlansExecution'
});
assert.commandFailed(res);

// Asserts that the explain command ran on the specified shard and used the given stage
// for performing the findAndModify command.
function assertExplainResult(explainOut, outerKey, innerKey, shardName, expectedStage) {
    assert(explainOut.hasOwnProperty(outerKey));
    assert(explainOut[outerKey].hasOwnProperty(innerKey));

    var shardStage = explainOut[outerKey][innerKey];
    assert.eq('SINGLE_SHARD', shardStage.stage);
    assert.eq(1, shardStage.shards.length);
    assert.eq(shardName, shardStage.shards[0].shardName);
    assert.eq(expectedStage, shardStage.shards[0][innerKey].stage);
}

// Test that the explain command is routed to "st.shard0.shardName" when targeting the lower
// chunk range.
res = testDB.runCommand({
    explain: {findAndModify: collName, query: {a: 0}, update: {$inc: {b: 7}}, upsert: true},
    verbosity: 'queryPlanner'
});
assert.commandWorked(res);
assertExplainResult(res, 'queryPlanner', 'winningPlan', st.shard0.shardName, 'UPDATE');

// Test that the explain command is routed to "st.shard1.shardName" when targeting the higher
// chunk range.
res = testDB.runCommand({
    explain: {findAndModify: collName, query: {a: 20, c: 5}, remove: true},
    verbosity: 'executionStats'
});
assert.commandWorked(res);
assertExplainResult(res, 'executionStats', 'executionStages', st.shard1.shardName, 'DELETE');

st.stop();
})();