// @tags: [requires_non_retryable_writes, requires_fastcount]

// The positional operator allows an update modifier field path to contain a sentinel ('$') path
// part that is replaced with the numeric position of an array element matched by the update's query
// spec.  <http://dochub.mongodb.org/core/positionaloperator>

// If no array element position from a query is available to substitute for the positional operator
// setinel ('$'), the update fails with an error.  SERVER-6669 SERVER-4713

var res;
t = db.jstests_updatel;
t.drop();

// The collection is empty, forcing an upsert.  In this case the query has no array position match
// to substiture for the positional operator.  SERVER-4713
res = t.update({}, {$set: {'a.$.b': 1}}, true);
assert(res.hasWriteError(), "An error is reported.");
assert.eq(0, t.count(), "No upsert occurred.");

// Save a document to the collection so it is no longer empty.
t.save({_id: 0});

// Now, with an existing document, trigger an update rather than an upsert.  The query has no array
// position match to substiture for the positional operator.  SERVER-6669
res = t.update({}, {$set: {'a.$.b': 1}});
assert(res.hasWriteError(), "An error is reported.");
assert.eq([{_id: 0}], t.find().toArray(), "No update occurred.");

// Now, try with an update by _id (without a query array match).
res = t.update({_id: 0}, {$set: {'a.$.b': 1}});
assert(res.hasWriteError(), "An error is reported.");
assert.eq([{_id: 0}], t.find().toArray(), "No update occurred.");

// Seed the collection with a document suitable for the following check.
t.remove({});
t.save({_id: 0, a: [{b: {c: 1}}]});

// Now, attempt to apply an update with two nested positional operators.  There is a positional
// query match for the first positional operator but not the second.  Note that dollar sign
// substitution for multiple positional opertors is not implemented (SERVER-831).
res = t.update({'a.b.c': 1}, {$set: {'a.$.b.$.c': 2}});
assert(res.hasWriteError(), "An error is reported");
assert.eq([{_id: 0, a: [{b: {c: 1}}]}], t.find().toArray(), "No update occurred.");

// SERVER-1155 test an update with the positional operator
// that has a regex in the query field
t.drop();
t.insert({_id: 1, arr: [{a: "z", b: 1}]});
res = t.update({"arr.a": /^z$/}, {$set: {"arr.$.b": 2}}, false, true);
assert.commandWorked(res);
assert.eq(t.findOne().arr[0], {a: "z", b: 2});

t.drop();
t.insert({_id: 1, arr: [{a: "z", b: 1}, {a: "abc", b: 2}, {a: "lmn", b: 3}]});
res = t.update({"arr.a": /l/}, {$inc: {"arr.$.b": 2}}, false, true);
assert.commandWorked(res);
assert.eq(t.findOne().arr[2], {a: "lmn", b: 5});