/**
 * Test that $** indexes obey collation rules for document values, while the virtual $_path
 * components stored alongside these values in the index always use simple binary comparison.
 *
 * The tags below are necessary because collation requires that we use read/write commands rather
 * than legacy operations. We also require that collections are unsharded, since we perform queries
 * which we expect to be covered.
 * @tags: [assumes_unsharded_collection, requires_find_command, requires_non_retryable_commands,
 * requires_non_retryable_writes]
 */
(function() {
"user strict";

load("jstests/aggregation/extras/utils.js");       // For arrayEq.
load("jstests/libs/analyze_plan.js");              // For getPlanStages.
load("jstests/libs/get_index_helpers.js");         // For GetIndexHelpers.
load("jstests/libs/collection_drop_recreate.js");  // For assert[Drop|Create]Collection.
load("jstests/libs/fixture_helpers.js");           // For isMongos.

const assertArrayEq = (l, r) => assert(arrayEq(l, r));

// Create the collection and assign it a default case-insensitive collation.
const coll = assertDropAndRecreateCollection(
    db, "wildcard_collation", {collation: {locale: "en_US", strength: 1}});

// Extracts the winning plan for the given query and projection from the explain output.
const winningPlan = (query, proj) => FixtureHelpers.isMongos(db)
    ? coll.find(query, proj).explain().queryPlanner.winningPlan.shards[0].winningPlan
    : coll.find(query, proj).explain().queryPlanner.winningPlan;

// Runs the given query and confirms that: (1) the $** was used to answer the query, (2) the
// results produced by the $** index match the given 'expectedResults', and (3) the same output
// is produced by a COLLSCAN with the same collation.
function assertWildcardIndexAnswersQuery(query, expectedResults, projection) {
    // Verify that the $** index can answer this query.
    const ixScans = getPlanStages(winningPlan(query, (projection || {_id: 0})), "IXSCAN");
    assert.gt(ixScans.length, 0, tojson(coll.find(query).explain()));
    ixScans.forEach((ixScan) => assert(ixScan.keyPattern.$_path));

    // Assert that the $** index produces the expected results, and that these are the same
    // as those produced by a COLLSCAN with the same collation.
    const wildcardResults = coll.find(query, (projection || {_id: 0})).toArray();
    assertArrayEq(wildcardResults, expectedResults);
    assertArrayEq(wildcardResults,
                  coll.find(query, (projection || {_id: 0}))
                      .collation({locale: "en_US", strength: 1})
                      .hint({$natural: 1})
                      .toArray());
}

// Confirms that the index matching the given keyPattern has the specified collation.
function assertIndexHasCollation(keyPattern, collation) {
    var indexSpecs = coll.getIndexes();
    var found = GetIndexHelpers.findByKeyPattern(indexSpecs, keyPattern, collation);
    assert.neq(null,
               found,
               "Index with key pattern " + tojson(keyPattern) + " and collation " +
                   tojson(collation) + " not found: " + tojson(indexSpecs));
}

// Confirm that the $** index inherits the collection's default collation.
assert.commandWorked(coll.createIndex({"$**": 1}));
assertIndexHasCollation({"$**": 1}, {
    locale: "en_US",
    caseLevel: false,
    caseFirst: "off",
    strength: 1,
    numericOrdering: false,
    alternate: "non-ignorable",
    maxVariable: "punct",
    normalization: false,
    backwards: false,
    version: "57.1",
});

// Insert a series of documents whose fieldnames and values differ only by case.
assert.commandWorked(coll.insert({a: {b: "string", c: "STRING"}, d: "sTrInG", e: 5}));
assert.commandWorked(coll.insert({a: {b: "STRING", c: "string"}, d: "StRiNg", e: 5}));
assert.commandWorked(coll.insert({A: {B: "string", C: "STRING"}, d: "sTrInG", E: 5}));
assert.commandWorked(coll.insert({A: {B: "STRING", C: "string"}, d: "StRiNg", E: 5}));

// Confirm that only the document's values adhere to the case-insensitive collation. The field
// paths, which are also present in the $** index keys, are evaluated using simple binary
// comparison; so for instance, path "a.b" does *not* match path "A.B".
assertWildcardIndexAnswersQuery({"a.b": "string"}, [
    {a: {b: "string", c: "STRING"}, d: "sTrInG", e: 5},
    {a: {b: "STRING", c: "string"}, d: "StRiNg", e: 5}
]);
assertWildcardIndexAnswersQuery({"A.B": "string"}, [
    {A: {B: "string", C: "STRING"}, d: "sTrInG", E: 5},
    {A: {B: "STRING", C: "string"}, d: "StRiNg", E: 5}
]);

// All documents in the collection are returned if we query over both upper- and lower-case
// fieldnames, or when the fieldname has a consistent case across all documents.
const allDocs = coll.find({}, {_id: 0}).toArray();
assertWildcardIndexAnswersQuery({$or: [{"a.c": "string"}, {"A.C": "string"}]}, allDocs);
assertWildcardIndexAnswersQuery({d: "string"}, allDocs);

// Confirm that the $** index also differentiates between upper and lower fieldname case when
// querying fields which do not contain string values.
assertWildcardIndexAnswersQuery({e: 5}, [
    {a: {b: "string", c: "STRING"}, d: "sTrInG", e: 5},
    {a: {b: "STRING", c: "string"}, d: "StRiNg", e: 5}
]);
assertWildcardIndexAnswersQuery({E: 5}, [
    {A: {B: "string", C: "STRING"}, d: "sTrInG", E: 5},
    {A: {B: "STRING", C: "string"}, d: "StRiNg", E: 5}
]);

// Confirm that the $** index produces a covered plan for a query on non-string, non-object,
// non-array values.
assert(isIndexOnly(coll.getDB(), winningPlan({e: 5}, {_id: 0, e: 1})));
assert(isIndexOnly(coll.getDB(), winningPlan({E: 5}, {_id: 0, E: 1})));

// Confirm that the $** index differentiates fieldname case when attempting to cover.
assert(!isIndexOnly(coll.getDB(), winningPlan({e: 5}, {_id: 0, E: 1})));
assert(!isIndexOnly(coll.getDB(), winningPlan({E: 5}, {_id: 0, e: 1})));
})();