/**
 * Tests the behavior of views when the backing view or collection is changed.
 * @tags: [
 *   assumes_superuser_permissions,
 *   requires_find_command,
 *   requires_non_retryable_commands,
 * ]
 */
(function() {
"use strict";

// For arrayEq.
load("jstests/aggregation/extras/utils.js");

let viewDB = db.getSiblingDB("views_change");
let collection = viewDB.collection;
let view = viewDB.view;
let viewOnView = viewDB.viewOnView;

// Convenience functions.
let resetCollectionAndViews = function() {
    viewDB.runCommand({drop: "collection"});
    viewDB.runCommand({drop: "view"});
    viewDB.runCommand({drop: "viewOnView"});
    assert.commandWorked(viewDB.runCommand({create: "collection"}));
    assert.commandWorked(
        viewDB.runCommand({create: "view", viewOn: "collection", pipeline: [{$match: {a: 1}}]}));
    assert.commandWorked(
        viewDB.runCommand({create: "viewOnView", viewOn: "view", pipeline: [{$match: {b: 1}}]}));
};
let assertFindResultEq = function(collName, expected) {
    let res = viewDB.runCommand({find: collName, filter: {}, projection: {_id: 0, a: 1, b: 1}});
    assert.commandWorked(res);
    let arr = new DBCommandCursor(db, res).toArray();
    let errmsg = tojson({expected: expected, got: arr});
    assert(arrayEq(arr, expected), errmsg);
};

let doc = {a: 1, b: 1};

resetCollectionAndViews();

// A view is updated when its viewOn is modified. When auth is enabled, we expect collMod to
// fail when specifying "viewOn" but not "pipeline".
assert.writeOK(collection.insert(doc));
assertFindResultEq("view", [doc]);
let res = viewDB.runCommand({collMod: "view", viewOn: "nonexistent"});
if (jsTest.options().auth) {
    assert.commandFailedWithCode(res, ErrorCodes.InvalidOptions);
} else {
    assert.commandWorked(res);
    assertFindResultEq("view", []);
}

resetCollectionAndViews();

// A view is updated when its pipeline is modified. When auth is enabled, we expect collMod to
// fail when specifying "pipeline" but not "viewOn".
assert.writeOK(collection.insert(doc));
assert.writeOK(collection.insert({a: 7}));
assertFindResultEq("view", [doc]);
res = viewDB.runCommand({collMod: "view", pipeline: [{$match: {a: {$gt: 4}}}]});
if (jsTest.options().auth) {
    assert.commandFailedWithCode(res, ErrorCodes.InvalidOptions);
} else {
    assert.commandWorked(res);
    assertFindResultEq("view", [{a: 7}]);
}

resetCollectionAndViews();

// A view is updated when the backing collection is updated.
assert.writeOK(collection.insert(doc));
assertFindResultEq("view", [doc]);
assert.writeOK(collection.update({a: 1}, {$set: {a: 2}}));
assertFindResultEq("view", []);

resetCollectionAndViews();

// A view is updated when a backing view is updated.
assert.writeOK(collection.insert(doc));
assertFindResultEq("viewOnView", [doc]);
assert.commandWorked(viewDB.runCommand(
    {collMod: "view", viewOn: "collection", pipeline: [{$match: {nonexistent: 1}}]}));
assertFindResultEq("viewOnView", []);

resetCollectionAndViews();

// A view appears empty if the backing collection is dropped.
assert.writeOK(collection.insert(doc));
assertFindResultEq("view", [doc]);
assert.commandWorked(viewDB.runCommand({drop: "collection"}));
assertFindResultEq("view", []);

resetCollectionAndViews();

// A view appears empty if a backing view is dropped.
assert.writeOK(collection.insert(doc));
assertFindResultEq("viewOnView", [doc]);
assert.commandWorked(viewDB.runCommand({drop: "view"}));
assertFindResultEq("viewOnView", []);
}());