// $cond returns the evaluated second argument if the first evaluates to true but the evaluated
// third argument if the first evaluates to false.
load('jstests/aggregation/extras/utils.js');

t = db.jstests_aggregation_cond;
t.drop();

t.save({});

function assertError(expectedErrorCode, condSpec) {
    assertErrorCode(t, {$project: {a: {$cond: condSpec}}}, expectedErrorCode);
}

function assertResult(expectedResult, arg) {
    assert.eq(expectedResult, t.aggregate({$project: {a: {$cond: arg}}}).toArray()[0].a);
}

// Wrong number of args.
assertError(16020, []);
assertError(16020, [1]);
assertError(16020, [false]);
assertError(16020, [1, 1]);
assertError(16020, [1, 1, null, 1]);
assertError(16020, [1, 1, 1, undefined]);

// Bad object cases
assertError(17080, {"else": 1, then: 1});
assertError(17081, {"if": 1, "else": 1});
assertError(17082, {"if": 1, then: 1});
assertError(17083, {asdf: 1, then: 1});

// Literal expressions.
assertResult(1, [true, 1, 2]);
assertResult(2, [false, 1, 2]);

// Order independence for object case
assertResult(1, {"if": true, "then": 1, "else": 2});
assertResult(1, {"if": true, "else": 2, "then": 1});
assertResult(1, {"then": 1, "if": true, "else": 2});
assertResult(1, {"then": 1, "else": 2, "if": true});
assertResult(1, {"else": 2, "then": 1, "if": true});
assertResult(1, {"else": 2, "if": true, "then": 1});

// Computed expressions.
assertResult(1, [{$and: []}, {$add: [1]}, {$add: [1, 1]}]);
assertResult(2, [{$or: []}, {$add: [1]}, {$add: [1, 1]}]);

t.drop();
t.save({t: true, f: false, x: 'foo', y: 'bar'});

// Field path expressions.
assertResult('foo', ['$t', '$x', '$y']);
assertResult('bar', ['$f', '$x', '$y']);

t.drop();
t.save({});

// Coerce to bool.
assertResult('a', [1, 'a', 'b']);
assertResult('a', ['', 'a', 'b']);
assertResult('b', [0, 'a', 'b']);

// Nested.
t.drop();
t.save({noonSense: 'am', mealCombined: 'no'});
t.save({noonSense: 'am', mealCombined: 'yes'});
t.save({noonSense: 'pm', mealCombined: 'yes'});
t.save({noonSense: 'pm', mealCombined: 'no'});
assert.eq(['breakfast', 'brunch', 'linner', 'dinner'],
          t.aggregate({
               $project: {
                   a: {
                       $cond: [
                           {$eq: ['$noonSense', 'am']},
                           {$cond: [{$eq: ['$mealCombined', 'yes']}, 'brunch', 'breakfast']},
                           {$cond: [{$eq: ['$mealCombined', 'yes']}, 'linner', 'dinner']}
                       ]
                   }
               }
           }).map(function(x) {
              return x.a;
          }));