// SERVER-9841 $map expression to map over arrays
import {assertErrorCode} from "jstests/aggregation/extras/utils.js";

let t = db.server9841;
t.drop();
t.insert({
    simple: [1, 2, 3, 4],
    nested: [{a: 1}, {a: 2}],
    mixed: [{a: 1}, {}, {a: 2}, {a: null}],
    notArray: 1,
    null: null,
});

function test(expression, expected) {
    let result = t.aggregate({$project: {_id: 0, res: expression}}).toArray();
    assert.eq(result, [{res: expected}]);
}

test({$map: {input: "$simple", as: "var", in: "$$var"}}, [1, 2, 3, 4]);
test({$map: {input: "$simple", as: "var", in: {$add: [10, "$$var"]}}}, [11, 12, 13, 14]);
test({$map: {input: "$simple", in: "$$this"}}, [1, 2, 3, 4]);

test({$map: {input: "$nested", as: "var", in: "$$var.a"}}, [1, 2]);
test({$map: {input: "$nested", as: "CURRENT", in: "$a"}}, [1, 2]);

test({$map: {input: "$mixed", as: "var", in: "$$var.a"}}, [1, null, 2, null]); // missing becomes null

test({$map: {input: "$null", as: "var", in: "$$var"}}, null);

// Nested behavior with two named variables.
test(
    {
        $map: {
            input: "$simple",
            as: "outer",
            in: {$map: {input: "$simple", as: "inner", in: {$add: ["$$inner", "$$outer"]}}},
        },
    },
    [
        [2, 3, 4, 5],
        [3, 4, 5, 6],
        [4, 5, 6, 7],
        [5, 6, 7, 8],
    ],
);

// Nested behavior for shadowing variables.
test({$map: {input: "$simple", in: {$map: {input: "$simple", in: "$$this"}}}}, [
    [1, 2, 3, 4],
    [1, 2, 3, 4],
    [1, 2, 3, 4],
    [1, 2, 3, 4],
]);

// Nested behavior with named inner variable and default outer variable.
test({$map: {input: "$simple", as: "outer", in: {$map: {input: "$simple", in: {$add: ["$$this", "$$outer"]}}}}}, [
    [2, 3, 4, 5],
    [3, 4, 5, 6],
    [4, 5, 6, 7],
    [5, 6, 7, 8],
]);

// can't use default if 'as' is defined
assertErrorCode(t, {$map: {input: "$simple", as: "value", in: "$$this"}}, 40324);

// can't set ROOT
assertErrorCode(t, {$project: {a: {$map: {input: "$simple", as: "ROOT", in: "$$ROOT"}}}}, ErrorCodes.FailedToParse);

// error on non-array
assertErrorCode(t, {$project: {a: {$map: {input: "$notArray", as: "var", in: "$$var"}}}}, 16883);

// parse errors (missing or extra fields)
assertErrorCode(t, {$project: {a: {$map: {x: 1, input: "$simple", as: "var", in: "$$var"}}}}, 16879);
assertErrorCode(t, {$project: {a: {$map: {as: "var", in: "$$var"}}}}, 16880);
assertErrorCode(t, {$project: {a: {$map: {input: "$simple", as: "var"}}}}, 16882);

// 'in' uses undefined variable name.
assertErrorCode(t, {$project: {a: {$map: {input: "$simple", in: "$$var"}}}}, 17276);