/**
 * Test the behavior of the $map operator with the arrayIndexAs field.
 *
 * @tags: [requires_fcv_83]
 */
import {assertErrorCode} from "jstests/aggregation/extras/utils.js";
import {FeatureFlagUtil} from "jstests/libs/feature_flag_util.js";

function testError(expression, code, options = {}) {
    const projectSpec = {$project: {b: expression}};
    assertErrorCode(coll, projectSpec, code, "", options);
}

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

let coll = db[jsTestName()];
coll.drop();

if (FeatureFlagUtil.isPresentAndEnabled(db, "ExposeArrayIndexInMapFilterReduce")) {
    assert.commandWorked(
        coll.insert({
            simple: [1, 2, 3, 4],
            a4z: [0, 0, 0, 0],
            nested: [{a: 1}, {a: 2}],
            mixed: [{a: 1}, {}, {a: 2}, {a: null}],
            notArray: 1,
            null: null,
        }),
    );

    test({$map: {input: "$mixed", in: "$$IDX"}}, [0, 1, 2, 3]);

    test({$map: {input: "$mixed", arrayIndexAs: "σημείο", in: "$$σημείο"}}, [0, 1, 2, 3]);

    test(
        {
            $map: {
                input: "$simple",
                arrayIndexAs: "idx",
                as: "this",
                in: {$add: ["$$idx", "$$this"]},
            },
        },
        [1, 3, 5, 7],
    );

    // Nested behavior with two named index variables.
    test(
        {
            $map: {
                input: "$a4z",
                arrayIndexAs: "outer",
                in: {
                    $map: {
                        input: "$a4z",
                        arrayIndexAs: "inner",
                        in: {$add: [{$multiply: [4, "$$outer"]}, "$$inner", 1]},
                    },
                },
            },
        },
        [
            [1, 2, 3, 4],
            [5, 6, 7, 8],
            [9, 10, 11, 12],
            [13, 14, 15, 16],
        ],
    );

    // Nested behavior for shadowing variables.
    test({$map: {input: "$a4z", in: {$map: {input: "$a4z", in: "$$IDX"}}}}, [
        [0, 1, 2, 3],
        [0, 1, 2, 3],
        [0, 1, 2, 3],
        [0, 1, 2, 3],
    ]);

    // Nested behavior with named inner variable and default outer variable.
    test(
        {$map: {input: "$a4z", in: {$map: {input: "$a4z", arrayIndexAs: "inner", in: {$add: ["$$IDX", "$$inner"]}}}}},
        [
            [0, 1, 2, 3],
            [1, 2, 3, 4],
            [2, 3, 4, 5],
            [3, 4, 5, 6],
        ],
    );

    //
    // Test error conditions.
    //

    // Can't use default $$IDX if 'arrayIndexAs' is defined.
    testError({$map: {input: "$simple", arrayIndexAs: "index", in: "$$IDX"}}, 17276);

    // Can't use non-user definable names on 'arrayIndexAs'.
    testError({$map: {input: "$simple", arrayIndexAs: "IDX", in: []}}, ErrorCodes.FailedToParse);
    testError({$map: {input: "$simple", arrayIndexAs: "^", in: []}}, ErrorCodes.FailedToParse);
    testError({$map: {input: "$simple", arrayIndexAs: "", in: []}}, ErrorCodes.FailedToParse);

    // Can't use variable defined by 'arrayIndexAs' or $$IDX in the non-'in' arguments.
    testError({$map: {input: "$$IDX", in: {}}}, 17276);
    testError({$map: {input: "$$i", arrayIndexAs: "i", in: {}}}, 17276);

    // Can't reuse same variable.
    testError({$map: {input: "$simple", as: "i", arrayIndexAs: "i", in: "$$i"}}, 9375801);

    // Can't use 'arrayIndexAs' in API Version 1 with apiStrict.
    testError({$map: {input: "$simple", arrayIndexAs: "i", in: "$$i"}}, ErrorCodes.APIStrictError, {
        apiVersion: "1",
        apiStrict: true,
    });
} else {
    // TODO(SERVER-90514): remove these tests when the new features are enabled by default.
    testError({$map: {input: "$simple", in: "$$IDX"}}, 17276);
    testError({$map: {input: "$simple", arrayIndexAs: "i", in: "$$i"}}, 16879);
}