// Tests aggregation on views for proper pipeline concatenation and semantics.
(function() {
    "use strict";

    // For arrayEq, assertErrorCode, and orderedArrayEq.
    load("jstests/aggregation/extras/utils.js");

    let viewsDB = db.getSiblingDB("views_aggregation");
    assert.commandWorked(viewsDB.dropDatabase());

    // Helper functions.
    let assertAggResultEq = function(collection, pipeline, expected, ordered) {
        let coll = viewsDB.getCollection(collection);
        let arr = coll.aggregate(pipeline).toArray();
        let success = (typeof(ordered) === "undefined" || !ordered) ? arrayEq(arr, expected)
                                                                    : orderedArrayEq(arr, expected);
        assert(success, tojson({got: arr, expected: expected}));
    };
    let byPopulation = function(a, b) {
        if (a.pop < b.pop)
            return -1;
        else if (a.pop > b.pop)
            return 1;
        else
            return 0;
    };

    // Populate a collection with some test data.
    let allDocuments = [];
    allDocuments.push({_id: "New York", state: "NY", pop: 7});
    allDocuments.push({_id: "Newark", state: "NJ", pop: 3});
    allDocuments.push({_id: "Palo Alto", state: "CA", pop: 10});
    allDocuments.push({_id: "San Francisco", state: "CA", pop: 4});
    allDocuments.push({_id: "Trenton", state: "NJ", pop: 5});

    let coll = viewsDB.coll;
    let bulk = coll.initializeUnorderedBulkOp();
    allDocuments.forEach(function(doc) {
        bulk.insert(doc);
    });
    assert.writeOK(bulk.execute());

    // Create views on the data.
    assert.commandWorked(viewsDB.runCommand({create: "emptyPipelineView", viewOn: "coll"}));
    assert.commandWorked(
        viewsDB.runCommand({create: "identityView", viewOn: "coll", pipeline: [{$match: {}}]}));
    assert.commandWorked(viewsDB.runCommand(
        {create: "noIdView", viewOn: "coll", pipeline: [{$project: {_id: 0, state: 1, pop: 1}}]}));
    assert.commandWorked(viewsDB.runCommand({
        create: "popSortedView",
        viewOn: "identityView",
        pipeline: [{$match: {pop: {$gte: 0}}}, {$sort: {pop: 1}}]
    }));

    // Find all documents with empty aggregations.
    assertAggResultEq("emptyPipelineView", [], allDocuments);
    assertAggResultEq("identityView", [], allDocuments);
    assertAggResultEq("identityView", [{$match: {}}], allDocuments);

    // Filter documents on a view with $match.
    assertAggResultEq(
        "popSortedView", [{$match: {state: "NY"}}], [{_id: "New York", state: "NY", pop: 7}]);

    // An aggregation still works on a view that strips _id.
    assertAggResultEq("noIdView", [{$match: {state: "NY"}}], [{state: "NY", pop: 7}]);

    // Aggregations work on views that sort.
    const doOrderedSort = true;
    assertAggResultEq("popSortedView", [], allDocuments.sort(byPopulation), doOrderedSort);
    assertAggResultEq("popSortedView", [{$limit: 1}, {$project: {_id: 1}}], [{_id: "Palo Alto"}]);

    // Test that the $out stage errors when given a view namespace.
    assertErrorCode(coll, [{$out: "emptyPipelineView"}], 18631);

    // Test that the $lookup stage resolves the view namespace referenced in the 'from' field.
    assertAggResultEq(
        coll.getName(),
        [
          {$match: {_id: "New York"}},
          {$lookup: {from: "identityView", localField: "_id", foreignField: "_id", as: "matched"}},
          {$unwind: "$matched"},
          {$project: {_id: 1, matchedId: "$matched._id"}}
        ],
        [{_id: "New York", matchedId: "New York"}]);

    // Test that the $graphLookup stage resolves the view namespace referenced in the 'from' field.
    assertAggResultEq(coll.getName(),
                      [
                        {$match: {_id: "New York"}},
                        {
                          $graphLookup: {
                              from: "identityView",
                              startWith: "$_id",
                              connectFromField: "_id",
                              connectToField: "_id",
                              as: "matched"
                          }
                        },
                        {$unwind: "$matched"},
                        {$project: {_id: 1, matchedId: "$matched._id"}}
                      ],
                      [{_id: "New York", matchedId: "New York"}]);

    // Test that the $lookup stage resolves the view namespace referenced in the 'from' field of
    // another $lookup stage nested inside of it.
    assert.commandWorked(viewsDB.runCommand({
        create: "viewWithLookupInside",
        viewOn: coll.getName(),
        pipeline: [
            {
              $lookup:
                  {from: "identityView", localField: "_id", foreignField: "_id", as: "matched"}
            },
            {$unwind: "$matched"},
            {$project: {_id: 1, matchedId: "$matched._id"}}
        ]
    }));

    assertAggResultEq(
        coll.getName(),
        [
          {$match: {_id: "New York"}},
          {
            $lookup: {
                from: "viewWithLookupInside",
                localField: "_id",
                foreignField: "matchedId",
                as: "matched"
            }
          },
          {$unwind: "$matched"},
          {$project: {_id: 1, matchedId1: "$matched._id", matchedId2: "$matched.matchedId"}}
        ],
        [{_id: "New York", matchedId1: "New York", matchedId2: "New York"}]);

    // Test that the $graphLookup stage resolves the view namespace referenced in the 'from' field
    // of a $lookup stage nested inside of it.
    let graphLookupPipeline = [
        {$match: {_id: "New York"}},
        {
          $graphLookup: {
              from: "viewWithLookupInside",
              startWith: "$_id",
              connectFromField: "_id",
              connectToField: "matchedId",
              as: "matched"
          }
        },
        {$unwind: "$matched"},
        {$project: {_id: 1, matchedId1: "$matched._id", matchedId2: "$matched.matchedId"}}
    ];

    assertAggResultEq(coll.getName(),
                      graphLookupPipeline,
                      [{_id: "New York", matchedId1: "New York", matchedId2: "New York"}]);

    // Test that the $facet stage resolves the view namespace referenced in the 'from' field of a
    // $lookup stage nested inside of a $graphLookup stage.
    assertAggResultEq(
        coll.getName(),
        [{$facet: {nested: graphLookupPipeline}}],
        [{nested: [{_id: "New York", matchedId1: "New York", matchedId2: "New York"}]}]);
}());