memgraph/tests/integration/hardcoded_query/11856262817829095719.cpp

#include <iostream>
#include <queue>
#include <string>
#include <vector>

#include "query/i_plan_cpu.hpp"
#include "query/util.hpp"
#include "storage/edge_x_vertex.hpp"
#include "storage/model/properties/all.hpp"
#include "storage/vertex_accessor.hpp"
#include "using.hpp"
#include "utils/memory/stack_allocator.hpp"

using std::cout;
using std::endl;

// Dressipi astar query of 4 clicks.

// TODO: figure out from the pattern in a query
constexpr size_t max_depth = 3;

// TODO: from query LIMIT 10
constexpr size_t limit = 10;

class Node
{
public:
    Node *parent = {nullptr};
    VertexPropertyType<Float> tkey;
    double cost;
    int depth  = {0};
    double sum = {0.0};
    VertexAccessor vacc;

    Node(VertexAccessor vacc, double cost,
         VertexPropertyType<Float> const &tkey)
        : cost(cost), vacc(vacc), tkey(tkey)
    {
    }
    Node(VertexAccessor vacc, double cost, Node *parent,
         VertexPropertyType<Float> const &tkey)
        : cost(cost), vacc(vacc), parent(parent), depth(parent->depth + 1),
          tkey(tkey)
    {
    }

    double sum_vertex_score()
    {
        auto now   = this;
        double sum = 0;
        do
        {
            sum += (now->vacc.at(tkey).get())->value();
            now = now->parent;
        } while (now != nullptr);
        this->sum = sum;
        return sum;
    }
};

bool vertex_filter_contained(DbAccessor &t, VertexAccessor &v, Node *before)
{
    if (v.fill())
    {
        bool found;
        do
        {
            found  = false;
            before = before->parent;
            if (before == nullptr)
            {
                return true;
            }
        } while (v.in_contains(before->vacc));
    }
    return false;
}

template <typename Stream>
auto astar(VertexAccessor &va, DbAccessor &t, plan_args_t &, Stream &)
{
    StackAllocator stack;
    std::vector<Node *> results;

    // TODO: variable part (extract)
    VertexPropertyType<Float> tkey = t.vertex_property_key<Float>("score");

    auto cmp = [](Node *left, Node *right) { return left->cost > right->cost; };
    std::priority_queue<Node *, std::vector<Node *>, decltype(cmp)> queue(cmp);

    Node *start = new (stack.allocate<Node>()) Node(va, 0, tkey);
    queue.push(start);

    size_t count = 0;
    do
    {
        auto now = queue.top();
        queue.pop();

        if (now->depth >= max_depth)
        {
            now->sum_vertex_score();
            results.emplace_back(now);

            count++;

            if (count >= limit)
            {
                // the limit was reached -> STOP the execution
                break;
            }

            // if the limit wasn't reached -> POP the next vertex
            continue;
        }

        iter::for_all(now->vacc.out(), [&](auto edge) {
            VertexAccessor va = edge.to();
            if (vertex_filter_contained(t, va, now))
            {
                auto cost = 1 - va.at(tkey).get()->value();
                Node *n   = new (stack.allocate<Node>())
                    Node(va, now->cost + cost, now, tkey);
                queue.push(n);
            }
        });
    } while (!queue.empty());

    stack.free();

    return results;
}

void reverse_stream_ids(Node *node, Stream& stream, VertexPropertyKey key)
{
    if (node == nullptr)
        return;
    reverse_stream_ids(node->parent, stream, key);
    stream.write(node->vacc.at(key).template as<Int64>());
}

class PlanCPU : public IPlanCPU<Stream>
{
public:
    bool run(Db &db, plan_args_t &args, Stream &stream) override
    {
        DbAccessor t(db);

        indices_t indices = {{"garment_id", 0}};
        auto properties   = query_properties(indices, args);

        auto &label = t.label_find_or_create("garment");
        auto garment_id_prop_key =
            t.vertex_property_key("garment_id", args[0].key.flags());

        stream.write_fields(
            {{"a.garment_id", "b.garment_id", "c.garment_id", "d.garment_id"}});

        label.index()
            .for_range(t)
            .properties_filter(t, properties)
            .for_all([&](auto va) {
                auto results = astar(va, t, args, stream);
                std::sort(results.begin(), results.end(),
                          [](Node *a, Node *b) { return a->sum > b->sum; });
                for (auto node : results)
                {
                    stream.write_record();
                    stream.write_list_header(max_depth + 1);
                    reverse_stream_ids(node, stream, garment_id_prop_key);
                }
            });

        stream.write_empty_fields();
        stream.write_meta("r");

        return t.commit();
    }

    ~PlanCPU() {}
};

extern "C" IPlanCPU<Stream> *produce() { return new PlanCPU(); }

extern "C" void destruct(IPlanCPU<Stream> *p) { delete p; }