// Copyright (C) 2019-2020 Zilliz. All rights reserved.
//
// Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance
// with the License. You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software distributed under the License
// is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express
// or implied. See the License for the specific language governing permissions and limitations under the License.

#include <list>
#include <random>
#include "cache/GpuCacheMgr.h"
#include "scheduler/Algorithm.h"
#include "scheduler/action/Action.h"
#include "scheduler/tasklabel/SpecResLabel.h"

namespace milvus {
namespace scheduler {

std::vector<ResourcePtr>
get_neighbours(const ResourcePtr& self) {
    std::vector<ResourcePtr> neighbours;
    for (auto& neighbour_node : self->GetNeighbours()) {
        auto node = neighbour_node.neighbour_node;
        if (not node)
            continue;

        auto resource = std::static_pointer_cast<Resource>(node);
        //        if (not resource->HasExecutor()) continue;

        neighbours.emplace_back(resource);
    }
    return neighbours;
}

// This function has not been invoked, comment it for code coverage
#if 0
std::vector<std::pair<ResourcePtr, Connection>>
get_neighbours_with_connetion(const ResourcePtr& self) {
    std::vector<std::pair<ResourcePtr, Connection>> neighbours;
    for (auto& neighbour_node : self->GetNeighbours()) {
        auto node = neighbour_node.neighbour_node;
        if (not node)
            continue;

        auto resource = std::static_pointer_cast<Resource>(node);
        //        if (not resource->HasExecutor()) continue;
        Connection conn = neighbour_node.connection;
        neighbours.emplace_back(std::make_pair(resource, conn));
    }
    return neighbours;
}

void
Action::PushTaskToNeighbourRandomly(TaskTableItemPtr task_item, const ResourcePtr& self) {
    auto neighbours = get_neighbours_with_connetion(self);
    if (not neighbours.empty()) {
        std::vector<uint64_t> speeds;
        uint64_t total_speed = 0;
        for (auto& neighbour : neighbours) {
            uint64_t speed = neighbour.second.speed();
            speeds.emplace_back(speed);
            total_speed += speed;
        }

        unsigned seed1 = std::chrono::system_clock::now().time_since_epoch().count();
        std::mt19937 mt(seed1);
        std::uniform_int_distribution<int> dist(0, total_speed);
        uint64_t index = 0;
        int64_t rd_speed = dist(mt);
        for (uint64_t i = 0; i < speeds.size(); ++i) {
            rd_speed -= speeds[i];
            if (rd_speed <= 0) {
                neighbours[i].first->task_table().Put(task_item->task, task_item);
                return;
            }
        }

    } else {
        // TODO(wxyu): process
    }
}
#endif

void
Action::PushTaskToAllNeighbour(TaskTableItemPtr task_item, const ResourcePtr& self) {
    auto neighbours = get_neighbours(self);
    for (auto& neighbour : neighbours) {
        neighbour->task_table().Put(task_item->task, task_item);
    }
}

#if 0
void
Action::PushTaskToResource(TaskTableItemPtr task_item, const ResourcePtr& dest) {
    dest->task_table().Put(task_item->task, task_item);
}
#endif

void
Action::SpecifiedResourceLabelTaskScheduler(const ResourceMgrPtr& res_mgr, ResourcePtr resource,
                                            std::shared_ptr<LoadCompletedEvent> event) {
    auto task_item = event->task_table_item_;
    auto task = event->task_table_item_->task;

    if (resource->name() == task->path().Last()) {
        resource->WakeupExecutor();
    } else {
        auto next_res_name = task->path().Next();
        auto next_res = res_mgr->GetResource(next_res_name);
        //        if (event->task_table_item_->Move()) {
        //            next_res->task_table().Put(task);
        //        }
        event->task_table_item_->Move();
        next_res->task_table().Put(task, task_item);
    }
}

}  // namespace scheduler
}  // namespace milvus