// This file is part of OpenCV project.
// It is subject to the license terms in the LICENSE file found in the top-level directory
// of this distribution and at http://opencv.org/license.html.
//
// Copyright (C) 2018-2021 Intel Corporation


#include "precomp.hpp"

#include <sstream>
#include <unordered_set>
#include <unordered_map>
#include <typeinfo> // typeid
#include <cctype> // std::isdigit

#include <ade/util/checked_cast.hpp>
#include <ade/util/zip_range.hpp> // zip_range, indexed

#include "api/gbackend_priv.hpp" // GBackend::Priv().compile()
#include "compiler/gmodel.hpp"
#include "compiler/gislandmodel.hpp"
#include "compiler/gmodel.hpp"

#include "logger.hpp"    // GAPI_LOG

namespace cv { namespace gimpl {

GIsland::GIsland(const gapi::GBackend &bknd,
                 ade::NodeHandle op,
                 util::optional<std::string> &&user_tag)
    : m_backend(bknd)
    , m_user_tag(std::move(user_tag))
{
    m_all.insert(op);
    m_in_ops.insert(op);
    m_out_ops.insert(op);
}

// _ because of gcc4.8 wanings on ARM
GIsland::GIsland(const gapi::GBackend &_bknd,
                 node_set &&_all,
                 node_set &&_in_ops,
                 node_set &&_out_ops,
                 util::optional<std::string> &&_user_tag)
    : m_backend(_bknd)
    , m_all(std::move(_all))
    , m_in_ops(std::move(_in_ops))
    , m_out_ops(std::move(_out_ops))
    , m_user_tag(std::move(_user_tag))
{
}

const GIsland::node_set& GIsland::contents() const
{
    return m_all;
}

const GIsland::node_set& GIsland::in_ops() const
{
    return m_in_ops;
}

const GIsland::node_set& GIsland::out_ops() const
{
    return m_out_ops;
}

gapi::GBackend GIsland::backend() const
{
    return m_backend;
}

bool GIsland::is_user_specified() const
{
    return m_user_tag.has_value();
}

void GIsland::debug() const
{
    std::stringstream stream;
    stream << name() << " {{\n  input ops: ";
    for (const auto& nh : m_in_ops) stream << nh << "; ";
    stream << "\n  output ops: ";
    for (const auto& nh : m_out_ops) stream << nh << "; ";
    stream << "\n  contents: ";
    for (const auto& nh : m_all) stream << nh << "; ";
    stream << "\n}}" << std::endl;
    GAPI_LOG_INFO(NULL, stream.str());
}

GIsland::node_set GIsland::consumers(const ade::Graph &g,
                                     const ade::NodeHandle &slot_nh) const
{
    GIslandModel::ConstGraph gim(g);
    auto data_nh = gim.metadata(slot_nh).get<DataSlot>().original_data_node;
    GIsland::node_set result;
    for (const auto& in_op : m_in_ops)
    {
        auto it = std::find(in_op->inNodes().begin(),
                            in_op->inNodes().end(),
                            data_nh);
        if (it != in_op->inNodes().end())
            result.insert(in_op);
    }
    return result;
}

ade::NodeHandle GIsland::producer(const ade::Graph &g,
                                  const ade::NodeHandle &slot_nh) const
{
    GIslandModel::ConstGraph gim(g);
    auto data_nh = gim.metadata(slot_nh).get<DataSlot>().original_data_node;
    for (const auto& out_op : m_out_ops)
    {
        auto it = std::find(out_op->outNodes().begin(),
                            out_op->outNodes().end(),
                            data_nh);
        if (it != out_op->outNodes().end())
            return out_op;
    }
    // Consistency: A GIsland requested for producer() of slot_nh should
    // always had the appropriate GModel node handle in its m_out_ops vector.
    GAPI_Assert(false && "Broken GIslandModel ?.");
}

std::string GIsland::name() const
{
    if (is_user_specified())
        return m_user_tag.value();

    std::stringstream ss;
    ss << "island_#" << std::hex << static_cast<const void*>(this);
    return ss.str();
}

void GIslandModel::generateInitial(GIslandModel::Graph &g,
                                   const ade::Graph &src_graph)
{
    const GModel::ConstGraph src_g(src_graph);

    // Initially GIslandModel is a 1:1 projection from GModel:
    // 1) Every GModel::OP becomes a separate GIslandModel::FusedIsland;
    // 2) Every GModel::DATA becomes GIslandModel::DataSlot;
    // 3) Single-operation FusedIslands are connected with DataSlots in the
    //    same way as OPs and DATA (edges with the same metadata)

    using node_set = std::unordered_set
        < ade::NodeHandle
        , ade::HandleHasher<ade::Node>
        >;
    using node_map = std::unordered_map
        < ade::NodeHandle
        , ade::NodeHandle
        , ade::HandleHasher<ade::Node>
        >;

    node_set all_operations;
    node_map data_to_slot;

    // First, list all operations and build create DataSlots in <g>
    for (auto src_nh : src_g.nodes())
    {
        switch (src_g.metadata(src_nh).get<NodeType>().t)
        {
        case NodeType::OP:   all_operations.insert(src_nh);                break;
        case NodeType::DATA: data_to_slot[src_nh] = mkSlotNode(g, src_nh); break;
        default: GAPI_Assert(false); break;
        }
    } // for (src_g.nodes)

    // Now put single-op islands and connect it with DataSlots
    for (auto src_op_nh : all_operations)
    {
        auto nh = mkIslandNode(g, src_g.metadata(src_op_nh).get<Op>().backend, src_op_nh, src_graph);
        for (auto in_edge : src_op_nh->inEdges())
        {
            auto src_data_nh = in_edge->srcNode();
            auto isl_slot_nh = data_to_slot.at(src_data_nh);
            auto isl_new_eh  = g.link(isl_slot_nh, nh); // no other data stored yet
            // Propagate some special metadata from the GModel to GIslandModel
            // TODO: Make it a single place (a function) for both inputs/outputs?
            // (since it is duplicated in the below code block)
            if (src_g.metadata(in_edge).contains<DesyncEdge>())
            {
                const auto idx = src_g.metadata(in_edge).get<DesyncEdge>().index;
                g.metadata(isl_new_eh).set(DesyncIslEdge{idx});
            }
        }
        for (auto out_edge : src_op_nh->outEdges())
        {
            auto dst_data_nh = out_edge->dstNode();
            auto isl_slot_nh = data_to_slot.at(dst_data_nh);
            auto isl_new_eh  = g.link(nh, isl_slot_nh);
            if (src_g.metadata(out_edge).contains<DesyncEdge>())
            {
                const auto idx = src_g.metadata(out_edge).get<DesyncEdge>().index;
                g.metadata(isl_new_eh).set(DesyncIslEdge{idx});
            }
        }
    } // for(all_operations)
}

ade::NodeHandle GIslandModel::mkSlotNode(Graph &g, const ade::NodeHandle &data_nh)
{
    auto nh = g.createNode();
    g.metadata(nh).set(DataSlot{data_nh});
    g.metadata(nh).set(NodeKind{NodeKind::SLOT});
    return nh;
}

ade::NodeHandle GIslandModel::mkIslandNode(Graph &g, const gapi::GBackend& bknd, const ade::NodeHandle &op_nh, const ade::Graph &orig_g)
{
    const GModel::ConstGraph src_g(orig_g);
    util::optional<std::string> user_tag;
    if (src_g.metadata(op_nh).contains<Island>())
    {
        user_tag = util::make_optional(src_g.metadata(op_nh).get<Island>().island);
    }

    auto nh = g.createNode();
    std::shared_ptr<GIsland> island(new GIsland(bknd, op_nh, std::move(user_tag)));
    g.metadata(nh).set(FusedIsland{std::move(island)});
    g.metadata(nh).set(NodeKind{NodeKind::ISLAND});
    return nh;
}

ade::NodeHandle GIslandModel::mkIslandNode(Graph &g, std::shared_ptr<GIsland>&& isl)
{
    ade::NodeHandle nh = g.createNode();
    g.metadata(nh).set(cv::gimpl::NodeKind{cv::gimpl::NodeKind::ISLAND});
    g.metadata(nh).set<cv::gimpl::FusedIsland>({std::move(isl)});
    return nh;
}

ade::NodeHandle GIslandModel::mkEmitNode(Graph &g, std::size_t in_idx)
{
    ade::NodeHandle nh = g.createNode();
    g.metadata(nh).set(cv::gimpl::NodeKind{cv::gimpl::NodeKind::EMIT});
    g.metadata(nh).set(cv::gimpl::Emitter{in_idx, {}});
    return nh;
}

ade::NodeHandle GIslandModel::mkSinkNode(Graph &g, std::size_t out_idx)
{
    ade::NodeHandle nh = g.createNode();
    g.metadata(nh).set(cv::gimpl::NodeKind{cv::gimpl::NodeKind::SINK});
    g.metadata(nh).set(cv::gimpl::Sink{out_idx});
    return nh;
}

void GIslandModel::syncIslandTags(Graph &g, ade::Graph &orig_g)
{
    GModel::Graph gm(orig_g);
    for (auto nh : g.nodes())
    {
        if (NodeKind::ISLAND == g.metadata(nh).get<NodeKind>().k)
        {
            auto island = g.metadata(nh).get<FusedIsland>().object;
            auto isl_tag = island->name();
            for (const auto& orig_nh_inside : island->contents())
            {
                gm.metadata(orig_nh_inside).set(Island{isl_tag});
            }
        }
    }
}

void GIslandModel::compileIslands(Graph &g, const ade::Graph &orig_g, const GCompileArgs &args)
{
    GModel::ConstGraph gm(orig_g);
    if (gm.metadata().contains<HasIntrinsics>()) {
        util::throw_error(std::logic_error("FATAL: The graph has unresolved intrinsics"));
    }

    auto original_sorted = gm.metadata().get<ade::passes::TopologicalSortData>();
    for (auto nh : g.nodes())
    {
        if (NodeKind::ISLAND == g.metadata(nh).get<NodeKind>().k)
        {
            auto nodes_to_data = [&](const ade::NodeHandle& dnh)
            {
                GAPI_Assert(g.metadata(dnh).get<NodeKind>().k == NodeKind::SLOT);
                const auto& orig_data_nh = g.metadata(dnh).get<DataSlot>().original_data_node;
                const auto& data = gm.metadata(orig_data_nh).get<Data>();
                return data;
            };

            std::vector<cv::gimpl::Data> ins_data;
            ade::util::transform(nh->inNodes(), std::back_inserter(ins_data), nodes_to_data);

            std::vector<cv::gimpl::Data> outs_data;
            ade::util::transform(nh->outNodes(), std::back_inserter(outs_data), nodes_to_data);

            auto island_obj = g.metadata(nh).get<FusedIsland>().object;
            auto island_ops = island_obj->contents();

            std::vector<ade::NodeHandle> topo_sorted_list;
            ade::util::copy_if(original_sorted.nodes(),
                               std::back_inserter(topo_sorted_list),
                               [&](ade::NodeHandle sorted_nh) {
                                   return ade::util::contains(island_ops, sorted_nh);
                               });

            auto island_exe = island_obj->backend().priv()
                .compile(orig_g, args, topo_sorted_list, ins_data, outs_data);
            GAPI_Assert(nullptr != island_exe);

            g.metadata(nh).set(IslandExec{std::move(island_exe)});
        }
    }
    g.metadata().set(IslandsCompiled{});
}

ade::NodeHandle GIslandModel::producerOf(const ConstGraph &g, ade::NodeHandle &data_nh)
{
    for (auto nh : g.nodes())
    {
        // find a data slot...
        if (NodeKind::SLOT == g.metadata(nh).get<NodeKind>().k)
        {
            // which is associated with the given data object...
            if (data_nh == g.metadata(nh).get<DataSlot>().original_data_node)
            {
                // which probably has a produrer...
                if (0u != nh->inNodes().size())
                {
                    // ...then the answer is that producer
                    return nh->inNodes().front();
                }
                else return ade::NodeHandle(); // input data object?
                                               // return empty to break the cycle
            }
        }
    }
    // No appropriate data slot found - probably, the object has been
    // optimized out during fusion
    return ade::NodeHandle();
}

std::string GIslandModel::traceIslandName(const ade::NodeHandle& island_nh, const Graph& g) {
    auto island_ptr = g.metadata(island_nh).get<FusedIsland>().object;
    std::string island_name = island_ptr->name();

    std::string backend_name = "";

    auto& backend_impl = island_ptr->backend().priv();
    std::string backend_impl_type_name = typeid(backend_impl).name();

    // NOTE: Major part of already existing backends implementaion classes are called using
    //       "*G[Name]BackendImpl*" pattern.
    //       We are trying to match against this pattern and retrive just [Name] part.
    //       If matching isn't successful, full mangled class name will be used.
    //
    //       To match we use following algorithm:
    //           1) Find "BackendImpl" substring, if it doesn't exist, go to step 5.
    //           2) Let from_pos be second character in a string.
    //           3) Starting from from_pos, seek for "G" symbol in a string.
    //              If it doesn't exist or exists after "BackendImpl" position, go to step 5.
    //           4) Check that previous character before found "G" is digit, means that this is
    //              part of characters number in a new word in a string (previous words may be
    //              namespaces).
    //              If it is so, match is found. Return name between found "G" and "BackendImpl".
    //              If it isn't so, assign from_pos to found "G" position + 1 and loop to step 3.
    //           5) Matching is not successful, return full class name.
    bool matched = false;
    bool stop = false;
    auto to_pos = backend_impl_type_name.find("BackendImpl");
    std::size_t from_pos = 0UL;
    if (to_pos != std::string::npos) {
        while (!matched  && !stop) {
            from_pos = backend_impl_type_name.find("G", from_pos + 1);
            stop = from_pos == std::string::npos || from_pos >= to_pos;
            matched = !stop && std::isdigit(backend_impl_type_name[from_pos - 1]);
        }
    }

    if (matched) {
        backend_name = backend_impl_type_name.substr(from_pos + 1, to_pos - from_pos - 1);
    }
    else {
        backend_name = backend_impl_type_name;
    }

    return island_name + "_" + backend_name;
}

void GIslandExecutable::run(GIslandExecutable::IInput &in, GIslandExecutable::IOutput &out)
{
    // Default implementation: just reuse the existing old-fashioned run
    // Build a single synchronous execution frame for it.
    std::vector<InObj>  in_objs;
    std::vector<OutObj> out_objs;
    const auto &in_desc  = in.desc();
    const auto &out_desc = out.desc();
    const auto  in_msg   = in.get();
    if (cv::util::holds_alternative<cv::gimpl::EndOfStream>(in_msg))
    {
        out.post(cv::gimpl::EndOfStream{});
        return;
    }
    GAPI_Assert(cv::util::holds_alternative<cv::GRunArgs>(in_msg));
    const auto in_vector = cv::util::get<cv::GRunArgs>(in_msg);
    in_objs.reserve(in_desc.size());
    out_objs.reserve(out_desc.size());
    for (auto &&it: ade::util::zip(ade::util::toRange(in_desc),
                                   ade::util::toRange(in_vector)))
    {
        in_objs.emplace_back(std::get<0>(it), std::get<1>(it));
    }
    for (auto &&it: ade::util::indexed(ade::util::toRange(out_desc)))
    {
        out_objs.emplace_back(ade::util::value(it),
                              out.get(ade::util::checked_cast<int>(ade::util::index(it))));
    }
    run(std::move(in_objs), std::move(out_objs));

    // Propagate in-graph meta down to the graph
    // Note: this is not a complete implementation! Mainly this is a stub
    // and the proper implementation should come later.
    //
    // Propagating the meta information here has its pros and cons.
    // Pros: it works here uniformly for both regular and streaming cases,
    //   also for the majority of old-fashioned (synchronous) backends
    // Cons: backends implementing the asynchronous run(IInput,IOutput)
    //   won't get it out of the box
    cv::GRunArg::Meta stub_meta;
    for (auto &&in_arg : in_vector)
    {
        stub_meta.insert(in_arg.meta.begin(), in_arg.meta.end());
    }
    // Report output objects as "ready" to the executor, also post
    // calculated in-graph meta for the objects
    for (auto &&it: out_objs)
    {
        out.meta(it.second, stub_meta);
        out.post(std::move(it.second));
    }
}

} // namespace cv
} // namespace gimpl
