// Copyright 2019 yuzu Emulator Project
// Licensed under GPLv2 or any later version
// Refer to the license.txt file included.

#include <algorithm>
#include <cstring>
#include <memory>
#include <unordered_map>
#include <utility>
#include <vector>

#include <glad/glad.h>

#include "common/assert.h"
#include "core/core.h"
#include "video_core/engines/maxwell_3d.h"
#include "video_core/memory_manager.h"
#include "video_core/renderer_opengl/gl_query_cache.h"
#include "video_core/renderer_opengl/gl_rasterizer.h"

namespace OpenGL {

namespace {

constexpr std::array<GLenum, VideoCore::NumQueryTypes> QueryTargets = {GL_SAMPLES_PASSED};

constexpr GLenum GetTarget(VideoCore::QueryType type) {
    return QueryTargets[static_cast<std::size_t>(type)];
}

} // Anonymous namespace

QueryCache::QueryCache(Core::System& system, RasterizerOpenGL& gl_rasterizer)
    : VideoCommon::QueryCacheBase<
          QueryCache, CachedQuery, CounterStream, HostCounter,
          std::vector<OGLQuery>>{system,
                                 static_cast<VideoCore::RasterizerInterface&>(gl_rasterizer)},
      gl_rasterizer{gl_rasterizer} {}

QueryCache::~QueryCache() = default;

OGLQuery QueryCache::AllocateQuery(VideoCore::QueryType type) {
    auto& reserve = query_pools[static_cast<std::size_t>(type)];
    OGLQuery query;
    if (reserve.empty()) {
        query.Create(GetTarget(type));
        return query;
    }

    query = std::move(reserve.back());
    reserve.pop_back();
    return query;
}

void QueryCache::Reserve(VideoCore::QueryType type, OGLQuery&& query) {
    query_pools[static_cast<std::size_t>(type)].push_back(std::move(query));
}

bool QueryCache::AnyCommandQueued() const noexcept {
    return gl_rasterizer.AnyCommandQueued();
}

HostCounter::HostCounter(QueryCache& cache, std::shared_ptr<HostCounter> dependency,
                         VideoCore::QueryType type)
    : VideoCommon::HostCounterBase<QueryCache, HostCounter>{std::move(dependency)}, cache{cache},
      type{type}, query{cache.AllocateQuery(type)} {
    glBeginQuery(GetTarget(type), query.handle);
}

HostCounter::~HostCounter() {
    cache.Reserve(type, std::move(query));
}

void HostCounter::EndQuery() {
    if (!cache.AnyCommandQueued()) {
        // There are chances a query waited on without commands (glDraw, glClear, glDispatch). Not
        // having any of these causes a lock. glFlush is considered a command, so we can safely wait
        // for this. Insert to the OpenGL command stream a flush.
        glFlush();
    }
    glEndQuery(GetTarget(type));
}

u64 HostCounter::BlockingQuery() const {
    GLint64 value;
    glGetQueryObjecti64v(query.handle, GL_QUERY_RESULT, &value);
    return static_cast<u64>(value);
}

CachedQuery::CachedQuery(QueryCache& cache, VideoCore::QueryType type, VAddr cpu_addr, u8* host_ptr)
    : VideoCommon::CachedQueryBase<HostCounter>{cpu_addr, host_ptr}, cache{&cache}, type{type} {}

CachedQuery::CachedQuery(CachedQuery&& rhs) noexcept
    : VideoCommon::CachedQueryBase<HostCounter>(std::move(rhs)), cache{rhs.cache}, type{rhs.type} {}

CachedQuery& CachedQuery::operator=(CachedQuery&& rhs) noexcept {
    cache = rhs.cache;
    type = rhs.type;
    CachedQueryBase<HostCounter>::operator=(std::move(rhs));
    return *this;
}

void CachedQuery::Flush() {
    // Waiting for a query while another query of the same target is enabled locks Nvidia's driver.
    // To avoid this disable and re-enable keeping the dependency stream.
    // But we only have to do this if we have pending waits to be done.
    auto& stream = cache->Stream(type);
    const bool slice_counter = WaitPending() && stream.IsEnabled();
    if (slice_counter) {
        stream.Update(false);
    }

    VideoCommon::CachedQueryBase<HostCounter>::Flush();

    if (slice_counter) {
        stream.Update(true);
    }
}

} // namespace OpenGL
