/**
 * @file test_concurrent.cpp
 * @brief 无锁并发数据结构测试 — LockFreeQueue, LockFreeStack,
 *        ConcurrentHashMap, ReadWriteSpinLock
 *
 * 测试项 (10项):
 *   1. LockFreeQueue push/pop (单线程)
 *   2. LockFreeQueue 空/满检测
 *   3. LockFreeQueue 多生产者-多消费者
 *   4. LockFreeStack push/pop (单线程)
 *   5. LockFreeStack 清空
 *   6. LockFreeStack 多线程
 *   7. ConcurrentHashMap insert/find/erase
 *   8. ConcurrentHashMap 多线程并发
 *   9. ReadWriteSpinLock 基本锁
 *  10. ReadWriteSpinLock 多读者+单写者
 */
#include <gtest/gtest.h>
#include "vde/core/concurrent_data.h"
#include <thread>
#include <vector>
#include <algorithm>

using namespace vde::core;

// ═══════════════════════════════════════════════════════════════════════════
//  测试 1: LockFreeQueue push/pop (单线程)
// ═══════════════════════════════════════════════════════════════════════════
TEST(LockFreeQueueTest, SingleThreadPushPop) {
    LockFreeQueue<int> q(16);
    EXPECT_TRUE(q.empty());

    for (int i = 0; i < 10; ++i) {
        EXPECT_TRUE(q.try_push(i));
    }
    EXPECT_FALSE(q.empty());

    for (int i = 0; i < 10; ++i) {
        int val = -1;
        EXPECT_TRUE(q.try_pop(val));
        EXPECT_EQ(val, i);
    }
    EXPECT_TRUE(q.empty());
}

// ═══════════════════════════════════════════════════════════════════════════
//  测试 2: LockFreeQueue 空/满检测
// ═══════════════════════════════════════════════════════════════════════════
TEST(LockFreeQueueTest, FullAndEmptyDetection) {
    LockFreeQueue<int> q(8);  // 自动向上取整到 8
    EXPECT_TRUE(q.empty());
    EXPECT_EQ(q.capacity(), 8u);

    // 填满 (capacity-1 个元素，因为一个 slot 要用于区分空/满)
    int pushed = 0;
    for (int i = 0; i < 10; ++i) {
        if (!q.try_push(i)) break;
        ++pushed;
    }
    EXPECT_GT(pushed, 0);
    EXPECT_LE(pushed, 8);
    EXPECT_FALSE(q.empty());
}

// ═══════════════════════════════════════════════════════════════════════════
//  测试 3: LockFreeQueue 多生产者-多消费者
// ═══════════════════════════════════════════════════════════════════════════
TEST(LockFreeQueueTest, MultiProducerMultiConsumer) {
    constexpr int NUM_PRODUCERS = 4;
    constexpr int NUM_CONSUMERS = 4;
    constexpr int ITEMS_PER_PRODUCER = 250;
    constexpr int TOTAL = NUM_PRODUCERS * ITEMS_PER_PRODUCER;

    LockFreeQueue<int> q(1024);
    std::atomic<int> produced{0};
    std::atomic<int> consumed{0};
    std::atomic<int> sum_produced{0};
    std::atomic<int> sum_consumed{0};

    // 生产者
    std::vector<std::thread> producers;
    for (int p = 0; p < NUM_PRODUCERS; ++p) {
        producers.emplace_back([&, p]() {
            for (int i = 0; i < ITEMS_PER_PRODUCER; ++i) {
                int val = p * 1000 + i;
                while (!q.try_push(val)) {
                    std::this_thread::yield();
                }
                sum_produced.fetch_add(val);
                produced.fetch_add(1);
            }
        });
    }

    // 消费者
    std::vector<std::thread> consumers;
    for (int c = 0; c < NUM_CONSUMERS; ++c) {
        consumers.emplace_back([&]() {
            int val;
            while (consumed.load() < TOTAL) {
                if (q.try_pop(val)) {
                    sum_consumed.fetch_add(val);
                    consumed.fetch_add(1);
                } else {
                    std::this_thread::yield();
                }
            }
        });
    }

    for (auto& t : producers) t.join();
    for (auto& t : consumers) t.join();

    EXPECT_EQ(produced.load(), TOTAL);
    EXPECT_EQ(consumed.load(), TOTAL);
    EXPECT_EQ(sum_produced.load(), sum_consumed.load());
    EXPECT_TRUE(q.empty());
}

// ═══════════════════════════════════════════════════════════════════════════
//  测试 4: LockFreeStack push/pop (单线程)
// ═══════════════════════════════════════════════════════════════════════════
TEST(LockFreeStackTest, SingleThreadPushPop) {
    LockFreeStack<int> s;
    EXPECT_TRUE(s.empty());

    s.push(1);
    s.push(2);
    s.push(3);
    EXPECT_FALSE(s.empty());

    int val;
    EXPECT_TRUE(s.try_pop(val));  EXPECT_EQ(val, 3);
    EXPECT_TRUE(s.try_pop(val));  EXPECT_EQ(val, 2);
    EXPECT_TRUE(s.try_pop(val));  EXPECT_EQ(val, 1);
    EXPECT_FALSE(s.try_pop(val));
    EXPECT_TRUE(s.empty());
}

// ═══════════════════════════════════════════════════════════════════════════
//  测试 5: LockFreeStack 清空
// ═══════════════════════════════════════════════════════════════════════════
TEST(LockFreeStackTest, Clear) {
    LockFreeStack<int> s;
    s.push(10);
    s.push(20);
    s.push(30);
    EXPECT_FALSE(s.empty());

    s.clear();
    EXPECT_TRUE(s.empty());

    int val;
    EXPECT_FALSE(s.try_pop(val));
}

// ═══════════════════════════════════════════════════════════════════════════
//  测试 6: LockFreeStack 多线程
// ═══════════════════════════════════════════════════════════════════════════
TEST(LockFreeStackTest, MultiThreaded) {
    constexpr int NUM_THREADS = 4;
    constexpr int PER_THREAD = 500;

    LockFreeStack<int> s;
    std::atomic<int> pop_count{0};
    std::atomic<int64_t> pop_sum{0};

    // 推送线程
    std::vector<std::thread> pushers;
    for (int t = 0; t < NUM_THREADS; ++t) {
        pushers.emplace_back([&, t]() {
            for (int i = 0; i < PER_THREAD; ++i) {
                s.push(t * 1000 + i);
            }
        });
    }

    // 等待推送完成
    for (auto& t : pushers) t.join();

    // 弹出线程
    std::vector<std::thread> poppers;
    for (int t = 0; t < NUM_THREADS; ++t) {
        poppers.emplace_back([&]() {
            int val;
            while (pop_count.load() < NUM_THREADS * PER_THREAD) {
                if (s.try_pop(val)) {
                    pop_sum.fetch_add(val);
                    pop_count.fetch_add(1);
                } else {
                    std::this_thread::yield();
                }
            }
        });
    }

    for (auto& t : poppers) t.join();

    EXPECT_EQ(pop_count.load(), NUM_THREADS * PER_THREAD);
}

// ═══════════════════════════════════════════════════════════════════════════
//  测试 7: ConcurrentHashMap insert/find/erase
// ═══════════════════════════════════════════════════════════════════════════
TEST(ConcurrentHashMapTest, BasicOps) {
    ConcurrentHashMap<int, int> map;

    // insert
    map.insert(1, 100);
    map.insert(2, 200);
    map.insert(3, 300);

    int val;
    EXPECT_TRUE(map.find(1, val));  EXPECT_EQ(val, 100);
    EXPECT_TRUE(map.find(2, val));  EXPECT_EQ(val, 200);
    EXPECT_TRUE(map.contains(3));
    EXPECT_FALSE(map.contains(99));

    // update
    map.insert(1, 111);
    EXPECT_TRUE(map.find(1, val));  EXPECT_EQ(val, 111);

    // erase
    EXPECT_TRUE(map.erase(2));
    EXPECT_FALSE(map.contains(2));
    EXPECT_FALSE(map.erase(2));  // 重复删除

    EXPECT_EQ(map.size(), 2u);
}

// ═══════════════════════════════════════════════════════════════════════════
//  测试 8: ConcurrentHashMap 多线程并发
// ═══════════════════════════════════════════════════════════════════════════
TEST(ConcurrentHashMapTest, ConcurrentInsert) {
    ConcurrentHashMap<int, int> map;
    constexpr int NUM_THREADS = 8;
    constexpr int PER_THREAD = 500;

    std::vector<std::thread> threads;
    for (int t = 0; t < NUM_THREADS; ++t) {
        threads.emplace_back([&, t]() {
            for (int i = 0; i < PER_THREAD; ++i) {
                int key = t * PER_THREAD + i;
                map.insert(key, key * 10);
            }
        });
    }
    for (auto& t : threads) t.join();

    EXPECT_EQ(map.size(), size_t(NUM_THREADS * PER_THREAD));

    // 验证部分键值
    int val;
    EXPECT_TRUE(map.find(0, val));       EXPECT_EQ(val, 0);
    EXPECT_TRUE(map.find(500, val));     EXPECT_EQ(val, 5000);
    EXPECT_TRUE(map.find(3999, val));    EXPECT_EQ(val, 39990);
}

// ═══════════════════════════════════════════════════════════════════════════
//  测试 9: ReadWriteSpinLock 基本锁
// ═══════════════════════════════════════════════════════════════════════════
TEST(ReadWriteSpinLockTest, BasicLockUnlock) {
    ReadWriteSpinLock rwlock;

    EXPECT_FALSE(rwlock.is_write_locked());

    // 写锁
    rwlock.lock_write();
    EXPECT_TRUE(rwlock.is_write_locked());
    rwlock.unlock_write();
    EXPECT_FALSE(rwlock.is_write_locked());

    // 读锁
    rwlock.lock_read();
    EXPECT_FALSE(rwlock.is_write_locked());  // 读者不加写锁
    rwlock.unlock_read();
}

// ═══════════════════════════════════════════════════════════════════════════
//  测试 10: ReadWriteSpinLock 多读者+单写者
// ═══════════════════════════════════════════════════════════════════════════
TEST(ReadWriteSpinLockTest, ReadersWriter) {
    ReadWriteSpinLock rwlock;
    std::atomic<int> shared{0};
    std::atomic<bool> done{false};
    std::atomic<int> max_readers{0};
    std::atomic<int> current_readers{0};

    // 读者线程 (3 个)
    std::vector<std::thread> readers;
    for (int i = 0; i < 3; ++i) {
        readers.emplace_back([&]() {
            while (!done.load()) {
                rwlock.lock_read();
                int r = current_readers.fetch_add(1) + 1;
                int m = max_readers.load();
                while (r > m) max_readers.compare_exchange_weak(m, r);

                EXPECT_GE(shared.load(), 0);  // 读取共享数据

                current_readers.fetch_sub(1);
                rwlock.unlock_read();

                std::this_thread::yield();
            }
        });
    }

    // 写者线程
    std::thread writer([&]() {
        for (int i = 0; i < 100; ++i) {
            rwlock.lock_write();
            shared.fetch_add(1);
            rwlock.unlock_write();
            std::this_thread::yield();
        }
    });

    writer.join();
    done.store(true);
    for (auto& t : readers) t.join();

    EXPECT_EQ(shared.load(), 100);
    EXPECT_GT(max_readers.load(), 0);  // 至少有一个读者进入过
}