/*
 * @file event_bus_test.cpp
 * @brief EventBus unit tests: subscribe, emit, unsubscribe, multi-handler
 *        dispatch order, independent event types.
 * EventBus 单元测试：订阅、发布、取消订阅、多处理器分发顺序、独立事件类型。
 * Copyright (c) 2026 dstalk contributors. GPLv3.
 */

#include <algorithm>
#include <iostream>
#include <string>
#include <vector>

#include "event_bus.hpp"

// ---- 轻量断言 ----
static int g_failures = 0;
// Lightweight assertion helper: increments g_failures counter on failure
#define TCHECK(cond, msg) do {                            \
    if (cond) {                                           \
        std::cout << "[OK] " << (msg) << "\n";            \
    } else {                                              \
        std::cerr << "[FAIL] " << (msg) << "\n";          \
        g_failures++;                                     \
    }                                                     \
} while (0)

// EventBus 单元测试：订阅+发布、取消订阅、多处理器分发顺序、空总线、独立事件类型路由、取消不存在的订阅。
// EventBus unit tests: subscribe+emit, unsubscribe, multi-handler dispatch order,
// empty bus, independent event type routing, and non-existent unsubscribe safety.
int main()
{
    std::cout << "=== dstalk event_bus unit tests ===\n\n";

    // ====================================================================
    // Test 1: subscribe + emit — 基本发布订阅流程
    // Test 1: subscribe + emit — basic pub/sub flow
    // ====================================================================
    {
        dstalk::EventBus bus;
        int call_count = 0;
        int received_type = 0;

        int id = bus.subscribe(42, [&](int event_type, const void* data) {
            call_count++;
            received_type = event_type;
        });
        TCHECK(id >= 1, "subscribe returns valid subscription ID");

        int emitted = bus.emit(42, nullptr);
        TCHECK(emitted == 1, "emit returns 1 handler called");
        TCHECK(call_count == 1, "handler was invoked exactly once");
        TCHECK(received_type == 42, "handler received correct event_type");
    }

    // ====================================================================
    // Test 2: unsubscribe — 取消订阅后 handler 不再被调用
    // Test 2: unsubscribe — handler NOT called after unsubscription
    // ====================================================================
    {
        dstalk::EventBus bus;
        int call_count = 0;

        int id = bus.subscribe(10, [&](int, const void*) { call_count++; });
        bus.unsubscribe(id);

        int emitted = bus.emit(10, nullptr);
        TCHECK(emitted == 0, "emit after unsubscribe returns 0");
        TCHECK(call_count == 0, "unsubscribed handler was NOT called");
    }

    // ====================================================================
    // Test 3: 多订阅者 — 同一事件多个 handler 按订阅顺序全部调用
    // Test 3: multi-subscriber — all handlers for same event invoked in subscription order
    // ====================================================================
    {
        dstalk::EventBus bus;
        std::vector<int> order;

        bus.subscribe(1, [&](int, const void*) { order.push_back(1); });
        bus.subscribe(1, [&](int, const void*) { order.push_back(2); });
        bus.subscribe(1, [&](int, const void*) { order.push_back(3); });

        int emitted = bus.emit(1, nullptr);
        TCHECK(emitted == 3, "emit returns 3 handlers called");
        TCHECK(order.size() == 3, "all 3 handlers invoked");

        // 验证订阅顺序 (FIFO: 按 subscribe 顺序触发) / Verify subscription order (FIFO: in subscribe order)
        bool ordered = (order[0] == 1 && order[1] == 2 && order[2] == 3);
        TCHECK(ordered, "handlers invoked in subscription order (1,2,3)");
    }

    // ====================================================================
    // Test 4: 空总线 emit 不崩溃，返回 0
    // Test 4: emit on empty bus no crash, returns 0
    // ====================================================================
    {
        dstalk::EventBus bus;
        int emitted = bus.emit(99, nullptr);
        TCHECK(emitted == 0, "emit on empty bus returns 0 (no crash)");
    }

    // ====================================================================
    // Test 5: 不同 event_type 独立分发 — 只触发匹配的 handler
    // Test 5: independent event_type dispatch — only matching handler triggered
    // ====================================================================
    {
        dstalk::EventBus bus;
        int count_a = 0, count_b = 0;

        bus.subscribe(100, [&](int, const void*) { count_a++; });
        bus.subscribe(200, [&](int, const void*) { count_b++; });

        bus.emit(100, nullptr);
        TCHECK(count_a == 1 && count_b == 0,
               "emit type=100 only triggers type-100 handler");

        bus.emit(200, nullptr);
        TCHECK(count_a == 1 && count_b == 1,
               "emit type=200 only triggers type-200 handler");
    }

    // ====================================================================
    // Test 6: 退订不存在的 ID 不崩溃
    // Test 6: unsubscribe non-existent ID does not crash
    // ====================================================================
    {
        dstalk::EventBus bus;
        bus.unsubscribe(99999);  // 不存在的 ID / non-existent ID
        std::cout << "[OK] unsubscribe non-existent ID (99999) did not crash\n";
    }

    // ====================================================================
    // 结果 / Result
    // ====================================================================
    std::cout << "\n";
    if (g_failures == 0) {
        std::cout << "=== All event_bus tests passed ===\n";
        return 0;
    } else {
        std::cerr << "=== " << g_failures << " event_bus test(s) FAILED ===\n";
        return 1;
    }
}