1
static void fn(struct mg_connection *c, int ev, void *ev_data, void *fn_data) {
2
    if (ev == MG_EV_HTTP_MSG) {
3
        struct mg_http_message *hm = (struct mg_http_message *) ev_data;
4
        // ... (读取 body 逻辑)
5

6
        // 路由分发示例
7
        if (mg_match(hm->uri, mg_str("/api/login"), NULL)) {
8
            // 处理登录逻辑...
9
        }
10
        else if (mg_match(hm->uri, mg_str("/api/change"), NULL)) {
11
            // 处理活动修改逻辑...
12
        }else if
13
        //其他api...
14
        }else {
15
            // 静态文件服务：前端页面
16
            struct mg_http_serve_opts o = {.root_dir = "./frontend"};
17
            mg_http_serve_dir(c, hm, &o);
18
        }
19
    }
20
}

1
void save_activities() {
2
    FILE *fp = fopen("Data/activity.txt", "w"); // 指定 Data 目录
3
    if (!fp) return;
4
    Activity *curr = activity_head;
5
    while (curr) {
6
        check_expiry(curr); // 保存前先更新过期状态
7
        // 1. 写入基本属性
8
        fprintf(fp, "%d %s %s %s %d %s %s ", curr->id, curr->name, curr->category,
9
                curr->location, curr->max_capacity, curr->status, curr->deadline);
10
        // 2. 写入嵌套的报名名单
11
        if (!curr->enrolled_head) fprintf(fp, "None");
12
        else {
13
            EnrolledNode *e = curr->enrolled_head;
14
            while (e) {
15
                fprintf(fp, "%s", e->student_id);
16
                if (e->next) fprintf(fp, "|"); // 学号间用竖线分隔
17
                e = e->next;
18
            }
19
        }
20
        fprintf(fp, "\n");
21
        curr = curr->next;
22
    }
23
    fclose(fp);
24
}

1
int enroll_student(int act_id, const char *stu_id) {
2
    Activity *curr = activity_head;
3
    while (curr) {
4
        if (curr->id == act_id) {
5
            check_expiry(curr); // 1. 实时检查时间状态
6

7
            // 2. 状态与容量校验
8
            if (strcmp(curr->status, "已结束") == 0) return -2;
9
            if (curr->current_count >= curr->max_capacity) return -1;
10

11
            // 3. 查重校验 (遍历内部链表)
12
            EnrolledNode *chk = curr->enrolled_head;
13
            while (chk) {
14
                if (strcmp(chk->student_id, stu_id) == 0) return 0;
15
                chk = chk->next;
16
            }
17

18
            // 4. 执行写入
19
            EnrolledNode *node = (EnrolledNode *) malloc(sizeof(EnrolledNode));
20
            strcpy(node->student_id, stu_id);
21
            node->next = curr->enrolled_head; // 头插法
22
            curr->enrolled_head = node;
23
            curr->current_count++;
24

25
            save_activities(); // 数据落盘
26
            return 1;
27
        }
28
        curr = curr->next;
29
    }
30
    return -404;
31
}

1
// 格式化时间为 20250114 形式
2
void get_current_time_str(char *buffer) {
3
    time_t t = time(NULL);
4
    struct tm *tm_info = localtime(&t);
5
    sprintf(buffer, "%04d%02d%02d",
6
            tm_info->tm_year + 1900, tm_info->tm_mon + 1, tm_info->tm_mday);
7
}
8

9
// 自动更新状态机
10
void check_expiry(Activity *act) {
11
    char now[25];
12
    get_current_time_str(now);
13
    // 字符串比较: ASCII码比较，"20250115" > "20250114"
14
    if (strcmp(now, act->deadline) > 0) {
15
        strcpy(act->status, "已结束");
16
    } else {
17
        // 支持状态回滚（如管理员延长了截止日期）
18
        if (strcmp(act->status, "已结束") == 0)
19
            strcpy(act->status, "报名中");
20
    }
21
}

1
// 在 fn 函数路由中
2
else if (mg_match(hm->uri,mg_str("/api/change"),NULL)){
3
    // ... 解析 JSON 参数 ...
4

5
    Activity *curr = activity_head;
6
    while (curr) {
7
        if (curr->id == aid) {
8
            // 简单的格式校验 (防止非法日期)
9
            if (ddl[4]=='1' && ddl[5]>'2' && ddl[5]<='9') { // 简易逻辑示意
10
                flag = 2; break;
11
            }
12

13
            // 更新内存数据
14
            strcpy(curr->name, name);
15
            strcpy(curr->deadline, ddl);
16
            curr->max_capacity = max;
17
            // 修改后默认重置为报名中，由 check_expiry 后续自动判断
18
            strcpy(curr->status, "报名中");
19

20
            save_activities(); // 立即保存
21
            flag = 1; break;
22
        }
23
        curr = curr->next;
24
    }
25
    // ... 返回 JSON 结果 ...
26
}