#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <arpa/inet.h>
#include <fcntl.h>
#include <time.h>

#define PORT 8080
#define MAXSIZE 1024
#define EXIT_SYMBOL "exit"

int main() {
    int server_fd, client_fd;
    struct sockaddr_in server_addr, client_addr;
    socklen_t client_len = sizeof(client_addr);
    char buffer[MAXSIZE];
    char file1_data[MAXSIZE];
    int file1_fd, file2_fd;
    ssize_t bytes_read, bytes_written;
    int read_size;

    srand((unsigned int)time(NULL));

    // 创建socket文件描述符
    server_fd = socket(AF_INET, SOCK_STREAM, 0);
    if (server_fd == -1) {
        perror("socket");
        exit(EXIT_FAILURE);
    }

    // 初始化服务器地址结构
    memset(&server_addr, 0, sizeof(server_addr));
    server_addr.sin_family = AF_INET;
    server_addr.sin_addr.s_addr = INADDR_ANY;
    server_addr.sin_port = htons(PORT);

    // 绑定socket到端口
    if (bind(server_fd, (struct sockaddr*)&server_addr, sizeof(server_addr)) == -1) {
        perror("bind");
        close(server_fd);
        exit(EXIT_FAILURE);
    }

    // 监听连接请求
    if (listen(server_fd, 5) == -1) {
        perror("listen");
        close(server_fd);
        exit(EXIT_FAILURE);
    }

    printf("Server is listening on port %d...\n", PORT);

    // 接受客户端连接
    client_fd = accept(server_fd, (struct sockaddr*)&client_addr, &client_len);
    if (client_fd == -1) {
        perror("accept");
        close(server_fd);
        exit(EXIT_FAILURE);
    }

    printf("Client connected!\n");

    // 打开file1进行读取
    file1_fd = open("file1.txt", O_RDONLY);
    if (file1_fd == -1) {
        perror("open file1");
        close(client_fd);
        close(server_fd);
        exit(EXIT_FAILURE);
    }

    // 打开file2进行写入
    file2_fd = open("file2.txt", O_WRONLY | O_CREAT | O_TRUNC, 0644);
    if (file2_fd == -1) {
        perror("open file2");
        close(file1_fd);
        close(client_fd);
        close(server_fd);
        exit(EXIT_FAILURE);
    }

    // 客户端与服务器之间的通信循环
    while (1) {
        // 从客户端接收数据
        bytes_read = read(client_fd, buffer, MAXSIZE-1);
        if (bytes_read == -1) {
            perror("read from client");
            break;
        }
        buffer[bytes_read] = '\0'; // 确保字符串以null结尾

        // 检查是否输入了退出符号
        if (strncmp(buffer, EXIT_SYMBOL, strlen(EXIT_SYMBOL)) == 0) {
            printf("Received exit command from client.\n");
            break;
        }

        // 将接收到的数据写入file2
        write(file2_fd, buffer, bytes_read);

        // 从file1读取数据并发送给客户端
        lseek(file1_fd, 0, SEEK_SET); // 每次从文件开头读取
        bytes_read = read(file1_fd, file1_data, MAXSIZE-1);
        if (bytes_read == -1) {
            perror("read from file1");
            break;
        }
        file1_data[bytes_read] = '\0'; // 确保字符串以null结尾

        // 生成一个随机的数据长度
        int data_len =rand() % bytes_read + 1;
        // 发送数据到客户端
        bytes_written = write(client_fd, file1_data, data_len);
        if (bytes_written == -1) {
            perror("write to client");
            break;
        }
    }

    // 关闭文件描述符和socket
    close(file1_fd);
    close(file2_fd);
    close(client_fd);
    close(server_fd);
    printf("Server closed.\n");
    return 0;
}