#include "nginx.h"
#include "ip2region/ip2region.h" 

#define EVENT_SIZE (sizeof(struct inotify_event))
#define EVENT_BUF_LEN (1024 * (EVENT_SIZE + 16))
#define INITIAL_BUFFER_SIZE 8192

int IP_location(char *string) {
    char *area = NULL;
    char *xdb_path = "ip2region.xdb";
    char *p = strchr(string, ' ');
    char IP[64];
    memset(IP, 0, 64);

    if ((p - string) > 0) {
        memmove(IP, string, p - string);
    } else {
        printf("Invalid IP string format.\n");
        return -1;
    }

    if (access(xdb_path, F_OK) == -1) { // 判断 ip2region 地址定位库是否存在
        xdb_path = "ip2region/ip2region.xdb";
        if (access(xdb_path, F_OK) == -1) {
            printf("ip2region.xdb DOESN'T EXIST!\n");
            return -1;
        }
    }

    area = ip2region(xdb_path, IP);
    if (area == NULL) {
        printf("ip2region解析地域错误\n");
        return -1;
    }

    printf("IP地址:%s, %s\n", IP, area);

    return 0;
}

void nginx_read_log(const char *filename) {
    int fd = open(filename, O_RDONLY);
    if (fd == -1) {
        perror("open");
        exit(EXIT_FAILURE);
    }

    // Move to the end of the file
    if (lseek(fd, 0, SEEK_END) == -1) {
        perror("lseek");
        close(fd);
        exit(EXIT_FAILURE);
    }

    int inotify_fd = inotify_init();
    if (inotify_fd < 0) {
        perror("inotify_init");
        close(fd);
        exit(EXIT_FAILURE);
    }

    int wd = inotify_add_watch(inotify_fd, filename, IN_MODIFY);
    if (wd == -1) {
        perror("inotify_add_watch");
        close(inotify_fd);
        close(fd);
        exit(EXIT_FAILURE);
    }

    char buffer[EVENT_BUF_LEN];

    // Set the file descriptor to non-blocking mode
    int flags = fcntl(fd, F_GETFL, 0);
    if (flags == -1) {
        perror("fcntl F_GETFL");
        inotify_rm_watch(inotify_fd, wd);
        close(inotify_fd);
        close(fd);
        exit(EXIT_FAILURE);
    }
    if (fcntl(fd, F_SETFL, flags | O_NONBLOCK) == -1) {
        perror("fcntl F_SETFL");
        inotify_rm_watch(inotify_fd, wd);
        close(inotify_fd);
        close(fd);
        exit(EXIT_FAILURE);
    }

    // Initial dynamic buffer allocation
    size_t buffer_size = INITIAL_BUFFER_SIZE;
    char *read_buf = alloca(buffer_size);
    if (!read_buf) {
        perror("alloca");
        inotify_rm_watch(inotify_fd, wd);
        close(inotify_fd);
        close(fd);
        exit(EXIT_FAILURE);
    }

    while (1) {
        int length = read(inotify_fd, buffer, EVENT_BUF_LEN);
        if (length < 0) {
            perror("read");
            break;
        }

        for (int i = 0; i < length;) {
            struct inotify_event *event = (struct inotify_event *) &buffer[i];
            if (event->mask & IN_MODIFY) {
                int bytes_read;
                while ((bytes_read = read(fd, read_buf, buffer_size - 1)) > 0) {
                    read_buf[bytes_read] = '\0';
                    IP_location(read_buf);
                }
                if (bytes_read == -1 && errno != EAGAIN) {
                    perror("read");
                    break;
                }
            }
            i += EVENT_SIZE + event->len;
        }
    }

    inotify_rm_watch(inotify_fd, wd);
    close(inotify_fd);
    close(fd);
}