#include "kernel/types.h"
#include "kernel/stat.h"
#include "user/user.h"
#include "kernel/fs.h"
#include "kernel/fcntl.h"
#include "kernel/param.h"

// 一次性读完，存储到buf中
void read_in(char *buf)
{
    int cur_size = 0, size = 0;
    while ((cur_size = read(0, buf + size, 1)) > 0)
        size += cur_size;
}

// 从str读取一行字符串到buf中，去掉\n补上0
int next_line(char *buf, char *str)
{
    // printf("str: %s\n", str);
    if (*str == 0)
        return 0;

    char *p = str; // 会直接遇到\n
    int cnt = 0;
    while (*p != '\n' && *p != 0)
    {
        p++;
        cnt++;
    }
    memmove(buf, str, cnt);
    // printf("next_line :%s, cnt: %d\n", buf, cnt);
    return cnt;
}

// 去除buf中的空格，将结果存储到result中
int parse_line(char **result, char *buf)
{
    int cnt = 0;
    char *p = buf;
    while (1)
    {
        while (*p == ' ' && *p != 0)
            p++;
        if (*p == 0)
            return cnt;

        int arg_len = 0; // 遇到非空白非0字符，解析参数
        char *arg_start = p;
        while (*p != ' ' && *p != 0)
        {
            p++;
            arg_len++;
        }

        *(result + cnt) = (char *)malloc(arg_len + 1); // 指针运算需要注意
        memmove(*(result + cnt), arg_start, arg_len);
        result[cnt++][arg_len] = 0;
    }
}

int main(int argc, char *argv[])
{
    if (argc < 2)
    {
        printf("xargs 参数个数不正确\n");
        return -1;
    }
    // printf("argc=%d\n", argc);
    char *args[MAXARG];
    for (int i = 2; i < argc; i++)
    {
        args[i - 2] = argv[i];
        // printf("copied argv:%s\n", argv[i]);
    }

    char buf[512] = {0};
    read_in(buf);
    // printf("buf:%s。\n", buf);

    int cur_size = 0, index = 0;
    char line[512] = {0};
    while ((cur_size = next_line(line, buf + index)) > 0)
    {
        printf("\n newline, cmd:%s\n", argv[1]);
        if (fork() == 0)
        {
            int total = argc - 2 + parse_line(args + argc - 2, line);
            args[total] = 0; // 参数数组以 NULL 结束
            for (int i = 0; i < total; i++)
                printf("args:%s\n", args[i]);

            exec(argv[1], args);
            printf("exec %s 失败\n", argv[1]);
        }
        wait(0);
        index += cur_size + 1; // +1因为\n
        memset(line, 0, cur_size + 1);
    }

    exit(0);
}