#include <stdio.h>
#include <stdlib.h>
#include <stdbool.h>
#include <stdint.h>
#include <pwd.h>

#include <sys/types.h>
#include <sys/stat.h>
#include <unistd.h>
#include <fcntl.h>

#define osErrorFatal(userMsg) osErrorFatalImpl((userMsg), __FILE__, __func__, __LINE__)
#define osAssert(expr, userMsg) \
    do { \
        if (!(expr)) \
            osErrorFatal(userMsg); \
    } while(0)

static const char* osUsage = "Usage: ./userinfo user_name";

void osErrorFatalImpl(const char *userMsg, const char *fileName,
                      const char *functionName, const int lineNum);
bool osWriteUserInfo(const char* username, FILE* out);

int main(int argc, char** argv)
{
    osAssert(argc == 2, osUsage);
    osAssert(osWriteUserInfo(argv[1], stdout),"Writing info failed");

    exit(EXIT_SUCCESS);
}

bool osWriteUserInfo(const char* username, FILE* out)
{
    struct passwd* userInfo = getpwnam(username);
    if (username == NULL)
        return false;

    fprintf(out, "Username: %s\n", username);
    //fprintf(out, "Password: %s\n", userInfo->pw_passwd);
    fprintf(out, "Home directory: %s\n", userInfo->pw_dir);
    fprintf(out, "User ID: %jd\n", (intmax_t)userInfo->pw_uid);
    fprintf(out, "Group ID: %jd\n", (intmax_t)userInfo->pw_gid);
    fprintf(out, "User information: %s\n", userInfo->pw_gecos);
    //fprintf(out, "Shell program: %s\n", userInfo->pw_shell);

    return !ferror(out);
}

void osErrorFatalImpl(const char *userMsg, const char *fileName,
                      const char *functionName, const int lineNum) {
    perror(userMsg);
    fprintf(stderr, "File: '%s'\nFunction: '%s'\nLine: '%d'\n", fileName, functionName, lineNum);

    exit(EXIT_FAILURE);
}