#include <sys/stat.h>
#include <fcntl.h>
#include <sys/types.h>
#include <unistd.h>
#include <stdio.h>
#include <stdlib.h>
#include <stdbool.h>
#include <stdint.h>

#include <signal.h>

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

#define PIPE_RD 0
#define PIPE_WR 1

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

int main(int argc, char** argv) {
    osAssert(2 == argc, "./2 path/to/file.");

    int pipeFd1[2], pipeFd2[2];
    osAssert(-1 != pipe(pipeFd1), "Failed to make pipe.");
    osAssert(-1 != pipe(pipeFd2), "Failed to make pipe.");
    int fd = open(argv[1], O_RDONLY);
    osAssert(-1 != fd, "Failed to open file.");

    pid_t childPid = fork();
    osAssert(-1 != childPid, "Fork failed.");

    if(childPid > 0) { //parent
        close(pipeFd1[PIPE_RD]);
        close(pipeFd2[PIPE_WR]);
        unsigned bufLen = 1 << 13;
        char* buf = malloc(bufLen);
        osAssert(NULL != buf, "Failed to allocate memory for bufer.");

        int bytesRead = 0;
        osAssert(-1 != (bytesRead = read(fd, buf, bufLen)), "Failed to read from file.");
        buf[bytesRead] = 0;
//      printf("%s\n", buf);
        osAssert(-1 != write(pipeFd1[PIPE_WR], buf, bytesRead), "Failed to write from parent.");
        osAssert(-1 != wait(NULL), "Failed to wait for child.");
        osAssert(-1 != (bytesRead = read(pipeFd2[PIPE_RD], buf, bufLen)), "Failed to read from child.");

        buf[bytesRead - 1] = 0;
        printf("After tr:\n%s\n", buf);

        close(pipeFd1[PIPE_WR]);
        close(pipeFd2[PIPE_RD]);
        free(buf);
    }

    else { //child
        close(pipeFd2[PIPE_RD]);
        close(pipeFd1[PIPE_WR]);
        unsigned bufLen = 1 << 13;
        char* buf = malloc(bufLen);
        osAssert(NULL != buf, "Failed to allocate memory for bufer.");

        int bytesRead = 0;
        osAssert(-1 != (bytesRead = read(pipeFd1[PIPE_RD], buf, bufLen)), "Failed to read from file.");
        buf[bytesRead] = 0;

        int fdSave = dup(STDOUT_FILENO);
        osAssert(-1 != dup2(pipeFd2[PIPE_WR], STDOUT_FILENO), "Failed to replace STDOUT_FILENO.");

        char* cmd = malloc(bufLen+15);
        osAssert(NULL != cmd, "Failed to allocate memory for system command.");

        sprintf(cmd, "echo \"%s\" | tr a A", buf);
        int returnSys =  system(cmd);
        osAssert(returnSys != -1, "System failed.");
        osAssert(EXIT_SUCCESS == WEXITSTATUS(returnSys), "System did not exit with EXIT_SUCCESS.");

        osAssert(-1 != dup2(fdSave, STDOUT_FILENO), "Failed to return STDOUT_FILENO.");
        close(pipeFd1[PIPE_RD]);
        close(pipeFd2[PIPE_WR]);
        free(cmd);
        free(buf);
    }


    return 0;
}