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

int read_stdin();
void reverse_string(char* str);


int main(int argc, char **argv) {

  for(int i = 1; i < argc; i++) {

    char *filename = argv[i];
    int open_file = open(filename,O_RDONLY);
    char symbol;
    int lines = 0;


        if(open_file < 0) {

    char first = strlen("tail: cannot open '");
    char second = strlen("' for reading");
    char* err = malloc(first + strlen(filename) + second);

    strcat(err, "tail: cannot open '");
    strcat(err, filename);
    strcat(err, "' for reading");
    perror(err);
    free(err);

    continue;


    }

/*if(argc > 2) {
            write(1, "==> ", 4);
            write(1, argv[i], strlen(argv[i]));
            write(1, " <==\n", 5);
        }*/

    //char ch;

    int read_file = read(open_file, &symbol, 1);
    if(read_file < 0) {
        char first = strlen("tail: error reading '");
        char second = strlen("'");
        char* err = malloc(first + strlen(filename) + second);

        strcat(err, "tail: error reading '");
        strcat(err, filename);
        strcat(err, "'");
        perror(err);
        free(err);
        continue;
        //return 3;

    }

    /*int write_file = write(STDOUT_FILENO, &symbol, 1);
    if(write_file < 0) {
        perror("tail: error writing");
        return 5;
    }*/


    if(argc > 2) {
            write(1, "==> ", 4);
            write(1, argv[i], strlen(argv[i]));
            write(1, " <==\n", 5);
        }


    off_t size = lseek(open_file,0,SEEK_END);
        ssize_t rb;

    for(int r = -2; lines < 10; r-- ) {
      size = lseek(open_file, r, SEEK_END);
      ssize_t already_read = read(open_file, &symbol ,1);
      if(symbol == '\n') lines++;
    }

    lines = 0;

      do{
         rb = read(open_file, &symbol, 1);
         ssize_t wb = write(STDOUT_FILENO,&symbol,1);
         if(symbol == '\n') lines++;

    if(wb < 0) {
        char *first = "tail: error writing 'standard output'";
        perror(first);
        break;

    }
      }while(rb > 0 && lines < 10);
if(i != argc - 1) write(STDOUT_FILENO, "\n", 1);
    int close_file = close(open_file);

    if(close_file < 0) {
        char first = strlen("tail: error reading '");
        char second = strlen("'");
        char* err = malloc(first + strlen(filename) + second);

        strcat(err, "tail: error reading '");
        strcat(err, filename);
        strcat(err, "'");
        perror(err);
        free(err);


    }
  }
//}
  return 0;
}