/* This file is a part of rvsh
 *
 * Copyright (C) 2021  Robby Zambito
 * Copyright (C) 2022  Spencer Hall
 *
 * rvsh is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * rvsh is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <https://www.gnu.org/licenses/>.
 */

#define _POSIX_C_SOURCE 200809L

#include <errno.h>
#include <stdio.h>

#include <readline/readline.h>

#include <readline/history.h>
#include <stdlib.h>
#include <string.h>
#include <sys/types.h>
#include <sys/wait.h>
#include <unistd.h>

union pipe {
  int filedes[2];
  struct {
    int read_end;
    int write_end;
  };
};

char *strrev(char *input) {
  size_t len, i;
  char a, z;

  len = strlen(input);

  while (isspace(input[len - 1])) {
    len--;
  }

  for (i = 0; i < len / 2; i++) {
    a = input[i];
    z = input[len - i - 1];

    input[i] = z;
    input[len - i - 1] = a;
  }
  return input;
}

char *get_bash_prompt() {
  pid_t bash_pid;
  union pipe bash_input, bash_output;
  FILE *bash_output_f;
  ssize_t len;
  int status;

  static char *prompt = NULL;
  static size_t prompt_capacity = 0;

  pipe(bash_input.filedes);
  pipe(bash_output.filedes);

  bash_pid = fork();
  if (bash_pid == -1) {
    exit(EXIT_FAILURE);
  }

  if (bash_pid == 0) {
    close(bash_input.write_end);
    close(bash_output.read_end);

    dup2(bash_input.read_end, STDIN_FILENO);
    dup2(bash_output.write_end, STDOUT_FILENO);
    close(STDERR_FILENO);

    execlp("bash", "bash", "-i", "-c", "echo \"${PS1@P}\"", NULL);
  }

  close(bash_input.read_end);
  close(bash_output.write_end);

  bash_output_f = fdopen(bash_output.read_end, "r");

  len = getline(&prompt, &prompt_capacity, bash_output_f);

  if (prompt[len - 1] == '\n') {
    prompt[len - 1] = '\0';
  }

  fclose(bash_output_f);

  do {
    waitpid(bash_pid, &status, WUNTRACED);
  } while(!WIFEXITED(status) && !WIFSIGNALED(status));

  return prompt;
}

void put_stream_rev(FILE *stream) {
  pid_t pid;
  char *line;
  size_t line_capacity;

  pid = fork();

  if (pid == -1) {
    exit(EXIT_FAILURE);
  }

  if (pid == 0) {
    line = NULL;
    line_capacity = 0;
    while (getline(&line, &line_capacity, stream) > 0) {
      strrev(line);
      printf("%s", line);
    }

    free(line);
  }
}

void run_reverse_command(char *command) {
  pid_t bash_pid;
  union pipe bash_input, bash_output;
  FILE *bash_input_f, *bash_output_f;
  char *line;
  size_t line_capacity;
  int status;

  pipe(bash_input.filedes);
  pipe(bash_output.filedes);

  bash_pid = fork();
  if (bash_pid == -1) {
    exit(EXIT_FAILURE);
  }

  if (bash_pid == 0) {
    close(bash_input.write_end);
    close(bash_output.read_end);

    dup2(bash_input.read_end, STDIN_FILENO);
    dup2(bash_output.write_end, STDOUT_FILENO);
    /*close(STDERR_FILENO);*/

    execlp("bash", "bash", "-c", command, NULL);
  }

  close(bash_input.read_end);
  close(bash_output.write_end);

  bash_input_f = fdopen(bash_input.write_end, "w");
  bash_output_f = fdopen(bash_output.read_end, "r");

  line = NULL;
  line_capacity = 0;
  while (getline(&line, &line_capacity, bash_output_f) > 0) {
    strrev(line);
    printf("%s", line);
  }

  free(line);

  do {
    waitpid(bash_pid, &status, WUNTRACED);
  } while(!WIFEXITED(status) && !WIFSIGNALED(status));

  fclose(bash_input_f);
  fclose(bash_output_f);
}

int main(void) {
  char *prompt;
  char *line;

  using_history();
  while ((line = readline(strrev(prompt = get_bash_prompt()))) != NULL) {
    add_history(line);

    strrev(line);

    run_reverse_command(line);

    free(line);
  }

  if (errno != 0) {
    perror("End");
  }

  rl_clear_history();
  free(prompt);
  return EXIT_SUCCESS;
}