#include<stdio.h>
#include<stdlib.h>
#include<sys/wait.h>
#include<unistd.h>
#include<string.h>
#include<readline/readline.h>
#include<readline/history.h>
#include<signal.h>
#include"include/redirection.h"
pid_t backgroundPids[64];
int backgroundCount = 0;
void handleSIGINT(int sig) {
  printf("\n");
}
void handleSIGCHLD(int sig) {
    int pid = waitpid(-1, NULL, WNOHANG);
    for(int i = 0; i < backgroundCount; i++) {
        if(backgroundPids[i] == pid) {
            printf("\n[done] %d\n", pid);
            backgroundPids[i] = 0;  // clear it
        }
    }
}
int detectBackground(char **args) {
  for (int i = 0; args[i] != NULL; i++) {
    if (strcmp(args[i], "&") == 0) {
      args[i] = NULL;
      return 1;
    }
    }
  return 0;
}
int seperatePipe(char **args) {
  for(int i = 0; args[i] != NULL; i++) {
    if (strcmp(args[i], "|") == 0) return i;
  }
  return -1;
  }
void executePipe(char **args, int pipeIndex) {
  args[pipeIndex] = NULL;
  char **cmd1 = args;
  char **cmd2 = args + pipeIndex + 1;
  int fd[2];
  pipe(fd);
  pid_t pid1 = fork();
  if (pid1 == 0) {
    dup2(fd[1], STDOUT_FILENO);
    close(fd[0]);
    close(fd[1]);
    signal(SIGINT, SIG_DFL);
    execvp(cmd1[0], cmd1);
    perror("tinysh");
    exit(1);
  }
  pid_t pid2 = fork();
  if (pid2 == 0) {
    dup2(fd[0], STDIN_FILENO);
    close(fd[0]);
    close(fd[1]);
    signal(SIGINT, SIG_DFL);
    execvp(cmd2[0], cmd2);
    perror("tinysh");
    exit(1);
  }
  close(fd[0]);
  close(fd[1]);
  if (pid1 > 0) wait(NULL);
  if(pid2 > 0) wait(NULL);
}
int handleBuiltins(char **args) {
  if(strcmp(args[0], "cd") == 0) {
    chdir(args[1] == NULL ? getenv("HOME") : args[1]);
    return 1;
  }
  else if(strcmp(args[0], "exit") == 0) {
    exit(0);
  } else { return 0;}
}
char **parse(char *line) {
  char **args= malloc(64 * sizeof(char *));
  int i = 0;
  char *token = strtok(line, " \t\n");
  while(token !=NULL) {
    args[i] = token;
    i++;
    token = strtok(NULL, " \t\n");
  }
  args[i] = NULL;
  return args;
}
int main() {
	signal(SIGINT, handleSIGINT);
	signal(SIGCHLD, handleSIGCHLD);
	while(1) {
		char *user = getenv("USER");
		char dir[1024];
		getcwd(dir, sizeof(dir));
		char host[1024];
		gethostname(host, sizeof(host));
		char prompt[2051];
char *home = getenv("HOME");
if(strncmp(dir, home, strlen(home)) == 0) {
    snprintf(prompt, sizeof(prompt), "%s@%s ~%s$ ", user, host, dir + strlen(home));
} else {
    snprintf(prompt, sizeof(prompt), "%s@%s %s$ ", user, host, dir);
}
		char *line = readline(prompt);
		if(line == NULL) return 0;
		if(line && *line) add_history(line);
		char **parsed = parse(line);
		if(parsed[0] == NULL) { free(parsed); free(line); continue; }
		if(handleBuiltins(parsed)) { free(line); free(parsed); continue; }
		int background = detectBackground(parsed);
		int pipeIndex = seperatePipe(parsed);
		if (pipeIndex != -1) { 
		  executePipe(parsed, pipeIndex);
		  free(line);
		  free(parsed);
		  continue;
		}
		char *filename;
		int redirectionType = detectRedirect(parsed, &filename);
		if (redirectionType) {
		  executeRedirect(parsed, redirectionType, filename);
		  free(parsed);
		  free(line);
		  continue;
		}
		pid_t pid = fork();
		if(pid == 0) {
		  signal(SIGINT, SIG_DFL);
		  if(execvp(parsed[0], parsed) == -1 ) {
		    perror("tinysh");
		    exit(1);
		  }
		} else if(pid > 0) {
		  if(background) { 
		    printf("{background} %d \n", pid);
		    backgroundPids[backgroundCount++] = pid;
		  }
		  else wait(NULL);
		} 
		free(parsed);
		free(line);
	}
}