/*
 * src/hush.c
 *
 * HUSH -- The HU Shell
 * A minimal shell for CISC 301, Operating Systems
 *
 * CISC 301 -- Operating Systems, Project 2
 *
 * Copyright (C) 2025  Douglas B. Rumbaugh <dbrumbaugh@harrisburgu.edu>
 *
 * Distributed under the Modified BSD License
 *
 */
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <sys/wait.h>

#include "config.h"
#include "lexer.h"
#include "command.h"
#include "variables.h"
#include "builtin.h"

FILE *open_input(int argc, char **argv) {
  FILE *input_file = (argc > 1) ? fopen(argv[1], "r") : stdin;
  if (!input_file) {
    fprintf(stderr, "ERROR: Failed to open input file %s\n", argv[1]);
    exit(EXIT_FAILURE);
  }

  return input_file;
}

static size_t get_command_len(char *cmdstr) {
  size_t len = strlen(cmdstr);
  if (cmdstr[len - 1] != '\n') {
    len = 0;
  }

  return len;
}

void variable_substitution(command *cmds) {
  for (command *cmd = cmds; cmd; cmd = cmd->next) {
    for (size_t i=0; i < MAX_ARGUMENT_CNT + 1; i++) {
      if (is_variable(cmd->args[i])) { 
        cmd->args[i] = get_variable(cmd->args[i]);
      }
    }

    if (is_variable(cmd->outfile)) {
      cmd->outfile = get_variable(cmd->outfile);
    }

    if (is_variable(cmd->infile)) {
      cmd->infile = get_variable(cmd->infile);
    }
  }
}

int main(int argc, char **argv) {
  FILE *input_file = open_input(argc, argv);
  char buffer[MAX_LINE_LEN];

  if (!init_variable_store()) {
    fprintf(stderr, "ERROR: Failed to initialize variable store\n");
    exit(EXIT_FAILURE);
  }

  fprintf(stdout, "$ ");
  while (fgets(buffer, MAX_LINE_LEN, input_file)) {
    char *cmdstr = trim(buffer);
    if (!cmdstr) { 
      fprintf(stderr, "ERROR: Specified command is too long\n");
      goto draw_prompt;
    }

    if (strlen(cmdstr) == 0) {
      goto draw_prompt;
    }

    token *parsed_cmd;
    if (!(parsed_cmd = parse_command(cmdstr))) {
      fprintf(stderr, "ERROR: Failed to parse command\n");
      goto draw_prompt;
    }

    {
      token *error;
      if ((error = validate_command(parsed_cmd))) {
        fprintf(stderr, "ERROR: Invalid syntax near %s\n", error->text);
        print_parsed_command(stdout, parsed_cmd);
        goto free_tokens;
      }
    }

    if (parsed_cmd->type == TKN_VARKEY) {
      if (!add_variable(parsed_cmd->text, parsed_cmd->next->text)) {
        fprintf(stderr, "ERROR: Failed to create variable\n");
      }
      goto free_tokens;
    }

    size_t commands;
    command *cmds;
    if (!(cmds = commands_from_tokens(parsed_cmd, &commands ))) {
      fprintf(stderr, "ERROR: Unable to create commands from tokens");
      goto free_tokens;
    }

    variable_substitution(cmds);

    for (command *cmd = cmds; cmd; cmd = cmd->next) {
      if (!run_builtin(cmd)) {
        pid_t result = execute_command(cmd);
        if (result < 0) {
          break;
        }
      }
    }

    for (command *cmd = cmds; cmd; cmd = cmd->next) {
      if (cmd->pid > 0) {
        waitpid(cmd->pid, NULL, 0);
      }
    }


  free_commands:
  destroy_commands(cmds);

  free_tokens:
    destroy_tokens(parsed_cmd);

  draw_prompt:
    fprintf(stdout, "$ ");
  }

  destroy_variable_store();
}