/**
 * autocorrect.c
 * Implementation of command auto-correction functionality
 */

#include "autocorrect.h"
#include "builtins.h"

/**
 * Calculate Levenshtein distance between two strings
 * Used to determine similarity between mistyped command and potential
 * corrections
 */
int levenshtein_distance(const char *s1, const char *s2) {
  int len1 = strlen(s1);
  int len2 = strlen(s2);

  // Create a matrix to store distances
  int **matrix = (int **)malloc((len1 + 1) * sizeof(int *));
  if (!matrix) return -1;

  for (int i = 0; i <= len1; i++) {
    matrix[i] = (int *)malloc((len2 + 1) * sizeof(int));
    if (!matrix[i]) {
      for (int j = 0; j < i; j++) {
        free(matrix[j]);
      }
      free(matrix);
      return -1;
    }
  }

  // Initialize the matrix
  for (int i = 0; i <= len1; i++) {
    matrix[i][0] = i;
  }
  for (int j = 0; j <= len2; j++) {
    matrix[0][j] = j;
  }

  // Fill the matrix
  for (int i = 1; i <= len1; i++) {
    for (int j = 1; j <= len2; j++) {
      int cost = (s1[i - 1] == s2[j - 1]) ? 0 : 1;
      matrix[i][j] = min3(matrix[i - 1][j] + 1,      // deletion
                          matrix[i][j - 1] + 1,      // insertion
                          matrix[i - 1][j - 1] + cost // substitution
      );
    }
  }

  // Get the result and free the matrix
  int result = matrix[len1][len2];
  for (int i = 0; i <= len1; i++) {
    free(matrix[i]);
  }
  free(matrix);

  return result;
}

/**
 * Helper function to find minimum of three integers
 */
int min3(int a, int b, int c) {
  int min = a;
  if (b < min)
    min = b;
  if (c < min)
    min = c;
  return min;
}

/**
 * Initialize the autocorrect system
 */
void init_autocorrect(void) {
  // No initialization required currently
}

/**
 * Shutdown the autocorrect system
 */
void shutdown_autocorrect(void) {
  // No cleanup required currently
}

/**
 * Check a command for possible corrections and suggest alternative
 */

/**
 * Check a command for possible corrections and suggest alternative
 */

/**
 * Check a command for possible corrections and suggest alternative
 */
char **check_for_corrections(char **args) {
  if (!args || !args[0]) {
    return NULL;
  }

  const char *command = args[0];
  
  // Skip very short commands or commands that start with ./ or /
  if (strlen(command) < 3 || command[0] == '.' || command[0] == '/') {
    return NULL;
  }

  // Don't try to correct arguments, only the command itself
  // Check if the command is valid, if it is, no correction needed
  if (is_valid_command(command)) {
    return NULL;
  }

  // List of common commands to check against
  const char *common_commands[] = {
      "ls", "cd", "grep", "find", "cat", "mv", "cp", "rm", "mkdir", "rmdir",
      "chmod", "chown", "ps", "top", "df", "du", "free", "mount", "umount",
      "tar", "zip", "unzip", "ssh", "scp", "ping", "netstat", "ifconfig",
      "route", "traceroute", "wget", "curl", "apt", "apt-get", "yum", "dnf",
      "pacman", "git", "make", "gcc", "g++", "python", "python3", "node",
      "npm", "vim", "nano", "history", "clear", "exit", "alias", "man", "help", 
      "touch", "echo", "pwd", "sudo", "shutdown", "reboot", NULL
  };

  // Check built-in commands too
  int best_distance = 3; // Maximum edit distance to consider a correction
  const char *best_match = NULL;

  // First check among built-in commands
  for (int i = 0; i < lsh_num_builtins(); i++) {
    int distance = levenshtein_distance(command, builtin_str[i]);
    if (distance < best_distance) {
      best_distance = distance;
      best_match = builtin_str[i];
    }
  }

  // Then check common commands
  for (int i = 0; common_commands[i] != NULL; i++) {
    int distance = levenshtein_distance(command, common_commands[i]);
    if (distance < best_distance) {
      best_distance = distance;
      best_match = common_commands[i];
    }
  }

  // If we found a good match, suggest it
  if (best_match) {
    printf("Command '%s' not found. Did you mean '%s'?\n", command, best_match);
    // No longer waiting for input - just return NULL
  }
  
  return NULL;
}

/**
 * Count the number of arguments in a NULL-terminated array
 */
int count_args(char **args) {
  int count = 0;
  while (args[count] != NULL) {
    count++;
  }
  return count;
}