smart quit detection for common mistypes

Quake/cmd.c

@@ -1242,6 +1242,22 @@ const char *Cmd_CompleteCommand (const char *partial)
 	return NULL;
 }
 
+qboolean Cmd_IsQuitMistype (const char* input) // woods -- #smartquit
+{
+	if (Cvar_FindVar(input) || Cmd_Exists2(input) || Cmd_AliasExists(input))
+		return false;
+
+	if (q_strncasecmp(input, "qu", 2) != 0) 
+		return false; // Not a mistype for "quit"
+
+	const char* correct_cmd = "quit"; // Define the correct command
+
+	int threshold = 2; 	// Define a threshold for mistypes (e.g., distance <= 2)
+	int distance = LevenshteinDistance(input, correct_cmd); // Calculate the Levenshtein distance
+
+	return distance > 0 && distance <= threshold; 	// Return true if within the threshold, else false
+}
+
 /*
 ============
 Cmd_ExecuteString
@@ -1262,6 +1278,13 @@ qboolean	Cmd_ExecuteString (const char *text, cmd_source_t src)
 	if (!Cmd_Argc())
 		return true;		// no tokens
 
+	if (Cmd_IsQuitMistype(Cmd_Argv(0))) // // woods -- #smartquit -- check for mistyped "quit" command
+	{
+		if (SCR_ModalMessage(va("you typed: %s\n\n do you want to quit? (y/n)\n", Cmd_Argv(0)), 0.0f))
+			Host_Quit_f();
+		return true;
+	}
+
 // check functions
 	for (cmd=cmd_functions ; cmd ; cmd=cmd->next)
 	{

Quake/common.c

@@ -4644,4 +4644,47 @@ void SetChatInfo (int flags) // woods #chatinfo
 
 	snprintf(command, sizeof(command), "setinfo chat %d\n", chat_value);
 	Cbuf_AddText(command);
+}
+
+int LevenshteinDistance (const char* s, const char* t) // woods -- #smartquit -- function to calculate the Levenshtein Distance
+{
+	int len_s = strlen(s);
+	int len_t = strlen(t);
+
+	// Allocate a matrix dynamically
+	int** matrix = malloc((len_s + 1) * sizeof(int*));
+	for (int i = 0; i <= len_s; i++)
+	{
+		matrix[i] = malloc((len_t + 1) * sizeof(int));
+	}
+
+	// Initialize the matrix
+	for (int i = 0; i <= len_s; i++) matrix[i][0] = i;
+	for (int j = 0; j <= len_t; j++) matrix[0][j] = j;
+
+
+	for (int i = 1; i <= len_s; i++) // Compute the Levenshtein distance
+	{
+		for (int j = 1; j <= len_t; j++) {
+			if (tolower(s[i - 1]) == tolower(t[j - 1]))
+				matrix[i][j] = matrix[i - 1][j - 1];
+			else {
+				int insert = matrix[i][j - 1] + 1;
+				int delete = matrix[i - 1][j] + 1;
+				int substitute = matrix[i - 1][j - 1] + 1;
+				matrix[i][j] = insert < delete ? (insert < substitute ? insert : substitute) :
+					(delete < substitute ? delete : substitute);
+			}
+		}
+	}
+
+	int distance = matrix[len_s][len_t];
+
+	// Free the matrix
+	for (int i = 0; i <= len_s; i++) {
+		free(matrix[i]);
+	}
+	free(matrix);
+
+	return distance;
 }

Quake/common.h

@@ -348,6 +348,7 @@ size_t UTF8_WriteCodePoint(char* dst, size_t maxbytes, uint32_t codepoint); // w
 #define CIF_AFK   (1<<1) // set this flag if app loses focus, ie alt+tab -- woods #chatinfo
 
 void SetChatInfo (int flags); // woods #chatinfo
+int LevenshteinDistance (const char* s, const char* t); // woods -- #smartquit
 
 //============================================================================