User defined decimal separator for values

Partially solves #1161

components/nspanel_ha_blueprint/text.h

@@ -1,6 +1,8 @@
 // text.h
 #pragma once
 
+#include <algorithm>
+#include <cctype>
 #include <cstring>
 #include <string>
 
@@ -34,15 +36,65 @@ namespace nspanel_ha_blueprint {
      * Note: The destination array is always null-terminated, even if the source string
      * is truncated to fit into the array.
      */
-    template<size_t N>
+    template <unsigned int N>
     void copyStringToCharArray(char (&dest)[N], const std::string& src) {
-        static_assert(N > 0, "Destination array size must be greater than 0.");
+        // Ensure we do not exceed the buffer size, leaving space for the null terminator
+        size_t length = std::min(src.size(), N - 1);
 
-        // Copy up to N - 1 characters to ensure there's room for the null terminator
-        std::strncpy(dest, src.c_str(), N - 1);
+        // Copy the string data into the destination buffer
+        std::strncpy(dest, src.c_str(), length);
 
-        // Manually null-terminate the destination array
-        dest[N - 1] = '\0';
+        // Explicitly null-terminate the destination buffer
+        dest[length] = '\0';
+    }
+
+    // Helper function to determine if a character is part of a number
+    bool isNumberChar(char c) {
+        return std::isdigit(c) || c == '.' || c == '-' || c == ',';
+    }
+
+    /**
+    * Adjusts the decimal separator in a numeric string to a specified character.
+    * This function identifies and modifies the decimal separator of a number within a string,
+    * ensuring that only the first occurrence is replaced if it is a valid number followed by
+    * any non-numeric characters (e.g., units of measurement). If the input string does not 
+    * start with a valid number, it is returned unchanged.
+    * 
+    * @param input The string potentially containing a numeric value followed by text.
+    * @param decimalSeparator The character to use as the decimal separator.
+    * @return A string with the decimal separator adjusted if the input is a valid number,
+    *         otherwise the original input string.
+    */
+    std::string adjustDecimalSeparator(const std::string& input, char decimalSeparator) {
+        // Immediately return the original string if the desired decimal separator is "."
+        if (decimalSeparator == '.') {
+            return input;
+        }
+
+        // Find the end of the numeric part of the string
+        size_t numericEnd = 0;
+        for (; numericEnd < input.size() && isNumberChar(input[numericEnd]); ++numericEnd);
+
+        // Extract the numeric part and the suffix (if any)
+        std::string numericPart = input.substr(0, numericEnd);
+        std::string suffix = input.substr(numericEnd);
+
+        // Attempt to convert the numeric part to a double
+        char* end;
+        double val = strtod(numericPart.c_str(), &end);
+
+        // Check if conversion was successful (end points to a null terminator if so)
+        if (end != numericPart.c_str() && *end == '\0') {
+            // Find and replace only the first occurrence of '.' with the specified decimalSeparator
+            size_t decimalPointPos = numericPart.find('.');
+            if (decimalPointPos != std::string::npos) {
+                numericPart[decimalPointPos] = decimalSeparator;
+            }
+            return numericPart + suffix;
+        } else {
+            // If the input is not a number, return it as is
+            return input;
+        }
     }
 
 }  // namespace nspanel_ha_blueprint