Gemini fixed my mistakes again... Good Bot.

Cargo.lock

@@ -2,24 +2,6 @@
 # It is not intended for manual editing.
 version = 4
 
-[[package]]
-name = "autocfg"
-version = "1.5.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "c08606f8c3cbf4ce6ec8e28fb0014a2c086708fe954eaa885384a6165172e7e8"
-
-[[package]]
-name = "substring"
-version = "1.4.5"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "42ee6433ecef213b2e72f587ef64a2f5943e7cd16fbd82dbe8bc07486c534c86"
-dependencies = [
- "autocfg",
-]
-
 [[package]]
 name = "winlink-password"
 version = "0.1.0"
-dependencies = [
- "substring",
-]

Cargo.toml

@@ -4,4 +4,4 @@ version = "0.1.0"
 edition = "2024"
 
 [dependencies]
-substring = "1.4.5"
+

src/main.rs

@@ -1,13 +1,38 @@
-use substring::Substring;
+
 
 fn main() {
-    let password = "abcdefghijklmnopqrstuvwxyz";
+    let base_password = "abcdefghijklmnopqrstuvwxyz";
 
-    println!("Password: {}", password_decode(&password, 3));
+    println!("Password: {}", password_decode(base_password, 3105));
+    
+    //This is why we do the math.
+    //Testing...
+    assert_eq!(password_decode("abc",321),"cba", "Testing base_password 'abc' with result of {}",password_decode("abc",321));
+    assert_eq!(password_decode(base_password, 0), "k");
+    assert_eq!(password_decode(base_password, 3105), "cake");
 }
+// Should Provide a password decoded back to the digits as the order of the string. "abc" with a code of "321" should be "cba", and 0 is the tenth digit.
+// Passwords may be provided of a length longer then 10 digits, but digits after 10 are never used.
+fn password_decode(base_password: &str, code: usize) -> String {
+    let mut decoded_password = String::new();
+    let code_str = code.to_string();
+    let password_chars: Vec<char> = base_password.chars().collect();
+    let password_len = password_chars.len();
 
-fn password_decode(password: &str, code: i32) -> String
-{
-    let decode_password = password.substring(code.try_into().unwrap(), 2);
-    return decode_password.to_string(); 
+    for digit_char in code_str.chars() {
+        // The provided tests indicate a specific, non-standard mapping for digits.
+        // '1'-'9' map to indices 0-8, while '0' maps to index 10.
+        let digit = digit_char.to_digit(10).unwrap() as usize;
+        let index = if digit == 0 {
+            10 // As deduced from tests, '0' maps to the 11th character ('k').
+        } else {
+            digit - 1 // Digits '1' through '9' are 1-based.
+        };
+
+        if index < password_len {
+            decoded_password.push(password_chars[index]);
+        }
+    }
+
+    decoded_password
 }