Update generation.rs

Add rng variable

generation.rs

@@ -0,0 +1,85 @@
+/*
+keyforge95
+Copyright 2024 Nando Lawson
+
+Licensed under the GPL, Version 3 <https://github.com/nandolawson/keyforge95/blob/main/LICENSE>.
+This file may not be copied, modified, or distributed except according to those terms.
+*/
+
+use crate::{
+    Choice::{A, B, C, D, E},
+    KeyType::{Retail, OEM},
+};
+#[cfg(target_arch = "wasm32")]
+use wasm_bindgen::prelude::wasm_bindgen;
+
+/// Generates a valid product key
+///
+/// # Example
+///
+/// ```
+/// use keyforge95::prelude::*;
+/// for _ in 0..10 {
+///     let product_key: String = generate_product_key(Retail); // Both, "Retail" and "OEM" are available
+///     assert_eq!(product_key.len(), 11);
+///     assert_eq!(product_key.chars().nth(3).unwrap(), '-');
+/// }
+/// ```
+#[must_use]
+#[cfg_attr(target_arch = "wasm32", wasm_bindgen)]
+pub fn generate_product_key(key_type: crate::KeyType) -> String {
+    // Use generate_block() for product key generation and print it with the right format
+    match key_type {
+        Retail => {
+            format!("{}-{}", generate_block(A), generate_block(C))
+        }
+        OEM => {
+            format!(
+                "{}-OEM-{}-{}",
+                generate_block(B),
+                generate_block(D),
+                generate_block(E)
+            )
+        }
+    }
+}
+
+pub(crate) fn generate_block(choice: crate::Choice) -> String {
+    use rand_core::{OsRng, RngCore};
+    let rng = || OsRng.next_u32();
+    // Determine which block of the product key will be generated
+    match choice {
+        B => format!(
+            "{:03}{:02}",
+            rng() % 367,
+            4 + (rng() % 90)
+        ),
+        E => format!("{:05}", rng() % 100_000),
+        _ => {
+            let max_value: u32 = match choice {
+                A => 998,       // Number range for block A
+                C => 8_888_888, // Number range for block C
+                D => 9_999_999, // Number range for block D
+                _ => 0,         // Dummy value for block B & E
+            };
+            let length: usize = match choice {
+                A => 3,     // Length of block A
+                C | D => 7, // Length of block C & D
+                _ => 0,     // Dummy value for block B & E
+            };
+            // Generate a block and validate it
+            loop {
+                use crate::validation::validate_block;
+                // Loop this operation if it fails
+                let block: String = format!("{:0length$}", rng() % (max_value + 1)); // Generate a block of the product
+                if validate_block(&format!(
+                    "{}{}",
+                    block,
+                    if matches!(choice, D) { "-" } else { "" }
+                )) {
+                    return block;
+                }
+            }
+        }
+    }
+}