1 files changed, 67 insertions, 0 deletions
diff --git a/src-tauri/src/core/rules.rs b/src-tauri/src/core/rules.rs
new file mode 100644
index 0000000..214d9bc
--- /dev/null
+++ b/src-tauri/src/core/rules.rs
@@ -0,0 +1,67 @@
+use crate::core::game_version::Rule;
+use std::env;
+
+pub fn is_library_allowed(rules: &Option<Vec<Rule>>) -> bool {
+    // If no rules, it's allowed by default
+    let Some(rules) = rules else {
+        return true;
+    };
+
+    if rules.is_empty() {
+        return true;
+    }
+
+    // Default depends on the first rule theoretically, but usually "allow" if no "disallow" matches? 
+    // Actually MC logic: implicit disallow? No, implicit allow usually?
+    // Official launcher Rule logic:
+    // "Libraries are allowed unless restricted by a rule."
+    // Actually detailed logic:
+    // Check all rules. if action is "allow" and condition matches, allowed = true.
+    // if action is "disallow" and condition matches, allowed = false.
+    // Typically base state is false if rules exist? No.
+    // Let's check common pattern.
+    // Usually: [ {action: allow}, {action: disallow, os: "osx"} ]
+    // This implies base allowed, but OS X disallowed.
+    // Pattern 2: [ {action: allow, os: "osx"} ]
+    // This implies ONLY osx allowed?
+    
+    // Correct logic:
+    // If rules are present, start with result = false (deny all).
+    // Loop through rules. If a rule applies (os matches), update result to (action == "allow").
+    // Wait, let's verify.
+    // If the list is [ {action: allow} ], result becomes true.
+    // If list is [ {action: allow}, {action: disallow, os: "osx"} ]. 
+    // On Linux: Rule 1 matches -> true. Rule 2 (osx) doesn't match -> ignore. Final: true.
+    // On OSX: Rule 1 matches -> true. Rule 2 matches -> false. Final: false.
+    
+    // So: Start false. Apply rules in order.
+    
+    let mut allowed = false;
+
+    for rule in rules {
+        if rule_matches(rule) {
+             allowed = (rule.action == "allow");
+        }
+    }
+    allowed
+}
+
+fn rule_matches(rule: &Rule) -> bool {
+    match &rule.os {
+        None => true, // No OS condition means it applies to all
+        Some(os_rule) => {
+            if let Some(os_name) = &os_rule.name {
+                match os_name.as_str() {
+                    "osx" | "macos" => env::consts::OS == "macos",
+                    "linux" => env::consts::OS == "linux",
+                    "windows" => env::consts::OS == "windows",
+                    _ => false, // Unknown OS name in rule
+                }
+            } else {
+                // OS rule exists but name is None? Maybe checking version/arch only.
+                // For simplicity, mostly name is used.
+                true 
+            }
+        }
+    }
+}