Model AppCacheFormat explicitly

This will future-proof it better.
selesse · Jul 13, 2024 · b7bbc1b · b7bbc1b
1 parent b41f9a9
commit b7bbc1b
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Showing 2 changed files with 38 additions and 7 deletions.
diff --git a/steam-config-reader/src/main/java/com/selesse/steam/appcache/AppCacheBufferedReader.java b/steam-config-reader/src/main/java/com/selesse/steam/appcache/AppCacheBufferedReader.java
@@ -33,17 +33,13 @@ public AppCacheBufferedReader(Path path) {
     public AppCache call() throws Exception {
         try (BufferedInputStream bufferedInputStream = new BufferedInputStream(new FileInputStream(path.toFile()))) {
             String firstFourBytes = readFourBytes(bufferedInputStream);
-            if (!(firstFourBytes.equals("27 44 56 7")
-                    || firstFourBytes.equals("28 44 56 7")
-                    || firstFourBytes.equals("29 44 56 7"))) {
-                throw new IllegalStateException("Unknown app cache format: " + firstFourBytes);
-            }
-            boolean parseSha1Binary = firstFourBytes.equals("28 44 56 7") || firstFourBytes.equals("29 44 56 7");
+            AppCacheFormat appCacheFormat = AppCacheFormat.fromFirstFourBytes(firstFourBytes);
+            boolean parseSha1Binary = appCacheFormat.isAtLeast(AppCacheFormat.TWENTY_EIGHT);
             String nextByte = readFourBytes(bufferedInputStream);
             assert nextByte.equals("1 0 0 0");
             AppCache appCache = new AppCache();
             StringCache stringCache = null;
-            if (firstFourBytes.equals("29 44 56 7")) {
+            if (appCacheFormat.isAtLeast(AppCacheFormat.TWENTY_NINE)) {
                 long offsetToStringTable = parse64Int(bufferedInputStream);
                 stringCache = new StringCacheReader(path, offsetToStringTable).read();
             }

diff --git a/steam-config-reader/src/main/java/com/selesse/steam/appcache/AppCacheFormat.java b/steam-config-reader/src/main/java/com/selesse/steam/appcache/AppCacheFormat.java
@@ -0,0 +1,35 @@
+package com.selesse.steam.appcache;
+
+import java.util.Arrays;
+
+public enum AppCacheFormat {
+    TWENTY_SEVEN("27"),
+    TWENTY_EIGHT("28"),
+    TWENTY_NINE("29"),
+    ;
+
+    private final String number;
+
+    AppCacheFormat(String number) {
+        this.number = number;
+    }
+
+    public static AppCacheFormat fromFirstFourBytes(String bytes) {
+        if (!bytes.endsWith("44 56 7")) {
+            throw new IllegalStateException("First four bytes didn't end in '44 56 7'");
+        }
+        String magicNumber = bytes.split(" ")[0];
+        return fromString(magicNumber);
+    }
+
+    private static AppCacheFormat fromString(String value) {
+        return Arrays.stream(values())
+                .filter(x -> x.number.equals(value))
+                .findFirst()
+                .orElseThrow();
+    }
+
+    public boolean isAtLeast(AppCacheFormat appCacheFormat) {
+        return this.ordinal() >= appCacheFormat.ordinal();
+    }
+}