move ostype to drongo

src/main/java/com/sparrowwallet/drongo/OsType.java

@@ -0,0 +1,48 @@
+package com.sparrowwallet.drongo;
+
+public enum OsType {
+    WINDOWS("Windows"),
+    MACOS("macOS"),
+    UNIX("Unix"),
+    UNKNOWN("");
+
+    private static final OsType current = getCurrentPlatform();
+    private final String platformId;
+
+    OsType(String platformId) {
+        this.platformId = platformId;
+    }
+
+    /**
+     * Returns platform id. Usually used to specify platform dependent styles
+     *
+     * @return platform id
+     */
+    public String getPlatformId() {
+        return platformId;
+    }
+
+    /**
+     * @return the current OS.
+     */
+    public static OsType getCurrent() {
+        return current;
+    }
+
+    private static OsType getCurrentPlatform() {
+        String osName = System.getProperty("os.name");
+        if(osName.startsWith("Windows")) {
+            return WINDOWS;
+        }
+        if(osName.startsWith("Mac")) {
+            return MACOS;
+        }
+        if(osName.startsWith("SunOS")) {
+            return UNIX;
+        }
+        if(osName.startsWith("Linux")) {
+            return UNIX;
+        }
+        return UNKNOWN;
+    }
+}