add support for .file_header_ignore file

src/main/java/org/cobbzilla/util/main/FileHeaderMain.java

@@ -4,15 +4,19 @@ import org.cobbzilla.util.io.FileUtil;
 import org.cobbzilla.util.io.FilesystemWalker;
 
 import java.io.File;
-import java.util.Arrays;
-import java.util.Map;
-import java.util.Objects;
+import java.util.*;
+import java.util.concurrent.ConcurrentHashMap;
 import java.util.regex.Matcher;
+import java.util.regex.Pattern;
 
+import static org.cobbzilla.util.daemon.ZillaRuntime.empty;
+import static org.cobbzilla.util.daemon.ZillaRuntime.shortError;
 import static org.cobbzilla.util.io.FileUtil.*;
 
 public class FileHeaderMain extends BaseMain<FileHeaderOptions> {
 
+    public static final String FILE_HEADER_IGNORE = ".file_header_ignore";
+
     public static void main (String[] args) { main(FileHeaderMain.class, args); }
 
     @Override protected void run() throws Exception {
@@ -38,6 +42,10 @@ public class FileHeaderMain extends BaseMain<FileHeaderOptions> {
             err("skipping non-file: "+abs(file));
             return;
         }
+        if (isIgnored(file)) {
+            err("skipping ignored file: "+abs(file));
+            return;
+        }
         final String ext = FileUtil.extension(file);
         final FileHeader header = headers.get(ext.length() > 0 ? ext.substring(1) : ext);
         if (header != null) {
@@ -69,4 +77,36 @@ public class FileHeaderMain extends BaseMain<FileHeaderOptions> {
         }
     }
 
+    private final Map<String, List<Pattern>> ignoreFileCache = new ConcurrentHashMap<>(100);
+
+    private boolean isIgnored(File file) {
+        final File dir = file.getParentFile();
+        final File ignoreFile = new File(dir, FILE_HEADER_IGNORE);
+        if (ignoreFile.exists()) {
+            final List<Pattern> patterns = ignoreFileCache.computeIfAbsent(abs(dir), k -> {
+                final List<String> regexes;
+                try {
+                    regexes = FileUtil.toStringList(ignoreFile);
+                } catch (Exception e) {
+                    err("isIgnored: error reading "+abs(ignoreFile)+" (all files will be ignored): "+shortError(e));
+                    return null;
+                }
+                final List<Pattern> list = new ArrayList<>();
+                for (String regex : regexes) {
+                    regex = regex.trim();
+                    if (empty(regex)) continue;
+                    try {
+                        list.add(Pattern.compile(regex));
+                    } catch (Exception e) {
+                        err("isIgnored: skipping invalid regex in "+abs(ignoreFile)+": '"+regex+"': "+shortError(e));
+                    }
+                }
+                return list;
+            });
+            final String name = file.getName();
+            return patterns == null || patterns.isEmpty() || patterns.stream().anyMatch(p -> p.matcher(name).matches());
+        }
+        return false;
+    }
+
 }