src/main/java/ch/unibas/dmi/dbis/cs108/casono/server/network/parser/RequestParameterAccessor.java

@@ -0,0 +1,59 @@
+package ch.unibas.dmi.dbis.cs108.casono.server.network.parser;
+
+import java.util.List;
+import java.util.Map;
+import java.util.stream.Collectors;
+
+public class RequestParameterAccessor {
+    private final Map<String, String> index;
+
+    public RequestParameterAccessor(List<Parameter> parameters) {
+        this.index = parameters.stream()
+            .collect(Collectors.toUnmodifiableMap(
+                Parameter::key,
+                Parameter::value
+            ));
+    }
+
+    public String require(String key) throws MissingParameterException {
+        String value = index.get(key);
+        if (value == null) {
+            throw new MissingParameterException("Required parameter with key '" + key + "' is missing.", key);
+        }
+        return value;
+    }
+
+    public <T> T require(String key, ThrowingParser<T> parser) throws MissingParameterException, ParameterParseException {
+        String value = require(key);
+        try {
+            return parser.parse(value);
+        } catch (Exception e) {
+            throw new ParameterParseException("Error while parsing with specified parser", e);
+        }
+    }
+
+    public String optional(String key, String defaultValue) {
+        String value = index.get(key);
+        if (value == null) {
+            return defaultValue;
+        }
+        return value;
+    }
+
+    public <T> T optional(String key, T defaultValue, ThrowingParser<T> parser) throws ParameterParseException {
+        String value = index.get(key);
+        if (value == null) {
+            return defaultValue;
+        }
+
+        try {
+            return parser.parse(value);
+        } catch (Exception e) {
+            throw new ParameterParseException("Error while parsing with specified parser", e);
+        }
+    }
+
+    public boolean containsKey(String key) {
+        return index.containsKey(key);
+    }
+}