Add: Implement ProtocolParser to parse RawPacket into PrimitiveRequest

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

@@ -0,0 +1,110 @@
+package ch.unibas.dmi.dbis.cs108.casono.server.network.parser;
+
+import ch.unibas.dmi.dbis.cs108.casono.server.network.transport.RawPacket;
+import ch.unibas.dmi.dbis.cs108.casono.server.tokenizer.RawToken;
+import ch.unibas.dmi.dbis.cs108.casono.server.tokenizer.Token;
+import ch.unibas.dmi.dbis.cs108.casono.server.tokenizer.TokenClassifier;
+import ch.unibas.dmi.dbis.cs108.casono.server.tokenizer.TokenType;
+import ch.unibas.dmi.dbis.cs108.casono.server.tokenizer.Tokenizer;
+import java.util.ArrayList;
+import java.util.Iterator;
+import java.util.List;
+import java.util.NoSuchElementException;
+
+/** ProtocolParser, used to parse RawPacket into a PrimitiveRequest */
+public class ProtocolParser {
+    /**
+     * Parses the payload of the provided RawPacket
+     *
+     * @param packet the RawPacket containing the recieved data
+     * @return created PrimitiveRequest
+     */
+    public static PrimitiveRequest parse(RawPacket packet) {
+        List<RawToken> rawTokens = Tokenizer.tokenize(packet.payload());
+        List<Token> tokens = TokenClassifier.classify(rawTokens);
+
+        Iterator<Token> iterator = tokens.iterator();
+        String command = readCommand(iterator);
+        List<Parameter> parameters = readParameters(iterator);
+
+        return new PrimitiveRequest(command, parameters);
+    }
+
+    /**
+     * Reads the first token, which is ensured to be the command of the request
+     *
+     * @param iterator
+     * @return read command
+     */
+    private static String readCommand(Iterator<Token> iterator) {
+        Token token = iterator.next();
+        if (token.type() != TokenType.COMMAND) {
+            throw new ProtocolParserException("Expected COMMAND got " + token.type());
+        }
+
+        return token.value();
+    }
+
+    /**
+     * Iterates over the remaining tokens, calling helperfunctions to validate token type
+     *
+     * @param iterator
+     * @return list containing all parsed parameters
+     */
+    private static List<Parameter> readParameters(Iterator<Token> iterator) {
+        List<Parameter> parameters = new ArrayList<>();
+
+        try {
+            while (iterator.hasNext()) {
+                Token nextToken = iterator.next();
+
+                if (nextToken.type() == TokenType.EOF) {
+                    break;
+                }
+
+                String key = readKey(nextToken);
+                readSeperator(iterator.next());
+                String value = readValue(iterator.next());
+
+                parameters.add(new Parameter(key, value));
+            }
+        } catch (NoSuchElementException e) {
+            throw new ProtocolParserException("Ran out of tokens while reading parameter");
+        }
+
+        return parameters;
+    }
+
+    /**
+     * @param token the current token
+     * @return
+     */
+    private static String readKey(Token token) {
+        if (token.type() != TokenType.KEY) {
+            throw new ProtocolParserException("Expected KEY got " + token.type());
+        }
+
+        return token.value();
+    }
+
+    /**
+     * @param token the current token
+     */
+    private static void readSeperator(Token token) {
+        if (token.type() != TokenType.SEPARATOR) {
+            throw new ProtocolParserException("Expected SEPARATOR got " + token.type());
+        }
+    }
+
+    /**
+     * @param token the current token
+     * @return
+     */
+    private static String readValue(Token token) {
+        if (token.type() != TokenType.VALUE) {
+            throw new ProtocolParserException("Expected VALUE got " + token.type());
+        }
+
+        return token.value();
+    }
+}