23 define and create filter interface (#46)

* initial commit, added interfaces Filter and FilterChain

* Added HttpRequest class, groups together all information about a request that the server needs and easier to handle by future filters

* added interfaces Filter and FilterChain with Java Servlet Filter architecture.

* added FilterChainImpl

* Corrected imports from JDKS HttpRequest, to projects HttpRequest class

* Changed, params for FilterChain

* Updated HttpRequest with attributes,

* Revert "Updated HttpRequest with attributes,"

This reverts commit 0fd490e.

Author: eraiicphu

src/main/java/org/example/filter/Filter.java

@@ -0,0 +1,14 @@
+package org.example.filter;
+
+import org.example.http.HttpResponseBuilder;
+
+import org.example.httpparser.HttpRequest;
+
+public interface Filter {
+    void init();
+
+    void doFilter(HttpRequest request, HttpResponseBuilder response, FilterChain chain);
+
+    void destroy();
+
+}

src/main/java/org/example/filter/FilterChain.java

@@ -0,0 +1,10 @@
+package org.example.filter;
+
+import org.example.http.HttpResponseBuilder;
+import org.example.httpparser.HttpRequest;
+
+
+public interface FilterChain {
+
+    void doFilter(HttpRequest request, HttpResponseBuilder response);
+}

src/main/java/org/example/filter/FilterChainImpl.java

@@ -0,0 +1,33 @@
+package org.example.filter;
+
+import org.example.http.HttpResponseBuilder;
+import org.example.httpparser.HttpRequest;
+
+
+import java.util.List;
+
+/*
+* The default class of FilterChain,
+* Contains a list of filters. For each of the filter, will execute the doFilter method.
+*
+ */
+
+public class FilterChainImpl implements FilterChain {
+
+    private final List<Filter> filters;
+    private int index = 0;
+
+    public FilterChainImpl(List<Filter> filters) {
+        this.filters = filters;
+    }
+
+    @Override
+    public void doFilter(HttpRequest request, HttpResponseBuilder response) {
+        if (index < filters.size()) {
+            Filter next = filters.get(index++);
+            next.doFilter(request, response, this);
+        } else {
+            // TODO: when no more filters, should execute the request
+        }
+    }
+}

src/main/java/org/example/httpparser/HttpRequest.java

@@ -0,0 +1,41 @@
+package org.example.httpparser;
+
+import java.util.Collections;
+import java.util.Map;
+
+/*
+*
+*This class groups together all information about a request that the server needs
+ */
+
+public class HttpRequest {
+
+        private final String method;
+        private final String path;
+        private final String version;
+        private final Map<String, String> headers;
+        private final String body;
+
+        public HttpRequest(String method,
+                           String path,
+                           String version,
+                           Map<String, String> headers,
+                           String body) {
+            this.method = method;
+            this.path = path;
+            this.version = version;
+            this.headers = headers != null ? Map.copyOf(headers) : Collections.emptyMap();
+            this.body = body;
+        }
+
+        public String getMethod() {
+            return method; }
+        public String getPath() {
+            return path; }
+        public String getVersion() {
+            return version; }
+        public Map<String, String> getHeaders() {
+            return headers; }
+        public String getBody() {
+            return body; }
+    }