package http.server;

import http.gen.HTTPReq;
import http.gen.HTTPResp;
import java.io.IOException;
import java.lang.reflect.Method;
import edu.neu.ccs.demeterf.demfgen.lib.List;
import edu.neu.ccs.demeterf.demfgen.lib.Map;

/** Web Server Factory class */
public class Factory {
    private Factory(){}
    static boolean verbose = false;
    /** Set to true in order to get Output for Server/Dispatch descisions. */
    public static void setVerbose(boolean v){ verbose = v; } 

    static void p(String s){ if (verbose)System.err.println(" ** " + s); }
    
    /** Create a new Server using the given Handler.  A {@link http.server.Server Server}
     *    Annotation is used to describe the Port the Server will Listen on, and methods 
     *    should be Annotated with {@link http.server.Path Path} to describe responses
     *    to various Path requests.  See {@link http.Test Test} for an Example. */
    public static ServerThread create(Object handler) throws IOException
    { return create(handler,false); }
    /** Create a Single/Multi-threaded Server */
    public static ServerThread create(Object handler, boolean single) throws IOException{
        Class<?> c = handler.getClass();
        if (!c.isAnnotationPresent(Server.class)) {
            throw error("Cannot Create Server for unannotated class '"
                    + c.getCanonicalName() + "'");
        }
        Server s = c.getAnnotation(Server.class);
        p("Server Port = " + s.value());
        return new ServerThread(s, single, List.create(c.getDeclaredMethods()).fold(
                new List.Fold<Method, Map<String, Method>>() {
                    public Map<String, Method> fold(Method m, Map<String, Method> res){
                        if (!m.isAnnotationPresent(Path.class))return res;
                        String p = check(m);
                        m.setAccessible(true);
                        p("Mapping '" + p + "' to " + m.getName());
                        return res.put(p, m);
                    }
                }, Map.<String, Method> create()), handler);
    }
    /** Do a sanity check of the types of an annotated method */
    private static String check(Method m){
        Path p = m.getAnnotation(Path.class);
        if (!HTTPResp.class.equals(m.getReturnType())) {
            throw error("Return Type is incorrect: '"
                    + m.getReturnType().getClass() + "'");
        }
        Class<?>[] params = m.getParameterTypes();
        if (params.length > 1)
            throw error("Too many Parameters for Server Method '" + m.getName() + "'");
        if (!params[0].equals(HTTPReq.class))
            throw error("Wrong parameters type for method '" + m.getName() + "'");
        return p.value();
    }

    private static RuntimeException error(String e){ return new RuntimeException(e); }
}