Initial commit.

[jagi.git] / src / jagi / fs / Handler.java

package jagi.fs;

import java.util.*;
import java.util.function.*;
import java.util.logging.*;
import java.lang.reflect.*;
import java.io.*;
import java.nio.file.*;
import jagi.*;

public class Handler implements Function<Map<Object, Object>, Map<Object, Object>> {
    private static final Logger log = Logger.getLogger("jagi-fs");
    private Map<String, Function<Map<Object, Object>, Map<Object, Object>>> handlers = new HashMap<>();
    private Map<String, Function<Map<Object, Object>, Map<Object, Object>>> exts = new HashMap<>();

    @SuppressWarnings("unchecked")
    private static Function<Map<Object, Object>, Map<Object, Object>> resolve(ClassLoader loader, String nm) {
	Class<?> cl;
	try {
	    cl = loader.loadClass(nm);
	} catch(ClassNotFoundException e) {
	    try {
		cl = loader.loadClass(nm + ".Bootstrap");
	    } catch(ClassNotFoundException e2) {
		throw(new RuntimeException("could not find handler class or package: " + nm, e2));
	    }
	}
	Method wmain;
	try {
	    wmain = cl.getDeclaredMethod("wmain", String[].class);
	    int mod = wmain.getModifiers();
	    if(((mod & Modifier.STATIC) == 0) || ((mod & Modifier.PUBLIC) == 0))
		throw(new NoSuchMethodException());
	} catch(NoSuchMethodException e) {
	    throw(new RuntimeException("could not find wmain method in " + cl.getName(), e));
	}
	Object handler;
	try {
	    handler = wmain.invoke(null, new Object[] {new String[] {}});
	} catch(IllegalAccessException e) {
	    throw(new RuntimeException("could not call wmain in " + cl.getName(), e));
	} catch(InvocationTargetException e) {
	    throw(new RuntimeException("wmain in " + cl.getName() + " failed", e.getCause()));
	}
	if(!(handler instanceof Function))
	    throw(new RuntimeException("wmain in " + cl.getName() + " returned " + ((handler == null) ? "null" : ("a " + handler.getClass()))));
	return((Function<Map<Object, Object>, Map<Object, Object>>)handler);
    }

    public Function<Map<Object, Object>, Map<Object, Object>> resolve(String nm) {
	synchronized(handlers) {
	    Function<Map<Object, Object>, Map<Object, Object>> handler = handlers.get(nm);
	    if(handler == null)
		handlers.put(nm, handler = resolve(Thread.currentThread().getContextClassLoader(), nm));
	    return(handler);
	}
    }

    public void addext(String ext, String name) {
	addext(ext, resolve(name));
    }

    public void addext(String ext, Function<Map<Object, Object>, Map<Object, Object>> handler) {
	Map<String, Function<Map<Object, Object>, Map<Object, Object>>> exts = new HashMap<>(this.exts);
	synchronized(exts) {
	    exts.put(ext, handler);
	}
	this.exts = exts;
    }

    {
	addext("jagi", new JavaHandler());
    }

    public Map<Object, Object> apply(Map<Object, Object> req) {
	String filename = (String)req.get("SCRIPT_FILENAME");
	if(filename == null) {
	    log.warning("jagi-fs called without SCRIPT_FILENAME set");
	    return(Utils.simpleerror(500, "Internal Error", "The server is erroneously configured"));
	}
	Path path = Paths.get(filename);
	if(!Files.isReadable(path)) {
	    log.warning(path + ": not readable");
	    return(Utils.simpleerror(500, "Internal Error", "The server is erroneously configured"));
	}
	String hname = (String)req.get("HTTP_X_ASH_JAVA_HANDLER");
	if(hname != null) {
	    Function<Map<Object, Object>, Map<Object, Object>> handler;
	    try {
		handler = resolve(hname);
	    } catch(Exception e) {
		log.log(Level.WARNING, "could not load handler " + hname, e);
		return(Utils.simpleerror(500, "Internal Error", "The server is erroneously configured"));
	    }
	    return(handler.apply(req));
	} else {
	    String base = path.getFileName().toString();
	    int p = base.lastIndexOf('.');
	    if(p < 0) {
		log.warning(path + ": no file extension");
		return(Utils.simpleerror(500, "Internal Error", "The server is erroneously configured"));
	    }
	    String ext = base.substring(p + 1);
	    Function<Map<Object, Object>, Map<Object, Object>> handler = exts.get(ext);
	    if(handler == null) {
		log.warning("non-registered file extension: " + ext);
		return(Utils.simpleerror(500, "Internal Error", "The server is erroneously configured"));
	    }
	    return(handler.apply(req));
	}
    }
}