package org.jruby.java.invokers;

import java.lang.reflect.AccessibleObject;
import java.lang.reflect.Array;
import java.lang.reflect.Member;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.concurrent.ConcurrentHashMap;
import org.jruby.Ruby;
import org.jruby.RubyModule;
import org.jruby.internal.runtime.methods.JavaMethod;
import org.jruby.java.dispatch.CallableSelector;
import org.jruby.java.proxies.ArrayJavaProxy;
import org.jruby.java.proxies.JavaProxy;
import org.jruby.javasupport.JavaCallable;
import org.jruby.runtime.Arity;
import org.jruby.runtime.Visibility;
import org.jruby.runtime.builtin.IRubyObject;

public abstract class RubyToJavaInvoker extends JavaMethod {
    protected static final Object[] EMPTY_OBJECT_ARRAY = new Object[0];
    protected final JavaCallable javaCallable;
    protected final JavaCallable[][] javaCallables;
    protected final JavaCallable[] javaVarargsCallables;
    protected final int minVarargsArity;
    protected final Map cache;
    private Member[] members;
    
    RubyToJavaInvoker(RubyModule host, Member[] members) {
        super(host, Visibility.PUBLIC);
        this.members = members;
        // we set all Java methods to optional, since many/most have overloads
        setArity(Arity.OPTIONAL);

        Ruby runtime = host.getRuntime();

        // initialize all the callables for this method
        JavaCallable callable = null;
        JavaCallable[][] callables = null;
        JavaCallable[] varargsCallables = null;
        int varargsArity = Integer.MAX_VALUE;
        
        if (members.length == 1) {
            callable = createCallable(runtime, members[0]);
            if (callable.isVarArgs()) {
                varargsCallables = createCallableArray(callable);
            }
        } else {
            Map<Integer, List<JavaCallable>> methodsMap = new HashMap<Integer, List<JavaCallable>>();
            List<JavaCallable> varargsMethods = new ArrayList();
            int maxArity = 0;
            for (Member method: members) {
                int currentArity = getMemberParameterTypes(method).length;
                maxArity = Math.max(currentArity, maxArity);
                List<JavaCallable> methodsForArity = (ArrayList<JavaCallable>)methodsMap.get(currentArity);
                if (methodsForArity == null) {
                    methodsForArity = new ArrayList<JavaCallable>();
                    methodsMap.put(currentArity,methodsForArity);
                }
                JavaCallable javaMethod = createCallable(runtime,method);
                methodsForArity.add(javaMethod);

                if (isMemberVarArgs(method)) {
                    varargsArity = Math.min(currentArity - 1, varargsArity);
                    varargsMethods.add(javaMethod);
                }
            }

            callables = createCallableArrayArray(maxArity + 1);
            for (Map.Entry<Integer,List<JavaCallable>> entry : methodsMap.entrySet()) {
                List<JavaCallable> methodsForArity = (List<JavaCallable>)entry.getValue();

                JavaCallable[] methodsArray = methodsForArity.toArray(createCallableArray(methodsForArity.size()));
                callables[((Integer)entry.getKey()).intValue()] = methodsArray;
            }

            if (varargsMethods.size() > 0) {
                // have at least one varargs, build that map too
                varargsCallables = createCallableArray(varargsMethods.size());
                varargsMethods.toArray(varargsCallables);
            }
        }
        members = null;

        // initialize cache of parameter types to method
        // FIXME: No real reason to use CHM, is there?
        cache = new ConcurrentHashMap(0, 0.75f, 1);

        this.javaCallable = callable;
        this.javaCallables = callables;
        this.javaVarargsCallables = varargsCallables;
        this.minVarargsArity = varargsArity;
    }

    protected Member[] getMembers() {
        return members;
    }

    protected AccessibleObject[] getAccessibleObjects() {
        return (AccessibleObject[])getMembers();
    }

    protected abstract JavaCallable createCallable(Ruby ruby, Member member);

    protected abstract JavaCallable[] createCallableArray(JavaCallable callable);

    protected abstract JavaCallable[] createCallableArray(int size);

    protected abstract JavaCallable[][] createCallableArrayArray(int size);

    protected abstract Class[] getMemberParameterTypes(Member member);

    protected abstract boolean isMemberVarArgs(Member member);

    static Object convertArg(IRubyObject arg, JavaCallable method, int index) {
        return arg.toJava(method.getParameterTypes()[index]);
    }

    static Object convertVarargs(IRubyObject[] args, JavaCallable method) {
        Class[] types = method.getParameterTypes();
        Class varargArrayType = types[types.length - 1];
        Class varargType = varargArrayType.getComponentType();
        int varargsStart = types.length - 1;
        int varargsCount = args.length - varargsStart;

        Object varargs;
        if (varargsCount == 1 && args[varargsStart] instanceof ArrayJavaProxy) {
            // we may have a pre-created array to pass; try that first
            varargs = args[varargsStart].toJava(varargArrayType);
        } else {
            varargs = Array.newInstance(varargType, varargsCount);

            for (int i = 0; i < varargsCount; i++) {
                Array.set(varargs, i, args[varargsStart + i].toJava(varargType));
            }
        }
        return varargs;
    }

    static JavaProxy castJavaProxy(IRubyObject self) {
        assert self instanceof JavaProxy : "Java methods can only be invoked on Java objects";
        return (JavaProxy)self;
    }

    static void trySetAccessible(AccessibleObject[] accObjs) {
        if (!Ruby.isSecurityRestricted()) {
            try {
                AccessibleObject.setAccessible(accObjs, true);
            } catch(SecurityException e) {}
        }
    }

    void raiseNoMatchingCallableError(String name, IRubyObject proxy, Object... args) {
        int len = args.length;
        Class[] argTypes = new Class[args.length];
        for (int i = 0; i < len; i++) {
            argTypes[i] = args[i].getClass();
        }
        throw proxy.getRuntime().newArgumentError("no " + name + " with arguments matching " + Arrays.toString(argTypes) + " on object " + proxy.getMetaClass());
    }

    protected JavaCallable findCallable(IRubyObject self, String name, IRubyObject[] args, int arity) {
        JavaCallable callable;
        if ((callable = javaCallable) == null) {
            JavaCallable[] callablesForArity = null;
            if (arity >= javaCallables.length || (callablesForArity = javaCallables[arity]) == null) {
                if (javaVarargsCallables != null) {
                    callable = CallableSelector.matchingCallableArityN(cache, javaVarargsCallables, args, arity);
                    if (callable == null) {
                        throw CallableSelector.argTypesDoNotMatch(self.getRuntime(), self, javaVarargsCallables, (Object[])args);
                    }
                    return callable;
                } else {
                    throw self.getRuntime().newArgumentError(args.length, javaCallables.length - 1);
                }
            }
            callable = CallableSelector.matchingCallableArityN(cache, callablesForArity, args, arity);
            if (callable == null && javaVarargsCallables != null) {
                callable = CallableSelector.matchingCallableArityN(cache, javaVarargsCallables, args, arity);
                if (callable == null) {
                    throw CallableSelector.argTypesDoNotMatch(self.getRuntime(), self, javaVarargsCallables, (Object[])args);
                }
                return callable;
            }
            if (callable == null) {
                throw CallableSelector.argTypesDoNotMatch(self.getRuntime(), self, callablesForArity, (Object[])args);
            }
        } else {
            if (!callable.isVarArgs() && callable.getParameterTypes().length != args.length) {
                throw self.getRuntime().newArgumentError(args.length, callable.getParameterTypes().length);
            }
        }
        return callable;
    }

    protected JavaCallable findCallableArityZero(IRubyObject self, String name) {
        JavaCallable callable;
        if ((callable = javaCallable) == null) {
            // TODO: varargs?
            JavaCallable[] callablesForArity = null;
            if (javaCallables.length == 0 || (callablesForArity = javaCallables[0]) == null) {
                raiseNoMatchingCallableError(name, self, EMPTY_OBJECT_ARRAY);
            }
            callable = callablesForArity[0];
        } else {
            if (callable.getParameterTypes().length != 0) {
                throw self.getRuntime().newArgumentError(0, callable.getParameterTypes().length);
            }
        }
        return callable;
    }

    protected JavaCallable findCallableArityOne(IRubyObject self, String name, IRubyObject arg0) {
        JavaCallable callable;
        if ((callable = javaCallable) == null) {
            // TODO: varargs?
            JavaCallable[] callablesForArity = null;
            if (javaCallables.length <= 1 || (callablesForArity = javaCallables[1]) == null) {
                throw self.getRuntime().newArgumentError(1, javaCallables.length - 1);
            }
            callable = CallableSelector.matchingCallableArityOne(cache, callablesForArity, arg0);
            if (callable == null) {
                throw CallableSelector.argTypesDoNotMatch(self.getRuntime(), self, callablesForArity, arg0);
            }
        } else {
            if (callable.getParameterTypes().length != 1) {
                throw self.getRuntime().newArgumentError(1, callable.getParameterTypes().length);
            }
        }
        return callable;
    }

    protected JavaCallable findCallableArityTwo(IRubyObject self, String name, IRubyObject arg0, IRubyObject arg1) {
        JavaCallable callable;
        if ((callable = javaCallable) == null) {
            // TODO: varargs?
            JavaCallable[] callablesForArity = null;
            if (javaCallables.length <= 2 || (callablesForArity = javaCallables[2]) == null) {
                throw self.getRuntime().newArgumentError(2, javaCallables.length - 1);
            }
            callable = CallableSelector.matchingCallableArityTwo(cache, callablesForArity, arg0, arg1);
            if (callable == null) {
                throw CallableSelector.argTypesDoNotMatch(self.getRuntime(), self, callablesForArity, arg0, arg1);
            }
        } else {
            if (callable.getParameterTypes().length != 2) {
                throw self.getRuntime().newArgumentError(2, callable.getParameterTypes().length);
            }
        }
        return callable;
    }

    protected JavaCallable findCallableArityThree(IRubyObject self, String name, IRubyObject arg0, IRubyObject arg1, IRubyObject arg2) {
        JavaCallable callable;
        if ((callable = javaCallable) == null) {
            // TODO: varargs?
            JavaCallable[] callablesForArity = null;
            if (javaCallables.length <= 3 || (callablesForArity = javaCallables[3]) == null) {
                throw self.getRuntime().newArgumentError(3, javaCallables.length - 1);
            }
            callable = CallableSelector.matchingCallableArityThree(cache, callablesForArity, arg0, arg1, arg2);
            if (callable == null) {
                throw CallableSelector.argTypesDoNotMatch(self.getRuntime(), self, callablesForArity, arg0, arg1, arg2);
            }
        } else {
            if (callable.getParameterTypes().length != 3) {
                throw self.getRuntime().newArgumentError(3, callable.getParameterTypes().length);
            }
        }
        return callable;
    }

    protected JavaCallable findCallableArityFour(IRubyObject self, String name, IRubyObject arg0, IRubyObject arg1, IRubyObject arg2, IRubyObject arg3) {
        JavaCallable callable;
        if ((callable = javaCallable) == null) {
            // TODO: varargs?
            JavaCallable[] callablesForArity = null;
            if (javaCallables.length <= 4 || (callablesForArity = javaCallables[4]) == null) {
                throw self.getRuntime().newArgumentError(4, javaCallables.length - 1);
            }
            callable = CallableSelector.matchingCallableArityFour(cache, callablesForArity, arg0, arg1, arg2, arg3);
            if (callable == null) {
                throw CallableSelector.argTypesDoNotMatch(self.getRuntime(), self, callablesForArity, arg0, arg1, arg2, arg3);
            }
        } else {
            if (callable.getParameterTypes().length != 4) {
                throw self.getRuntime().newArgumentError(4, callable.getParameterTypes().length);
            }
        }
        return callable;
    }
}