// Copyright (c) Corporation for National Research Initiatives
// Copyright (c)2019 Jython Developers.
// Licensed to PSF under a Contributor Agreement.
package org.python.core;

import java.lang.reflect.Constructor;
import java.lang.reflect.Modifier;
import java.lang.reflect.InvocationTargetException;
import java.lang.InstantiationException;

@Untraversable
public class PyReflectedConstructor extends PyReflectedFunction {

    public PyReflectedConstructor(String name) {
        super(name);
    }

    public PyReflectedConstructor(Constructor c) {
        this(c.getDeclaringClass().getName());
        addConstructor(c);
    }

    private ReflectedArgs makeArgs(Constructor m) {
        return new ReflectedArgs(m, m.getParameterTypes(), m.getDeclaringClass(), true, m.isVarArgs());
    }

    public void addConstructor(Constructor m) {
        int mods = m.getModifiers();
        // Only add public methods unless we're overriding
        if (!Modifier.isPublic(mods) && Options.respectJavaAccessibility) {
            return;
        }
        addArgs(makeArgs(m));
    }

    // xxx temporary solution, type ctr will go through __new__ ...
    PyObject make(PyObject[] args, String[] keywords) {
        ReflectedCallData callData = new ReflectedCallData();
        Object method = null;
        boolean consumes_keywords = false;
        PyObject[] allArgs = null;
        // Check for a matching constructor to call
        if (nargs > 0) { // PyArgsKeywordsCall signature, if present, is the first
            if (argslist[0].matches(null, args, keywords, callData)) {
                method = argslist[0].method;
                consumes_keywords = argslist[0].flags == ReflectedArgs.PyArgsKeywordsCall;
            } else {
                allArgs = args;
                int i = 1;
                if (keywords.length > 0) {
                    args = new PyObject[allArgs.length - keywords.length];
                    System.arraycopy(allArgs, 0, args, 0, args.length);
                    i = 0;
                }
                for (; i < nargs; i++) {
                    if (argslist[i].matches(null, args, Py.NoKeywords, callData)) {
                        method = argslist[i].method;
                        break;
                    }
                }
            }
        }
        // Throw an error if no valid set of arguments
        if (method == null) {
            throwError(callData.errArg, args.length, true /* xxx? */, false);
        }
        // Do the actual constructor call
        PyObject obj;
        try {
            obj = (PyObject)((Constructor)method).newInstance(callData.getArgsArray());
        } catch (Throwable t) {
            throw Py.JavaError(t);
        }
        if (!consumes_keywords) {
            int offset = args.length;
            for (int i = 0; i < keywords.length; i++) {
                obj.__setattr__(keywords[i], allArgs[i + offset]);
            }
        }
        return obj;
    }

    @Override
    public PyObject __call__(PyObject self, PyObject[] args, String[] keywords) {
        if (self == null) {
            throw Py.TypeError("invalid self argument to constructor");
        }
        Class javaClass = self.getType().getProxyType();
        if (javaClass == null) {
            throw Py.TypeError("self invalid - must be a Java subclass [self=" + self + "]");
        }
        Class declaringClass = argslist[0] == null ? null : argslist[0].declaringClass;
        // If the declaring class is a pure Java type but we're instantiating a Python proxy,
        // grab the proxy version of the constructor to instantiate the proper type
        if ((declaringClass == null || !PyProxy.class.isAssignableFrom(declaringClass))
                && !(self.getType() instanceof PyJavaType)) {
            return PyType.fromClass(javaClass).lookup("__init__").__call__(self, args, keywords);
        }
        if (nargs == 0) {
            throw Py.TypeError("No visible constructors for class (" + javaClass.getName() + ")");
        }
        if (!declaringClass.isAssignableFrom(javaClass)) {
            throw Py.TypeError("self invalid - must implement: " + declaringClass.getName());
        }

        int mods = declaringClass.getModifiers();
        if (Modifier.isInterface(mods)) {
            throw Py.TypeError("can't instantiate interface (" + declaringClass.getName() + ")");
        } else if (Modifier.isAbstract(mods)) {
            throw Py.TypeError("can't instantiate abstract class (" + declaringClass.getName() + ")");
        }
        if (JyAttribute.hasAttr(self, JyAttribute.JAVA_PROXY_ATTR)) {
            Class sup = javaClass;
            if (PyProxy.class.isAssignableFrom(sup)) {
                sup = sup.getSuperclass();
            }
            throw Py.TypeError("instance already instantiated for " + sup.getName());
        }
        ReflectedCallData callData = new ReflectedCallData();
        Object method = null;

        // If we have keyword args, there are two ways this can be handled;
        // a) we find a constructor that takes keyword args, and use it.
        // b) we don't, in which case we strip the keyword args, and pass the
        //     non-keyword args, and then use the keyword args to set bean properties
        // If we don't have keyword args; just look for a constructor that
        // takes the right number of args.
        int nkeywords = keywords.length;
        ReflectedArgs rargs = null;
        PyObject[] allArgs = args;
        boolean usingKeywordArgsCtor = false;
        if (nkeywords > 0) {
            // We have keyword args.

            // Look for a constructor; the ReflectedArgs#matches() method exits early in the case
            // where keyword args are used
            int n = nargs;
            for (int i = 0; i < n; i++) {
                rargs = argslist[i];
                if (rargs.matches(null, args, keywords, callData)) {
                    method = rargs.method;
                    break;
                }
            }

            if (method != null) {
                // Constructor found that will accept the keyword args
                usingKeywordArgsCtor = true;
            } else {
                // No constructor found that will take keyword args

                // Remove the keyword args
                args = new PyObject[allArgs.length - nkeywords];
                System.arraycopy(allArgs, 0, args, 0, args.length);

                // Look for a constructor with no keyword args
                for (int i = 0; i < n; i++) {
                    rargs = argslist[i];
                    if (rargs.matches(null, args, Py.NoKeywords, callData)) {
                        method = rargs.method;
                        break;
                    }
                }
            }
       } else {
           // Just look for a constructor with no keyword args
           int n = nargs;
           for (int i = 0; i < n; i++) {
               rargs = argslist[i];
               if (rargs.matches(null, args, Py.NoKeywords, callData)) {
                   method = rargs.method;
                   break;
               }
           }
       }

        // Throw an error if no valid set of arguments
        if (method == null) {
            throwError(callData.errArg, args.length, false, false);
        }
        // Do the actual constructor call
        constructProxy(self, (Constructor)method, callData.getArgsArray(), javaClass);
        // Do setattr's for keyword args. This convenience allows Java bean properties to be set in
        // by a Python constructor call.
        // However, this is not done if the Java constructor accepts (PyObject[], String[]) as its arguments,
        // in which case the intention is that the Java constructor will handle the keyword arguments itself.
        if (!usingKeywordArgsCtor) {
            int offset = args.length;
            for (int i = 0; i < nkeywords; i++) {
                self.__setattr__(keywords[i], allArgs[i + offset]);
            }
        }
        return Py.None;
    }

    @Override
    public PyObject __call__(PyObject[] args, String[] keywords) {
        if (args.length < 1) {
            throw Py.TypeError("constructor requires self argument");
        }
        PyObject[] newArgs = new PyObject[args.length - 1];
        System.arraycopy(args, 1, newArgs, 0, newArgs.length);
        return __call__(args[0], newArgs, keywords);
    }

    protected void constructProxy(PyObject obj, Constructor ctor, Object[] args, Class proxy) {
        // Do the actual constructor call
        Object jself = null;
        Object[] previous = ThreadContext.initializingProxy.get();
        ThreadContext.initializingProxy.set(new Object[] { obj });
        try {
            try {
                jself = ctor.newInstance(args);
            } catch (InvocationTargetException e) {
                if (e.getTargetException() instanceof InstantiationException) {
                    Class sup = proxy.getSuperclass();
                    String msg = "Constructor failed for Java superclass";
                    if (sup != null) {
                        msg += " " + sup.getName();
                    }
                    throw Py.TypeError(msg);
                } else {
                    throw Py.JavaError(e);
                }
            } catch (Throwable t) {
                throw Py.JavaError(t);
            }
        } finally {
            ThreadContext.initializingProxy.set(previous);
        }
        JyAttribute.setAttr(obj, JyAttribute.JAVA_PROXY_ATTR, jself);
    }

    @Override
    public PyObject _doget(PyObject container, PyObject wherefound) {
        if (container == null) {
            return this;
        }
        return new PyMethod(this, container, wherefound);
    }

    @Override
    public String toString() {
        // printArgs();
        return "";
    }
}