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/* Copyright (c) Jython Developers */
package org.python.modules.itertools;

import org.python.core.Py;
import org.python.core.PyIterator;
import org.python.core.PyObject;
import org.python.core.PyString;
import org.python.core.PyTuple;
import org.python.core.PyType;
import org.python.core.PyXRange;
import org.python.expose.ExposedGet;
import org.python.expose.ExposedNew;
import org.python.expose.ExposedMethod;
import org.python.expose.ExposedType;

@ExposedType(name = "itertools.izip", base = PyObject.class)
public class izip extends PyIterator {

    public static final PyType TYPE = PyType.fromClass(izip.class);
    private PyIterator iter;

    @ExposedGet
    public static PyString __doc__ = new PyString(
            "izip(iter1 [,iter2 [...]]) --> izip object\n\nReturn an izip object "
                    + "whose .next() method returns a tuple where\nthe i-th element comes from the i-th iterable argument.  "
                    + "The .next()\nmethod continues until the shortest iterable in the argument sequence\nis exhausted and then it "
                    + "raises StopIteration.  Works like the zip()\nfunction but consumes less memory by returning an iterator "
                    + "instead of\na list.");

    public izip() {
        super();
    }

    public izip(PyType subType) {
        super(subType);
    }

    public izip(PyObject... args) {
        super();
        izip___init__(args);
    }


    /**
     * Create an iterator whose next() method returns a tuple where the i-th element
     * comes from the i-th iterable argument. Continues until the shortest iterable is exhausted.
     * (Code in this method is based on __builtin__.zip()).
     * 
     */
    @ExposedNew
    @ExposedMethod
    final void izip___init__(PyObject[] args, String[] kwds) {
        if (kwds.length > 0) {
            throw Py.TypeError(String.format("izip does not take keyword arguments"));
        }
        izip___init__(args);
    }

    private void izip___init__(final PyObject[] argstar) {

        final int itemsize = argstar.length;
        
        if (itemsize == 0) {
            iter = (PyIterator)(new PyXRange(0).__iter__());
            return;
        }

        // Type check the arguments; they must be sequences.
        final PyObject[] iters = new PyObject[itemsize];

        for (int i = 0; i < itemsize; i++) {
            PyObject iter = argstar[i].__iter__();
            if (iter == null) {
                throw Py.TypeError("izip argument #" + (i + 1)
                        + " must support iteration");
            }
            iters[i] = iter;
        }

        iter = new itertools.ItertoolsIterator() {

            public PyObject __iternext__() {
                if (itemsize == 0)
                    return null;

                PyObject[] next = new PyObject[itemsize];
                PyObject item;

                for (int i = 0; i < itemsize; i++) {

                    item = nextElement(iters[i]);

                    if (item == null) {
                        return null;
                    }
                    next[i] = item;
                }
                return new PyTuple(next);
            }

        };

    }

    public PyObject __iternext__() {
        return iter.__iternext__();
    }

    @ExposedMethod
    @Override
    public PyObject next() {
        return doNext(__iternext__());
    }
}