/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *   http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 * KIND, either express or implied.  See the License for the
 * specific language governing permissions and limitations
 * under the License.
 */

/* $Rev$ $Date$ */

#ifndef tuscany_modpython_hpp
#define tuscany_modpython_hpp

/**
 * Evaluation functions used by mod-eval to evaluate Python
 * component implementations.
 */

#include "string.hpp"
#include "stream.hpp"
#include "function.hpp"
#include "list.hpp"
#include "value.hpp"
#include "monad.hpp"
#include "eval.hpp"

namespace tuscany {
namespace server {
namespace modpython {

/**
 * Apply a Python component implementation function.
 */
struct applyImplementation {
    PyObject* impl;
    const list<value> px;
    python::PythonRuntime& py;
    applyImplementation(PyObject* impl, const list<value>& px, python::PythonRuntime& py) : impl(impl), px(px), py(py) {
    }
    const value operator()(const list<value>& params) const {
        const value expr = append<value>(params, px);
        debug(expr, "modeval::python::applyImplementation::input");
        const failable<value> res = python::evalScript(expr, impl, py);
        const value val = !hasContent(res)? mklist<value>(value(), reason(res), rcode(res)) : mklist<value>(content(res));
        debug(val, "modeval::python::applyImplementation::result");
        return val;
    }
};

/**
 * Evaluate a Python component implementation and convert it to an applicable
 * lambda function.
 */
const failable<lambda<value(const list<value>&)> > evalImplementation(const string& path, const value& impl, const list<value>& px, python::PythonRuntime& py) {
    const string spath(attributeValue("script", impl));
    const string fpath(path + spath);
    ifstream is(fpath);
    if (fail(is))
        return mkfailure<lambda<value(const list<value>&)> >(string("Could not read implementation: ") + fpath);
    const failable<PyObject*> script = python::readScript(python::moduleName(spath), fpath, is, py);
    if (!hasContent(script))
        return mkfailure<lambda<value(const list<value>&)> >(script);
    return lambda<value(const list<value>&)>(applyImplementation(content(script), px, py));
}

}
}
}

#endif /* tuscany_modpython_hpp */