/*
 * 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.
 */
package org.apache.flink.agents.plan;

import pemja.core.PythonInterpreter;

import java.util.Objects;

/** Represent a Python function. */
public class PythonFunction implements Function {
    private static final String CALL_PYTHON_FUNCTION = "function.call_python_function";

    private final String module;
    private final String qualName;

    private transient PythonInterpreter interpreter;

    public PythonFunction(String module, String qualName) {
        this.module = module;
        this.qualName = qualName;
    }

    public void setInterpreter(PythonInterpreter interpreter) {
        this.interpreter = interpreter;
    }

    @Override
    public Object call(Object... args) throws Exception {
        if (interpreter == null) {
            throw new IllegalStateException(
                    "PythonFunction requires the Python interpreter; not set on this "
                            + "descriptor. The runtime injects it via setInterpreter before "
                            + "invocation.");
        }

        return interpreter.invoke(CALL_PYTHON_FUNCTION, module, qualName, args);
    }

    @Override
    public void checkSignature(Class<?>[] parameterTypes) throws Exception {
        // No-op: descriptor carries no parameter types, and the Python module
        // cannot be inspected without an interpreter. Mismatches surface at
        // dispatch time.
    }

    public String getModule() {
        return module;
    }

    public String getQualName() {
        return qualName;
    }

    @Override
    public boolean equals(Object o) {
        if (this == o) return true;
        if (o == null || getClass() != o.getClass()) return false;
        PythonFunction other = (PythonFunction) o;
        return Objects.equals(this.module, other.module)
                && Objects.equals(this.qualName, other.qualName);
    }

    @Override
    public int hashCode() {
        return Objects.hash(module, qualName);
    }
}
