/*
 * Copyright (c) 2016, 2020, Oracle and/or its affiliates.
 *
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without modification, are
 * permitted provided that the following conditions are met:
 *
 * 1. Redistributions of source code must retain the above copyright notice, this list of
 * conditions and the following disclaimer.
 *
 * 2. Redistributions in binary form must reproduce the above copyright notice, this list of
 * conditions and the following disclaimer in the documentation and/or other materials provided
 * with the distribution.
 *
 * 3. Neither the name of the copyright holder nor the names of its contributors may be used to
 * endorse or promote products derived from this software without specific prior written
 * permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS
 * OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
 * COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE
 * GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
 * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
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 */
package com.oracle.truffle.llvm.runtime;

import com.oracle.truffle.api.TruffleFile;
import com.oracle.truffle.api.TruffleLanguage.Registration;
import java.io.IOException;
import java.io.InputStream;
import java.nio.ByteBuffer;
import java.nio.ByteOrder;
import java.nio.charset.Charset;
import java.nio.file.StandardOpenOption;

Used by Truffle to determine the mime-type of input files. Registered by Registration.fileTypeDetectors(). /**
 * Used by Truffle to determine the mime-type of input files. Registered by
 * {@link Registration#fileTypeDetectors()}.
 */
public class LLVMFileDetector implements TruffleFile.FileTypeDetector {

    @Override
    public String findMimeType(TruffleFile file) throws IOException {
        long magicWord = readMagicWord(file);
        return Magic.get(magicWord).mimeType;
    }

    @Override
    public Charset findEncoding(TruffleFile file) throws IOException {
        return null;
    }

    private static long readMagicWord(TruffleFile file) {
        try (InputStream is = file.newInputStream(StandardOpenOption.READ)) {
            byte[] buffer = new byte[4];
            if (is.read(buffer) != buffer.length) {
                return 0;
            }
            return Integer.toUnsignedLong(ByteBuffer.wrap(buffer).order(ByteOrder.nativeOrder()).getInt());
        } catch (IOException | SecurityException e) {
            return 0;
        }
    }
}