/*
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 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * The Universal Permissive License (UPL), Version 1.0
 *
 * Subject to the condition set forth below, permission is hereby granted to any
 * person obtaining a copy of this software, associated documentation and/or
 * data (collectively the "Software"), free of charge and under any and all
 * copyright rights in the Software, and any and all patent rights owned or
 * freely licensable by each licensor hereunder covering either (i) the
 * unmodified Software as contributed to or provided by such licensor, or (ii)
 * the Larger Works (as defined below), to deal in both
 *
 * (a) the Software, and
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 * (b) any piece of software and/or hardware listed in the lrgrwrks.txt file if
 * one is included with the Software each a "Larger Work" to which the Software
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 * without restriction, including without limitation the rights to copy, create
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 * Software and the Larger Work(s), and to sublicense the foregoing rights on
 * either these or other terms.
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 * This license is subject to the following condition:
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package com.oracle.truffle.js.parser;

import java.nio.ByteBuffer;

import com.oracle.truffle.api.source.Source;
import com.oracle.truffle.js.codec.BinaryDecoder;
import com.oracle.truffle.js.codec.NodeDecoder;
import com.oracle.truffle.js.nodes.JSNodeDecoder;
import com.oracle.truffle.js.nodes.NodeFactory;
import com.oracle.truffle.js.runtime.JSContext;

public class BinarySnapshotProvider implements SnapshotProvider {
    public static final int MAGIC = 0x314e4942;
    private final ByteBuffer buffer;

    public BinarySnapshotProvider(ByteBuffer buffer) {
        this.buffer = buffer;
        assert checkFormat(new BinaryDecoder(buffer));
    }

    private static boolean checkFormat(BinaryDecoder decoder) {
        int magic = decoder.getInt32();
        if (magic != MAGIC) {
            throw new IllegalArgumentException("Unknown format");
        }
        int checksum = decoder.getInt32();
        if (checksum != JSNodeDecoder.getChecksum()) {
            throw new IllegalArgumentException("Snapshot verification failed");
        }
        return true;
    }

    public BinarySnapshotProvider(byte[] bytes) {
        this(ByteBuffer.wrap(bytes));
    }

    @Override
    public Object apply(NodeFactory nodeFactory, JSContext context, Source source) {
        BinaryDecoder decoder = new BinaryDecoder(buffer);
        checkFormat(decoder);
        int sourceLength = decoder.getInt32();
        int sourceHash = decoder.getInt32();
        CharSequence code = source.getCharacters();
        if (code.length() != sourceLength || code.hashCode() != sourceHash) {
            throw new IllegalArgumentException("Snapshot verification failed");
        }
        return new JSNodeDecoder().decodeNode(new NodeDecoder.DecoderState(decoder), nodeFactory, context, source);
    }
}