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 * (a) the Software, and
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 * (b) any piece of software and/or hardware listed in the lrgrwrks.txt file if
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 * Software and the Larger Work(s), and to sublicense the foregoing rights on
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package com.oracle.graal.python.builtins.objects.cext.capi;

import java.nio.ByteBuffer;
import java.nio.ByteOrder;

import com.oracle.graal.python.builtins.objects.bytes.PBytes;
import com.oracle.graal.python.builtins.objects.str.PString;
import com.oracle.graal.python.builtins.objects.str.StringNodes.StringMaterializeNode;
import com.oracle.graal.python.runtime.object.PythonObjectFactory;
import com.oracle.truffle.api.CompilerDirectives.TruffleBoundary;
import com.oracle.truffle.api.dsl.Cached;
import com.oracle.truffle.api.dsl.Cached.Shared;
import com.oracle.truffle.api.dsl.GenerateUncached;
import com.oracle.truffle.api.dsl.Specialization;
import com.oracle.truffle.api.nodes.Node;
import com.oracle.truffle.api.strings.TruffleString;

public abstract class UnicodeObjectNodes {

    @GenerateUncached
    public abstract static class UnicodeAsWideCharNode extends Node {

        public final PBytes executeNativeOrder(Object obj, long elementSize) {
            return execute(obj, elementSize, ByteOrder.nativeOrder());
        }

        public final PBytes executeLittleEndian(Object obj, long elementSize) {
            return execute(obj, elementSize, ByteOrder.LITTLE_ENDIAN);
        }

        public final PBytes executeBigEndian(Object obj, long elementSize) {
            return execute(obj, elementSize, ByteOrder.BIG_ENDIAN);
        }

        public abstract PBytes execute(Object obj, long elementSize, ByteOrder byteOrder);

        @Specialization
        static PBytes doUnicode(PString s, long elementSize, ByteOrder byteOrder,
                        @Cached StringMaterializeNode materializeNode,
                        @Cached TruffleString.SwitchEncodingNode switchEncodingNode,
                        @Cached TruffleString.CopyToByteArrayNode copyToByteArrayNode,
                        @Shared("factory") @Cached PythonObjectFactory factory) {
            return doUnicode(materializeNode.execute(s), elementSize, byteOrder, switchEncodingNode, copyToByteArrayNode, factory);
        }

        @Specialization
        @TruffleBoundary
        static PBytes doUnicode(TruffleString s, long elementSize, ByteOrder byteOrder,
                        @Cached TruffleString.SwitchEncodingNode switchEncodingNode,
                        @Cached TruffleString.CopyToByteArrayNode copyToByteArrayNode,
                        @Shared("factory") @Cached PythonObjectFactory factory) {
            TruffleString.Encoding encoding = byteOrder == ByteOrder.LITTLE_ENDIAN ? TruffleString.Encoding.UTF_32LE : TruffleString.Encoding.UTF_32BE;

            // elementSize == 2: Store String in 'wchar_t' of size == 2, i.e., use UCS2. This is
            // achieved by decoding to UTF32 (which is basically UCS4) and ignoring the two
            // MSBs.
            if (elementSize == 2L) {
                ByteBuffer bytes = ByteBuffer.wrap(getBytes(s, switchEncodingNode, copyToByteArrayNode, encoding));
                // FIXME unsafe narrowing
                int size = bytes.remaining() / 2;
                ByteBuffer buf = ByteBuffer.allocate(size);
                while (bytes.remaining() >= 4) {
                    if (byteOrder != ByteOrder.nativeOrder()) {
                        buf.putChar((char) ((bytes.getInt() & 0xFFFF0000) >> 16));
                    } else {
                        buf.putChar((char) (bytes.getInt() & 0x0000FFFF));
                    }
                }
                buf.flip();
                byte[] barr = new byte[buf.remaining()];
                buf.get(barr);
                return factory.createBytes(barr);
            } else if (elementSize == 4L) {
                return factory.createBytes(getBytes(s, switchEncodingNode, copyToByteArrayNode, encoding));
            } else {
                throw new RuntimeException("unsupported wchar size; was: " + elementSize);
            }
        }

        private static byte[] getBytes(TruffleString s, TruffleString.SwitchEncodingNode switchEncodingNode, TruffleString.CopyToByteArrayNode copyToByteArrayNode, TruffleString.Encoding encoding) {
            TruffleString utf32String = switchEncodingNode.execute(s, encoding);
            int len = utf32String.byteLength(encoding);
            byte[] b = new byte[len];
            copyToByteArrayNode.execute(utf32String, 0, b, 0, len, encoding);
            return b;
        }
    }
}
