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package com.oracle.graal.python.builtins.modules.io;

import static com.oracle.graal.python.builtins.PythonBuiltinClassType.BlockingIOError;
import static com.oracle.graal.python.builtins.modules.io.BufferedIOUtil.SEEK_CUR;
import static com.oracle.graal.python.builtins.modules.io.BufferedIOUtil.isValidReadBuffer;
import static com.oracle.graal.python.builtins.modules.io.BufferedIOUtil.isValidWriteBuffer;
import static com.oracle.graal.python.builtins.modules.io.BufferedIOUtil.rawOffset;
import static com.oracle.graal.python.builtins.modules.io.IONodes.WRITE;
import static com.oracle.graal.python.nodes.ErrorMessages.IO_S_INVALID_LENGTH;
import static com.oracle.graal.python.nodes.ErrorMessages.WRITE_COULD_NOT_COMPLETE_WITHOUT_BLOCKING;
import static com.oracle.graal.python.runtime.exception.PythonErrorType.OSError;
import static com.oracle.graal.python.runtime.exception.PythonErrorType.ValueError;

import com.oracle.graal.python.builtins.objects.PNone;
import com.oracle.graal.python.builtins.objects.buffer.PythonBufferAccessLibrary;
import com.oracle.graal.python.builtins.objects.bytes.PBytes;
import com.oracle.graal.python.lib.PyNumberAsSizeNode;
import com.oracle.graal.python.lib.PyObjectCallMethodObjArgs;
import com.oracle.graal.python.nodes.PNodeWithRaise;
import com.oracle.graal.python.nodes.object.IsBuiltinClassProfile;
import com.oracle.graal.python.runtime.exception.PException;
import com.oracle.graal.python.runtime.object.PythonObjectFactory;
import com.oracle.graal.python.util.PythonUtils;
import com.oracle.truffle.api.dsl.Cached;
import com.oracle.truffle.api.dsl.Specialization;
import com.oracle.truffle.api.frame.VirtualFrame;
import com.oracle.truffle.api.library.CachedLibrary;

public class BufferedWriterNodes {

    private static void adjustPosition(PBuffered self, int newPos) {
        self.setPos(newPos);
        if (isValidReadBuffer(self) && self.getReadEnd() < newPos) {
            self.setReadEnd(newPos);
        }
    }

    abstract static class WriteNode extends PNodeWithRaise {

        public abstract int execute(VirtualFrame frame, PBuffered self, Object buffer);

        /**
         * implementation of cpython/Modules/_io/bufferedio.c:_io_BufferedWriter_write_impl
         */
        @Specialization
        static int bufferedWriterWrite(VirtualFrame frame, PBuffered self, Object buffer,
                        @CachedLibrary(limit = "3") PythonBufferAccessLibrary bufferLib,
                        @Cached AbstractBufferedIOBuiltins.RaiseBlockingIOError raiseBlockingIOError,
                        @Cached IsBuiltinClassProfile isBuiltinClassProfile,
                        @Cached BufferedIONodes.RawSeekNode rawSeekNode,
                        @Cached RawWriteNode rawWriteNode,
                        @Cached FlushUnlockedNode flushUnlockedNode) {
            final int bufLen = bufferLib.getBufferLength(buffer);

            // TODO: check ENTER_BUFFERED(self)

            /* Fast path: the data to write can be fully buffered. */
            if (!isValidReadBuffer(self) && !isValidWriteBuffer(self)) {
                self.setPos(0);
                self.setRawPos(0);
            }
            int avail = self.getBufferSize() - self.getPos();
            if (bufLen <= avail) {
                // memcpy(self->buffer + self.getPos(), buffer, buffer.length);
                bufferLib.readIntoByteArray(buffer, 0, self.getBuffer(), self.getPos(), bufLen);
                if (!isValidWriteBuffer(self) || self.getWritePos() > self.getPos()) {
                    self.setWritePos(self.getPos());
                }
                adjustPosition(self, self.getPos() + bufLen);
                if (self.getPos() > self.getWriteEnd()) {
                    self.setWriteEnd(self.getPos());
                }
                return bufLen;
            }

            /* First write the current buffer */
            try {
                flushUnlockedNode.execute(frame, self);
            } catch (PException e) {
                e.expect(BlockingIOError, isBuiltinClassProfile);
                if (self.isReadable()) {
                    self.resetRead();
                }
                /* Make some place by shifting the buffer. */
                assert isValidWriteBuffer(self);
                int n = self.getWriteEnd() - self.getWritePos();
                byte[] from = PythonUtils.arrayCopyOfRange(self.getBuffer(), self.getWritePos(), self.getWritePos() + n);
                PythonUtils.arraycopy(from, 0, self.getBuffer(), 0, n);
                self.setWriteEnd(n);
                self.setRawPos(self.getRawPos() - self.getWritePos());
                self.setPos(self.getPos() - self.getWritePos());
                self.setWritePos(0);
                avail = self.getBufferSize() - self.getWriteEnd();
                if (bufLen <= avail) {
                    /* Everything can be buffered */
                    bufferLib.readIntoByteArray(buffer, 0, self.getBuffer(), self.getWriteEnd(), bufLen);
                    self.incWriteEnd(bufLen);
                    self.incPos(bufLen);
                    return bufLen;
                }
                bufferLib.readIntoByteArray(buffer, 0, self.getBuffer(), self.getWriteEnd(), avail);
                self.incWriteEnd(avail);
                self.incPos(avail);
                /*
                 * XXX Modifying the existing exception e using the pointer w will change
                 * e.characters_written but not e.args[2]. Therefore we just replace with a new
                 * error.
                 */
                Object errno = e.getUnreifiedException().getArgs().getSequenceStorage().getItemNormalized(0);
                throw raiseBlockingIOError.raise(errno, WRITE_COULD_NOT_COMPLETE_WITHOUT_BLOCKING, avail);
            }
            /*
             * Adjust the raw stream position if it is away from the logical stream position. This
             * happens if the read buffer has been filled but not modified (and therefore
             * _bufferedwriter_flush_unlocked() didn't rewind the raw stream by itself). Fixes issue
             * #6629.
             */
            long offset = rawOffset(self);
            if (offset != 0) {
                rawSeekNode.execute(frame, self, -offset, 1);
                self.setRawPos(self.getRawPos() - offset);
            }

            /* Then write buf itself. At this point the buffer has been emptied. */
            int remaining = bufLen;
            int written = 0;
            while (remaining > self.getBufferSize()) {
                // TODO use memoryview
                byte[] buf = new byte[bufLen];
                bufferLib.readIntoByteArray(buffer, written, buf, 0, bufLen - written);
                int n = rawWriteNode.execute(frame, self, buf, bufLen - written);
                if (n == -2) {
                    if (remaining > self.getBufferSize()) {
                        bufferLib.readIntoByteArray(buffer, written, self.getBuffer(), 0, self.getBufferSize());
                        self.setRawPos(0);
                        adjustPosition(self, self.getBufferSize());
                        self.setWriteEnd(self.getBufferSize());
                        written += self.getBufferSize();
                        throw raiseBlockingIOError.raiseEWOULDBLOCK(WRITE_COULD_NOT_COMPLETE_WITHOUT_BLOCKING, written);
                    }
                    break;
                }
                written += n;
                remaining -= n;
            }
            if (self.isReadable()) {
                self.resetRead(); // _bufferedreader_reset_buf
            }
            if (remaining > 0) {
                // memcpy(self->buffer, buffer + written, remaining);
                bufferLib.readIntoByteArray(buffer, written, self.getBuffer(), 0, remaining);
                written += remaining;
            }
            self.setWritePos(0);
            /* TODO: sanity check (remaining >= 0) */
            self.setWriteEnd(remaining);
            adjustPosition(self, remaining);
            self.setRawPos(0);

            // TODO: LEAVE_BUFFERED(self)
            return written;
        }
    }

    abstract static class RawWriteNode extends PNodeWithRaise {

        public abstract int execute(VirtualFrame frame, PBuffered self, byte[] buf, int len);

        /**
         * implementation of cpython/Modules/_io/bufferedio.c:_bufferedwriter_raw_write
         */
        @Specialization
        int bufferedwriterRawWrite(VirtualFrame frame, PBuffered self, byte[] buf, int len,
                        @Cached PythonObjectFactory factory,
                        @Cached PyObjectCallMethodObjArgs callMethod,
                        @Cached PyNumberAsSizeNode asSizeNode) {
            PBytes memobj = factory.createBytes(buf, len);
            Object res = callMethod.execute(frame, self.getRaw(), WRITE, memobj);
            if (res == PNone.NONE) {
                /*
                 * Non-blocking stream would have blocked. Special return code!
                 */
                return -2;
            }
            int n = asSizeNode.executeExact(frame, res, ValueError);
            if (n < 0 || n > len) {
                throw raise(OSError, IO_S_INVALID_LENGTH, "write()", n, len);
            }
            if (n > 0 && self.getAbsPos() != -1) {
                self.incAbsPos(n);
            }
            return n;
        }
    }

    abstract static class FlushUnlockedNode extends PNodeWithRaise {

        public abstract void execute(VirtualFrame frame, PBuffered self);

        /**
         * implementation of cpython/Modules/_io/bufferedio.c:_bufferedwriter_flush_unlocked
         */
        @Specialization
        protected static void bufferedwriterFlushUnlocked(VirtualFrame frame, PBuffered self,
                        @Cached AbstractBufferedIOBuiltins.RaiseBlockingIOError raiseBlockingIOError,
                        @Cached RawWriteNode rawWriteNode,
                        @Cached BufferedIONodes.RawSeekNode rawSeekNode) {
            if (!isValidWriteBuffer(self) || self.getWritePos() == self.getWriteEnd()) {
                self.resetWrite(); // _bufferedwriter_reset_buf
                return;
            }
            /* First, rewind */
            long rewind = rawOffset(self) + (self.getPos() - self.getWritePos());
            if (rewind != 0) {
                rawSeekNode.execute(frame, self, -rewind, SEEK_CUR);
                self.incRawPos(-rewind);
            }
            while (self.getWritePos() < self.getWriteEnd()) {
                byte[] buf = PythonUtils.arrayCopyOfRange(self.getBuffer(), self.getWritePos(), self.getWriteEnd());
                int n = rawWriteNode.execute(frame, self, buf, buf.length);
                if (n == -2) {
                    throw raiseBlockingIOError.raiseEAGAIN(WRITE_COULD_NOT_COMPLETE_WITHOUT_BLOCKING, 0);
                }
                self.incWritePos(n);
                self.setRawPos(self.getWritePos());
                /*- Partial writes can return successfully when interrupted by a
                   signal (see write(2)).  We must run signal handlers before
                   blocking another time, possibly indefinitely. */
                /*-
                (mq) Singles will be thrown elsewhere,
                 so we might not need to check it. 
                 Though, mutil-threading might require it.
                if (PyErr_CheckSignals() < 0)
                    return null;
                */
            }

            /*- 
               This ensures that after return from this function,
               VALID_WRITE_BUFFER(self) returns false.
            
               This is a required condition because when a tell() is called
               after flushing and if VALID_READ_BUFFER(self) is false, we need
               VALID_WRITE_BUFFER(self) to be false to have
               RAW_OFFSET(self) == 0.
            
               Issue: https://bugs.python.org/issue32228 
            */
            self.resetWrite(); // _bufferedwriter_reset_buf
        }

    }
}
