package lz4stream

import (
	
	
	
	

	
	
	
)

type Blocks struct {
	Block  *FrameDataBlock
	Blocks chan chan *FrameDataBlock
	mu     sync.Mutex
	err    error
}

func ( *Blocks) ( *Frame,  io.Writer,  int) {
	if  == 1 {
		.Blocks = nil
		.Block = NewFrameDataBlock()
		return
	}
	.Block = nil
	if cap(.Blocks) !=  {
		.Blocks = make(chan chan *FrameDataBlock, )
	}
	// goroutine managing concurrent block compression goroutines.
	go func() {
		// Process next block compression item.
		for  := range .Blocks {
			// Read the next compressed block result.
			// Waiting here ensures that the blocks are output in the order they were sent.
			// The incoming channel is always closed as it indicates to the caller that
			// the block has been processed.
			 := <-
			if  == nil {
				// Notify the block compression routine that we are done with its result.
				// This is used when a sentinel block is sent to terminate the compression.
				close()
				return
			}
			// Do not attempt to write the block upon any previous failure.
			if .err == nil {
				// Write the block.
				if  := .Write(, );  != nil {
					// Keep the first error.
					.err = 
					// All pending compression goroutines need to shut down, so we need to keep going.
				}
			}
			close()
		}
	}()
}

func ( *Blocks) ( *Frame,  int) error {
	if  == 1 {
		if .Block != nil {
			.Block.Close()
		}
		 := .err
		.err = nil
		return 
	}
	if .Blocks == nil {
		 := .err
		.err = nil
		return 
	}
	 := make(chan *FrameDataBlock)
	.Blocks <- 
	 <- nil
	<-
	 := .err
	.err = nil
	return 
}

// ErrorR returns any error set while uncompressing a stream.
func ( *Blocks) () error {
	.mu.Lock()
	defer .mu.Unlock()
	return .err
}

// initR returns a channel that streams the uncompressed blocks if in concurrent
// mode and no error. When the channel is closed, check for any error with b.ErrorR.
//
// If not in concurrent mode, the uncompressed block is b.Block and the returned error
// needs to be checked.
func ( *Blocks) ( *Frame,  int,  io.Reader) (chan []byte, error) {
	 := .Descriptor.Flags.BlockSizeIndex()
	if  == 1 {
		.Blocks = nil
		.Block = NewFrameDataBlock()
		return nil, nil
	}
	.Block = nil
	 := make(chan chan []byte, )
	// data receives the uncompressed blocks.
	 := make(chan []byte)
	// Read blocks from the source sequentially
	// and uncompress them concurrently.

	// In legacy mode, accrue the uncompress sizes in cum.
	var  uint32
	go func() {
		var  uint32
		var  error
		for .ErrorR() == nil {
			 := NewFrameDataBlock()
			,  = .Read(, , 0)
			if  != nil {
				.Close()
				break
			}
			// Recheck for an error as reading may be slow and uncompressing is expensive.
			if .ErrorR() != nil {
				.Close()
				break
			}
			 := make(chan []byte)
			 <- 
			go func() {
				defer .Close()
				,  := .Uncompress(, .Get(), nil, false)
				if  != nil {
					.closeR()
					// Close the block channel to indicate an error.
					close()
				} else {
					 <- 
				}
			}()
		}
		// End the collection loop and the data channel.
		 := make(chan []byte)
		 <- 
		 <- nil // signal the collection loop that we are done
		<-      // wait for the collect loop to complete
		if .isLegacy() &&  ==  {
			 = io.EOF
		}
		.closeR()
		close()
	}()
	// Collect the uncompressed blocks and make them available
	// on the returned channel.
	go func( bool) {
		defer close()
		 := false
		for  := range  {
			,  := <-
			if ! {
				// A closed channel indicates an error.
				// All remaining channels should be discarded.
				 = true
				continue
			}
			if  == nil {
				// Signal to end the loop.
				close()
				return
			}
			if  {
				// A previous error has occurred, skipping remaining channels.
				continue
			}
			// Perform checksum now as the blocks are received in order.
			if .Descriptor.Flags.ContentChecksum() {
				_, _ = .checksum.Write()
			}
			if  {
				 += uint32(len())
			}
			 <- 
			close()
		}
	}(.isLegacy())
	return , nil
}

// closeR safely sets the error on b if not already set.
func ( *Blocks) ( error) {
	.mu.Lock()
	if .err == nil {
		.err = 
	}
	.mu.Unlock()
}

func ( *Frame) *FrameDataBlock {
	 := .Descriptor.Flags.BlockSizeIndex().Get()
	return &FrameDataBlock{Data: , data: }
}

type FrameDataBlock struct {
	Size     DataBlockSize
	Data     []byte // compressed or uncompressed data (.data or .src)
	Checksum uint32
	data     []byte // buffer for compressed data
	src      []byte // uncompressed data
	err      error  // used in concurrent mode
}

func ( *FrameDataBlock) ( *Frame) {
	.Size = 0
	.Checksum = 0
	.err = nil
	if .data != nil {
		// Block was not already closed.
		lz4block.Put(.data)
		.Data = nil
		.data = nil
		.src = nil
	}
}

// Block compression errors are ignored since the buffer is sized appropriately.
func ( *FrameDataBlock) ( *Frame,  []byte,  lz4block.CompressionLevel) *FrameDataBlock {
	 := .data
	if .isLegacy() {
		 = [:cap()]
	} else {
		 = [:len()] // trigger the incompressible flag in CompressBlock
	}
	var  int
	switch  {
	case lz4block.Fast:
		, _ = lz4block.CompressBlock(, )
	default:
		, _ = lz4block.CompressBlockHC(, , )
	}
	if  == 0 {
		.Size.UncompressedSet(true)
		.Data = 
	} else {
		.Size.UncompressedSet(false)
		.Data = [:]
	}
	.Size.sizeSet(len(.Data))
	.src =  // keep track of the source for content checksum

	if .Descriptor.Flags.BlockChecksum() {
		.Checksum = xxh32.ChecksumZero(.Data)
	}
	return 
}

func ( *FrameDataBlock) ( *Frame,  io.Writer) error {
	// Write is called in the same order as blocks are compressed,
	// so content checksum must be done here.
	if .Descriptor.Flags.ContentChecksum() {
		_, _ = .checksum.Write(.src)
	}
	 := .buf[:]
	binary.LittleEndian.PutUint32(, uint32(.Size))
	if ,  := .Write([:4]);  != nil {
		return 
	}

	if ,  := .Write(.Data);  != nil {
		return 
	}

	if .Checksum == 0 {
		return nil
	}
	binary.LittleEndian.PutUint32(, .Checksum)
	,  := .Write([:4])
	return 
}

// Read updates b with the next block data, size and checksum if available.
func ( *FrameDataBlock) ( *Frame,  io.Reader,  uint32) (uint32, error) {
	,  := .readUint32()
	if  != nil {
		return 0, 
	}
	if .isLegacy() {
		switch  {
		case frameMagicLegacy:
			// Concatenated legacy frame.
			return .(, , )
		case :
			// Only works in non concurrent mode, for concurrent mode
			// it is handled separately.
			// Linux kernel format appends the total uncompressed size at the end.
			return 0, io.EOF
		}
	} else if  == 0 {
		// Marker for end of stream.
		return 0, io.EOF
	}
	.Size = DataBlockSize()

	 := .Size.size()
	if  > cap(.data) {
		return , lz4errors.ErrOptionInvalidBlockSize
	}
	.data = .data[:]
	if ,  := io.ReadFull(, .data);  != nil {
		return , 
	}
	if .Descriptor.Flags.BlockChecksum() {
		,  := .readUint32()
		if  != nil {
			return 0, 
		}
		.Checksum = 
	}
	return , nil
}

func ( *FrameDataBlock) ( *Frame, ,  []byte,  bool) ([]byte, error) {
	if .Size.Uncompressed() {
		 := copy(, .data)
		 = [:]
	} else {
		,  := lz4block.UncompressBlock(.data, , )
		if  != nil {
			return nil, 
		}
		 = [:]
	}
	if .Descriptor.Flags.BlockChecksum() {
		if  := xxh32.ChecksumZero(.data);  != .Checksum {
			 := fmt.Errorf("%w: got %x; expected %x", lz4errors.ErrInvalidBlockChecksum, , .Checksum)
			return nil, 
		}
	}
	if  && .Descriptor.Flags.ContentChecksum() {
		_, _ = .checksum.Write()
	}
	return , nil
}

func ( *Frame) ( io.Reader) ( uint32,  error) {
	if _,  = io.ReadFull(, .buf[:4]);  != nil {
		return
	}
	 = binary.LittleEndian.Uint32(.buf[:4])
	return
}