package pipe

import "io"

type PipeReader struct {
	last      []byte
	semaphore chan struct{}
	hasWrite  chan struct{}
	closed    bool
	buffer    []byte
	lastWrite int
	capacity  int64
	r         io.ReadCloser
	w         io.WriteCloser
}

func New() *PipeReader {
	r, w := io.Pipe()
	return &PipeReader{
		semaphore: make(chan struct{}, 1),
		hasWrite:  make(chan struct{}),
		buffer:    make([]byte, 64000),
		capacity:  64000,
		last:      nil,
		r:         r,
		w:         w,
	}
}

func (pr *PipeReader) Read(b []byte) (int, error) {
	return pr.r.Read(b)
}

func (pr *PipeReader) Write(b []byte) (int, error) {
	chunks := int(int64(len(b)) / pr.capacity)
	if int64(len(b))%pr.capacity > 0 {
		chunks += 1
	}
	ttl := 0
	for i := 0; i < chunks-1; i++ {
		n, err := pr.w.Write(b[ttl:pr.capacity])
		if err != nil {
			return ttl, err
		}
		ttl += n
	}
	n, err := pr.w.Write(b[ttl:])
	return ttl + n, err
}

func (pr *PipeReader) Close() error {
	return pr.w.Close()
}

func (pr *PipeReader) SetCap(n int64) {
	pr.capacity = n
}

/*

type PipeReader struct {
	last      []byte
	semaphore chan struct{}
	hasWrite  chan struct{}
	closed    bool
	buffer    []byte
	lastWrite int
	capacity  int
}

func New() *PipeReader {
	return &PipeReader{
		semaphore: make(chan struct{}, 1),
		hasWrite:  make(chan struct{}),
		buffer:    make([]byte, 64000),
		capacity:  64000,
		last:      nil,
	}
}

func (pr *PipeReader) SetCap(n int) {
	pr.capacity = n
	pr.buffer = make([]byte, n)
}

func (pr *PipeReader) String() string {
	return fmt.Sprintf("buf=%v, cap=%v, last=%v", len(pr.buffer), pr.capacity, len(pr.last))
}

func (pr *PipeReader) lock() {
	pr.semaphore <- struct{}{}
}

func (pr *PipeReader) unlock() {
	for _ = range pr.semaphore {
		return
	}
}

func (pr *PipeReader) blockUntilWrite() {
	for _ = range pr.hasWrite {
		return
	}
}

func (pr *PipeReader) unblockOnWrite() {
	pr.hasWrite <- struct{}{}
}

func (pr *PipeReader) readCurrentBuffer() []byte {
	pr.blockUntilWrite()
	pr.lock()
	defer pr.unlock()
	ret := pr.buffer[:pr.lastWrite]
	pr.lastWrite = 0
	return ret
}

func (pr *PipeReader) writeBuffer(b []byte) {
	pr.lock()
	defer pr.unblockOnWrite()
	defer pr.unlock()
	copy(pr.buffer[:len(b)], b)
	pr.lastWrite = len(b)
}

func (pr *PipeReader) Read(b []byte) (int, error) {
	logger.Log("READ", len(b), pr.isClosed())
	defer logger.Log("/READ")
	ttl := 0
	m, n, hasMore := xfer(b, pr.last)
	pr.last = m
	ttl = n
	if hasMore {
		return ttl, nil
	}
	for {
		m, n, hasMore := xfer(b[ttl:], pr.readCurrentBuffer())
		logger.Log("XFER", m, n, hasMore, ttl, pr.isClosed())
		pr.last = m
		ttl += n
		if hasMore {
			return ttl, nil
		}
		if n == 0 && pr.isClosed() {
			return ttl, io.EOF
		}
	}
	return ttl, io.EOF
}

func (pr *PipeReader) Write(b []byte) (int, error) {
	logger.Log("WRIT", len(b), pr.isClosed())
	defer logger.Log("/WRIT")
	chunklen := pr.capacity
	wrote := 0
	for wrote+chunklen < len(b) {
		pr.writeBuffer(b[wrote : wrote+chunklen])
		wrote += chunklen
	}
	pr.writeBuffer(b[wrote:])
	return wrote + len(b[wrote:]), nil
}

func (pr *PipeReader) isClosed() bool {
	pr.lock()
	defer pr.unlock()
	return pr.closed
}

func (pr *PipeReader) Close() error {
	pr.lock()
	pr.closed = true
	close(pr.hasWrite)
	pr.unlock()
	return nil
}

func copyByteSlice(b []byte) []byte {
	return append([]byte{}, b...)
}

func xfer(dst, src []byte) ([]byte, int, bool) {
	min := len(dst)
	if len(src) < min {
		min = len(src)
	}
	copy(dst[:min], src[:min])
	src = src[min:]
	if len(src) > 0 {
		return src, min, true
	}
	return src, min, false
}
*/