// Package ioutil contains various constructs for io operations
package ioutil

import (
	//"fmt"
	"io"
)

// An function alias type that implements io.Writer
type WriterFunc func([]byte) (int, error)

// Delegates the call to the WriterFunc while implementing io.Writer

}

// Returns a reader that will delegate calls to Read(...) while ensuring
// that the output buffer will never be smaller than the required size
func MinReader(reader io.Reader, size int) io.Reader {
	var buffer []byte = make([]byte, 0, size)

	return ReaderFunc(func(output []byte) (readCount int, e error) {
	return ReaderFunc(func(output []byte) (int, error) {
		var (
			bufferLength int = len(buffer)
			err          error
			readCount int
			err       error
		)
	start:
		//fmt.Println("Requesting read with length ", len(output), "buffer's length is ", len(buffer))

		// Reply with the buffered data if there is any
		if bufferLength > 0 {
		if len(buffer) > 0 {
			readCount = copy(output, buffer)

			if readCount < bufferLength {
				// Advance the data in the buffer
				buffer = buffer[:copy(buffer, buffer[readCount:])]
			} else {
				// Clear the buffer
				buffer = buffer[:0]
			// Advance the data in the buffer
			buffer = buffer[:copy(buffer, buffer[readCount:])]

			//fmt.Println("After buffer read - buffer lenght is", len(buffer))

			if len(buffer) == 0 {
				return readCount, err
			}
			// Stage any error for returning
			e, err = err, nil
			return readCount, e

			// Do not propagate an error until the buffer is exhausted
			return readCount, nil
		}

		// Delegate if the buffer is empty and the destination buffer is large enough
		if len(output) >= size {
			//fmt.Println("Delegating read for output length ", len(output), " and size ", size)
			return reader.Read(output[:len(output)/size])
			return reader.Read(output[:(len(output)/size)*size])
		}

		// Extend the buffer up to the desired size and perform a Read
		buffer = buffer[:size]
		readCount, err = reader.Read(buffer)
		// Perform a read into the buffer
		readCount, err = reader.Read(buffer[:size])

		// Size the buffer down to the read data size and restart
		buffer = buffer[:readCount]
		bufferLength = len(buffer)

		//fmt.Println("Read into buffer: ", len(buffer), "bytes")

		if bufferLength > 0 {
		if len(buffer) > 0 {
			goto start
		}
		// Stage any error for returning
		e, err = err, nil
		return 0, e
		return 0, err
	})
}