// Copyright 2024 Matthew Rich <matthewrich.conf@gmail.com>. All rights reserved.

package transport

import (
_	"errors"
_	"fmt"
_	"net/url"
_	"net/http"
_	"strings"
_	"path/filepath"
	"io"
_	"os"
_	"context"
)

type ReadFilter func([]byte, int, error) (int, error)

var ReadBufferSize int = 32 * 1024

type readerFrom struct {
	io.Writer
	filter ReadFilter
}

func (w readerFrom) ReadFrom(r io.Reader) (n int64, err error) {
	readBuffer := make([]byte, ReadBufferSize)
	for {
		var readBytes int
		if readBytes, err = r.Read(readBuffer); readBytes > 0 {
			if w.filter != nil {
				readBytes, err = w.filter(readBuffer, readBytes, err)
			}
			writeBytes, writeErr := w.Write(readBuffer[0:readBytes])
			if writeBytes > 0 {
				n += int64(writeBytes)
			}
			if readBytes != writeBytes {
				writeErr = io.ErrShortWrite
			}
			if writeErr != nil {
				break
			}
		}
		if err != nil {
			if err == io.EOF {
				err = nil
			}
			break
		}
	}
	return
}

func NewReaderFrom(w io.Writer, filter ReadFilter) io.ReaderFrom {
	return readerFrom{ Writer: w, filter: filter}
}