http-progress.go

/*
 * Copyright (c) 2019. Abstrium SAS <team (at) pydio.com>
 * This file is part of Pydio Cells.
 *
 * Pydio Cells is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Affero General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * Pydio Cells is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU Affero General Public License for more details.
 *
 * You should have received a copy of the GNU Affero General Public License
 * along with Pydio Cells.  If not, see <http://www.gnu.org/licenses/>.
 *
 * The latest code can be found at <https://pydio.com>.
 */

package net

import (
	"io"
	"math"
	"net/http"
)

// ProgressMonitor provides a TeeReader to wrap a reader and send a progress inside a dedicated channel
type ProgressMonitor struct {
	expectedSize uint64
	currentSize  uint64
	currentPg    float64
	progressChan chan float64
	doneChan     chan bool
	SizeChan     chan uint64
}

// BodyWithProgressMonitor creates a ProgressMonitor directly from an http.Response
func BodyWithProgressMonitor(resp *http.Response, progress chan float64, done chan bool) io.Reader {
	expected := uint64(0)
	if resp.ContentLength > 0 {
		expected = uint64(resp.ContentLength)
	}
	return io.TeeReader(resp.Body, NewProgressMonitor(expected, progress, done))
}

// NewProgressMonitor initialize a ProgressMonitor with the channels
func NewProgressMonitor(expected uint64, progress chan float64, done chan bool) *ProgressMonitor {
	m := &ProgressMonitor{
		expectedSize: expected,
		progressChan: progress,
		doneChan:     done,
	}
	return m
}

// Write implements the io.Writer interface to be used by a TeeReader
func (m *ProgressMonitor) Write(p []byte) (int, error) {
	n := len(p)
	m.currentSize += uint64(n)
	if m.progressChan != nil && m.expectedSize > 0 {
		progress100 := math.Floor(100 * float64(m.currentSize) / float64(m.expectedSize))
		if progress100 != m.currentPg {
			m.progressChan <- float64(m.currentSize) / float64(m.expectedSize)
		}
		m.currentPg = progress100
	}
	if m.SizeChan != nil {
		m.SizeChan <- m.currentSize
	}
	if m.doneChan != nil && m.expectedSize > 0 && m.currentSize == m.expectedSize {
		m.doneChan <- true
	}
	return n, nil
}