deluan/bring

package bring

import (
    "bytes"
    "encoding/base64"
    "image"
)

type onEndFunc func(s *stream)

type stream struct {
    buffer *bytes.Buffer
    onEnd  onEndFunc
}

func (s *stream) image() (image.Image, error) {
    dec := base64.NewDecoder(base64.StdEncoding, s.buffer)
    img, _, err := image.Decode(dec)
    return img, err
}

type streams map[int]*stream

func newStreams() streams {
    return make(map[int]*stream)
}

func (ss streams) get(id int) *stream {
    if s, ok := ss[id]; ok {
        return s
    }
    s := &stream{
        buffer: &bytes.Buffer{},
    }
    ss[id] = s
    return s
}

func (ss streams) append(id int, data string) error {
    s := ss.get(id)
    _, err := s.buffer.WriteString(data)
    return err
}

func (ss streams) end(id int) {
    s := ss.get(id)
    if s.onEnd != nil {
        s.onEnd(s)
    }
}

func (ss streams) delete(id int) {
    ss[id].buffer = nil
    ss[id] = nil
    delete(ss, id)
}