package core

import (
    "errors"
    "github.com/sirupsen/logrus"
)

type dispatcher struct {
    listeners map[int16]chan string
    counter   int16
}

func NewDispatcher() *dispatcher {
    return &dispatcher{
        listeners: make(map[int16]chan string),
        counter:   0,
    }
}

func (d *dispatcher) Publish(message string) {
    logrus.Debugf("publish to %v listeners:\n%v\n", len(d.listeners))
    logrus.Debug(message)
    for _, ch := range d.listeners {
        ch <- message
    }
}

func (d *dispatcher) Subscribe() (id int16, receiver <-chan string) {
    key := d.counter
    d.counter++
    rec := make(chan string)
    d.listeners[key] = rec
    return key, rec
}

func (d *dispatcher) Unsubscribe(id int16) error {
    receiver, ok := d.listeners[id]
    if !ok {
        return errors.New("no subscription with id")
    }
    delete(d.listeners, id)
    close(receiver)
    return nil
}