soumya92/barista

// Copyright 2018 Google Inc.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

// Package netinfo provides an i3bar module for network information.
package netinfo // import "barista.run/modules/netinfo"

import (
    "barista.run/bar"
    "barista.run/base/value"
    "barista.run/base/watchers/netlink"
    l "barista.run/logging"
    "barista.run/outputs"
)

// State represents the network state.
type State struct {
    netlink.Link
}

// Connecting returns true if a connection is in progress.
func (s State) Connecting() bool {
    return s.State == netlink.Dormant
}

// Connected returns true if connected to a network.
func (s State) Connected() bool {
    return s.State == netlink.Up
}

// Enabled returns true if a network interface is enabled.
func (s State) Enabled() bool {
    return s.State > netlink.NotPresent
}

// Unknown returns true if a network interface is in Unknown state.
func (s State) Unknown() bool {
    return s.State == netlink.Unknown
}

// Gone returns true if a network interface just disappeared..
func (s State) Gone() bool {
    return s.State == netlink.Gone
}

// Module represents a netinfo bar module.
type Module struct {
    subscriber func() *netlink.Subscription
    outputFunc value.Value // of func(State) bar.Output
}

// netWithSubscriber constructs a netinfo module using the given
// subscriber function.
func newWithSubscriber(subscriber func() *netlink.Subscription) *Module {
    m := &Module{subscriber: subscriber}
    l.Register(m, "outputFunc")
    // Default output is the name of the connected interface.
    m.Output(func(s State) bar.Output {
        if s.Connected() {
            return outputs.Text(s.Name)
        }
        return nil
    })
    return m
}

// New constructs a netinfo module that scans all interfaces.
func New() *Module {
    m := newWithSubscriber(netlink.Any)
    l.Label(m, "*")
    return m
}

// Interface constructs an instance of the netinfo module
// restricted to the specified interface.
func Interface(iface string) *Module {
    m := newWithSubscriber(func() *netlink.Subscription {
        return netlink.ByName(iface)
    })
    l.Label(m, iface)
    return m
}

// Prefix constructs an instance of the netinfo module restricted
// to interfaces with the given prefix.
func Prefix(prefix string) *Module {
    m := newWithSubscriber(func() *netlink.Subscription {
        return netlink.WithPrefix(prefix)
    })
    l.Labelf(m, "%s*", prefix)
    return m
}

// Output configures a module to display the output of a user-defined function.
func (m *Module) Output(outputFunc func(State) bar.Output) *Module {
    m.outputFunc.Set(outputFunc)
    return m
}

// Stream starts the module.
func (m *Module) Stream(s bar.Sink) {
    outputFunc := m.outputFunc.Get().(func(State) bar.Output)
    nextOutputFunc, done := m.outputFunc.Subscribe()
    defer done()

    linkSub := m.subscriber()
    defer linkSub.Unsubscribe()

    state := State{linkSub.Get()}
    for {
        s.Output(outputFunc(state))
        select {
        case <-linkSub.C:
            state = State{linkSub.Get()}
        case <-nextOutputFunc:
            outputFunc = m.outputFunc.Get().(func(State) bar.Output)
        }
    }
}