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cchat-gtk/internal/ui/messages/typing/state.go
diamondburned (Forefront) 2fae6ffbb3 UI changes; typing state working
This commit refactors the input container's UI as well as fixing some
bugs related to asynchronous fetching of images.

It also adds complete typing indicator capabilities, all without using a
single mutex!
2020-07-08 02:17:54 -07:00

146 lines
2.9 KiB
Go

package typing
import (
"sort"
"time"
"github.com/diamondburned/cchat"
"github.com/diamondburned/cchat-gtk/internal/gts"
"github.com/pkg/errors"
)
type State struct {
// states
typers []cchat.Typer
timeout time.Duration
canceler func()
invalidated bool
// consts
changed func(s *State, empty bool)
stopper func() // stops the event loop, not used atm
}
var _ cchat.TypingIndicator = (*State)(nil)
func NewState(changed func(s *State, empty bool)) *State {
s := &State{changed: changed}
s.stopper = gts.AfterFunc(time.Second/2, s.loop)
return s
}
func (s *State) reset() {
if s.canceler != nil {
s.canceler()
s.canceler = nil
}
s.timeout = 0
s.typers = nil
s.invalidated = false
}
// Subscribe is thread-safe.
func (s *State) Subscribe(indicator cchat.ServerMessageTypingIndicator) {
gts.Async(func() (func(), error) {
c, err := indicator.TypingSubscribe(s)
if err != nil {
return nil, errors.Wrap(err, "Failed to subscribe to typing indicator")
}
return func() {
s.canceler = c
s.timeout = indicator.TypingTimeout()
}, nil
})
}
// loop runs a single iteration of the event loop. This function is not
// thread-safe.
func (s *State) loop() {
// Filter out any expired typers.
t, ok := filterTypers(s.typers, s.timeout)
if ok {
s.invalidated = true
s.typers = t
}
// Call the event handler if things are invalidated.
if s.invalidated {
s.changed(s, len(s.typers) == 0)
s.invalidated = false
}
}
// invalidate sorts and invalidates the state.
func (s *State) invalidate() {
// Sort the list of typers again.
sort.Slice(s.typers, func(i, j int) bool {
return s.typers[i].Time().Before(s.typers[j].Time())
})
s.invalidated = true
}
// AddTyper is thread-safe.
func (s *State) AddTyper(typer cchat.Typer) {
gts.ExecAsync(func() {
defer s.invalidate()
// If the typer already exists, then pop them to the start of the list.
for i, t := range s.typers {
if t.ID() == typer.ID() {
s.typers[i] = t
return
}
}
s.typers = append(s.typers, typer)
})
}
// RemoveTyper is thread-safe.
func (s *State) RemoveTyper(typerID string) {
gts.ExecAsync(func() { s.removeTyper(typerID) })
}
func (s *State) removeTyper(typerID string) {
defer s.invalidate()
for i, t := range s.typers {
if t.ID() == typerID {
// Remove the quick way. Sort will take care of ordering.
l := len(s.typers) - 1
s.typers[i] = s.typers[l]
s.typers[l] = nil
s.typers = s.typers[:l]
return
}
}
}
func filterTypers(typers []cchat.Typer, timeout time.Duration) ([]cchat.Typer, bool) {
// Fast path.
if len(typers) == 0 || timeout == 0 {
return nil, false
}
var now = time.Now()
var cut int
for _, t := range typers {
if now.Sub(t.Time()) < timeout {
typers[cut] = t
cut++
}
}
for i := cut; i < len(typers); i++ {
typers[i] = nil
}
var changed = cut != len(typers)
return typers[:cut], changed
}