package main

import (

"bufio"

"errors"

"fmt"

"io"

"os"

"os/signal"

"syscall"

"time"

"fortio.org/log"

"fortio.org/terminal"

)

func StdinTail(cfg *Config) int {

maxPoll := 100 * time.Millisecond

reader := terminal.NewTimeoutReader(os.Stdin, maxPoll)

var numStr string

ap := cfg.ap

var buf [4096]byte

ap.Out = bufio.NewWriter(os.Stdout)

defer ap.Out.Flush()

blink := false

var prevNow time.Time

prev := ""

c := make(chan os.Signal, 1)

signal.Notify(c, os.Interrupt, syscall.SIGTERM)

for {

select {

case <-c:

log.LogVf("Interrupted, exiting")

return 0

default:

}

doDraw := cfg.breath

now := time.Now()

if cfg.countDown {

left := cfg.end.Sub(now).Round(time.Second)

if left < 0 {

ap.WriteString(fmt.Sprintf("\n\n\aTime's up reached at %s\r\n", now.Format(cfg.format)))

return 0

}

numStr = DurationString(left, cfg.seconds)

} else {

numStr = now.Format(cfg.format)

}

if numStr != prev {

doDraw = true

}

prev = numStr

now = now.Truncate(time.Second) // change only when seconds change

if now != prevNow && cfg.blinkEnabled {

blink = !blink

doDraw = true

}

prevNow = now

n, err := reader.Read(buf[:])

if err != nil {

if !errors.Is(err, io.EOF) {

return log.FErrf("Error reading stdin: %v", err)

}

log.Debugf("EOF on stdin")

time.Sleep(maxPoll) // EOF is continuous until there is more in the file, so avoid too tight loop.

}

if doDraw || n > 0 {

cfg.frame++

ap.StartSyncMode()

if n > 0 {

_, _ = ap.Out.Write(buf[:n])

ap.SaveCursorPos()

}

cfg.DrawAt(-1, -1, TimeString(numStr, blink))

ap.RestoreCursorPos()

ap.EndSyncMode()

}

}

}