package printer

/*
Copyright © 2026 Thomas von Dein

This program is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.

This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.

You should have received a copy of the GNU General Public License
along with this program. If not, see <http://www.gnu.org/licenses/>.
*/

import (
	"fmt"
	"runtime/metrics"
	"strconv"
)

func printGoRoutineMetrics() {
	fmt.Println("\nGoroutine metrics:")
	printMetric("/sched/goroutines-created:goroutines", "Created")
	printMetric("/sched/goroutines:goroutines", "Live")
	printMetric("/sched/goroutines/not-in-go:goroutines", "Syscall/CGO")
	printMetric("/sched/goroutines/runnable:goroutines", "Runnable")
	printMetric("/sched/goroutines/running:goroutines", "Running")
	printMetric("/sched/goroutines/waiting:goroutines", "Waiting")

	fmt.Println("Thread metrics:")
	printMetric("/sched/gomaxprocs:threads", "Max")
	printMetric("/sched/threads/total:threads", "Live")
}

func printMetric(name string, descr string) {
	sample := []metrics.Sample{{Name: name}}
	metrics.Read(sample)

	var val string

	switch sample[0].Value.Kind() {
	case metrics.KindFloat64, metrics.KindFloat64Histogram:
		val = fmt.Sprintf("%.2f", sample[0].Value.Float64())
	case metrics.KindUint64:
		val = strconv.FormatUint(sample[0].Value.Uint64(), 10)
	case metrics.KindBad:
		val = "n/a"
	}

	fmt.Printf("  %s: %v\n", descr, val)
}