package background

import (
	"math"
	"os"
	"runtime"
	"time"

	"git.fjla.uk/owlboard/timetable-mgr/cif"
	"git.fjla.uk/owlboard/timetable-mgr/corpus"
	"git.fjla.uk/owlboard/timetable-mgr/helpers"
	"git.fjla.uk/owlboard/timetable-mgr/log"
	"git.fjla.uk/owlboard/timetable-mgr/stations"
	"go.uber.org/zap"
)

const frequency = 2 * time.Hour // Figure out a sensible frequency!

// Starts a background ticker to run background tasks.  Uses the frequency configured in the background/ticker.go file
func InitTicker(cfg *helpers.Configuration, stop <-chan struct{}) {
	go runTicker(cfg, stop)

	// Run goroutine logging ticker if env "perflog" is set to "on"
	if os.Getenv("perflog") == "on" {
		go goroutineTicker(stop)
	}
}

// Runs the ticker and handles tick events
func runTicker(cfg *helpers.Configuration, stop <-chan struct{}) {
	log.Info("Starting background task ticker", zap.Duration("frequency", frequency))
	ticker := time.NewTicker(frequency)
	defer ticker.Stop()

	for {
		select {
		case <-stop:
			log.Debug("Stopping background task ticker")
			return
		case <-ticker.C:
			log.Debug("Running background tasks")
			go cif.CheckCif(cfg)
			go corpus.CheckCorpus(cfg)
			go stations.Check()
		}
	}
}

// Starts a ticker that logs how many goroutines are running every two seconds
func goroutineTicker(stop <-chan struct{}) {
	log.Debug("Starting goroutine resource logging ticker")
	ticker := time.NewTicker(1000 * time.Millisecond)
	defer ticker.Stop()
	for {
		select {
		case <-stop:
			return
		case <-ticker.C:
			debugLog()
		}
	}
}

func debugLog() {
	var memStats runtime.MemStats
	runtime.ReadMemStats(&memStats)

	goroutines := runtime.NumGoroutine()
	heapMem := float64(memStats.HeapAlloc) / (1024 * 1024)
	heapMemRound := math.Round(heapMem*100) / 100

	log.Debug("Performance", zap.Int("goroutine-count", goroutines), zap.Float64("heap-mem (MB)", heapMemRound))
}