package kubeprobes

import (
	"sync"
	"time"
)

// ProbeFunction is a wrapper for a function that determines whether
// the given metric may be marked as correctly functioning.
// It not, the error should be returned.
type ProbeFunction interface {
	name() string
	status() error
}

type probeFunction struct {
	probeName       string
	probeFunc       func() error
	refreshInterval time.Duration

	mux sync.RWMutex
	err error
}

// NewProbeFunction returns new instance of [ProbeFunction].
//
// If update interval is less or equal zero then probe is updated only
// on its creation and remains in the same state forever.
func NewProbeFunction(
	name string,
	fn func() error,
	updateInterval time.Duration,
) (ProbeFunction, error) {
	if name == "" {
		return nil, errProbeNameEmpty
	}

	pf := &probeFunction{
		probeName:       name,
		probeFunc:       fn,
		refreshInterval: updateInterval,
		mux:             sync.RWMutex{},
	}

	defer pf.autoUpdate()
	return pf, nil
}

// name implements ProbeFunction.
func (pf *probeFunction) name() string {
	return pf.probeName
}

// status implements ProbeFunction.
func (pf *probeFunction) status() error {
	pf.mux.RLock()
	defer pf.mux.RUnlock()
	return pf.err
}

func (pf *probeFunction) update() {
	err := pf.probeFunc()
	pf.mux.Lock()
	pf.err = err
	pf.mux.Unlock()
}

func (pf *probeFunction) autoUpdate() {
	pf.update()
	if pf.refreshInterval <= 0 {
		return
	}

	go func() {
		ticker := time.NewTicker(pf.refreshInterval)
		for {
			<-ticker.C
			pf.update()
		}
	}()
}