package app

import (
	"os"
	"time"

	"github.com/robfig/cron/v3"
	"gopkg.in/yaml.v3"
)

type Scheduler struct {
	filePath        string
	lastSuccessTime map[string]time.Time
}

func NewScheduler(filePath string) (*Scheduler, error) {
	s := Scheduler{filePath: filePath}
	data, err := os.ReadFile(filePath)
	if err != nil {
		return nil, err
	}
	err = yaml.Unmarshal(data, &s.lastSuccessTime)
	if err != nil {
		return nil, err
	}
	return &s, nil
}

func (s *Scheduler) Save() error {
	data, err := yaml.Marshal(&s.lastSuccessTime)
	if err != nil {
		return err
	}
	return os.WriteFile(s.filePath, data, 0644)
}

func (s *Scheduler) Good(name string) {
	s.lastSuccessTime[name] = time.Now()
}

func (s *Scheduler) ShouldDownload(name string, scheduleSpec string) (bool, error) {
	lastSuccess, ok := s.lastSuccessTime[name]
	if !ok {
		return true, nil
	}
	cron, err := cron.ParseStandard(scheduleSpec)
	if err != nil {
		return false, err
	}
	n := cron.Next(lastSuccess)
	return n.Before(time.Now()), nil
}