package autocleanup

import (
	"time"

	"github.com/mattermost/mattermost/server/public/plugin"
	"github.com/mattermost/mattermost/server/public/pluginapi/cluster"
	"github.com/pkg/errors"
)

const dailyInterval = 24 * time.Hour

type ConfigStore interface {
	List() ([]Config, error)
}

// CleanupFunc deletes messages older than offsetDays from channelID.
type CleanupFunc func(channelID string, offsetDays int) (int, error)

// Runner executes automatic cleanup for configured channels.
type Runner struct {
	store   ConfigStore
	cleanup CleanupFunc
}

func NewRunner(store ConfigStore, cleanup CleanupFunc) *Runner {
	return &Runner{
		store:   store,
		cleanup: cleanup,
	}
}

func (r *Runner) Run() {
	configs, err := r.store.List()
	if err != nil {
		return
	}

	for _, config := range configs {
		if _, err := r.cleanup(config.ChannelID, config.OffsetDays); err != nil {
			continue
		}
	}
}

// ScheduleDaily registers a cluster-safe job that runs automatic cleanup once per day.
func ScheduleDaily(api plugin.API, runner *Runner) (*cluster.Job, error) {
	job, err := cluster.Schedule(
		api,
		autoCleanupJobKey,
		cluster.MakeWaitForRoundedInterval(dailyInterval),
		runner.Run,
	)
	if err != nil {
		return nil, errors.Wrap(err, "failed to schedule auto cleanup job")
	}

	return job, nil
}