package purge

import (
	"errors"
	"time"
)

var ErrInvalidPurgeInterval = errors.New("invalid purge interval")
var ErrPurgeConflict = errors.New("the library changed since the fingerprint")
var ErrPurgeBusy = errors.New("a purge is already running")

const (
	DefaultIntervalDays = 30
	MinIntervalDays     = 1
	MaxIntervalDays     = 365
)

type Settings struct {
	AutoPurgeEnabled         bool       `json:"auto_purge_enabled"`
	AutoPurgeIntervalDays    int        `json:"auto_purge_interval_days"`
	LastPurgeAt              *time.Time `json:"last_purge_at"`
	LastPurgeMerged          int        `json:"last_purge_merged"`
	LastPurgeArticlesUpdated int        `json:"last_purge_articles_updated"`
	EnabledAt                *time.Time `json:"enabled_at"`
}

func DefaultSettings() Settings {
	return Settings{AutoPurgeIntervalDays: DefaultIntervalDays}
}

func ValidateIntervalDays(days int) error {
	if days < MinIntervalDays || days > MaxIntervalDays {
		return ErrInvalidPurgeInterval
	}
	return nil
}

func (s Settings) NextPurgeAt() *time.Time {
	if !s.AutoPurgeEnabled || s.EnabledAt == nil {
		return nil
	}
	base := *s.EnabledAt
	if s.LastPurgeAt != nil && s.LastPurgeAt.After(base) {
		base = *s.LastPurgeAt
	}
	next := base.AddDate(0, 0, s.AutoPurgeIntervalDays)
	return &next
}

type RunResult struct {
	GroupsTotal     int
	GroupsPurged    int
	Merged          int
	ArticlesUpdated int
	SitesUpdated    int
	AuthorsUpdated  int
	FailedGroups    int
}