package useCases

import (
	"RenewCMS/internal/domain/audit"
	"context"
	"time"
)

const defaultCleanupBatchSize = 1000

type CleanupActivityUseCase struct {
	events    audit.Repository
	settings  audit.SettingsRepository
	recorder  audit.Recorder
	batchSize int
}

func NewCleanupActivityUseCase(events audit.Repository, settings audit.SettingsRepository, recorder audit.Recorder) *CleanupActivityUseCase {
	return &CleanupActivityUseCase{events, settings, recorder, defaultCleanupBatchSize}
}

func (c *CleanupActivityUseCase) WithBatchSize(batchSize int) *CleanupActivityUseCase {
	c.batchSize = batchSize
	return c
}

func (c *CleanupActivityUseCase) Tick(now time.Time) (audit.CleanupResult, bool, error) {
	settings, err := c.settings.Get()
	if err != nil {
		return audit.CleanupResult{}, false, err
	}
	if !settings.HasRetentionLimit() || !settings.CleanupDue(now) {
		return audit.CleanupResult{}, false, nil
	}

	removed := 0
	if settings.RetentionDays != audit.ForeverRetentionDays {
		removed, err = c.events.DeleteOlderThan(audit.RetentionCutoff(now, settings.RetentionDays))
		if err != nil {
			return audit.CleanupResult{}, false, err
		}
	}
	if settings.RetentionMaxGB != audit.NoSizeLimitGB {
		trimmed, err := c.trimToSize(now, settings.MaxLogSizeBytes())
		if err != nil {
			return audit.CleanupResult{}, false, err
		}
		removed += trimmed
	}
	if err := c.settings.SaveLastCleanup(now, removed); err != nil {
		return audit.CleanupResult{}, false, err
	}
	if removed > 0 {
		c.recordCleanup(removed)
	}
	return audit.CleanupResult{Removed: removed}, true, nil
}

func (c *CleanupActivityUseCase) trimToSize(now time.Time, limitBytes int64) (int, error) {
	guard := audit.GuardCutoff(now)
	removed := 0
	for {
		size, err := c.events.SizeBytes()
		if err != nil {
			return removed, err
		}
		if size <= limitBytes {
			return removed, nil
		}
		batch, err := c.events.DeleteOldest(c.batchSize, guard)
		if err != nil {
			return removed, err
		}
		if batch == 0 {
			return removed, nil
		}
		removed += batch
	}
}

func (c *CleanupActivityUseCase) recordCleanup(removed int) {
	event := audit.NewEvent(audit.ActionCleanup, audit.CategorySystem)
	event.Actor = audit.SystemActor()
	event.Source = audit.SourceSystem
	event.Params = map[string]any{audit.ParamRemoved: removed}
	c.recorder.Record(context.Background(), event)
}