package useCases

import (
	"RenewCMS/internal/domain/audit"
	"RenewCMS/internal/domain/language"
	"RenewCMS/internal/domain/localization"
	"RenewCMS/internal/domain/site"
	"RenewCMS/internal/domain/transaction"
	"context"
	"errors"
	"fmt"
	"slices"
)

type ApplyLanguageSetupUseCase struct {
	transactor transaction.Transactor
	recorder   audit.Recorder
}

func NewApplyLanguageSetupUseCase(transactor transaction.Transactor, recorder audit.Recorder) *ApplyLanguageSetupUseCase {
	return &ApplyLanguageSetupUseCase{transactor, recorder}
}

func (a *ApplyLanguageSetupUseCase) Apply(ctx context.Context, choices []localization.SetupChoice) (localization.SetupResult, error) {
	event := audit.NewEvent(audit.ActionSiteLanguageSetup, audit.CategorySites)
	result, confirmed, err := a.confirm(ctx, choices)
	if errors.Is(err, transaction.ErrLockContention) {
		err = fmt.Errorf("%w: %w", localization.ErrSetupInProgress, err)
	}
	if err != nil {
		recordFailure(ctx, a.recorder, event, err)
		return localization.SetupResult{}, err
	}
	for _, found := range confirmed {
		a.recordConfirmed(ctx, found, result)
	}
	return result, nil
}

func (a *ApplyLanguageSetupUseCase) confirm(ctx context.Context, choices []localization.SetupChoice) (localization.SetupResult, []site.Site, error) {
	chosen, err := normalizeSetupChoices(choices)
	if err != nil {
		return localization.SetupResult{}, nil, err
	}
	var result localization.SetupResult
	var confirmed []site.Site
	err = a.transactor.Run(ctx, func(tx transaction.Repositories) error {
		result = localization.SetupResult{Sites: []localization.SetupAssignment{}, Skipped: []string{}}
		confirmed = nil
		for key := range chosen {
			if _, err := tx.Sites.GetByKey(key); err != nil {
				return err
			}
		}
		pending, err := lockPendingSites(tx)
		if err != nil {
			return err
		}
		for _, found := range pending {
			if _, ok := chosen[found.Key]; !ok {
				return localization.ErrSetupIncomplete
			}
		}
		for _, found := range pending {
			assignment, err := confirmSite(tx, found, chosen[found.Key])
			if err != nil {
				return err
			}
			result.Assigned += assignment.Assigned
			result.Sites = append(result.Sites, assignment)
			confirmed = append(confirmed, found)
		}
		result.Skipped = skippedChoices(chosen, pending)
		return nil
	})
	if err != nil {
		return localization.SetupResult{}, nil, err
	}
	return result, confirmed, nil
}

func (a *ApplyLanguageSetupUseCase) recordConfirmed(ctx context.Context, found site.Site, result localization.SetupResult) {
	event := audit.NewEvent(audit.ActionSiteLanguageSetup, audit.CategorySites)
	event.Target = siteTarget(found)
	for _, assignment := range result.Sites {
		if assignment.Key == found.Key {
			event.Changes = []audit.Change{audit.TextChange(audit.FieldDefaultLanguage, "", assignment.Lang)}
			event.Params[audit.ParamAssigned] = assignment.Assigned
		}
	}
	a.recorder.Record(ctx, event)
}

func lockPendingSites(tx transaction.Repositories) ([]site.Site, error) {
	locked := map[uint32]bool{}
	for {
		pending, err := pendingSites(tx.Sites, tx.Localization)
		if err != nil {
			return nil, err
		}
		missing := []uint32{}
		for _, id := range siteIDs(pending) {
			if !locked[id] {
				missing = append(missing, id)
			}
		}
		if len(missing) == 0 {
			return pending, nil
		}
		if err := tx.Sites.TryLockSites(missing); err != nil {
			return nil, err
		}
		for _, id := range missing {
			locked[id] = true
		}
	}
}

func confirmSite(tx transaction.Repositories, found site.Site, tag string) (localization.SetupAssignment, error) {
	if err := tx.Localization.ConfirmSetup(found.ID, tag); err != nil {
		return localization.SetupAssignment{}, err
	}
	assigned, err := tx.Articles.AssignUnassignedLanguage(found.ID, tag)
	if err != nil {
		return localization.SetupAssignment{}, err
	}
	return localization.SetupAssignment{Key: found.Key, Lang: tag, Assigned: assigned}, nil
}

func skippedChoices(chosen map[string]string, pending []site.Site) []string {
	skipped := []string{}
	for key := range chosen {
		if !slices.ContainsFunc(pending, func(found site.Site) bool { return found.Key == key }) {
			skipped = append(skipped, key)
		}
	}
	slices.Sort(skipped)
	return skipped
}

func normalizeSetupChoices(choices []localization.SetupChoice) (map[string]string, error) {
	chosen := make(map[string]string, len(choices))
	for _, choice := range choices {
		tag, err := language.Normalize(choice.Lang)
		if err != nil {
			return nil, err
		}
		if _, repeated := chosen[choice.Key]; repeated {
			return nil, localization.ErrDuplicateSite
		}
		chosen[choice.Key] = tag
	}
	return chosen, nil
}

func siteIDs(sites []site.Site) []uint32 {
	ids := make([]uint32, 0, len(sites))
	for _, found := range sites {
		ids = append(ids, found.ID)
	}
	return ids
}