1 files changed, 159 insertions, 0 deletions
diff --git a/internal/db/bundb/tag.go b/internal/db/bundb/tag.go
index 5218a19d5..c6298ee64 100644
--- a/internal/db/bundb/tag.go
+++ b/internal/db/bundb/tag.go
@@ -19,9 +19,13 @@ package bundb
 
 import (
 	"context"
+	"errors"
 	"strings"
 
+	"github.com/superseriousbusiness/gotosocial/internal/db"
+	"github.com/superseriousbusiness/gotosocial/internal/gtserror"
 	"github.com/superseriousbusiness/gotosocial/internal/gtsmodel"
+	"github.com/superseriousbusiness/gotosocial/internal/paging"
 	"github.com/superseriousbusiness/gotosocial/internal/state"
 	"github.com/superseriousbusiness/gotosocial/internal/util"
 	"github.com/uptrace/bun"
@@ -131,3 +135,158 @@ func (t *tagDB) PutTag(ctx context.Context, tag *gtsmodel.Tag) error {
 
 	return nil
 }
+
+func (t *tagDB) GetFollowedTags(ctx context.Context, accountID string, page *paging.Page) ([]*gtsmodel.Tag, error) {
+	tagIDs, err := t.getTagIDsFollowedByAccount(ctx, accountID, page)
+	if err != nil {
+		return nil, err
+	}
+
+	tags, err := t.GetTags(ctx, tagIDs)
+	if err != nil {
+		return nil, err
+	}
+
+	return tags, nil
+}
+
+func (t *tagDB) getTagIDsFollowedByAccount(ctx context.Context, accountID string, page *paging.Page) ([]string, error) {
+	return loadPagedIDs(&t.state.Caches.DB.TagIDsFollowedByAccount, accountID, page, func() ([]string, error) {
+		var tagIDs []string
+
+		// Tag IDs not in cache. Perform DB query.
+		if _, err := t.db.
+			NewSelect().
+			Model((*gtsmodel.FollowedTag)(nil)).
+			Column("tag_id").
+			Where("? = ?", bun.Ident("account_id"), accountID).
+			OrderExpr("? DESC", bun.Ident("tag_id")).
+			Exec(ctx, &tagIDs); // nocollapse
+		err != nil && !errors.Is(err, db.ErrNoEntries) {
+			return nil, gtserror.Newf("error getting tag IDs followed by account %s: %w", accountID, err)
+		}
+
+		return tagIDs, nil
+	})
+}
+
+func (t *tagDB) getAccountIDsFollowingTag(ctx context.Context, tagID string) ([]string, error) {
+	return loadPagedIDs(&t.state.Caches.DB.AccountIDsFollowingTag, tagID, nil, func() ([]string, error) {
+		var accountIDs []string
+
+		// Account IDs not in cache. Perform DB query.
+		if _, err := t.db.
+			NewSelect().
+			Model((*gtsmodel.FollowedTag)(nil)).
+			Column("account_id").
+			Where("? = ?", bun.Ident("tag_id"), tagID).
+			OrderExpr("? DESC", bun.Ident("account_id")).
+			Exec(ctx, &accountIDs); // nocollapse
+		err != nil && !errors.Is(err, db.ErrNoEntries) {
+			return nil, gtserror.Newf("error getting account IDs following tag %s: %w", tagID, err)
+		}
+
+		return accountIDs, nil
+	})
+}
+
+func (t *tagDB) IsAccountFollowingTag(ctx context.Context, accountID string, tagID string) (bool, error) {
+	accountTagIDs, err := t.getTagIDsFollowedByAccount(ctx, accountID, nil)
+	if err != nil {
+		return false, err
+	}
+
+	for _, accountTagID := range accountTagIDs {
+		if accountTagID == tagID {
+			return true, nil
+		}
+	}
+
+	return false, nil
+}
+
+func (t *tagDB) PutFollowedTag(ctx context.Context, accountID string, tagID string) error {
+	// Insert the followed tag.
+	result, err := t.db.NewInsert().
+		Model(&gtsmodel.FollowedTag{
+			AccountID: accountID,
+			TagID:     tagID,
+		}).
+		On("CONFLICT (?, ?) DO NOTHING", bun.Ident("account_id"), bun.Ident("tag_id")).
+		Exec(ctx)
+	if err != nil {
+		return gtserror.Newf("error inserting followed tag: %w", err)
+	}
+
+	// If it fails because that account already follows that tag, that's fine, and we're done.
+	rows, err := result.RowsAffected()
+	if err != nil {
+		return gtserror.Newf("error getting inserted row count: %w", err)
+	}
+	if rows == 0 {
+		return nil
+	}
+
+	// Otherwise, this is a new followed tag, so we invalidate caches related to it.
+	t.state.Caches.DB.AccountIDsFollowingTag.Invalidate(tagID)
+	t.state.Caches.DB.TagIDsFollowedByAccount.Invalidate(accountID)
+
+	return nil
+}
+
+func (t *tagDB) DeleteFollowedTag(ctx context.Context, accountID string, tagID string) error {
+	result, err := t.db.NewDelete().
+		Model((*gtsmodel.FollowedTag)(nil)).
+		Where("? = ?", bun.Ident("account_id"), accountID).
+		Where("? = ?", bun.Ident("tag_id"), tagID).
+		Exec(ctx)
+	if err != nil {
+		return gtserror.Newf("error deleting followed tag %s for account %s: %w", tagID, accountID, err)
+	}
+
+	rows, err := result.RowsAffected()
+	if err != nil {
+		return gtserror.Newf("error getting inserted row count: %w", err)
+	}
+	if rows == 0 {
+		return nil
+	}
+
+	// If we deleted anything, invalidate caches related to it.
+	t.state.Caches.DB.AccountIDsFollowingTag.Invalidate(tagID)
+	t.state.Caches.DB.TagIDsFollowedByAccount.Invalidate(accountID)
+
+	return err
+}
+
+func (t *tagDB) DeleteFollowedTagsByAccountID(ctx context.Context, accountID string) error {
+	// Delete followed tags from the database, returning the list of tag IDs affected.
+	tagIDs := []string{}
+	if err := t.db.NewDelete().
+		Model((*gtsmodel.FollowedTag)(nil)).
+		Where("? = ?", bun.Ident("account_id"), accountID).
+		Returning("?", bun.Ident("tag_id")).
+		Scan(ctx, &tagIDs); // nocollapse
+	err != nil {
+		return gtserror.Newf("error deleting followed tags for account %s: %w", accountID, err)
+	}
+
+	// Invalidate account ID caches for the account and those tags.
+	t.state.Caches.DB.TagIDsFollowedByAccount.Invalidate(accountID)
+	t.state.Caches.DB.AccountIDsFollowingTag.Invalidate(tagIDs...)
+
+	return nil
+}
+
+func (t *tagDB) GetAccountIDsFollowingTagIDs(ctx context.Context, tagIDs []string) ([]string, error) {
+	// Accounts might be following multiple tags in this list, but we only want to return each account once.
+	accountIDs := []string{}
+	for _, tagID := range tagIDs {
+		tagAccountIDs, err := t.getAccountIDsFollowingTag(ctx, tagID)
+		if err != nil {
+			return nil, err
+		}
+		accountIDs = append(accountIDs, tagAccountIDs...)
+	}
+	return util.UniqueStrings(accountIDs), nil
+}