appview/languages: fix logic bug in updating language breakdowns

Signed-off-by: oppiliappan <[e-mail]>

appview/db/language.go

···
 package db
 
 import (
+	"database/sql"
 	"fmt"
 	"strings"
 
+	"github.com/bluesky-social/indigo/atproto/syntax"
 	"tangled.org/core/appview/models"
 )
 
···
 
 	return nil
 }
+
+func DeleteRepoLanguages(e Execer, filters ...filter) error {
+	var conditions []string
+	var args []any
+	for _, filter := range filters {
+		conditions = append(conditions, filter.Condition())
+		args = append(args, filter.Arg()...)
+	}
+
+	whereClause := ""
+	if conditions != nil {
+		whereClause = " where " + strings.Join(conditions, " and ")
+	}
+
+	query := fmt.Sprintf(`delete from repo_languages %s`, whereClause)
+
+	_, err := e.Exec(query, args...)
+	return err
+}
+
+func UpdateRepoLanguages(tx *sql.Tx, repoAt syntax.ATURI, ref string, langs []models.RepoLanguage) error {
+	err := DeleteRepoLanguages(
+		tx,
+		FilterEq("repo_at", repoAt),
+		FilterEq("ref", ref),
+	)
+	if err != nil {
+		return fmt.Errorf("failed to delete existing languages: %w", err)
+	}
+
+	return InsertRepoLanguages(tx, langs)
+}

appview/repo/index.go

···
 			})
 		}
 
+		tx, err := rp.db.Begin()
+		if err != nil {
+			return nil, err
+		}
+		defer tx.Rollback()
+
 		// update appview's cache
-		err = db.InsertRepoLanguages(rp.db, langs)
+		err = db.UpdateRepoLanguages(tx, f.RepoAt(), currentRef, langs)
 		if err != nil {
 			// non-fatal
 			log.Println("failed to cache lang results", err)
+		}
+
+		err = tx.Commit()
+		if err != nil {
+			return nil, err
 		}
 	}
 

appview/state/knotstream.go

···
 		})
 	}
 
+	tx, err := d.Begin()
+	if err != nil {
+		return err
+	}
+	defer tx.Rollback()
+
+	// update appview's cache
+	err = db.UpdateRepoLanguages(tx, repo.RepoAt(), ref.Short(), langs)
+	if err != nil {
+		// non-fatal
+	}
+
+	err = tx.Commit()
+	if err != nil {
+		return err
+	}
 	return db.InsertRepoLanguages(d, langs)
 }