import "server-only";
import { query, queryOne, withTransaction } from "@/lib/db";

export interface LanguageRow {
  code: string;
  label: string;
  is_base: boolean;
  active: boolean;
  template_version: string | null;
  updated_at: string;
}

export async function listLanguages(): Promise<LanguageRow[]> {
  return query<LanguageRow>(
    "select * from languages order by is_base desc, code"
  );
}

export async function listActiveLanguageCodes(): Promise<string[]> {
  const rows = await query<{ code: string }>(
    "select code from languages where active = true order by is_base desc, code"
  );
  return rows.map((r) => r.code);
}

export async function getLanguage(code: string): Promise<LanguageRow | null> {
  return queryOne<LanguageRow>("select * from languages where code = $1", [code]);
}

export async function createLanguage(code: string, label: string): Promise<LanguageRow> {
  return (await queryOne<LanguageRow>(
    `insert into languages (code, label, is_base, active, template_version)
     values ($1, $2, false, true, null) returning *`,
    [code, label]
  ))!;
}

export async function updateLanguageLabel(code: string, label: string): Promise<LanguageRow | null> {
  return queryOne<LanguageRow>(
    "update languages set label = $1, updated_at = now() where code = $2 returning *",
    [label, code]
  );
}

/** Wirft, wenn dadurch keine aktive Sprache mehr übrig bliebe. */
export async function setLanguageActive(code: string, active: boolean): Promise<LanguageRow> {
  return withTransaction(async (client) => {
    if (!active) {
      const { rows } = await client.query<{ count: string }>(
        "select count(*)::int as count from languages where active = true and code != $1",
        [code]
      );
      if (Number(rows[0].count) === 0) {
        throw new Error("cannot_deactivate_last");
      }
    }
    const { rows } = await client.query<LanguageRow>(
      "update languages set active = $1, updated_at = now() where code = $2 returning *",
      [active, code]
    );
    return rows[0];
  });
}

export async function deleteLanguage(code: string): Promise<void> {
  const lang = await getLanguage(code);
  if (lang?.is_base) throw new Error("cannot_delete_base");
  await query("delete from languages where code = $1", [code]);
}

export interface TranslationEntry {
  key: string;
  value: string;
}

export async function listTranslations(code: string): Promise<TranslationEntry[]> {
  return query<TranslationEntry>(
    "select key, value from ui_translations where language_code = $1",
    [code]
  );
}

/** Übernimmt neu importierte Übersetzungen (Insert/Update je Schlüssel)
 *  und aktualisiert den gespeicherten Vorlagen-Stand. Bewusst kein
 *  vollständiges Ersetzen: ein erneuter Import mit nur den zuvor
 *  fehlenden Schlüsseln darf bereits vorhandene Übersetzungen nicht
 *  löschen. */
export async function importTranslations(
  code: string,
  entries: TranslationEntry[],
  templateVersion: string
): Promise<void> {
  await withTransaction(async (client) => {
    for (const entry of entries) {
      await client.query(
        `insert into ui_translations (language_code, key, value) values ($1, $2, $3)
         on conflict (language_code, key) do update set value = excluded.value`,
        [code, entry.key, entry.value]
      );
    }
    await client.query(
      "update languages set template_version = $1, updated_at = now() where code = $2",
      [templateVersion, code]
    );
  });
}