// Built-in theme registry. Starters ship as frozen code, are merged into list()
// at read time, and are never inserted into the Table. They are not deletable,
// renamable, or save-able; "loading" a built-in for edit duplicates it to a
// fresh uuid row (handled in the store/handlers).

const themes = [require("./flatly"), require("./darkly"), require("./cosmo")];
const byId = Object.freeze(Object.fromEntries(themes.map((t) => [t.id, t])));


function listBuiltins() {
    return themes;
}


function getBuiltin(id) {
    return byId[id] || null;
}


function isBuiltinId(id) {
    return typeof id === "string" && id.startsWith("builtin:");
}


// The starter used as a last-resort successor (e.g. when the active theme is
// deleted and no other stored theme exists).
function defaultId() {
    return "builtin:flatly";
}


// Valid, empty CSS served on a transient miss (table not yet created, theme
// missing mid-activate). Never a white-screen; the active theme renders
// unchanged. Always sent with Cache-Control: no-store by the route.
function fallbackCss() {
    return "/* theme-builder: fallback (no compiled theme) */\n";
}


module.exports = {
    listBuiltins, getBuiltin, get: getBuiltin, isBuiltinId, defaultId, fallbackCss,
};