// lib/apiState.js
// GET /api/state payload builder (ARCHITECTURE.md 8.5).
//
// StateEnvelope = {
//   themes: ThemeListItem[],                  // metadata only (NOT full token payloads)
//   activeThemeId: string|null,
//   activeByRole?: { [roleId:number]: string },
//   manifest: TokenManifest,
//   caps: { layoutMode, canImport, engine, formatVersion, sizeCap },
//   ... plus active{}, layoutMode, csrfToken convenience fields for the shell.
// }
// ThemeListItem = { id, name, builtin, active, engine, updatedAt, hasLayoutTree }
//
// buildState merges builtins (builtin:true) + library rows (builtin:false) via
// themeStore.list(), annotates `active` from the LIVE pointer (read via
// getState().plugin_cfgs, no DB hit), and includes the token manifest. caps.layoutMode
// toggles the SPA canvas panel.

const { getState } = require("@saltcorn/data/db/state");

const themeStore = require("./themeStore");
const { TOKEN_SCHEMA, MAX_CSS_BYTES } = require("./tokenSchema");
const { DEFAULT_TOKENS } = require("./themeSchema");
const { PRESETS } = require("./layoutTree");
const {
  PLUGIN_NAME, API_VERSION, ENGINE, FORMAT_VERSION, MAX_IMPORT_BYTES, CFG,
} = require("./constants");


// Live merged plugin config for this tenant (no DB hit). Mirrors
// activePointer.getActivePointer / cfgReaders resolution.
function livePointer() {
  const cfg = getState().plugin_cfgs[PLUGIN_NAME] || {};
  return {
    activeThemeId: cfg[CFG.ACTIVE] || null,
    activeByRole:  cfg[CFG.BY_ROLE] || {},
    layoutMode:    !!cfg[CFG.LAYOUT_MODE],
  };
}


// The server-side TokenManifest: HOW each token maps to CSS, paired with its
// default value. Structurally parallel to the SPA manifest; derived from the
// single TOKEN_SCHEMA source of truth.
function buildManifest() {
  const flatDefaults = {};
  for (const [sec, obj] of Object.entries(DEFAULT_TOKENS)) {
    if (!obj || typeof obj !== "object") {
      continue;
    }
    for (const [k, v] of Object.entries(obj)) {
      // camelCase leaf -> kebab-case manifest key (matches compile.flattenTokens)
      const kebab = k.replace(/([a-z0-9])([A-Z])/g, "$1-$2").toLowerCase();
      flatDefaults[kebab] = v;
    }
  }
  const tokens = {};
  for (const [key, spec] of Object.entries(TOKEN_SCHEMA)) {
    tokens[key] = {
      kind:     spec.kind,
      cssVar:   spec.cssVar || null,
      selector: spec.selector || null,
      prop:     spec.prop || null,
      derive:   spec.derive || null,
      default:  flatDefaults[key] != null ? flatDefaults[key] : null,
    };
  }
  return { engine: ENGINE, apiVersion: API_VERSION, tokens };
}


// stored row / builtin ThemeDTO -> compact ThemeListItem (metadata only).
function toListItem(t, activeThemeId, activeByRole) {
  const isActive = t.id === activeThemeId || Object.values(activeByRole).includes(t.id);
  return {
    id:            t.id,
    name:          t.name,
    builtin:       !!t.builtin,
    active:        isActive,
    engine:        t.engine,
    updatedAt:     t.updated_at || null,
    hasLayoutTree: !!t.layoutTree,
  };
}


async function buildState(req) {
  const { activeThemeId, activeByRole, layoutMode } = livePointer();
  const all = await themeStore.list();
  const themes = all.map((t) => toListItem(t, activeThemeId, activeByRole));
  const csrfToken = (req && typeof req.csrfToken === "function") ? req.csrfToken() : "";

  return {
    themes,
    activeThemeId,
    activeByRole,
    active: { activeThemeId, activeByRole },
    layoutMode,
    csrfToken,
    manifest: buildManifest(),
    layoutPresets: PRESETS.map((p) => ({ id: p.id, label: p.label, tree: structuredClone(p.tree) })),
    caps: {
      layoutMode,
      canImport:     true,
      engine:        ENGINE,
      formatVersion: FORMAT_VERSION,
      sizeCap:       MAX_IMPORT_BYTES,
      maxCssBytes:   MAX_CSS_BYTES,
    },
  };
}


module.exports = { buildState, buildManifest };