// Plugin-tree maintenance for the embedded core (no Electron imports, so this
// is unit-testable with plain node).
//
// Two problems this solves, both invisible from the gateway side:
//   1. The core deliberately does NOT default `plugin_dir` (an operator opts
//      in). A desktop profile without it runs with ZERO plugins — the channels
//      plugin (account login, credential vault, auto check-in) never appears.
//   2. The core seeds bundled plugins only when the file is ABSENT, so a
//      desktop upgrade would keep the user's old channels.lua forever and
//      silently skip every channel fix. On version change the shell must drop
//      the built-in files so the new binary reseeds them.
const fs = require("fs");
const path = require("path");

const BUILTIN_PLUGINS = ["billing.lua", "channels.lua", "quota.lua", "usage.lua"];

// ensurePluginDirConfigured back-fills `plugin_dir` into an existing config.
// Appending a top-level YAML key is safe for the shapes this file can have
// (flat mapping + a keys list). Returns "added" | "present" | "absent" | "error".
function ensurePluginDirConfigured(configFile, pluginsDir, log) {
  try {
    if (!fs.existsSync(configFile)) return "absent";
    const cur = fs.readFileSync(configFile, "utf-8");
    if (/^\s*plugin_dir\s*:/m.test(cur)) return "present";
    fs.writeFileSync(
      configFile,
      cur.replace(/\s*$/, "") +
        "\n# added by ModelRouter Desktop: enables the plugin tree (channels etc.)\n" +
        "plugin_dir: " + JSON.stringify(pluginsDir) + "\n",
      "utf-8",
    );
    if (log) log("[gui] plugin_dir back-filled into " + configFile);
    return "added";
  } catch (e) {
    if (log) log("[gui] ensurePluginDirConfigured failed: " + e.message);
    return "error";
  }
}

// syncBundledPluginsOnUpgrade drops built-in plugin files when the app version
// changed, so the core reseeds them from the binary it shipped with. Returns
// { changed, dropped:[...], kept: "prev-<ver>" }.
function syncBundledPluginsOnUpgrade(profileDir, pluginsDir, version, log) {
  const stamp = path.join(profileDir, ".plugin-seed-version");
  let have = "";
  try {
    have = fs.readFileSync(stamp, "utf-8").trim();
  } catch (e) {
    /* first run */
  }
  if (have === version) return { changed: false, dropped: [] };
  const dropped = [];
  for (const name of BUILTIN_PLUGINS) {
    const f = path.join(pluginsDir, name);
    if (!fs.existsSync(f)) continue;
    try {
      if (have) fs.renameSync(f, f + ".prev-" + have);
      else fs.unlinkSync(f);
      dropped.push(name);
    } catch (e) {
      if (log) log("[gui] drop builtin plugin " + name + " failed: " + e.message);
    }
  }
  try {
    fs.writeFileSync(stamp, version + "\n", "utf-8");
  } catch (e) {
    if (log) log("[gui] write plugin seed stamp failed: " + e.message);
  }
  if (dropped.length && log) {
    log(
      "[gui] plugins refreshed for " + version + " (" + dropped.length +
        " builtin file(s) reseeded by core)",
    );
  }
  return { changed: true, dropped, kept: have ? "prev-" + have : "" };
}

module.exports = {
  BUILTIN_PLUGINS,
  ensurePluginDirConfigured,
  syncBundledPluginsOnUpgrade,
};