import { access, readFile, writeFile } from "node:fs/promises";
import path from "node:path";

const endpointCandidates = [
  "node_modules/@rmdes/indiekit-endpoint-activitypub",
  "node_modules/@indiekit/indiekit/node_modules/@rmdes/indiekit-endpoint-activitypub",
];

const sourceLocale = "en";
const targetLocales = ["de"];

const deTitleOverrides = {
  activitypub: {
    notifications: {
      title: "Benachrichtigungen",
    },
    myProfile: {
      title: "Mein Profil",
    },
  },
};

function isObject(value) {
  return Boolean(value) && typeof value === "object" && !Array.isArray(value);
}

function mergeMissing(target, fallback) {
  if (target === undefined) {
    return fallback;
  }

  if (!isObject(target) || !isObject(fallback)) {
    return target;
  }

  const merged = { ...target };

  for (const [key, fallbackValue] of Object.entries(fallback)) {
    merged[key] = mergeMissing(merged[key], fallbackValue);
  }

  return merged;
}

function applyOverrides(target, overrides) {
  if (!isObject(target) || !isObject(overrides)) {
    return target;
  }

  const merged = { ...target };

  for (const [key, value] of Object.entries(overrides)) {
    if (isObject(value)) {
      const existing = isObject(merged[key]) ? merged[key] : {};
      merged[key] = applyOverrides(existing, value);
      continue;
    }

    merged[key] = value;
  }

  return merged;
}

async function exists(filePath) {
  try {
    await access(filePath);
    return true;
  } catch {
    return false;
  }
}

let checkedEndpoints = 0;
let checkedLocales = 0;
let patchedLocales = 0;

for (const endpointPath of endpointCandidates) {
  if (!(await exists(endpointPath))) {
    continue;
  }

  checkedEndpoints += 1;

  const sourcePath = path.join(endpointPath, "locales", `${sourceLocale}.json`);

  if (!(await exists(sourcePath))) {
    continue;
  }

  let sourceLocaleJson;
  try {
    sourceLocaleJson = JSON.parse(await readFile(sourcePath, "utf8"));
  } catch {
    continue;
  }

  for (const locale of targetLocales) {
    const localePath = path.join(endpointPath, "locales", `${locale}.json`);
    checkedLocales += 1;

    let localeJson = {};
    if (await exists(localePath)) {
      try {
        localeJson = JSON.parse(await readFile(localePath, "utf8"));
      } catch {
        localeJson = {};
      }
    }

    const merged = mergeMissing(localeJson, sourceLocaleJson);
    const patched =
      locale === "de" ? applyOverrides(merged, deTitleOverrides) : merged;

    if (JSON.stringify(patched) === JSON.stringify(localeJson)) {
      continue;
    }

    await writeFile(localePath, `${JSON.stringify(patched, null, 2)}\n`, "utf8");
    patchedLocales += 1;
  }
}

if (checkedEndpoints === 0) {
  console.log("[postinstall] No activitypub endpoint directories found");
} else if (checkedLocales === 0) {
  console.log("[postinstall] No activitypub locale files checked");
} else if (patchedLocales === 0) {
  console.log("[postinstall] activitypub locale files already patched");
} else {
  console.log(
    `[postinstall] Patched activitypub locale files in ${patchedLocales}/${checkedLocales} file(s)`,
  );
}