#!/usr/bin/env node
import { promises as fs } from "node:fs";
import path from "node:path";
import { fileURLToPath } from "node:url";

const __filename = fileURLToPath(import.meta.url);
const __dirname = path.dirname(__filename);
const ROOT_DIR = path.resolve(__dirname, "..");
const LOCALE_DIR = path.resolve(ROOT_DIR, "src/locales/en");
const KEY_OUTPUT = path.resolve(ROOT_DIR, "src/types/generated/i18n-keys.ts");
const RESOURCE_OUTPUT = path.resolve(
  ROOT_DIR,
  "src/types/generated/i18n-resources.ts",
);

const isPlainObject = (value) =>
  typeof value === "object" && value !== null && !Array.isArray(value);

const flattenKeys = (data, prefix = "") => {
  const keys = [];
  for (const [key, value] of Object.entries(data)) {
    const nextPrefix = prefix ? `${prefix}.${key}` : key;
    if (isPlainObject(value)) {
      keys.push(...flattenKeys(value, nextPrefix));
    } else {
      keys.push(nextPrefix);
    }
  }
  return keys;
};

const buildType = (data, indent = 0) => {
  if (!isPlainObject(data)) {
    return "string";
  }

  const entries = Object.entries(data).sort(([a], [b]) => a.localeCompare(b));
  const pad = " ".repeat(indent);
  const inner = entries
    .map(([key, value]) => {
      const typeStr = buildType(value, indent + 2);
      return `${" ".repeat(indent + 2)}${JSON.stringify(key)}: ${typeStr};`;
    })
    .join("\n");

  return entries.length
    ? `{
${inner}
${pad}}`
    : "{}";
};

const loadNamespaceJson = async () => {
  const dirents = await fs.readdir(LOCALE_DIR, { withFileTypes: true });
  const namespaces = [];
  for (const dirent of dirents) {
    if (!dirent.isFile() || !dirent.name.endsWith(".json")) continue;
    const name = dirent.name.replace(/\.json$/, "");
    const filePath = path.join(LOCALE_DIR, dirent.name);
    const raw = await fs.readFile(filePath, "utf8");
    const json = JSON.parse(raw);
    namespaces.push({ name, json });
  }
  namespaces.sort((a, b) => a.name.localeCompare(b.name));
  return namespaces;
};

const buildKeysFile = (keys) => {
  const arrayLiteral = keys.map((key) => `  "${key}"`).join(",\n");
  return `// This file is auto-generated by scripts/generate-i18n-keys.mjs\n// Do not edit this file manually.\n\nexport const translationKeys = [\n${arrayLiteral}\n] as const;\n\nexport type TranslationKey = typeof translationKeys[number];\n`;
};

const buildResourcesFile = (namespaces) => {
  const namespaceEntries = namespaces
    .map(({ name, json }) => {
      const typeStr = buildType(json, 4);
      return `    ${JSON.stringify(name)}: ${typeStr};`;
    })
    .join("\n");

  return `// This file is auto-generated by scripts/generate-i18n-keys.mjs\n// Do not edit this file manually.\n\nexport interface TranslationResources {\n  translation: {\n${namespaceEntries}\n  };\n}\n`;
};

const main = async () => {
  const namespaces = await loadNamespaceJson();
  const keys = namespaces.flatMap(({ name, json }) => flattenKeys(json, name));
  const keysContent = buildKeysFile(keys);
  const resourcesContent = buildResourcesFile(namespaces);
  await fs.mkdir(path.dirname(KEY_OUTPUT), { recursive: true });
  await fs.writeFile(KEY_OUTPUT, keysContent, "utf8");
  await fs.writeFile(RESOURCE_OUTPUT, resourcesContent, "utf8");
  console.log(`Generated ${keys.length} translation keys.`);
};

main().catch((error) => {
  console.error("Failed to generate i18n metadata:", error);
  process.exitCode = 1;
});