const fs = require("fs");
const path = require("path");

const { createJsonStorage } = require("./providers/json");
const { createSqliteStorage } = require("./providers/sqlite");

async function createStorageProvider(config) {
  const providerId = String(config.storageProvider || "json").trim().toLowerCase();

  if (providerId === "json") {
    const provider = createJsonStorage({ dataDir: config.dataDir });
    await provider.init();
    return provider;
  }

  if (providerId === "sqlite") {
    const sqlitePath = config.storageSqlitePath || path.join(config.dataDir, "rms-storage.db");
    const provider = createSqliteStorage({
      sqlitePath
    });
    try {
      await provider.init();
      return provider;
    } catch (error) {
      const sqliteMissing = /node:sqlite/i.test(String(error && error.message ? error.message : error));
      const sqliteDbExists = fs.existsSync(sqlitePath);
      if (sqliteMissing && !sqliteDbExists) {
        console.warn(`WARN: SQLite not available (${String(error.message || error)}), falling back to JSON storage at ${config.dataDir}`);
        const fallback = createJsonStorage({ dataDir: config.dataDir });
        await fallback.init();
        return fallback;
      }
      throw error;
    }
  }

  if (providerId === "module") {
    const modulePath = config.storageModulePath;
    if (!modulePath) {
      throw new Error("STORAGE_PROVIDER=module requires STORAGE_MODULE_PATH");
    }
    const resolved = path.isAbsolute(modulePath) ? modulePath : path.resolve(config.rootDir, modulePath);
    const mod = require(resolved);
    const create = typeof mod.createStorage === "function" ? mod.createStorage : mod;
    const provider = await create(config);
    if (!provider || typeof provider.readJson !== "function" || typeof provider.writeJson !== "function") {
      throw new Error("Custom storage module must implement readJson/writeJson");
    }
    if (typeof provider.init === "function") {
      await provider.init();
    }
    return provider;
  }

  throw new Error(`Unknown STORAGE_PROVIDER: ${providerId}`);
}

module.exports = {
  createStorageProvider
};