/**
 * Compatibility wrapper around Node.js built-in node:sqlite (DatabaseSync).
 * Provides a better-sqlite3-compatible API so the rest of the codebase
 * works without the native module.
 *
 * Available on Node.js >= 22.5.0 (node:sqlite is experimental).
 * On older Node versions, require() will throw and the caller should
 * handle the error (e.g. show an informative message).
 *
 * @file This module exports a Database class that wraps node:sqlite's DatabaseSync to provide a better-sqlite3-like API: `pragma`, `transaction`, `function`, `stmt.pluck()` and the `readonly`/`fileMustExist` options. A plugin install has no better-sqlite3 build, so there this IS the driver.
 * @author Nguyễn Ngọc Trí Vĩ <vinnt@smartgift.vn>
 */

const fs = require("fs");
const { DatabaseSync } = require("node:sqlite");

class Database {
  /** better-sqlite3's `readonly` and `fileMustExist` options, mapped. */
  constructor(filePath, { readonly = false, fileMustExist = false } = {}) {
    if (fileMustExist && !fs.existsSync(filePath)) {
      throw new Error(`unable to open database file: ${filePath} does not exist`);
    }
    this._db = new DatabaseSync(filePath, { readOnly: readonly });
  }

  exec(sql) {
    this._db.exec(sql);
    return this;
  }

  pragma(str, options) {
    if (str.includes("=")) {
      this._db.exec(`PRAGMA ${str}`);
      return undefined;
    }
    const row = this._db.prepare(`PRAGMA ${str}`).get();
    if (!row) return undefined;
    const keys = Object.keys(row);
    if (options?.simple || keys.length === 1) return row[keys[0]];
    return row;
  }

  prepare(sql) {
    const stmt = this._db.prepare(sql);
    // better-sqlite3's pluck(): get/all/iterate yield the first column only.
    stmt.pluck = () => {
      const first = (row) => (row === undefined ? undefined : Object.values(row)[0]);
      const { get, all, iterate } = stmt;
      stmt.get = (...a) => first(get.apply(stmt, a));
      stmt.all = (...a) => all.apply(stmt, a).map(first);
      stmt.iterate = function* (...a) {
        for (const row of iterate.apply(stmt, a)) yield first(row);
      };
      return stmt;
    };
    return stmt;
  }

  /** better-sqlite3's db.function(name, [options], fn): a SQL function. */
  function(name, options, fn) {
    if (typeof options === "function") [fn, options] = [options, {}];
    this._db.function(name, options, fn);
    return this;
  }

  transaction(fn) {
    const db = this._db;
    const wrapper = (...args) => {
      db.exec("BEGIN");
      try {
        const result = fn(...args);
        db.exec("COMMIT");
        return result;
      } catch (err) {
        db.exec("ROLLBACK");
        throw err;
      }
    };
    return wrapper;
  }

  close() {
    this._db.close();
  }
}

module.exports = Database;