const electron = require('electron');
const Queue = require('p-queue');
const sql = require('./sql');
const { remove: removeUserConfig } = require('./user_config');
const { remove: removeEphemeralConfig } = require('./ephemeral_config');

const { ipcMain } = electron;

module.exports = {
  initialize,
};

let initialized = false;

const SQL_CHANNEL_KEY = 'sql-channel';
const ERASE_SQL_KEY = 'erase-sql-key';

const queue = new Queue({ concurrency: 1 });

function initialize() {
  if (initialized) {
    throw new Error('sqlChannels: already initialized!');
  }
  initialized = true;

  ipcMain.on(SQL_CHANNEL_KEY, async (event, jobId, callName, ...args) => {
    try {
      const fn = sql[callName];
      if (!fn) {
        throw new Error(
          `sql channel: ${callName} is not an available function`
        );
      }

      // Note: we queue here to keep multi-query operations atomic. Without it, any
      //   multistage data operation (even within a BEGIN/COMMIT) can become interleaved,
      //   since all requests share one database connection.
      const result = await queue.add(() => fn(...args));
      event.sender.send(`${SQL_CHANNEL_KEY}-done`, jobId, null, result);
    } catch (error) {
      const errorForDisplay = error && error.stack ? error.stack : error;
      console.log(
        `sql channel error with call ${callName}: ${errorForDisplay}`
      );
      if (!event.sender.isDestroyed()) {
        event.sender.send(`${SQL_CHANNEL_KEY}-done`, jobId, errorForDisplay);
      }
    }
  });

  ipcMain.on(ERASE_SQL_KEY, async event => {
    try {
      removeUserConfig();
      removeEphemeralConfig();
      event.sender.send(`${ERASE_SQL_KEY}-done`);
    } catch (error) {
      const errorForDisplay = error && error.stack ? error.stack : error;
      console.log(`sql-erase error: ${errorForDisplay}`);
      event.sender.send(`${ERASE_SQL_KEY}-done`, error);
    }
  });
}