import { exporterFactory } from '../services/exporter.factory';
import { CSV_PATH } from '../config';
import { validateGrafanaUrl } from '../services/api_keys';

import { ExportTask } from '../types';

import * as express from 'express';

import * as _ from 'lodash';

import * as path from 'path';
import * as fs from 'fs';


type TRequest = {
  body: {
    task: ExportTask,
    url: string,
    timeZoneName: string,
  },
};

async function getTasks(req, res) {
  const resp: ExportTask[] = [];
  fs.readdir(CSV_PATH, (err, items) => {
    if(err) {
      console.error(err);
      res.status(500).send(err.message);
    } else {
      for(let item of items) {
        let file = path.parse(item);
        if(file.ext !== '.json') {
          continue;
        }
        // TODO: read async
        let data = fs.readFileSync(path.join(CSV_PATH, item), 'utf8');
        try {
          let status = JSON.parse(data);
          resp.push(status);
        } catch(e) {
          console.log(`Cannot read file /exporter/${item}. if this error doesn't repeat, maybe the file is being updated at the moment`);
        }
      }

      res.status(200).send(resp);
    }
  });
}

async function addTask(req: TRequest, res) {
  const body = req.body;

  const clientUrl = body.url;
  if (_.isEmpty(clientUrl)) {
    res.status(400).send('"url" field is required');
    return;
  }
  const task = body.task;
  if (_.isEmpty(task)) {
    res.status(400).send('"task" field is required');
    return;
  }

  try {
    validateGrafanaUrl(clientUrl);
  } catch(e) {
    res.status(500).send(e.message);
    return;
  }

  const datasourceUrl = `${new URL(clientUrl).origin}/api/ds/query`;

  const from = +task.timeRange.from;
  const to = +task.timeRange.to;
  if (isNaN(from) || isNaN(to)) {
    res.status(400).send('Range error: please fill both "from" and "to" fields');
    return;
  } else if (from >= to) {
    res.status(400).send('Range error: "from" should be less than "to"');
    return;
  }

  const exporter = exporterFactory.getExporter();
  exporter.export(task, datasourceUrl, body.timeZoneName);
  res.status(200).send(`Export process started`);
}

async function deleteTask(req, res) {
  let taskId = req.body.taskId;
  let csvFilePath = path.join(CSV_PATH, `${taskId}.csv`);
  let jsonFilePath = path.join(CSV_PATH, `${taskId}.json`);

  if(fs.existsSync(csvFilePath)) {
    fs.unlink(csvFilePath, err => console.error(err));
  }
  if(fs.existsSync(jsonFilePath)) {
    fs.unlink(jsonFilePath, err => console.error(err));
  }

  res.status(200).send({ status: 'OK' });
}

export const router = express.Router();

router.get('/', getTasks);
router.post('/', addTask);
router.delete('/', deleteTask);