import { getApiKey } from './api_keys';
import {  toDateString, toIsoString } from '../utils';
import { DashboardQuery, ExportProgress, ExportStatus, ExportTask } from '../types';
import { CSV_PATH } from '../config';

import { QueryConfig, queryByConfig } from '@corpglory/tsdb-kit';
// TODO: export QueryType directly from @corpglory/tsdb-kit
import { DataTable, QueryType } from '@corpglory/tsdb-kit/lib/connectors';

import { v4 as uuidv4 } from 'uuid';

import * as moment from 'moment';
import * as csv from 'fast-csv';
import * as fs from 'fs';
import * as path from 'path';
import { URL } from 'url';
import { promisify } from 'util';

import * as _ from 'lodash';

const MS_IN_DAY = 24 * 60 * 60 * 1000;

const DEFAULT_PROGRESS = {
  exportedRowsCount: 0,
  progress: 0,
  status: ExportStatus.EXPORTING,
};

export class Exporter {
  private _task: ExportTask;

  public async export(task: ExportTask, datasourceUrl: string, timeZoneName: string, apiKey: string) {
    try {
      this._task = _.cloneDeep(task);
      this._task.id = uuidv4();
      this._task.progress = _.cloneDeep(DEFAULT_PROGRESS);

      this._validateQueries(task.queries);

      const panelName = _.snakeCase(task.queries[0].panel.title);
      const dateFrom = toDateString(task.timeRange.from, timeZoneName);
      const dateTo = toDateString(task.timeRange.to, timeZoneName);
      this._task.filename = `${panelName}_${task.dashboardUid}_${dateFrom}_${dateTo}`;

      await this._updateProgress();

      const queryConfigs = task.queries.map(
        query =>
          new QueryConfig(
            QueryType.GRAFANA,
            {
              ...query.datasource,
              url: datasourceUrl,
            },
            [query.target]
          )
      );

      let from = +this._task.timeRange.from;
      let to = +this._task.timeRange.to;
      const days = Math.ceil((to - from) / MS_IN_DAY);

      console.log(`Total days: ${days}`);

      const stream = this._initCsvStream();
      console.log("queryConfigs", queryConfigs);
      for(let day = 0; day < days; day++) {
        to = from + MS_IN_DAY;

        console.log(`${day} day: ${from}ms -> ${to}ms`);

        let columns = [];
        let rowsDict = {};

        for(const queryConfig of queryConfigs) {
          const datasourceMetrics: DataTable = await queryByConfig(queryConfig, datasourceUrl, from, to, apiKey);
          columns = this._updateColumns(columns, datasourceMetrics.columns);
          rowsDict = this._updateRows(rowsDict, datasourceMetrics.values, datasourceMetrics.columns);
        }
        const rows = this._getRowsFromDict(rowsDict, columns);
        // const formattedRows = rows.map((row: number[]) => [toIsoString(row[0], timeZoneName), ...row.slice(1)]);

        if(columns.length > 0) {
          this._writeCsv(stream, { columns, rows });
        }
        await this._updateProgress({ status: ExportStatus.EXPORTING, progress: (day + 1) / days });

        from += MS_IN_DAY;
      }
      stream.end();
    } catch (e) {
      await this._updateProgress({ status: ExportStatus.ERROR, errorMessage: e.message });
    }
  }

  private _updateColumns(columnsToUpdate: string[], queriedColumns: string[]): string[] {
    // slice(1) to avoid time fields
    return _.concat(columnsToUpdate, queriedColumns.slice(1));
  }

  private _updateRows(dict, queriedRows: (number | null)[][], queriedColumns: string[]): any {
    const columns = queriedColumns.slice(1);
    for(const rowIdx in queriedRows) {
      const key = queriedRows[rowIdx][0];
      const values = queriedRows[rowIdx].slice(1);
      dict[key] = dict[key] || {};
      for(const valueIdx in values) {
        dict[key][columns[valueIdx]] = values[valueIdx];
      }
    }
    return dict;
  }

  private _getRowsFromDict(dict: any, columns: string[]): (number | null)[][] {
    let keyList = _.orderBy(_.keys(dict));
    let rows = [];
    for(const keyIdx in keyList) {
      const key = keyList[keyIdx];
      rows[keyIdx] = [key];
      for(const column of columns) {
        const value = dict[key][column] || null;
        rows[keyIdx].push(value)
      }
    }
    return rows;
  }

  private _initCsvStream() {
    const csvStream = csv.createWriteStream({ headers: true, delimiter: this._task.csvDelimiter })
      .on('error', async e => await this._updateProgress({ status: ExportStatus.ERROR, errorMessage: e.message }));

    const writableStream = fs.createWriteStream(this._getCsvFilePath());

    csvStream.pipe(writableStream);
    writableStream.on('finish', async () => {
      if(this._task.progress.status !== ExportStatus.ERROR) {
        console.log(`Everything is written to ${this._getCsvFilename()}`);
        await this._updateProgress({ status: ExportStatus.FINISHED, progress: 1 });
      } else {
        console.log(`${this._getCsvFilename()} export is finished with error`);
      }
    });

    return csvStream;
  }

  private async _updateProgress(progress?: Partial<ExportProgress>) {
    try {
      let time = moment().valueOf();

      const data = {
        ...this._task,
        progress: _.assign(this._task.progress, progress, { time }),
      };

      await promisify(fs.writeFile)(this._getJsonFilePath(), JSON.stringify(data), 'utf8');
    } catch(err) {
      console.error(err);
      throw new Error('Can`t write file');
    }
  }

  private _validateQueries(queries: DashboardQuery[]) {
    if(!_.isArray(queries)) {
      throw new Error('`queries` field is required and should be an array');
    }

    for(const query of queries) {
      if(_.isEmpty(query.datasource)) {
        throw new Error('all queries should have a `datasource` field');
      }
      if(_.isEmpty(query.target)) {
        throw new Error('all queries should have a `target` field');
      }
    }
  }

  private _writeCsv(stream, series) {
    for(let row of series.rows) {
      let csvRow = {};
      for(let col in series.columns) {
        csvRow[series.columns[col]] = row[col];
      }
      stream.write(csvRow);
      this._task.progress.exportedRowsCount++;
    }
  }

  private _getCsvFilename(): string {
    return `${this._task.filename}.csv`;
  }

  private _getCsvFilePath(): string {
    let filename = this._getCsvFilename();
    return path.join(CSV_PATH, filename);
  }

  private _getJsonFilePath(): string {
    return path.join(CSV_PATH, `${this._task.id}.json`);
  }
}