import { spawn } from 'child_process';
import { existsSync, statSync } from 'fs';

import { getLogger } from './loggers';

const logger = getLogger('gifski');

const sizeLimit = 10 * 2 ** 20;
const roundToEven = (n: number) => Math.ceil(n / 2) * 2;

export default async (inputFilePath: string, targetWidth?: number) => {
  const outputFilePath = inputFilePath.replace(/(?:\.[^.]*)?$/, '.gif')
  try {
    const args = [
      inputFilePath,
      '-o',
      outputFilePath,
      '--fps',
      '12.5',
      '--quiet',
      '--quality',
      '90',
    ];
    if (typeof(targetWidth) === 'number') {
      args.push('--width', roundToEven(targetWidth).toString());
    }
    logger.info(` gifski ${args.join(' ')}`);
    const gifskiSpawn = spawn('gifski', args);
    const gifskiResult = new Promise<string>((resolve, reject) => {
      const sizeChecker = setInterval(() => {
        if (existsSync(outputFilePath) && statSync(outputFilePath).size > sizeLimit) gifskiSpawn.kill();
      }, 5000);
      gifskiSpawn.on('exit', () => {
        clearInterval(sizeChecker);
        if (!existsSync(outputFilePath) || statSync(outputFilePath).size === 0) return reject('no file was created on exit');
        logger.info(`gif conversion succeeded, file path: ${outputFilePath}`);
        resolve(outputFilePath);
      });
    });
    const stderr = [];
    gifskiSpawn.stderr.on('data', errdata => stderr.push(errdata));
    gifskiSpawn.stderr.on('end', () => {
      if (stderr.length !== 0) {
        if (!gifskiSpawn.killed) gifskiSpawn.kill();
        throw Error(Buffer.concat(stderr).toString());
      }
    });
    return await gifskiResult;
  } catch (error) {
    logger.error(`error converting video to gif ${error ? `message: ${error}` : ''}`);
    throw Error('error converting video to gif');
  }
};