import * as fs from 'fs';

import { createTheme } from '@grafana/data';
import { darkThemeVarsTemplate } from '@grafana/ui/src/themes/_variables.dark.scss.tmpl';
import { lightThemeVarsTemplate } from '@grafana/ui/src/themes/_variables.light.scss.tmpl';
import { commonThemeVarsTemplate } from '@grafana/ui/src/themes/_variables.scss.tmpl';

const darkThemeVariablesPath = __dirname + '/../../public/sass/_variables.dark.generated.scss';
const lightThemeVariablesPath = __dirname + '/../../public/sass/_variables.light.generated.scss';
const defaultThemeVariablesPath = __dirname + '/../../public/sass/_variables.generated.scss';

const darkThemeJsonPath = __dirname + '/../../public/sass/theme.dark.generated.json';
const lightThemeJsonPath = __dirname + '/../../public/sass/theme.light.generated.json';

const writeVariablesFile = async (path: string, data: string) => {
  return new Promise((resolve, reject) => {
    fs.writeFile(path, data, (e) => {
      if (e) {
        reject(e);
      } else {
        resolve(data);
      }
    });
  });
};

const generateSassVariableFiles = async () => {
  const darkTheme = createTheme();
  const lightTheme = createTheme({ colors: { mode: 'light' } });

  try {
    await Promise.all([
      writeVariablesFile(darkThemeVariablesPath, darkThemeVarsTemplate(darkTheme)),
      writeVariablesFile(lightThemeVariablesPath, lightThemeVarsTemplate(lightTheme)),
      writeVariablesFile(defaultThemeVariablesPath, commonThemeVarsTemplate(darkTheme)),
    ]);
    console.log('\nSASS variable files generated');
  } catch (error) {
    console.error('\nWriting SASS variable files failed', error);
    process.exit(1);
  }

  try {
    const darkJson = JSON.stringify(darkTheme, null, 2);
    const lightJson = JSON.stringify(lightTheme, null, 2);

    writeVariablesFile(darkThemeJsonPath, darkJson);
    writeVariablesFile(lightThemeJsonPath, lightJson);
  } catch (error) {
    console.error('\nWriting JSON variable files failed', error);
  }
};

generateSassVariableFiles();