import fs from 'node:fs';
import path from 'node:path';
import postcss from 'postcss';

function isInsideRoot(rule) {
  return rule.selectors.length !== 1 || rule.selectors[0] !== ':root' || rule.parent.type !== 'root';
}

function isVariableDeclaration(decl) {
  return Boolean(decl.value) && decl.prop.startsWith('--');
}

function parse(css, options) {
  const root = postcss.parse(css, {
    from: options.from,
    parser: options.parser,
  });

  const variables = {};
  root.walkRules((rule) => {
    if (isInsideRoot(rule)) {
      return;
    }

    rule.each((decl) => {
      if (isVariableDeclaration(decl)) {
        const name = decl.prop.slice(2);
        variables[name] = decl.value;
      }
    });
  });
  return variables;
}

function parseFileSync(fileName, options) {
  const css = fs.readFileSync(fileName, 'utf-8');
  return parse(css, { ...options, from: fileName });
}

function themeReplacements() {
  const fileName = path.resolve(__dirname, '../theme/theme.less');
  const variables = parseFileSync(fileName, {
    parser: 'postcss-scss',
  });
  return Object.entries(variables).reduce((memo, e) => {
    memo[`var(--${e[0]})`] = e[1];
    return memo;
  }, {});
}

function normalize(config) {
  const r = {};
  Object.keys(config).forEach((firKey) => {
    const colorVal = config[firKey];
    const key = firKey.replace('var(--', '').replace(')', '').replace(/-/g, '_');
    if (Array.isArray(colorVal)) {
      colorVal.forEach((v) => {
        r[`${firKey}_${v}`] = `var(--${firKey.replace(/_/g, '-')}-${v})`;
      });
    } else {
      r[key] = firKey;
    }
  });
  return r;
}

export { themeReplacements, normalize, borderReplacements, widthReplacements };