'use strict'
const vm = require('vm')
// WePY 2 escapes quotes in :class/:style expressions as if they were string
// contents. WXML expects an expression here, so those escapes are invalid.
// Repair only expressions that fail parsing and become valid after removing
// that extra layer. Preserve valid strings (including escaped apostrophes).
function valid(expr) {
  try { new vm.Script('(' + expr + ')'); return true } catch (_) { return false }
}
module.exports = function fixTemplates(markup) {
  return markup.replace(/\{\{([\s\S]*?)\}\}/g, (whole, expr) => {
    if (valid(expr) || !expr.includes("\\'")) return whole
    const fixed = expr.replace(/\\'/g, "'")
    if (!valid(fixed)) throw new Error('Unparseable generated WXML expression')
    return '{{' + fixed + '}}'
  })
}