var uncurryThis = require('../internals/function-uncurry-this');
var arraySlice = require('../internals/array-slice');

var replace = uncurryThis(''.replace);
var split = uncurryThis(''.split);
var join = uncurryThis([].join);

var TEST = (function (arg) { return String(Error(arg).stack); })('zxcasd');
var V8_OR_CHAKRA_STACK_ENTRY = /\n\s*at [^:]*:[^\n]*/;
var IS_V8_OR_CHAKRA_STACK = V8_OR_CHAKRA_STACK_ENTRY.test(TEST);
var IS_FIREFOX_OR_SAFARI_STACK = /@[^\n]*\n/.test(TEST) && !/zxcasd/.test(TEST);

module.exports = function (stack, dropEntries) {
  if (typeof stack != 'string') return stack;
  if (IS_V8_OR_CHAKRA_STACK) {
    while (dropEntries--) stack = replace(stack, V8_OR_CHAKRA_STACK_ENTRY, '');
  } else if (IS_FIREFOX_OR_SAFARI_STACK) {
    return join(arraySlice(split(stack, '\n'), dropEntries), '\n');
  } return stack;
};