import invariant from 'invariant'

invariant(condition, message_format, param1)

'use strict';

/**
 * Use invariant() to assert state which your program assumes to be true.
 *
 * Provide sprintf-style format (only %s is supported) and arguments
 * to provide information about what broke and what you were
 * expecting.
 *
 * The invariant message will be stripped in production, but the invariant
 * will remain to ensure logic does not differ in production.
 */

var NODE_ENV = process.env.NODE_ENV;

// 最多6个参数值，超出的打印为 undefined，这样的实现有点丑...
var invariant = function(condition, format, a, b, c, d, e, f) {
  if (NODE_ENV !== 'production') {
    if (format === undefined) {
      throw new Error('invariant requires an error message argument');
    }
  }

  if (!condition) {
    var error;
    if (format === undefined) {
      error = new Error(
        'Minified exception occurred; use the non-minified dev environment ' +
        'for the full error message and additional helpful warnings.'
      );
    } else {
      var args = [a, b, c, d, e, f];
      var argIndex = 0;
      error = new Error(
        format.replace(/%s/g, function() { return args[argIndex++]; })
      );
      error.name = 'Invariant Violation';
    }

    error.framesToPop = 1; // we don't care about invariant's own frame
    throw error;
  }
};

module.exports = invariant;