/**
 * Copyright (c) 2015-present, Facebook, Inc.
 *
 * This source code is licensed under the MIT license found in the
 * LICENSE file in the root directory of this source tree.
 */

'use strict';

var React = require('react');

var REACT_ELEMENT_TYPE =
  (typeof Symbol === 'function' && Symbol.for && Symbol.for('react.element')) ||
  0xeac7;

var emptyFunction = require('fbjs/lib/emptyFunction');
var invariant = require('fbjs/lib/invariant');
var warning = require('fbjs/lib/warning');

var SEPARATOR = '.';
var SUBSEPARATOR = ':';

var didWarnAboutMaps = false;

var ITERATOR_SYMBOL = typeof Symbol === 'function' && Symbol.iterator;
var FAUX_ITERATOR_SYMBOL = '@@iterator'; // Before Symbol spec.

function getIteratorFn(maybeIterable) {
  var iteratorFn =
    maybeIterable &&
    ((ITERATOR_SYMBOL && maybeIterable[ITERATOR_SYMBOL]) ||
      maybeIterable[FAUX_ITERATOR_SYMBOL]);
  if (typeof iteratorFn === 'function') {
    return iteratorFn;
  }
}

function escape(key) {
  var escapeRegex = /[=:]/g;
  var escaperLookup = {
    '=': '=0',
    ':': '=2'
  };
  var escapedString = ('' + key).replace(escapeRegex, function(match) {
    return escaperLookup[match];
  });

  return '$' + escapedString;
}

function getComponentKey(component, index) {
  // Do some typechecking here since we call this blindly. We want to ensure
  // that we don't block potential future ES APIs.
  if (component && typeof component === 'object' && component.key != null) {
    // Explicit key
    return escape(component.key);
  }
  // Implicit key determined by the index in the set
  return index.toString(36);
}

function traverseAllChildrenImpl(
  children,
  nameSoFar,
  callback,
  traverseContext
) {
  var type = typeof children;

  if (type === 'undefined' || type === 'boolean') {
    // All of the above are perceived as null.
    children = null;
  }

  if (
    children === null ||
    type === 'string' ||
    type === 'number' ||
    // The following is inlined from ReactElement. This means we can optimize
    // some checks. React Fiber also inlines this logic for similar purposes.
    (type === 'object' && children.$$typeof === REACT_ELEMENT_TYPE)
  ) {
    callback(
      traverseContext,
      children,
      // If it's the only child, treat the name as if it was wrapped in an array
      // so that it's consistent if the number of children grows.
      nameSoFar === '' ? SEPARATOR + getComponentKey(children, 0) : nameSoFar
    );
    return 1;
  }

  var child;
  var nextName;
  var subtreeCount = 0; // Count of children found in the current subtree.
  var nextNamePrefix = nameSoFar === '' ? SEPARATOR : nameSoFar + SUBSEPARATOR;

  if (Array.isArray(children)) {
    for (var i = 0; i < children.length; i++) {
      child = children[i];
      nextName = nextNamePrefix + getComponentKey(child, i);
      subtreeCount += traverseAllChildrenImpl(
        child,
        nextName,
        callback,
        traverseContext
      );
    }
  } else {
    var iteratorFn = getIteratorFn(children);
    if (iteratorFn) {
      if (process.env.NODE_ENV !== 'production') {
        // Warn about using Maps as children
        if (iteratorFn === children.entries) {
          warning(
            didWarnAboutMaps,
            'Using Maps as children is unsupported and will likely yield ' +
              'unexpected results. Convert it to a sequence/iterable of keyed ' +
              'ReactElements instead.'
          );
          didWarnAboutMaps = true;
        }
      }

      var iterator = iteratorFn.call(children);
      var step;
      var ii = 0;
      while (!(step = iterator.next()).done) {
        child = step.value;
        nextName = nextNamePrefix + getComponentKey(child, ii++);
        subtreeCount += traverseAllChildrenImpl(
          child,
          nextName,
          callback,
          traverseContext
        );
      }
    } else if (type === 'object') {
      var addendum = '';
      if (process.env.NODE_ENV !== 'production') {
        addendum =
          ' If you meant to render a collection of children, use an array ' +
          'instead or wrap the object using createFragment(object) from the ' +
          'React add-ons.';
      }
      var childrenString = '' + children;
      invariant(
        false,
        'Objects are not valid as a React child (found: %s).%s',
        childrenString === '[object Object]'
          ? 'object with keys {' + Object.keys(children).join(', ') + '}'
          : childrenString,
        addendum
      );
    }
  }

  return subtreeCount;
}

function traverseAllChildren(children, callback, traverseContext) {
  if (children == null) {
    return 0;
  }

  return traverseAllChildrenImpl(children, '', callback, traverseContext);
}

var userProvidedKeyEscapeRegex = /\/+/g;
function escapeUserProvidedKey(text) {
  return ('' + text).replace(userProvidedKeyEscapeRegex, '$&/');
}

function cloneAndReplaceKey(oldElement, newKey) {
  return React.cloneElement(
    oldElement,
    {key: newKey},
    oldElement.props !== undefined ? oldElement.props.children : undefined
  );
}

var DEFAULT_POOL_SIZE = 10;
var DEFAULT_POOLER = oneArgumentPooler;

var oneArgumentPooler = function(copyFieldsFrom) {
  var Klass = this;
  if (Klass.instancePool.length) {
    var instance = Klass.instancePool.pop();
    Klass.call(instance, copyFieldsFrom);
    return instance;
  } else {
    return new Klass(copyFieldsFrom);
  }
};

var addPoolingTo = function addPoolingTo(CopyConstructor, pooler) {
  // Casting as any so that flow ignores the actual implementation and trusts
  // it to match the type we declared
  var NewKlass = CopyConstructor;
  NewKlass.instancePool = [];
  NewKlass.getPooled = pooler || DEFAULT_POOLER;
  if (!NewKlass.poolSize) {
    NewKlass.poolSize = DEFAULT_POOL_SIZE;
  }
  NewKlass.release = standardReleaser;
  return NewKlass;
};

var standardReleaser = function standardReleaser(instance) {
  var Klass = this;
  invariant(
    instance instanceof Klass,
    'Trying to release an instance into a pool of a different type.'
  );
  instance.destructor();
  if (Klass.instancePool.length < Klass.poolSize) {
    Klass.instancePool.push(instance);
  }
};

var fourArgumentPooler = function fourArgumentPooler(a1, a2, a3, a4) {
  var Klass = this;
  if (Klass.instancePool.length) {
    var instance = Klass.instancePool.pop();
    Klass.call(instance, a1, a2, a3, a4);
    return instance;
  } else {
    return new Klass(a1, a2, a3, a4);
  }
};

function MapBookKeeping(mapResult, keyPrefix, mapFunction, mapContext) {
  this.result = mapResult;
  this.keyPrefix = keyPrefix;
  this.func = mapFunction;
  this.context = mapContext;
  this.count = 0;
}
MapBookKeeping.prototype.destructor = function() {
  this.result = null;
  this.keyPrefix = null;
  this.func = null;
  this.context = null;
  this.count = 0;
};
addPoolingTo(MapBookKeeping, fourArgumentPooler);

function mapSingleChildIntoContext(bookKeeping, child, childKey) {
  var result = bookKeeping.result;
  var keyPrefix = bookKeeping.keyPrefix;
  var func = bookKeeping.func;
  var context = bookKeeping.context;

  var mappedChild = func.call(context, child, bookKeeping.count++);
  if (Array.isArray(mappedChild)) {
    mapIntoWithKeyPrefixInternal(
      mappedChild,
      result,
      childKey,
      emptyFunction.thatReturnsArgument
    );
  } else if (mappedChild != null) {
    if (React.isValidElement(mappedChild)) {
      mappedChild = cloneAndReplaceKey(
        mappedChild,
        // Keep both the (mapped) and old keys if they differ, just as
        // traverseAllChildren used to do for objects as children
        keyPrefix +
          (mappedChild.key && (!child || child.key !== mappedChild.key)
            ? escapeUserProvidedKey(mappedChild.key) + '/'
            : '') +
          childKey
      );
    }
    result.push(mappedChild);
  }
}

function mapIntoWithKeyPrefixInternal(children, array, prefix, func, context) {
  var escapedPrefix = '';
  if (prefix != null) {
    escapedPrefix = escapeUserProvidedKey(prefix) + '/';
  }
  var traverseContext = MapBookKeeping.getPooled(
    array,
    escapedPrefix,
    func,
    context
  );
  traverseAllChildren(children, mapSingleChildIntoContext, traverseContext);
  MapBookKeeping.release(traverseContext);
}

var numericPropertyRegex = /^\d+$/;

var warnedAboutNumeric = false;

function createReactFragment(object) {
  if (typeof object !== 'object' || !object || Array.isArray(object)) {
    warning(
      false,
      'React.addons.createFragment only accepts a single object. Got: %s',
      object
    );
    return object;
  }
  if (React.isValidElement(object)) {
    warning(
      false,
      'React.addons.createFragment does not accept a ReactElement ' +
        'without a wrapper object.'
    );
    return object;
  }

  invariant(
    object.nodeType !== 1,
    'React.addons.createFragment(...): Encountered an invalid child; DOM ' +
      'elements are not valid children of React components.'
  );

  var result = [];

  for (var key in object) {
    if (process.env.NODE_ENV !== 'production') {
      if (!warnedAboutNumeric && numericPropertyRegex.test(key)) {
        warning(
          false,
          'React.addons.createFragment(...): Child objects should have ' +
            'non-numeric keys so ordering is preserved.'
        );
        warnedAboutNumeric = true;
      }
    }
    mapIntoWithKeyPrefixInternal(
      object[key],
      result,
      key,
      emptyFunction.thatReturnsArgument
    );
  }

  return result;
}

module.exports = createReactFragment;