/**
 * Copyright (c) 2013-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.
 *
 * @flow
 */

import type {ReactElement} from 'shared/ReactElementType';

import React from 'react';
import emptyFunction from 'fbjs/lib/emptyFunction';
import emptyObject from 'fbjs/lib/emptyObject';
import hyphenateStyleName from 'fbjs/lib/hyphenateStyleName';
import invariant from 'fbjs/lib/invariant';
import memoizeStringOnly from 'fbjs/lib/memoizeStringOnly';
import warning from 'fbjs/lib/warning';
import checkPropTypes from 'prop-types/checkPropTypes';
import describeComponentFrame from 'shared/describeComponentFrame';
import {ReactDebugCurrentFrame} from 'shared/ReactGlobalSharedState';
import {warnAboutDeprecatedLifecycles} from 'shared/ReactFeatureFlags';
import {
  REACT_FRAGMENT_TYPE,
  REACT_CALL_TYPE,
  REACT_RETURN_TYPE,
  REACT_PORTAL_TYPE,
} from 'shared/ReactSymbols';

import {
  createMarkupForCustomAttribute,
  createMarkupForProperty,
  createMarkupForRoot,
} from './DOMMarkupOperations';
import escapeTextForBrowser from './escapeTextForBrowser';
import {
  Namespaces,
  getIntrinsicNamespace,
  getChildNamespace,
} from '../shared/DOMNamespaces';
import ReactControlledValuePropTypes from '../shared/ReactControlledValuePropTypes';
import assertValidProps from '../shared/assertValidProps';
import dangerousStyleValue from '../shared/dangerousStyleValue';
import isCustomComponent from '../shared/isCustomComponent';
import omittedCloseTags from '../shared/omittedCloseTags';
import warnValidStyle from '../shared/warnValidStyle';
import {validateProperties as validateARIAProperties} from '../shared/ReactDOMInvalidARIAHook';
import {validateProperties as validateInputProperties} from '../shared/ReactDOMNullInputValuePropHook';
import {validateProperties as validateUnknownProperties} from '../shared/ReactDOMUnknownPropertyHook';

// Based on reading the React.Children implementation. TODO: type this somewhere?
type ReactNode = string | number | ReactElement;
type FlatReactChildren = Array<null | ReactNode>;
type toArrayType = (children: mixed) => FlatReactChildren;
const toArray = ((React.Children.toArray: any): toArrayType);

let currentDebugStack;
let currentDebugElementStack;

let getStackAddendum = emptyFunction.thatReturns('');
let describeStackFrame = emptyFunction.thatReturns('');

let validatePropertiesInDevelopment = (type, props) => {};
let setCurrentDebugStack = (stack: Array<Frame>) => {};
let pushElementToDebugStack = (element: ReactElement) => {};
let resetCurrentDebugStack = () => {};

if (__DEV__) {
  validatePropertiesInDevelopment = function(type, props) {
    validateARIAProperties(type, props);
    validateInputProperties(type, props);
    validateUnknownProperties(type, props, /* canUseEventSystem */ false);
  };

  describeStackFrame = function(element): string {
    const source = element._source;
    const type = element.type;
    const name = getComponentName(type);
    const ownerName = null;
    return describeComponentFrame(name, source, ownerName);
  };

  currentDebugStack = null;
  currentDebugElementStack = null;
  setCurrentDebugStack = function(stack: Array<Frame>) {
    const frame: Frame = stack[stack.length - 1];
    currentDebugElementStack = ((frame: any): FrameDev).debugElementStack;
    // We are about to enter a new composite stack, reset the array.
    currentDebugElementStack.length = 0;
    currentDebugStack = stack;
    ReactDebugCurrentFrame.getCurrentStack = getStackAddendum;
  };
  pushElementToDebugStack = function(element: ReactElement) {
    if (currentDebugElementStack !== null) {
      currentDebugElementStack.push(element);
    }
  };
  resetCurrentDebugStack = function() {
    currentDebugElementStack = null;
    currentDebugStack = null;
    ReactDebugCurrentFrame.getCurrentStack = null;
  };
  getStackAddendum = function(): null | string {
    if (currentDebugStack === null) {
      return '';
    }
    let stack = '';
    let debugStack = currentDebugStack;
    for (let i = debugStack.length - 1; i >= 0; i--) {
      const frame: Frame = debugStack[i];
      let debugElementStack = ((frame: any): FrameDev).debugElementStack;
      for (let ii = debugElementStack.length - 1; ii >= 0; ii--) {
        stack += describeStackFrame(debugElementStack[ii]);
      }
    }
    return stack;
  };
}

let didWarnDefaultInputValue = false;
let didWarnDefaultChecked = false;
let didWarnDefaultSelectValue = false;
let didWarnDefaultTextareaValue = false;
let didWarnInvalidOptionChildren = false;
const didWarnAboutNoopUpdateForComponent = {};
const didWarnAboutBadClass = {};
const didWarnAboutDeprecatedWillMount = {};
const didWarnAboutUndefinedDerivedState = {};
const didWarnAboutUninitializedState = {};
const valuePropNames = ['value', 'defaultValue'];
const newlineEatingTags = {
  listing: true,
  pre: true,
  textarea: true,
};

function getComponentName(type) {
  return typeof type === 'string'
    ? type
    : typeof type === 'function' ? type.displayName || type.name : null;
}

// We accept any tag to be rendered but since this gets injected into arbitrary
// HTML, we want to make sure that it's a safe tag.
// http://www.w3.org/TR/REC-xml/#NT-Name
const VALID_TAG_REGEX = /^[a-zA-Z][a-zA-Z:_\.\-\d]*$/; // Simplified subset
const validatedTagCache = {};
function validateDangerousTag(tag) {
  if (!validatedTagCache.hasOwnProperty(tag)) {
    invariant(VALID_TAG_REGEX.test(tag), 'Invalid tag: %s', tag);
    validatedTagCache[tag] = true;
  }
}

const processStyleName = memoizeStringOnly(function(styleName) {
  return hyphenateStyleName(styleName);
});

function createMarkupForStyles(styles): string | null {
  let serialized = '';
  let delimiter = '';
  for (const styleName in styles) {
    if (!styles.hasOwnProperty(styleName)) {
      continue;
    }
    const isCustomProperty = styleName.indexOf('--') === 0;
    const styleValue = styles[styleName];
    if (__DEV__) {
      if (!isCustomProperty) {
        warnValidStyle(styleName, styleValue, getStackAddendum);
      }
    }
    if (styleValue != null) {
      serialized += delimiter + processStyleName(styleName) + ':';
      serialized += dangerousStyleValue(
        styleName,
        styleValue,
        isCustomProperty,
      );

      delimiter = ';';
    }
  }
  return serialized || null;
}

function warnNoop(
  publicInstance: React$Component<any, any>,
  callerName: string,
) {
  if (__DEV__) {
    const constructor = publicInstance.constructor;
    const componentName =
      (constructor && getComponentName(constructor)) || 'ReactClass';
    const warningKey = `${componentName}.${callerName}`;
    if (didWarnAboutNoopUpdateForComponent[warningKey]) {
      return;
    }

    warning(
      false,
      '%s(...): Can only update a mounting component. ' +
        'This usually means you called %s() outside componentWillMount() on the server. ' +
        'This is a no-op.\n\nPlease check the code for the %s component.',
      callerName,
      callerName,
      componentName,
    );
    didWarnAboutNoopUpdateForComponent[warningKey] = true;
  }
}

function shouldConstruct(Component) {
  return Component.prototype && Component.prototype.isReactComponent;
}

function getNonChildrenInnerMarkup(props) {
  const innerHTML = props.dangerouslySetInnerHTML;
  if (innerHTML != null) {
    if (innerHTML.__html != null) {
      return innerHTML.__html;
    }
  } else {
    const content = props.children;
    if (typeof content === 'string' || typeof content === 'number') {
      return escapeTextForBrowser(content);
    }
  }
  return null;
}

function flattenTopLevelChildren(children: mixed): FlatReactChildren {
  if (!React.isValidElement(children)) {
    return toArray(children);
  }
  const element = ((children: any): ReactElement);
  if (element.type !== REACT_FRAGMENT_TYPE) {
    return [element];
  }
  const fragmentChildren = element.props.children;
  if (!React.isValidElement(fragmentChildren)) {
    return toArray(fragmentChildren);
  }
  const fragmentChildElement = ((fragmentChildren: any): ReactElement);
  return [fragmentChildElement];
}

function flattenOptionChildren(children: mixed): string {
  let content = '';
  // Flatten children and warn if they aren't strings or numbers;
  // invalid types are ignored.
  React.Children.forEach(children, function(child) {
    if (child == null) {
      return;
    }
    if (typeof child === 'string' || typeof child === 'number') {
      content += child;
    } else {
      if (__DEV__) {
        if (!didWarnInvalidOptionChildren) {
          didWarnInvalidOptionChildren = true;
          warning(
            false,
            'Only strings and numbers are supported as <option> children.',
          );
        }
      }
    }
  });
  return content;
}

function maskContext(type, context) {
  const contextTypes = type.contextTypes;
  if (!contextTypes) {
    return emptyObject;
  }
  const maskedContext = {};
  for (const contextName in contextTypes) {
    maskedContext[contextName] = context[contextName];
  }
  return maskedContext;
}

function checkContextTypes(typeSpecs, values, location: string) {
  if (__DEV__) {
    checkPropTypes(typeSpecs, values, location, 'Component', getStackAddendum);
  }
}

function processContext(type, context) {
  const maskedContext = maskContext(type, context);
  if (__DEV__) {
    if (type.contextTypes) {
      checkContextTypes(type.contextTypes, maskedContext, 'context');
    }
  }
  return maskedContext;
}

const STYLE = 'style';
const RESERVED_PROPS = {
  children: null,
  dangerouslySetInnerHTML: null,
  suppressContentEditableWarning: null,
  suppressHydrationWarning: null,
};

function createOpenTagMarkup(
  tagVerbatim: string,
  tagLowercase: string,
  props: Object,
  namespace: string,
  makeStaticMarkup: boolean,
  isRootElement: boolean,
): string {
  let ret = '<' + tagVerbatim;

  for (const propKey in props) {
    if (!props.hasOwnProperty(propKey)) {
      continue;
    }
    let propValue = props[propKey];
    if (propValue == null) {
      continue;
    }
    if (propKey === STYLE) {
      propValue = createMarkupForStyles(propValue);
    }
    let markup = null;
    if (isCustomComponent(tagLowercase, props)) {
      if (!RESERVED_PROPS.hasOwnProperty(propKey)) {
        markup = createMarkupForCustomAttribute(propKey, propValue);
      }
    } else {
      markup = createMarkupForProperty(propKey, propValue);
    }
    if (markup) {
      ret += ' ' + markup;
    }
  }

  // For static pages, no need to put React ID and checksum. Saves lots of
  // bytes.
  if (makeStaticMarkup) {
    return ret;
  }

  if (isRootElement) {
    ret += ' ' + createMarkupForRoot();
  }
  return ret;
}

function validateRenderResult(child, type) {
  if (child === undefined) {
    invariant(
      false,
      '%s(...): Nothing was returned from render. This usually means a ' +
        'return statement is missing. Or, to render nothing, ' +
        'return null.',
      getComponentName(type) || 'Component',
    );
  }
}

function resolve(
  child: mixed,
  context: Object,
): {|
  child: mixed,
  context: Object,
|} {
  let element: ReactElement;

  let Component;
  let publicContext;
  let inst, queue, replace;
  let updater;

  let initialState;
  let oldQueue, oldReplace;
  let nextState, dontMutate;
  let partial, partialState;

  let childContext;
  let childContextTypes, contextKey;

  while (React.isValidElement(child)) {
    // Safe because we just checked it's an element.
    element = ((child: any): ReactElement);
    if (__DEV__) {
      pushElementToDebugStack(element);
    }
    Component = element.type;
    if (typeof Component !== 'function') {
      break;
    }
    publicContext = processContext(Component, context);

    queue = [];
    replace = false;
    updater = {
      isMounted: function(publicInstance) {
        return false;
      },
      enqueueForceUpdate: function(publicInstance) {
        if (queue === null) {
          warnNoop(publicInstance, 'forceUpdate');
          return null;
        }
      },
      enqueueReplaceState: function(publicInstance, completeState) {
        replace = true;
        queue = [completeState];
      },
      enqueueSetState: function(publicInstance, currentPartialState) {
        if (queue === null) {
          warnNoop(publicInstance, 'setState');
          return null;
        }
        queue.push(currentPartialState);
      },
    };

    if (shouldConstruct(Component)) {
      inst = new Component(element.props, publicContext, updater);

      if (typeof Component.getDerivedStateFromProps === 'function') {
        if (__DEV__) {
          if (inst.state === null || inst.state === undefined) {
            const componentName = getComponentName(Component) || 'Unknown';
            if (!didWarnAboutUninitializedState[componentName]) {
              warning(
                false,
                '%s: Did not properly initialize state during construction. ' +
                  'Expected state to be an object, but it was %s.',
                componentName,
                inst.state === null ? 'null' : 'undefined',
              );
              didWarnAboutUninitializedState[componentName] = true;
            }
          }
        }

        partialState = Component.getDerivedStateFromProps.call(
          null,
          element.props,
          inst.state,
        );

        if (__DEV__) {
          if (partialState === undefined) {
            const componentName = getComponentName(Component) || 'Unknown';
            if (!didWarnAboutUndefinedDerivedState[componentName]) {
              warning(
                false,
                '%s.getDerivedStateFromProps(): A valid state object (or null) must be returned. ' +
                  'You have returned undefined.',
                componentName,
              );
              didWarnAboutUndefinedDerivedState[componentName] = true;
            }
          }
        }

        if (partialState != null) {
          inst.state = Object.assign({}, inst.state, partialState);
        }
      }
    } else {
      if (__DEV__) {
        if (
          Component.prototype &&
          typeof Component.prototype.render === 'function'
        ) {
          const componentName = getComponentName(Component) || 'Unknown';

          if (!didWarnAboutBadClass[componentName]) {
            warning(
              false,
              "The <%s /> component appears to have a render method, but doesn't extend React.Component. " +
                'This is likely to cause errors. Change %s to extend React.Component instead.',
              componentName,
              componentName,
            );
            didWarnAboutBadClass[componentName] = true;
          }
        }
      }
      inst = Component(element.props, publicContext, updater);
      if (inst == null || inst.render == null) {
        child = inst;
        validateRenderResult(child, Component);
        continue;
      }
    }

    inst.props = element.props;
    inst.context = publicContext;
    inst.updater = updater;

    initialState = inst.state;
    if (initialState === undefined) {
      inst.state = initialState = null;
    }
    if (inst.UNSAFE_componentWillMount || inst.componentWillMount) {
      if (inst.componentWillMount) {
        if (__DEV__) {
          if (warnAboutDeprecatedLifecycles) {
            const componentName = getComponentName(Component) || 'Unknown';

            if (!didWarnAboutDeprecatedWillMount[componentName]) {
              warning(
                false,
                '%s: componentWillMount() is deprecated and will be ' +
                  'removed in the next major version. Read about the motivations ' +
                  'behind this change: ' +
                  'https://fb.me/react-async-component-lifecycle-hooks' +
                  '\n\n' +
                  'As a temporary workaround, you can rename to ' +
                  'UNSAFE_componentWillMount instead.',
                componentName,
              );
              didWarnAboutDeprecatedWillMount[componentName] = true;
            }
          }
        }

        inst.componentWillMount();
      } else {
        inst.UNSAFE_componentWillMount();
      }
      if (queue.length) {
        oldQueue = queue;
        oldReplace = replace;
        queue = null;
        replace = false;

        if (oldReplace && oldQueue.length === 1) {
          inst.state = oldQueue[0];
        } else {
          nextState = oldReplace ? oldQueue[0] : inst.state;
          dontMutate = true;
          for (let i = oldReplace ? 1 : 0; i < oldQueue.length; i++) {
            partial = oldQueue[i];
            partialState =
              typeof partial === 'function'
                ? partial.call(inst, nextState, element.props, publicContext)
                : partial;
            if (partialState != null) {
              if (dontMutate) {
                dontMutate = false;
                nextState = Object.assign({}, nextState, partialState);
              } else {
                Object.assign(nextState, partialState);
              }
            }
          }
          inst.state = nextState;
        }
      } else {
        queue = null;
      }
    }
    child = inst.render();

    if (__DEV__) {
      if (child === undefined && inst.render._isMockFunction) {
        // This is probably bad practice. Consider warning here and
        // deprecating this convenience.
        child = null;
      }
    }
    validateRenderResult(child, Component);

    if (typeof inst.getChildContext === 'function') {
      childContextTypes = Component.childContextTypes;
      if (typeof childContextTypes === 'object') {
        childContext = inst.getChildContext();
        for (contextKey in childContext) {
          invariant(
            contextKey in childContextTypes,
            '%s.getChildContext(): key "%s" is not defined in childContextTypes.',
            getComponentName(Component) || 'Unknown',
            contextKey,
          );
        }
      } else {
        warning(
          false,
          '%s.getChildContext(): childContextTypes must be defined in order to ' +
            'use getChildContext().',
          getComponentName(Component) || 'Unknown',
        );
      }
    }
    if (childContext) {
      context = Object.assign({}, context, childContext);
    }
  }
  return {child, context};
}

type Frame = {
  domNamespace: string,
  children: FlatReactChildren,
  childIndex: number,
  context: Object,
  footer: string,
};

type FrameDev = Frame & {
  debugElementStack: Array<ReactElement>,
};

class ReactDOMServerRenderer {
  stack: Array<Frame>;
  exhausted: boolean;
  // TODO: type this more strictly:
  currentSelectValue: any;
  previousWasTextNode: boolean;
  makeStaticMarkup: boolean;

  constructor(children: mixed, makeStaticMarkup: boolean) {
    const flatChildren = flattenTopLevelChildren(children);

    const topFrame: Frame = {
      // Assume all trees start in the HTML namespace (not totally true, but
      // this is what we did historically)
      domNamespace: Namespaces.html,
      children: flatChildren,
      childIndex: 0,
      context: emptyObject,
      footer: '',
    };
    if (__DEV__) {
      ((topFrame: any): FrameDev).debugElementStack = [];
    }
    this.stack = [topFrame];
    this.exhausted = false;
    this.currentSelectValue = null;
    this.previousWasTextNode = false;
    this.makeStaticMarkup = makeStaticMarkup;
  }

  read(bytes: number): string | null {
    if (this.exhausted) {
      return null;
    }

    let out = '';
    while (out.length < bytes) {
      if (this.stack.length === 0) {
        this.exhausted = true;
        break;
      }
      const frame: Frame = this.stack[this.stack.length - 1];
      if (frame.childIndex >= frame.children.length) {
        const footer = frame.footer;
        out += footer;
        if (footer !== '') {
          this.previousWasTextNode = false;
        }
        this.stack.pop();
        if (frame.tag === 'select') {
          this.currentSelectValue = null;
        }
        continue;
      }
      const child = frame.children[frame.childIndex++];
      if (__DEV__) {
        setCurrentDebugStack(this.stack);
      }
      out += this.render(child, frame.context, frame.domNamespace);
      if (__DEV__) {
        // TODO: Handle reentrant server render calls. This doesn't.
        resetCurrentDebugStack();
      }
    }
    return out;
  }

  render(
    child: ReactNode | null,
    context: Object,
    parentNamespace: string,
  ): string {
    if (typeof child === 'string' || typeof child === 'number') {
      const text = '' + child;
      if (text === '') {
        return '';
      }
      if (this.makeStaticMarkup) {
        return escapeTextForBrowser(text);
      }
      if (this.previousWasTextNode) {
        return '<!-- -->' + escapeTextForBrowser(text);
      }
      this.previousWasTextNode = true;
      return escapeTextForBrowser(text);
    } else {
      let nextChild;
      ({child: nextChild, context} = resolve(child, context));
      if (nextChild === null || nextChild === false) {
        return '';
      } else if (!React.isValidElement(nextChild)) {
        if (nextChild != null && nextChild.$$typeof != null) {
          // Catch unexpected special types early.
          const $$typeof = nextChild.$$typeof;
          invariant(
            $$typeof !== REACT_PORTAL_TYPE,
            'Portals are not currently supported by the server renderer. ' +
              'Render them conditionally so that they only appear on the client render.',
          );
          // Catch-all to prevent an infinite loop if React.Children.toArray() supports some new type.
          invariant(
            false,
            'Unknown element-like object type: %s. This is likely a bug in React. ' +
              'Please file an issue.',
            ($$typeof: any).toString(),
          );
        }
        const nextChildren = toArray(nextChild);
        const frame: Frame = {
          domNamespace: parentNamespace,
          children: nextChildren,
          childIndex: 0,
          context: context,
          footer: '',
        };
        if (__DEV__) {
          ((frame: any): FrameDev).debugElementStack = [];
        }
        this.stack.push(frame);
        return '';
      }
      // Safe because we just checked it's an element.
      const nextElement = ((nextChild: any): ReactElement);
      const elementType = nextElement.type;
      switch (elementType) {
        case REACT_FRAGMENT_TYPE:
          const nextChildren = toArray(
            ((nextChild: any): ReactElement).props.children,
          );
          const frame: Frame = {
            domNamespace: parentNamespace,
            children: nextChildren,
            childIndex: 0,
            context: context,
            footer: '',
          };
          if (__DEV__) {
            ((frame: any): FrameDev).debugElementStack = [];
          }
          this.stack.push(frame);
          return '';
        case REACT_CALL_TYPE:
        case REACT_RETURN_TYPE:
          invariant(
            false,
            'The experimental Call and Return types are not currently ' +
              'supported by the server renderer.',
          );
        // eslint-disable-next-line-no-fallthrough
        default:
          return this.renderDOM(nextElement, context, parentNamespace);
      }
    }
  }

  renderDOM(
    element: ReactElement,
    context: Object,
    parentNamespace: string,
  ): string {
    const tag = element.type.toLowerCase();

    let namespace = parentNamespace;
    if (parentNamespace === Namespaces.html) {
      namespace = getIntrinsicNamespace(tag);
    }

    if (__DEV__) {
      if (namespace === Namespaces.html) {
        // Should this check be gated by parent namespace? Not sure we want to
        // allow <SVG> or <mATH>.
        warning(
          tag === element.type,
          '<%s /> is using uppercase HTML. Always use lowercase HTML tags ' +
            'in React.',
          element.type,
        );
      }
    }

    validateDangerousTag(tag);

    let props = element.props;
    if (tag === 'input') {
      if (__DEV__) {
        ReactControlledValuePropTypes.checkPropTypes(
          'input',
          props,
          getStackAddendum,
        );

        if (
          props.checked !== undefined &&
          props.defaultChecked !== undefined &&
          !didWarnDefaultChecked
        ) {
          warning(
            false,
            '%s contains an input of type %s with both checked and defaultChecked props. ' +
              'Input elements must be either controlled or uncontrolled ' +
              '(specify either the checked prop, or the defaultChecked prop, but not ' +
              'both). Decide between using a controlled or uncontrolled input ' +
              'element and remove one of these props. More info: ' +
              'https://fb.me/react-controlled-components',
            'A component',
            props.type,
          );
          didWarnDefaultChecked = true;
        }
        if (
          props.value !== undefined &&
          props.defaultValue !== undefined &&
          !didWarnDefaultInputValue
        ) {
          warning(
            false,
            '%s contains an input of type %s with both value and defaultValue props. ' +
              'Input elements must be either controlled or uncontrolled ' +
              '(specify either the value prop, or the defaultValue prop, but not ' +
              'both). Decide between using a controlled or uncontrolled input ' +
              'element and remove one of these props. More info: ' +
              'https://fb.me/react-controlled-components',
            'A component',
            props.type,
          );
          didWarnDefaultInputValue = true;
        }
      }

      props = Object.assign(
        {
          type: undefined,
        },
        props,
        {
          defaultChecked: undefined,
          defaultValue: undefined,
          value: props.value != null ? props.value : props.defaultValue,
          checked: props.checked != null ? props.checked : props.defaultChecked,
        },
      );
    } else if (tag === 'textarea') {
      if (__DEV__) {
        ReactControlledValuePropTypes.checkPropTypes(
          'textarea',
          props,
          getStackAddendum,
        );
        if (
          props.value !== undefined &&
          props.defaultValue !== undefined &&
          !didWarnDefaultTextareaValue
        ) {
          warning(
            false,
            'Textarea elements must be either controlled or uncontrolled ' +
              '(specify either the value prop, or the defaultValue prop, but not ' +
              'both). Decide between using a controlled or uncontrolled textarea ' +
              'and remove one of these props. More info: ' +
              'https://fb.me/react-controlled-components',
          );
          didWarnDefaultTextareaValue = true;
        }
      }

      let initialValue = props.value;
      if (initialValue == null) {
        let defaultValue = props.defaultValue;
        // TODO (yungsters): Remove support for children content in <textarea>.
        let textareaChildren = props.children;
        if (textareaChildren != null) {
          if (__DEV__) {
            warning(
              false,
              'Use the `defaultValue` or `value` props instead of setting ' +
                'children on <textarea>.',
            );
          }
          invariant(
            defaultValue == null,
            'If you supply `defaultValue` on a <textarea>, do not pass children.',
          );
          if (Array.isArray(textareaChildren)) {
            invariant(
              textareaChildren.length <= 1,
              '<textarea> can only have at most one child.',
            );
            textareaChildren = textareaChildren[0];
          }

          defaultValue = '' + textareaChildren;
        }
        if (defaultValue == null) {
          defaultValue = '';
        }
        initialValue = defaultValue;
      }

      props = Object.assign({}, props, {
        value: undefined,
        children: '' + initialValue,
      });
    } else if (tag === 'select') {
      if (__DEV__) {
        ReactControlledValuePropTypes.checkPropTypes(
          'select',
          props,
          getStackAddendum,
        );

        for (let i = 0; i < valuePropNames.length; i++) {
          const propName = valuePropNames[i];
          if (props[propName] == null) {
            continue;
          }
          const isArray = Array.isArray(props[propName]);
          if (props.multiple && !isArray) {
            warning(
              false,
              'The `%s` prop supplied to <select> must be an array if ' +
                '`multiple` is true.%s',
              propName,
              '', // getDeclarationErrorAddendum(),
            );
          } else if (!props.multiple && isArray) {
            warning(
              false,
              'The `%s` prop supplied to <select> must be a scalar ' +
                'value if `multiple` is false.%s',
              propName,
              '', // getDeclarationErrorAddendum(),
            );
          }
        }

        if (
          props.value !== undefined &&
          props.defaultValue !== undefined &&
          !didWarnDefaultSelectValue
        ) {
          warning(
            false,
            'Select elements must be either controlled or uncontrolled ' +
              '(specify either the value prop, or the defaultValue prop, but not ' +
              'both). Decide between using a controlled or uncontrolled select ' +
              'element and remove one of these props. More info: ' +
              'https://fb.me/react-controlled-components',
          );
          didWarnDefaultSelectValue = true;
        }
      }
      this.currentSelectValue =
        props.value != null ? props.value : props.defaultValue;
      props = Object.assign({}, props, {
        value: undefined,
      });
    } else if (tag === 'option') {
      let selected = null;
      const selectValue = this.currentSelectValue;
      const optionChildren = flattenOptionChildren(props.children);
      if (selectValue != null) {
        let value;
        if (props.value != null) {
          value = props.value + '';
        } else {
          value = optionChildren;
        }
        selected = false;
        if (Array.isArray(selectValue)) {
          // multiple
          for (let j = 0; j < selectValue.length; j++) {
            if ('' + selectValue[j] === value) {
              selected = true;
              break;
            }
          }
        } else {
          selected = '' + selectValue === value;
        }

        props = Object.assign(
          {
            selected: undefined,
            children: undefined,
          },
          props,
          {
            selected: selected,
            children: optionChildren,
          },
        );
      }
    }

    if (__DEV__) {
      validatePropertiesInDevelopment(tag, props);
    }

    assertValidProps(tag, props, getStackAddendum);

    let out = createOpenTagMarkup(
      element.type,
      tag,
      props,
      namespace,
      this.makeStaticMarkup,
      this.stack.length === 1,
    );
    let footer = '';
    if (omittedCloseTags.hasOwnProperty(tag)) {
      out += '/>';
    } else {
      out += '>';
      footer = '</' + element.type + '>';
    }
    let children;
    const innerMarkup = getNonChildrenInnerMarkup(props);
    if (innerMarkup != null) {
      children = [];
      if (newlineEatingTags[tag] && innerMarkup.charAt(0) === '\n') {
        // text/html ignores the first character in these tags if it's a newline
        // Prefer to break application/xml over text/html (for now) by adding
        // a newline specifically to get eaten by the parser. (Alternately for
        // textareas, replacing "^\n" with "\r\n" doesn't get eaten, and the first
        // \r is normalized out by HTMLTextAreaElement#value.)
        // See: <http://www.w3.org/TR/html-polyglot/#newlines-in-textarea-and-pre>
        // See: <http://www.w3.org/TR/html5/syntax.html#element-restrictions>
        // See: <http://www.w3.org/TR/html5/syntax.html#newlines>
        // See: Parsing of "textarea" "listing" and "pre" elements
        //  from <http://www.w3.org/TR/html5/syntax.html#parsing-main-inbody>
        out += '\n';
      }
      out += innerMarkup;
    } else {
      children = toArray(props.children);
    }
    const frame = {
      domNamespace: getChildNamespace(parentNamespace, element.type),
      tag,
      children,
      childIndex: 0,
      context: context,
      footer: footer,
    };
    if (__DEV__) {
      ((frame: any): FrameDev).debugElementStack = [];
    }
    this.stack.push(frame);
    this.previousWasTextNode = false;
    return out;
  }
}

export default ReactDOMServerRenderer;
