// TODO: This module should be ElementChildren, and should use named exports.

import React from 'react';

/**

* Iterates through children that are typically specified as `props.children`,

* but only maps over children that are "valid components".

*

* The mapFunction provided index will be normalised to the components mapped,

* so an invalid component would not increase the index.

*

* @param {?*} children Children tree container.

* @param {function(*, int)} func.

* @param {*} context Context for func.

* @return {object} Object containing the ordered map of results.

*/

function map(children, func, context) {

let index = 0;

return React.Children.map(children, child => {

if (!React.isValidElement(child)) {

return child;

}

return func.call(context, child, index++);

});

}

/**

* Iterates through children that are "valid components".

*

* The provided forEachFunc(child, index) will be called for each

* leaf child with the index reflecting the position relative to "valid components".

*

* @param {?*} children Children tree container.

* @param {function(*, int)} func.

* @param {*} context Context for context.

*/

function forEach(children, func, context) {

let index = 0;

React.Children.forEach(children, child => {

if (!React.isValidElement(child)) {

return;

}

func.call(context, child, index++);

});

}

/**

* Count the number of "valid components" in the Children container.

*

* @param {?*} children Children tree container.

* @returns {number}

*/

function count(children) {

let result = 0;

React.Children.forEach(children, child => {

if (!React.isValidElement(child)) {

return;

}

++result;

});

return result;

}

/**

* Finds children that are typically specified as `props.children`,

* but only iterates over children that are "valid components".

*

* The provided forEachFunc(child, index) will be called for each

* leaf child with the index reflecting the position relative to "valid components".

*

* @param {?*} children Children tree container.

* @param {function(*, int)} func.

* @param {*} context Context for func.

* @returns {array} of children that meet the func return statement

*/

function filter(children, func, context) {

let index = 0;

let result = [];

React.Children.forEach(children, child => {

if (!React.isValidElement(child)) {

return;

}

if (func.call(context, child, index++)) {

result.push(child);

}

});

return result;

}

function find(children, func, context) {

let index = 0;

let result = undefined;

React.Children.forEach(children, child => {

if (result) {

return;

}

if (!React.isValidElement(child)) {

return;

}

if (func.call(context, child, index++)) {

result = child;

}

});

return result;

}

function every(children, func, context) {

let index = 0;

let result = true;

React.Children.forEach(children, child => {

if (!result) {

return;

}

if (!React.isValidElement(child)) {

return;

}

if (!func.call(context, child, index++)) {

result = false;

}

});

return result;

}

function some(children, func, context) {

let index = 0;

let result = false;

React.Children.forEach(children, child => {

if (result) {

return;

}

if (!React.isValidElement(child)) {

return;

}

if (func.call(context, child, index++)) {

result = true;

}

});

return result;

}

function toArray(children) {

const result = [];

React.Children.forEach(children, child => {

if (!React.isValidElement(child)) {

return;

}

result.push(child);

});

return result;

}

export default {

map,

forEach,

count,

find,

filter,

every,

some,

toArray,

};