import {Map, WeakMap} from '../shared/poorlyfills.js';

import {G, UIDC, VOID_ELEMENTS} from '../shared/constants.js';

import Updates from '../objects/Updates.js';

import {

createFragment,

importNode,

unique,

TemplateMap

} from '../shared/utils.js';

import {selfClosing} from '../shared/re.js';

// a weak collection of contexts that

// are already known to hyperHTML

const bewitched = new WeakMap;

// all unique template literals

const templates = TemplateMap();

// better known as hyper.bind(node), the render is

// the main tag function in charge of fully upgrading

// or simply updating, contexts used as hyperHTML targets.

// The `this` context is either a regular DOM node or a fragment.

function render(template) {

const wicked = bewitched.get(this);

if (wicked && wicked.template === unique(template)) {

update.apply(wicked.updates, arguments);

} else {

upgrade.apply(this, arguments);

}

return this;

}

// an upgrade is in charge of collecting template info,

// parse it once, if unknown, to map all interpolations

// as single DOM callbacks, relate such template

// to the current context, and render it after cleaning the context up

function upgrade(template) {

template = unique(template);

const info = templates.get(template) ||

createTemplate.call(this, template);

const fragment = importNode(this.ownerDocument, info.fragment);

const updates = Updates.create(fragment, info.paths);

bewitched.set(this, {template, updates});

update.apply(updates, arguments);

this.textContent = '';

this.appendChild(fragment);

}

// an update simply loops over all mapped DOM operations

function update() {

const length = arguments.length;

for (let i = 1; i < length; i++) {

this[i - 1](arguments[i]);

}

}

// a template can be used to create a document fragment

// aware of all interpolations and with a list

// of paths used to find once those nodes that need updates,

// no matter if these are attributes, text nodes, or regular one

function createTemplate(template) {

const paths = [];

const html = template.join(UIDC).replace(SC_RE, SC_PLACE);

const fragment = createFragment(this, html);

Updates.find(fragment, paths, template.slice());

const info = {fragment, paths};

templates.set(template, info);

return info;

}

// some node could be special though, like a custom element

// with a self closing tag, which should work through these changes.

const SC_RE = selfClosing;

const SC_PLACE = ($0, $1, $2) => {

return VOID_ELEMENTS.test($1) ? $0 : ('<' + $1 + $2 + '></' + $1 + '>');

};

export default render;