/**

* Copyright 2018 Google Inc. All Rights Reserved.

* Licensed under the Apache License, Version 2.0 (the "License");

* you may not use this file except in compliance with the License.

* You may obtain a copy of the License at

* http://www.apache.org/licenses/LICENSE-2.0

* Unless required by applicable law or agreed to in writing, software

* distributed under the License is distributed on an "AS IS" BASIS,

* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.

* See the License for the specific language governing permissions and

* limitations under the License.

*/

const CACHE = {};

export default function html(statics) {

const str = statics.join('\0');

const tpl = CACHE[str] || (CACHE[str] = build(str));

// eslint-disable-next-line prefer-rest-params

return tpl(this, arguments);

}

const TAG_START = 60;

const TAG_END = 62;

const EQUALS = 61;

const QUOTE_DOUBLE = 34;

const QUOTE_SINGLE = 39;

const TAB = 9;

const NEWLINE = 10;

const RETURN = 13;

const SPACE = 32;

const SLASH = 47;

const MODE_WHITESPACE = 0;

const MODE_TEXT = 1;

const MODE_TAGNAME = 9;

const MODE_ATTRIBUTE = 13;

const MODE_SKIP = 47;

/** Create a template function given strings from a tagged template. */

function build(input) {

let out = 'return ';

let buffer = '';

let mode = MODE_WHITESPACE;

let fieldIndex = 1;

let field = '';

let hasChildren = 0;

let propCount = 0;

let spreads = 0;

let quote = 0;

let spread, slash, charCode, inTag, propName, propHasValue;

function commit() {

if (!inTag) {

if (field || (buffer = buffer.replace(/^\s*\n+\s*|\s*\n+\s*$/g,''))) {

if (hasChildren++) out += ',';

out += field || JSON.stringify(buffer);

}

}

else if (mode === MODE_TAGNAME) {

if (hasChildren++) out += ',';

out += 'h(' + (field || JSON.stringify(buffer));

mode = MODE_WHITESPACE;

}

else if (mode === MODE_ATTRIBUTE || (mode === MODE_WHITESPACE && buffer === '...')) {

if (mode === MODE_WHITESPACE) {

spread = true;

if (!spreads++) {

if (propCount === 0) out += ',Object.assign({},';

else out = out.replace(/,\(\{(.*?)$/, ',Object.assign({},{$1') + '},';

}

out += field + ',{';

propCount++;

}

else if (propName) {

if (!spread) out += ',';

if (propCount === 0) out += '({';

out += propName + ':';

out += field || ((propHasValue || buffer) && JSON.stringify(buffer)) || 'true';

propName = '';

spread = false;

propCount++;

}

propHasValue = false;

}

else if (mode === MODE_WHITESPACE) {

mode = MODE_ATTRIBUTE;

// we're in an attribute name

propName = buffer;

buffer = field = '';

commit();

mode = MODE_WHITESPACE;

}

buffer = field = '';

}

for (let i=0; i<input.length; i++) {

charCode = input.charCodeAt(i);

field = '';

if (charCode === QUOTE_SINGLE || charCode === QUOTE_DOUBLE) {

if (quote === charCode) {

quote = 0;

continue;

}

if (quote === 0) {

quote = charCode;

continue;

}

}

if (charCode === 0) {

if (!inTag) commit();

field = `$_h[${fieldIndex++}]`;

commit();

continue;

}

if (quote === 0) {

switch (charCode) {

case TAG_START:

if (!inTag) {

// commit buffer

commit();

inTag = true;

propCount = 0;

slash = spread = propHasValue = false;

mode = MODE_TAGNAME;

continue;

}

case TAG_END:

if (inTag) {

commit();

if (mode !== MODE_SKIP) {

if (propCount === 0) {

out += ',null';

}

else {

out += '})';

}

}

if (slash) {

out += ')';

}

inTag = false;

propCount = 0;

mode = MODE_TEXT;

continue;

}

case EQUALS:

if (inTag) {

mode = MODE_ATTRIBUTE;

propHasValue = true;

propName = buffer;

buffer = '';

continue;

}

case SLASH:

if (inTag) {

if (!slash) {

slash = true;

// </foo>

if (mode === MODE_TAGNAME && !field && !buffer.trim().length) {

buffer = field = '';

mode = MODE_SKIP;

}

}

continue;

}

case TAB:

case NEWLINE:

case RETURN:

case SPACE:

// <a disabled>

if (inTag) {

commit();

continue;

}

}

}

buffer += input.charAt(i);

}

commit();

return Function('h', '$_h', out);

}