‘use strict’;

// // Allowed token characters: // // ‘!’, ‘#’, ‘$’, ‘%’, ‘&’, ”‘, ’*‘, ’+‘, ’-‘, // ’.‘, 0-9, A-Z, ’^‘, ’_’, ‘`’, a-z, ‘|’, ‘~’ // // tokenChars === 0 // ‘ ’ // tokenChars === 1 // ‘!’ // tokenChars === 0 // ‘“’ // … // // prettier-ignore const tokenChars = [

0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, // 0 - 15
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, // 16 - 31
0, 1, 0, 1, 1, 1, 1, 1, 0, 0, 1, 1, 0, 1, 1, 0, // 32 - 47
1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0, 0, 0, 0, 0, // 48 - 63
0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, // 64 - 79
1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0, 0, 1, 1, // 80 - 95
1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, // 96 - 111
1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 1, 0, 1, 0 // 112 - 127

];

/**

* Adds an offer to the map of extension offers or a parameter to the map of
* parameters.
*
* @param {Object} dest The map of extension offers or parameters
* @param {String} name The extension or parameter name
* @param {(Object|Boolean|String)} elem The extension parameters or the
*     parameter value
* @private
*/

function push(dest, name, elem) {

if (dest[name] === undefined) dest[name] = [elem];
else dest[name].push(elem);

}

/**

* Parses the `Sec-WebSocket-Extensions` header into an object.
*
* @param {String} header The field value of the header
* @return {Object} The parsed object
* @public
*/

function parse(header) {

const offers = Object.create(null);

if (header === undefined || header === '') return offers;

let params = Object.create(null);
let mustUnescape = false;
let isEscaping = false;
let inQuotes = false;
let extensionName;
let paramName;
let start = -1;
let end = -1;
let i = 0;

for (; i < header.length; i++) {
  const code = header.charCodeAt(i);

  if (extensionName === undefined) {
    if (end === -1 && tokenChars[code] === 1) {
      if (start === -1) start = i;
    } else if (code === 0x20 /* ' ' */ || code === 0x09 /* '\t' */) {
      if (end === -1 && start !== -1) end = i;
    } else if (code === 0x3b /* ';' */ || code === 0x2c /* ',' */) {
      if (start === -1) {
        throw new SyntaxError(`Unexpected character at index ${i}`);
      }

      if (end === -1) end = i;
      const name = header.slice(start, end);
      if (code === 0x2c) {
        push(offers, name, params);
        params = Object.create(null);
      } else {
        extensionName = name;
      }

      start = end = -1;
    } else {
      throw new SyntaxError(`Unexpected character at index ${i}`);
    }
  } else if (paramName === undefined) {
    if (end === -1 && tokenChars[code] === 1) {
      if (start === -1) start = i;
    } else if (code === 0x20 || code === 0x09) {
      if (end === -1 && start !== -1) end = i;
    } else if (code === 0x3b || code === 0x2c) {
      if (start === -1) {
        throw new SyntaxError(`Unexpected character at index ${i}`);
      }

      if (end === -1) end = i;
      push(params, header.slice(start, end), true);
      if (code === 0x2c) {
        push(offers, extensionName, params);
        params = Object.create(null);
        extensionName = undefined;
      }

      start = end = -1;
    } else if (code === 0x3d /* '=' */ && start !== -1 && end === -1) {
      paramName = header.slice(start, i);
      start = end = -1;
    } else {
      throw new SyntaxError(`Unexpected character at index ${i}`);
    }
  } else {
    //
    // The value of a quoted-string after unescaping must conform to the
    // token ABNF, so only token characters are valid.
    // Ref: https://tools.ietf.org/html/rfc6455#section-9.1
    //
    if (isEscaping) {
      if (tokenChars[code] !== 1) {
        throw new SyntaxError(`Unexpected character at index ${i}`);
      }
      if (start === -1) start = i;
      else if (!mustUnescape) mustUnescape = true;
      isEscaping = false;
    } else if (inQuotes) {
      if (tokenChars[code] === 1) {
        if (start === -1) start = i;
      } else if (code === 0x22 /* '"' */ && start !== -1) {
        inQuotes = false;
        end = i;
      } else if (code === 0x5c /* '\' */) {
        isEscaping = true;
      } else {
        throw new SyntaxError(`Unexpected character at index ${i}`);
      }
    } else if (code === 0x22 && header.charCodeAt(i - 1) === 0x3d) {
      inQuotes = true;
    } else if (end === -1 && tokenChars[code] === 1) {
      if (start === -1) start = i;
    } else if (start !== -1 && (code === 0x20 || code === 0x09)) {
      if (end === -1) end = i;
    } else if (code === 0x3b || code === 0x2c) {
      if (start === -1) {
        throw new SyntaxError(`Unexpected character at index ${i}`);
      }

      if (end === -1) end = i;
      let value = header.slice(start, end);
      if (mustUnescape) {
        value = value.replace(/\\/g, '');
        mustUnescape = false;
      }
      push(params, paramName, value);
      if (code === 0x2c) {
        push(offers, extensionName, params);
        params = Object.create(null);
        extensionName = undefined;
      }

      paramName = undefined;
      start = end = -1;
    } else {
      throw new SyntaxError(`Unexpected character at index ${i}`);
    }
  }
}

if (start === -1 || inQuotes) {
  throw new SyntaxError('Unexpected end of input');
}

if (end === -1) end = i;
const token = header.slice(start, end);
if (extensionName === undefined) {
  push(offers, token, params);
} else {
  if (paramName === undefined) {
    push(params, token, true);
  } else if (mustUnescape) {
    push(params, paramName, token.replace(/\\/g, ''));
  } else {
    push(params, paramName, token);
  }
  push(offers, extensionName, params);
}

return offers;

}

/**

* Builds the `Sec-WebSocket-Extensions` header field value.
*
* @param {Object} extensions The map of extensions and parameters to format
* @return {String} A string representing the given object
* @public
*/

function format(extensions) {

return Object.keys(extensions)
  .map((extension) => {
    let configurations = extensions[extension];
    if (!Array.isArray(configurations)) configurations = [configurations];
    return configurations
      .map((params) => {
        return [extension]
          .concat(
            Object.keys(params).map((k) => {
              let values = params[k];
              if (!Array.isArray(values)) values = [values];
              return values
                .map((v) => (v === true ? k : `${k}=${v}`))
                .join('; ');
            })
          )
          .join('; ');
      })
      .join(', ');
  })
  .join(', ');

}

module.exports = { format, parse };