// Sshwifty - A Web SSH client
//
// Copyright (C) 2019-2020 Rui NI <nirui@gmx.com>
//
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU Affero General Public License as
// published by the Free Software Foundation, either version 3 of the
// License, or (at your option) any later version.
//
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU Affero General Public License for more details.
//
// You should have received a copy of the GNU Affero General Public License
// along with this program.  If not, see <https://www.gnu.org/licenses/>.

/**
 * Get one unsafe random number
 *
 * @param {number} min Min value (included)
 * @param {number} max Max value (not included)
 *
 * @returns {number} Get random number
 *
 */
export function getRand(min, max) {
  return Math.floor(Math.random() * (max - min + 1) + min);
}

/**
 * Get a group of random number
 *
 * @param {number} n How many number to get
 * @param {number} min Min value (included)
 * @param {number} max Max value (not included)
 *
 * @returns {Array<number>} A group of random number
 */
export function getRands(n, min, max) {
  let r = [];

  for (let i = 0; i < n; i++) {
    r.push(getRand(min, max));
  }

  return r;
}

/**
 * Separate given buffer to multiple ones based on input max length
 *
 * @param {Uint8Array} buf Buffer to separate
 * @param {number} max Max length of each buffer
 *
 * @returns {Array<Uint8Array>} Separated buffers
 *
 */
export function separateBuffer(buf, max) {
  let start = 0,
    result = [];

  while (start < buf.length) {
    let remain = buf.length - start;

    if (remain <= max) {
      result.push(buf.slice(start, start + remain));

      return result;
    }

    remain = max;

    result.push(buf.slice(start, start + remain));
    start += remain;
  }
}

/**
 * Create an Uint8Array out of given binary string
 *
 * @param {string} str binary string
 *
 * @returns {Uint8Array} Separated buffers
 *
 */
export function buildBufferFromString(str) {
  let r = [],
    t = [];

  for (let i in str) {
    let c = str.charCodeAt(i);

    while (c > 0xff) {
      t.push(c & 0xff);
      c >>= 8;
    }

    r.push(c);

    for (let j = t.length; j > 0; j--) {
      r.push(t[j]);
    }

    t = [];
  }

  return new Uint8Array(r);
}