/*
 * Copyright 2015 The Netty Project
 *
 * The Netty Project licenses this file to you 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.
 */
package play.core.cookie.encoding;

import java.util.BitSet;

final class CookieUtil {

  private static final BitSet VALID_COOKIE_NAME_OCTETS = validCookieNameOctets();

  private static final BitSet VALID_COOKIE_VALUE_OCTETS = validCookieValueOctets();

  private static final BitSet VALID_COOKIE_ATTRIBUTE_VALUE_OCTETS =
      validCookieAttributeValueOctets();

  // token = 1*<any CHAR except CTLs or separators>
  // separators = "(" | ")" | "<" | ">" | "@"
  // | "," | ";" | ":" | "\" | <">
  // | "/" | "[" | "]" | "?" | "="
  // | "{" | "}" | SP | HT
  private static BitSet validCookieNameOctets() {
    BitSet bits = new BitSet();
    for (int i = 32; i < 127; i++) {
      bits.set(i);
    }
    int[] separators =
        new int[] {
          '(', ')', '<', '>', '@', ',', ';', ':', '\\', '"', '/', '[', ']', '?', '=', '{', '}', ' ',
          '\t'
        };
    for (int separator : separators) {
      bits.set(separator, false);
    }
    return bits;
  }

  // cookie-octet = %x21 / %x23-2B / %x2D-3A / %x3C-5B / %x5D-7E
  // US-ASCII characters excluding CTLs, whitespace, DQUOTE, comma, semicolon, and backslash
  private static BitSet validCookieValueOctets() {
    BitSet bits = new BitSet();
    bits.set(0x21);
    for (int i = 0x23; i <= 0x2B; i++) {
      bits.set(i);
    }
    for (int i = 0x2D; i <= 0x3A; i++) {
      bits.set(i);
    }
    for (int i = 0x3C; i <= 0x5B; i++) {
      bits.set(i);
    }
    for (int i = 0x5D; i <= 0x7E; i++) {
      bits.set(i);
    }
    return bits;
  }

  // path-value        = <any CHAR except CTLs or ";">
  private static BitSet validCookieAttributeValueOctets() {
    BitSet bits = new BitSet();
    for (int i = 32; i < 127; i++) {
      bits.set(i);
    }
    bits.set(';', false);
    return bits;
  }

  /**
   * @param buf a buffer where some cookies were maybe encoded
   * @return the buffer String without the trailing separator, or null if no cookie was appended.
   */
  static String stripTrailingSeparatorOrNull(StringBuilder buf) {
    return buf.length() == 0 ? null : stripTrailingSeparator(buf);
  }

  static String stripTrailingSeparator(StringBuilder buf) {
    if (buf.length() > 0) {
      buf.setLength(buf.length() - 2);
    }
    return buf.toString();
  }

  static void add(StringBuilder sb, String name, long val) {
    sb.append(name);
    sb.append((char) HttpConstants.EQUALS);
    sb.append(val);
    sb.append((char) HttpConstants.SEMICOLON);
    sb.append((char) HttpConstants.SP);
  }

  static void add(StringBuilder sb, String name, String val) {
    sb.append(name);
    sb.append((char) HttpConstants.EQUALS);
    sb.append(val);
    sb.append((char) HttpConstants.SEMICOLON);
    sb.append((char) HttpConstants.SP);
  }

  static void add(StringBuilder sb, String name) {
    sb.append(name);
    sb.append((char) HttpConstants.SEMICOLON);
    sb.append((char) HttpConstants.SP);
  }

  static void addQuoted(StringBuilder sb, String name, String val) {
    if (val == null) {
      val = "";
    }

    sb.append(name);
    sb.append((char) HttpConstants.EQUALS);
    sb.append((char) HttpConstants.DOUBLE_QUOTE);
    sb.append(val);
    sb.append((char) HttpConstants.DOUBLE_QUOTE);
    sb.append((char) HttpConstants.SEMICOLON);
    sb.append((char) HttpConstants.SP);
  }

  static int firstInvalidCookieNameOctet(CharSequence cs) {
    return firstInvalidOctet(cs, VALID_COOKIE_NAME_OCTETS);
  }

  static int firstInvalidCookieValueOctet(CharSequence cs) {
    return firstInvalidOctet(cs, VALID_COOKIE_VALUE_OCTETS);
  }

  static int firstInvalidOctet(CharSequence cs, BitSet bits) {
    for (int i = 0; i < cs.length(); i++) {
      char c = cs.charAt(i);
      if (!bits.get(c)) {
        return i;
      }
    }
    return -1;
  }

  static CharSequence unwrapValue(CharSequence cs) {
    final int len = cs.length();
    if (len > 0 && cs.charAt(0) == '"') {
      if (len >= 2 && cs.charAt(len - 1) == '"') {
        // properly balanced
        return len == 2 ? "" : cs.subSequence(1, len - 1);
      } else {
        return null;
      }
    }
    return cs;
  }

  static String validateAttributeValue(String name, String value) {
    if (value == null) {
      return null;
    }
    value = value.trim();
    if (value.isEmpty()) {
      return null;
    }
    int i = firstInvalidOctet(value, VALID_COOKIE_ATTRIBUTE_VALUE_OCTETS);
    if (i != -1) {
      throw new IllegalArgumentException(
          name + " contains the prohibited characters: " + value.charAt(i));
    }
    return value;
  }

  private CookieUtil() {
    // Unused
  }
}
