// Copyright 2009 The Closure Library Authors. 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.

/**
 * @fileoverview Defines a Long class for representing a 64-bit two's-complement
 * integer value, which faithfully simulates the behavior of a Java "long". This
 * implementation is derived from LongLib in GWT.
 *
 */
class gLong {
  private low_ : number
  private high_ : number
  // A cache of the Long representations of small integer values.
  private static IntCache_: { [val: number]: gLong } = {}
  // Commonly used constant values.
  private static TWO_PWR_16_DBL_ = 1 << 16;
  private static TWO_PWR_24_DBL_ = 1 << 24;
  private static TWO_PWR_32_DBL_ = gLong.TWO_PWR_16_DBL_ * gLong.TWO_PWR_16_DBL_;
  private static TWO_PWR_31_DBL_ = gLong.TWO_PWR_32_DBL_ / 2;
  private static TWO_PWR_48_DBL_ = gLong.TWO_PWR_32_DBL_ * gLong.TWO_PWR_16_DBL_;
  private static TWO_PWR_64_DBL_ = gLong.TWO_PWR_32_DBL_ * gLong.TWO_PWR_32_DBL_;
  private static TWO_PWR_63_DBL_ = gLong.TWO_PWR_64_DBL_ / 2;

  public static ZERO = gLong.fromInt(0);
  public static ONE = gLong.fromInt(1);
  public static NEG_ONE = gLong.fromInt(-1);
  public static MAX_VALUE = gLong.fromBits(0xFFFFFFFF, 0x7FFFFFFF);
  public static MIN_VALUE = gLong.fromBits(0, 0x80000000);
  private static TWO_PWR_24_ = gLong.fromInt(gLong.TWO_PWR_24_DBL_);

  /**
   * Constructs a 64-bit two's-complement integer, given its low and high 32-bit
   * values as *signed* integers.  See the from* functions below for more
   * convenient ways of constructing Longs.
   *
   * The internal representation of a long is the two given signed, 32-bit values.
   * We use 32-bit pieces because these are the size of integers on which
   * Javascript performs bit-operations.  For operations like addition and
   * multiplication, we split each number into 16-bit pieces, which can easily be
   * multiplied within Javascript's floating-point representation without overflow
   * or change in sign.
   *
   * In the algorithms below, we frequently reduce the negative case to the
   * positive case by negating the input(s) and then post-processing the result.
   * Note that we must ALWAYS check specially whether those values are MIN_VALUE
   * (-2^63) because -MIN_VALUE == MIN_VALUE (since 2^63 cannot be represented as
   * a positive number, it overflows back into a negative).  Not handling this
   * case would often result in infinite recursion.
   *
   * @param {number} low  The low (signed) 32 bits of the long.
   * @param {number} high  The high (signed) 32 bits of the long.
   * @constructor
   */
  constructor(low: number, high: number) {
    this.low_ = low | 0;  // force into 32 signed bits.
    this.high_ = high | 0;  // force into 32 signed bits.
  }

  /**
   * Returns a Long representing the given (32-bit) integer value.
   * @param {number} value The 32-bit integer in question.
   * @return {!gLong} The corresponding Long value.
   */
  public static fromInt(value: number): gLong {
    if (-128 <= value && value < 128) {
      var cachedObj = gLong.IntCache_[value];
      if (cachedObj) {
        return cachedObj;
      }
    }

    var obj = new gLong(value, value < 0 ? -1 : 0);
    if (-128 <= value && value < 128) {
      gLong.IntCache_[value] = obj;
    }
    return obj;
  }

  /**
   * Returns a Long representing the given value, provided that it is a finite
   * number.  Otherwise, zero is returned.
   * @param {number} value The number in question.
   * @return {!gLong} The corresponding Long value.
   */
  public static fromNumber(value: number): gLong {
    if (isNaN(value) || !isFinite(value)) {
      return gLong.ZERO;
    } else if (value <= -gLong.TWO_PWR_63_DBL_) {
      return gLong.MIN_VALUE;
    } else if (value + 1 >= gLong.TWO_PWR_63_DBL_) {
      return gLong.MAX_VALUE;
    } else if (value < 0) {
      return gLong.fromNumber(-value).negate();
    } else {
      return new gLong(
          (value % gLong.TWO_PWR_32_DBL_) | 0,
          (value / gLong.TWO_PWR_32_DBL_) | 0);
    }
  }

  /**
   * Returns a Long representing the 64-bit integer that comes by concatenating
   * the given high and low bits.  Each is assumed to use 32 bits.
   * @param {number} lowBits The low 32-bits.
   * @param {number} highBits The high 32-bits.
   * @return {!gLong} The corresponding Long value.
   */
  public static fromBits(lowBits: number, highBits: number): gLong {
    return new gLong(lowBits, highBits);
  }

  /**
   * Returns a Long representation of the given string, written using the given
   * radix.
   * @param {string} str The textual representation of the Long.
   * @param {number=} opt_radix The radix in which the text is written.
   * @return {!gLong} The corresponding Long value.
   */
  public static fromString(str: string, opt_radix?: number): gLong {
    if (str.length == 0) {
      throw Error('number format error: empty string');
    }

    var radix = opt_radix || 10;
    if (radix < 2 || 36 < radix) {
      throw Error('radix out of range: ' + radix);
    }

    if (str.charAt(0) == '-') {
      return gLong.fromString(str.substring(1), radix).negate();
    } else if (str.indexOf('-') >= 0) {
      throw Error('number format error: interior "-" character: ' + str);
    }

    // Do several (8) digits each time through the loop, so as to
    // minimize the calls to the very expensive emulated div.
    var radixToPower = gLong.fromNumber(Math.pow(radix, 8));

    var result = gLong.ZERO;
    for (var i = 0; i < str.length; i += 8) {
      var size = Math.min(8, str.length - i);
      var value = parseInt(str.substring(i, i + size), radix);
      if (size < 8) {
        var power = gLong.fromNumber(Math.pow(radix, size));
        result = result.multiply(power).add(gLong.fromNumber(value));
      } else {
        result = result.multiply(radixToPower);
        result = result.add(gLong.fromNumber(value));
      }
    }
    return result;
  }

  /** @return {number} The value, assuming it is a 32-bit integer. */
  public toInt(): number {
    return this.low_;
  }

  /** @return {number} The closest floating-point representation to this value. */
  public toNumber(): number {
    return this.high_ * gLong.TWO_PWR_32_DBL_ + this.getLowBitsUnsigned();
  }

  /**
   * @param {number=} opt_radix The radix in which the text should be written.
   * @return {string} The textual representation of this value.
   */
  public toString(opt_radix?: number): string {
    var radix = opt_radix || 10;
    if (radix < 2 || 36 < radix) {
      throw Error('radix out of range: ' + radix);
    }

    if (this.isZero()) {
      return '0';
    }

    if (this.isNegative()) {
      if (this.equals(gLong.MIN_VALUE)) {
        // We need to change the Long value before it can be negated, so we remove
        // the bottom-most digit in this base and then recurse to do the rest.
        var radixLong = gLong.fromNumber(radix);
        var div = this.div(radixLong);
        var rem = div.multiply(radixLong).subtract(this);
        return div.toString(radix) + rem.toInt().toString(radix);
      } else {
        return '-' + this.negate().toString(radix);
      }
    }

    // Do several (6) digits each time through the loop, so as to
    // minimize the calls to the very expensive emulated div.
    var radixToPower = gLong.fromNumber(Math.pow(radix, 6));
    var rem: gLong = this;
    var result = '';
    while (true) {
      var remDiv = rem.div(radixToPower);
      var intval = rem.subtract(remDiv.multiply(radixToPower)).toInt();
      var digits = intval.toString(radix);

      rem = remDiv;
      if (rem.isZero()) {
        return digits + result;
      } else {
        while (digits.length < 6) {
          digits = '0' + digits;
        }
        result = '' + digits + result;
      }
    }
  }

  /** @return {number} The high 32-bits as a signed value. */
  public getHighBits(): number {
    return this.high_;
  }

  /** @return {number} The low 32-bits as a signed value. */
  public getLowBits(): number {
    return this.low_;
  }

  /** @return {number} The low 32-bits as an unsigned value. */
  public getLowBitsUnsigned(): number {
    return (this.low_ >= 0) ? this.low_ : gLong.TWO_PWR_32_DBL_ + this.low_;
  }

  /**
   * @return {number} Returns the number of bits needed to represent the absolute
   *     value of this Long.
   */
  public getNumBitsAbs(): number {
    if (this.isNegative()) {
      if (this.equals(gLong.MIN_VALUE)) {
        return 64;
      } else {
        return this.negate().getNumBitsAbs();
      }
    } else {
      var val = this.high_ != 0 ? this.high_ : this.low_;
      for (var bit = 31; bit > 0; bit--) {
        if ((val & (1 << bit)) != 0) {
          break;
        }
      }
      return this.high_ != 0 ? bit + 33 : bit + 1;
    }
  }

  /** @return {boolean} Whether this value is zero. */
  public isZero(): boolean {
    return this.high_ == 0 && this.low_ == 0;
  }

  /** @return {boolean} Whether this value is negative. */
  public isNegative(): boolean {
    return this.high_ < 0;
  }

  /** @return {boolean} Whether this value is odd. */
  public isOdd(): boolean {
    return (this.low_ & 1) == 1;
  }

  /**
   * @param {gLong} other Long to compare against.
   * @return {boolean} Whether this Long equals the other.
   */
  public equals(other: gLong): boolean {
    return (this.high_ == other.high_) && (this.low_ == other.low_);
  }

  /**
   * @param {gLong} other Long to compare against.
   * @return {boolean} Whether this Long does not equal the other.
   */
  public notEquals(other: gLong): boolean {
    return (this.high_ != other.high_) || (this.low_ != other.low_);
  }

  /**
   * @param {gLong} other Long to compare against.
   * @return {boolean} Whether this Long is less than the other.
   */
  public lessThan(other: gLong): boolean {
    return this.compare(other) < 0;
  }

  /**
   * @param {gLong} other Long to compare against.
   * @return {boolean} Whether this Long is less than or equal to the other.
   */
  public lessThanOrEqual(other: gLong): boolean {
    return this.compare(other) <= 0;
  }

  /**
   * @param {gLong} other Long to compare against.
   * @return {boolean} Whether this Long is greater than the other.
   */
  public greaterThan(other: gLong): boolean {
    return this.compare(other) > 0;
  }

  /**
   * @param {gLong} other Long to compare against.
   * @return {boolean} Whether this Long is greater than or equal to the other.
   */
  public greaterThanOrEqual(other: gLong): boolean {
    return this.compare(other) >= 0;
  }

  /**
   * Compares this Long with the given one.
   * @param {gLong} other Long to compare against.
   * @return {number} 0 if they are the same, 1 if the this is greater, and -1
   *     if the given one is greater.
   */
  public compare(other: gLong): number {
    if (this.equals(other)) {
      return 0;
    }

    var thisNeg = this.isNegative();
    var otherNeg = other.isNegative();
    if (thisNeg && !otherNeg) {
      return -1;
    }
    if (!thisNeg && otherNeg) {
      return 1;
    }

    // at this point, the signs are the same, so subtraction will not overflow
    if (this.subtract(other).isNegative()) {
      return -1;
    } else {
      return 1;
    }
  }

  /** @return {!gLong} The negation of this value. */
  public negate(): gLong {
    if (this.equals(gLong.MIN_VALUE)) {
      return gLong.MIN_VALUE;
    } else {
      return this.not().add(gLong.ONE);
    }
  }

  /**
   * Returns the sum of this and the given Long.
   * @param {gLong} other Long to add to this one.
   * @return {!gLong} The sum of this and the given Long.
   */
  public add(other: gLong): gLong {
    // Divide each number into 4 chunks of 16 bits, and then sum the chunks.

    var a48 = this.high_ >>> 16;
    var a32 = this.high_ & 0xFFFF;
    var a16 = this.low_ >>> 16;
    var a00 = this.low_ & 0xFFFF;

    var b48 = other.high_ >>> 16;
    var b32 = other.high_ & 0xFFFF;
    var b16 = other.low_ >>> 16;
    var b00 = other.low_ & 0xFFFF;

    var c48 = 0, c32 = 0, c16 = 0, c00 = 0;
    c00 += a00 + b00;
    c16 += c00 >>> 16;
    c00 &= 0xFFFF;
    c16 += a16 + b16;
    c32 += c16 >>> 16;
    c16 &= 0xFFFF;
    c32 += a32 + b32;
    c48 += c32 >>> 16;
    c32 &= 0xFFFF;
    c48 += a48 + b48;
    c48 &= 0xFFFF;
    return gLong.fromBits((c16 << 16) | c00, (c48 << 16) | c32);
  }

  /**
   * Returns the difference of this and the given Long.
   * @param {gLong} other Long to subtract from this.
   * @return {!gLong} The difference of this and the given Long.
   */
  public subtract(other: gLong): gLong {
    return this.add(other.negate());
  }

  /**
   * Returns the product of this and the given long.
   * @param {gLong} other Long to multiply with this.
   * @return {!gLong} The product of this and the other.
   */
  public multiply(other: gLong): gLong {
    if (this.isZero()) {
      return gLong.ZERO;
    } else if (other.isZero()) {
      return gLong.ZERO;
    }

    if (this.equals(gLong.MIN_VALUE)) {
      return other.isOdd() ? gLong.MIN_VALUE : gLong.ZERO;
    } else if (other.equals(gLong.MIN_VALUE)) {
      return this.isOdd() ? gLong.MIN_VALUE : gLong.ZERO;
    }

    if (this.isNegative()) {
      if (other.isNegative()) {
        return this.negate().multiply(other.negate());
      } else {
        return this.negate().multiply(other).negate();
      }
    } else if (other.isNegative()) {
      return this.multiply(other.negate()).negate();
    }

    // If both longs are small, use float multiplication
    if (this.lessThan(gLong.TWO_PWR_24_) &&
        other.lessThan(gLong.TWO_PWR_24_)) {
      return gLong.fromNumber(this.toNumber() * other.toNumber());
    }

    // Divide each long into 4 chunks of 16 bits, and then add up 4x4 products.
    // We can skip products that would overflow.

    var a48 = this.high_ >>> 16;
    var a32 = this.high_ & 0xFFFF;
    var a16 = this.low_ >>> 16;
    var a00 = this.low_ & 0xFFFF;

    var b48 = other.high_ >>> 16;
    var b32 = other.high_ & 0xFFFF;
    var b16 = other.low_ >>> 16;
    var b00 = other.low_ & 0xFFFF;

    var c48 = 0, c32 = 0, c16 = 0, c00 = 0;
    c00 += a00 * b00;
    c16 += c00 >>> 16;
    c00 &= 0xFFFF;
    c16 += a16 * b00;
    c32 += c16 >>> 16;
    c16 &= 0xFFFF;
    c16 += a00 * b16;
    c32 += c16 >>> 16;
    c16 &= 0xFFFF;
    c32 += a32 * b00;
    c48 += c32 >>> 16;
    c32 &= 0xFFFF;
    c32 += a16 * b16;
    c48 += c32 >>> 16;
    c32 &= 0xFFFF;
    c32 += a00 * b32;
    c48 += c32 >>> 16;
    c32 &= 0xFFFF;
    c48 += a48 * b00 + a32 * b16 + a16 * b32 + a00 * b48;
    c48 &= 0xFFFF;
    return gLong.fromBits((c16 << 16) | c00, (c48 << 16) | c32);
  }

  /**
   * Returns this Long divided by the given one.
   * @param {gLong} other Long by which to divide.
   * @return {!gLong} This Long divided by the given one.
   */
  public div(other: gLong): gLong {
    if (other.isZero()) {
      throw Error('division by zero');
    } else if (this.isZero()) {
      return gLong.ZERO;
    }

    if (this.equals(gLong.MIN_VALUE)) {
      if (other.equals(gLong.ONE) ||
          other.equals(gLong.NEG_ONE)) {
        return gLong.MIN_VALUE;  // recall that -MIN_VALUE == MIN_VALUE
      } else if (other.equals(gLong.MIN_VALUE)) {
        return gLong.ONE;
      } else {
        // At this point, we have |other| >= 2, so |this/other| < |MIN_VALUE|.
        var halfThis = this.shiftRight(1);
        var l_approx = halfThis.div(other).shiftLeft(1);
        if (l_approx.equals(gLong.ZERO)) {
          return other.isNegative() ? gLong.ONE : gLong.NEG_ONE;
        } else {
          var rem = this.subtract(other.multiply(l_approx));
          var result = l_approx.add(rem.div(other));
          return result;
        }
      }
    } else if (other.equals(gLong.MIN_VALUE)) {
      return gLong.ZERO;
    }

    if (this.isNegative()) {
      if (other.isNegative()) {
        return this.negate().div(other.negate());
      } else {
        return this.negate().div(other).negate();
      }
    } else if (other.isNegative()) {
      return this.div(other.negate()).negate();
    }

    // Repeat the following until the remainder is less than other:  find a
    // floating-point that approximates remainder / other *from below*, add this
    // into the result, and subtract it from the remainder.  It is critical that
    // the approximate value is less than or equal to the real value so that the
    // remainder never becomes negative.
    var res = gLong.ZERO;
    var rem: gLong = this;
    while (rem.greaterThanOrEqual(other)) {
      // Approximate the result of division. This may be a little greater or
      // smaller than the actual value.
      var approx = Math.max(1, Math.floor(rem.toNumber() / other.toNumber()));

      // We will tweak the approximate result by changing it in the 48-th digit or
      // the smallest non-fractional digit, whichever is larger.
      var log2 = Math.ceil(Math.log(approx) / Math.LN2);
      var delta = 1;
      if (log2 > 48)
        delta = Math.pow(2, log2 - 48);

      // Decrease the approximation until it is smaller than the remainder.  Note
      // that if it is too large, the product overflows and is negative.
      var approxRes = gLong.fromNumber(approx);
      var approxRem = approxRes.multiply(other);
      while (approxRem.isNegative() || approxRem.greaterThan(rem)) {
        approx -= delta;
        approxRes = gLong.fromNumber(approx);
        approxRem = approxRes.multiply(other);
      }

      // We know the answer can't be zero... and actually, zero would cause
      // infinite recursion since we would make no progress.
      if (approxRes.isZero()) {
        approxRes = gLong.ONE;
      }

      res = res.add(approxRes);
      rem = rem.subtract(approxRem);
    }
    return res;
  }

  /**
   * Returns this Long modulo the given one.
   * @param {gLong} other Long by which to mod.
   * @return {!gLong} This Long modulo the given one.
   */
  public modulo(other: gLong): gLong {
    return this.subtract(this.div(other).multiply(other));
  }

  /** @return {!gLong} The bitwise-NOT of this value. */
  public not(): gLong {
    return gLong.fromBits(~this.low_, ~this.high_);
  }

  /**
   * Returns the bitwise-AND of this Long and the given one.
   * @param {gLong} other The Long with which to AND.
   * @return {!gLong} The bitwise-AND of this and the other.
   */
  public and(other: gLong): gLong {
    return gLong.fromBits(this.low_ & other.low_,
                          this.high_ & other.high_);
  }

  /**
   * Returns the bitwise-OR of this Long and the given one.
   * @param {gLong} other The Long with which to OR.
   * @return {!gLong} The bitwise-OR of this and the other.
   */
  public or(other: gLong): gLong {
    return gLong.fromBits(this.low_ | other.low_,
                          this.high_ | other.high_);
  }

  /**
   * Returns the bitwise-XOR of this Long and the given one.
   * @param {gLong} other The Long with which to XOR.
   * @return {!gLong} The bitwise-XOR of this and the other.
   */
  public xor(other: gLong): gLong {
    return gLong.fromBits(this.low_ ^ other.low_, this.high_ ^ other.high_);
  }

  /**
   * Returns this Long with bits shifted to the left by the given amount.
   * @param {number} numBits The number of bits by which to shift.
   * @return {!gLong} This shifted to the left by the given amount.
   */
  public shiftLeft(numBits: number): gLong {
    numBits &= 63;
    if (numBits == 0) {
      return this;
    } else {
      var low = this.low_;
      if (numBits < 32) {
        var high = this.high_;
        return gLong.fromBits(low << numBits,
                              (high << numBits) | (low >>> (32 - numBits)));
      } else {
        return gLong.fromBits(0, low << (numBits - 32));
      }
    }
  }

  /**
   * Returns this Long with bits shifted to the right by the given amount.
   * @param {number} numBits The number of bits by which to shift.
   * @return {!gLong} This shifted to the right by the given amount.
   */
  public shiftRight(numBits: number): gLong {
    numBits &= 63;
    if (numBits == 0) {
      return this;
    } else {
      var high = this.high_;
      if (numBits < 32) {
        var low = this.low_;
        return gLong.fromBits(
            (low >>> numBits) | (high << (32 - numBits)),
            high >> numBits);
      } else {
        return gLong.fromBits(
            high >> (numBits - 32),
            high >= 0 ? 0 : -1);
      }
    }
  }

  /**
   * Returns this Long with bits shifted to the right by the given amount, with
   * the new top bits matching the current sign bit.
   * @param {number} numBits The number of bits by which to shift.
   * @return {!gLong} This shifted to the right by the given amount, with
   *     zeros placed into the new leading bits.
   */
  public shiftRightUnsigned(numBits: number): gLong {
    numBits &= 63;
    if (numBits == 0) {
      return this;
    } else {
      var high = this.high_;
      if (numBits < 32) {
        var low = this.low_;
        return gLong.fromBits(
            (low >>> numBits) | (high << (32 - numBits)),
            high >>> numBits);
      } else if (numBits == 32) {
        return gLong.fromBits(high, 0);
      } else {
        return gLong.fromBits(high >>> (numBits - 32), 0);
      }
    }
  }
}
// Export only the class.
export = gLong