// © 2017 and later: Unicode, Inc. and others.

// License & terms of use: http://www.unicode.org/copyright.html

#include "unicode/utypes.h"

#if !UCONFIG_NO_FORMATTING

#ifndef __NUMBER_DECIMALQUANTITY_H__

#define __NUMBER_DECIMALQUANTITY_H__

#include <cstdint>

#include "unicode/umachine.h"

#include "standardplural.h"

#include "plurrule_impl.h"

#include "number_types.h"

U_NAMESPACE_BEGIN

namespace number::impl {

// Forward-declare (maybe don't want number_utils.h included here):

class DecNum;

/**

 * A class for representing a number to be processed by the decimal formatting pipeline. Includes

 * methods for rounding, plural rules, and decimal digit extraction.

 *

 * <p>By design, this is NOT IMMUTABLE and NOT THREAD SAFE. It is intended to be an intermediate

 * object holding state during a pass through the decimal formatting pipeline.

 *

 * <p>Represents numbers and digit display properties using Binary Coded Decimal (BCD).

 *

 * <p>Java has multiple implementations for testing, but C++ has only one implementation.

 */

class U_I18N_API DecimalQuantity : public IFixedDecimal, public UMemory {

  public:

    /** Copy constructor. */

    DecimalQuantity(const DecimalQuantity &other);

    /** Move constructor. */

    DecimalQuantity(DecimalQuantity &&src) noexcept;

    DecimalQuantity();

    ~DecimalQuantity() override;

    /**

     * Sets this instance to be equal to another instance.

     *

     * @param other The instance to copy from.

     */

    DecimalQuantity &operator=(const DecimalQuantity &other);

    /** Move assignment */

    DecimalQuantity &operator=(DecimalQuantity&& src) noexcept;

    /**

     * If the minimum integer digits are greater than `minInt`,

     * sets it to `minInt`.

     *

     * @param minInt The minimum number of integer digits.

     */

    void decreaseMinIntegerTo(int32_t minInt);

    /**

     * Sets the minimum integer digits that this {@link DecimalQuantity} should generate.

     * This method does not perform rounding.

     *

     * @param minInt The minimum number of integer digits.

     */

    void increaseMinIntegerTo(int32_t minInt);

    /**

     * Sets the minimum fraction digits that this {@link DecimalQuantity} should generate.

     * This method does not perform rounding.

     *

     * @param minFrac The minimum number of fraction digits.

     */

    void setMinFraction(int32_t minFrac);

    /**

     * Truncates digits from the upper magnitude of the number in order to satisfy the

     * specified maximum number of integer digits.

     *

     * @param maxInt The maximum number of integer digits.

     */

    void applyMaxInteger(int32_t maxInt);

    /**

     * Rounds the number to a specified interval, such as 0.05.

     *

     * <p>If rounding to a power of ten, use the more efficient {@link #roundToMagnitude} instead.

     *

     * @param increment The increment to which to round.

     * @param magnitude The power of 10 to which to round.

     * @param roundingMode The {@link RoundingMode} to use if rounding is necessary.

     */

    void roundToIncrement(

        uint64_t increment,

        digits_t magnitude,

        RoundingMode roundingMode,

        UErrorCode& status);

    /** Removes all fraction digits. */

    void truncate();

    /**

     * Rounds the number to the nearest multiple of 5 at the specified magnitude.

     * For example, when magnitude == -2, this performs rounding to the nearest 0.05.

     *

     * @param magnitude The magnitude at which the digit should become either 0 or 5.

     * @param roundingMode Rounding strategy.

     */

    void roundToNickel(int32_t magnitude, RoundingMode roundingMode, UErrorCode& status);

    /**

     * Rounds the number to a specified magnitude (power of ten).

     *

     * @param roundingMagnitude The power of ten to which to round. For example, a value of -2 will

     *     round to 2 decimal places.

     * @param roundingMode The {@link RoundingMode} to use if rounding is necessary.

     */

    void roundToMagnitude(int32_t magnitude, RoundingMode roundingMode, UErrorCode& status);

    /**

     * Rounds the number to an infinite number of decimal points. This has no effect except for

     * forcing the double in {@link DecimalQuantity_AbstractBCD} to adopt its exact representation.

     */

    void roundToInfinity();

    /**

     * Multiply the internal value. Uses decNumber.

     *

     * @param multiplicand The value by which to multiply.

     */

    void multiplyBy(const DecNum& multiplicand, UErrorCode& status);

    /**

     * Divide the internal value. Uses decNumber.

     *

     * @param multiplicand The value by which to multiply.

     */

    void divideBy(const DecNum& divisor, UErrorCode& status);

    /** Flips the sign from positive to negative and back. */

    void negate();

    /**

     * Scales the number by a power of ten. For example, if the value is currently "1234.56", calling

     * this method with delta=-3 will change the value to "1.23456".

     *

     * @param delta The number of magnitudes of ten to change by.

     * @return true if integer overflow occurred; false otherwise.

     */

    bool adjustMagnitude(int32_t delta);

    /**

     * Scales the number such that the least significant nonzero digit is at magnitude 0.

     *

     * @return The previous magnitude of the least significant digit.

     */

    int32_t adjustToZeroScale();

    /**

     * @return The power of ten corresponding to the most significant nonzero digit.

     * The number must not be zero.

     */

    int32_t getMagnitude() const;

    /**

     * @return The value of the (suppressed) exponent after the number has been

     * put into a notation with exponents (ex: compact, scientific).  Ex: given

     * the number 1000 as "1K" / "1E3", the return value will be 3 (positive).

     */

    int32_t getExponent() const;

    /**

     * Adjusts the value for the (suppressed) exponent stored when using

     * notation with exponents (ex: compact, scientific).

     *

     * <p>Adjusting the exponent is decoupled from {@link #adjustMagnitude} in

     * order to allow flexibility for {@link StandardPlural} to be selected in

     * formatting (ex: for compact notation) either with or without the exponent

     * applied in the value of the number.

     * @param delta

     *             The value to adjust the exponent by.

     */

    void adjustExponent(int32_t delta);

    /**

     * Resets the DecimalQuantity to the value before adjustMagnitude and adjustExponent.

     */

    void resetExponent();

    /**

     * @return Whether the value represented by this {@link DecimalQuantity} is

     * zero, infinity, or NaN.

     */

    bool isZeroish() const;

    /** @return Whether the value represented by this {@link DecimalQuantity} is less than zero. */

    bool isNegative() const;

    /** @return The appropriate value from the Signum enum. */

    Signum signum() const;

    /** @return Whether the value represented by this {@link DecimalQuantity} is infinite. */

    bool isInfinite() const override;

    /** @return Whether the value represented by this {@link DecimalQuantity} is not a number. */

    bool isNaN() const override;

    /**  

     * Note: this method incorporates the value of {@code exponent}

     * (for cases such as compact notation) to return the proper long value

     * represented by the result.

     * @param truncateIfOverflow if false and the number does NOT fit, fails with an assertion error. 

     */

    int64_t toLong(bool truncateIfOverflow = false) const;

    /**

     * Note: this method incorporates the value of {@code exponent}

     * (for cases such as compact notation) to return the proper long value

     * represented by the result.

     */

    uint64_t toFractionLong(bool includeTrailingZeros) const;

    /**

     * Returns whether or not a Long can fully represent the value stored in this DecimalQuantity.

     * @param ignoreFraction if true, silently ignore digits after the decimal place.

     */

    bool fitsInLong(bool ignoreFraction = false) const;

    /** @return The value contained in this {@link DecimalQuantity} approximated as a double. */

    double toDouble() const;

    /** Computes a DecNum representation of this DecimalQuantity, saving it to the output parameter. */

    DecNum& toDecNum(DecNum& output, UErrorCode& status) const;

    DecimalQuantity &setToInt(int32_t n);

    DecimalQuantity &setToLong(int64_t n);

    DecimalQuantity &setToDouble(double n);

    /**

     * Produces a DecimalQuantity that was parsed from a string by the decNumber

     * C Library.

     *

     * decNumber is similar to BigDecimal in Java, and supports parsing strings

     * such as "123.456621E+40".

     */

    DecimalQuantity &setToDecNumber(StringPiece n, UErrorCode& status);

    /** Internal method if the caller already has a DecNum. */

    DecimalQuantity &setToDecNum(const DecNum& n, UErrorCode& status);

    /** Returns a DecimalQuantity after parsing the input string. */

    static DecimalQuantity fromExponentString(UnicodeString n, UErrorCode& status);

    /**

     * Appends a digit, optionally with one or more leading zeros, to the end of the value represented

     * by this DecimalQuantity.

     *

     * <p>The primary use of this method is to construct numbers during a parsing loop. It allows

     * parsing to take advantage of the digit list infrastructure primarily designed for formatting.

     *

     * @param value The digit to append.

     * @param leadingZeros The number of zeros to append before the digit. For example, if the value

     *     in this instance starts as 12.3, and you append a 4 with 1 leading zero, the value becomes

     *     12.304.

     * @param appendAsInteger If true, increase the magnitude of existing digits to make room for the

     *     new digit. If false, append to the end like a fraction digit. If true, there must not be

     *     any fraction digits already in the number.

     * @internal

     * @deprecated This API is ICU internal only.

     */

    void appendDigit(int8_t value, int32_t leadingZeros, bool appendAsInteger);

    double getPluralOperand(PluralOperand operand) const override;

    bool hasIntegerValue() const override;

    /**

     * Gets the digit at the specified magnitude. For example, if the represented number is 12.3,

     * getDigit(-1) returns 3, since 3 is the digit corresponding to 10^-1.

     *

     * @param magnitude The magnitude of the digit.

     * @return The digit at the specified magnitude.

     */

    int8_t getDigit(int32_t magnitude) const;

    /**

     * Gets the largest power of ten that needs to be displayed. The value returned by this function

     * will be bounded between minInt and maxInt.

     *

     * @return The highest-magnitude digit to be displayed.

     */

    int32_t getUpperDisplayMagnitude() const;

    /**

     * Gets the smallest power of ten that needs to be displayed. The value returned by this function

     * will be bounded between -minFrac and -maxFrac.

     *

     * @return The lowest-magnitude digit to be displayed.

     */

    int32_t getLowerDisplayMagnitude() const;

    int32_t fractionCount() const;

    int32_t fractionCountWithoutTrailingZeros() const;

    void clear();

    /** This method is for internal testing only. */

    uint64_t getPositionFingerprint() const;

//    /**

//     * If the given {@link FieldPosition} is a {@link UFieldPosition}, populates it with the fraction

//     * length and fraction long value. If the argument is not a {@link UFieldPosition}, nothing

//     * happens.

//     *

//     * @param fp The {@link UFieldPosition} to populate.

//     */

//    void populateUFieldPosition(FieldPosition fp);

    /**

     * Checks whether the bytes stored in this instance are all valid. For internal unit testing only.

     *

     * @return An error message if this instance is invalid, or null if this instance is healthy.

     */

    const char16_t* checkHealth() const;

    UnicodeString toString() const;

    /** Returns the string in standard exponential notation. */

    UnicodeString toScientificString() const;

    /** Returns the string without exponential notation. Slightly slower than toScientificString(). */

    UnicodeString toPlainString() const;

    /** Returns the string using ASCII digits and using exponential notation for non-zero

    exponents, following the UTS 35 specification for plural rule samples. */

    UnicodeString toExponentString() const;

    /** Visible for testing */

    inline bool isUsingBytes() { return usingBytes; }

    /** Visible for testing */

    inline bool isExplicitExactDouble() { return explicitExactDouble; }

    bool operator==(const DecimalQuantity& other) const;

    inline bool operator!=(const DecimalQuantity& other) const {

        return !(*this == other);

    }

    /**

     * Bogus flag for when a DecimalQuantity is stored on the stack.

     */

    bool bogus = false;

  private:

    /**

     * The power of ten corresponding to the least significant digit in the BCD. For example, if this

     * object represents the number "3.14", the BCD will be "0x314" and the scale will be -2.

     *

     * <p>Note that in {@link java.math.BigDecimal}, the scale is defined differently: the number of

     * digits after the decimal place, which is the negative of our definition of scale.

     */

    int32_t scale;

    /**

     * The number of digits in the BCD. For example, "1007" has BCD "0x1007" and precision 4. The

     * maximum precision is 16 since a long can hold only 16 digits.

     *

     * <p>This value must be re-calculated whenever the value in bcd changes by using {@link

     * #computePrecisionAndCompact()}.

     */

    int32_t precision;

    /**

     * A bitmask of properties relating to the number represented by this object.

     *

     * @see #NEGATIVE_FLAG

     * @see #INFINITY_FLAG

     * @see #NAN_FLAG

     */

    int8_t flags;

    // The following three fields relate to the double-to-ascii fast path algorithm.

    // When a double is given to DecimalQuantityBCD, it is converted to using a fast algorithm. The

    // fast algorithm guarantees correctness to only the first ~12 digits of the double. The process

    // of rounding the number ensures that the converted digits are correct, falling back to a slow-

    // path algorithm if required.  Therefore, if a DecimalQuantity is constructed from a double, it

    // is *required* that roundToMagnitude(), roundToIncrement(), or roundToInfinity() is called. If

    // you don't round, assertions will fail in certain other methods if you try calling them.

    /**

     * Whether the value in the BCD comes from the double fast path without having been rounded to

     * ensure correctness

     */

    UBool isApproximate;

    /**

     * The original number provided by the user and which is represented in BCD. Used when we need to

     * re-compute the BCD for an exact double representation.

     */

    double origDouble;

    /**

     * The change in magnitude relative to the original double. Used when we need to re-compute the

     * BCD for an exact double representation.

     */

    int32_t origDelta;

    // Positions to keep track of leading and trailing zeros.

    // lReqPos is the magnitude of the first required leading zero.

    // rReqPos is the magnitude of the last required trailing zero.

    int32_t lReqPos = 0;

    int32_t rReqPos = 0;

    // The value of the (suppressed) exponent after the number has been put into

    // a notation with exponents (ex: compact, scientific).

    int32_t exponent = 0;

    /**

     * The BCD of the 16 digits of the number represented by this object. Every 4 bits of the long map

     * to one digit. For example, the number "12345" in BCD is "0x12345".

     *

     * <p>Whenever bcd changes internally, {@link #compact()} must be called, except in special cases

     * like setting the digit to zero.

     */

    union {

        struct {

            int8_t *ptr;

            int32_t len;

        } bcdBytes;

        uint64_t bcdLong;

    } fBCD;

    bool usingBytes = false;

    /**

     * Whether this {@link DecimalQuantity} has been explicitly converted to an exact double. true if

     * backed by a double that was explicitly converted via convertToAccurateDouble; false otherwise.

     * Used for testing.

     */

    bool explicitExactDouble = false;

    void roundToMagnitude(int32_t magnitude, RoundingMode roundingMode, bool nickel, UErrorCode& status);

    /**

     * Returns a single digit from the BCD list. No internal state is changed by calling this method.

     *

     * @param position The position of the digit to pop, counted in BCD units from the least

     *     significant digit. If outside the range supported by the implementation, zero is returned.

     * @return The digit at the specified location.

     */

    int8_t getDigitPos(int32_t position) const;

    /**

     * Sets the digit in the BCD list. This method only sets the digit; it is the caller's

     * responsibility to call {@link #compact} after setting the digit, and to ensure

     * that the precision field is updated to reflect the correct number of digits if a

     * nonzero digit is added to the decimal.

     *

     * @param position The position of the digit to pop, counted in BCD units from the least

     *     significant digit. If outside the range supported by the implementation, an AssertionError

     *     is thrown.

     * @param value The digit to set at the specified location.

     */

    void setDigitPos(int32_t position, int8_t value);

    /**

     * Adds zeros to the end of the BCD list. This will result in an invalid BCD representation; it is

     * the caller's responsibility to do further manipulation and then call {@link #compact}.

     *

     * @param numDigits The number of zeros to add.

     */

    void shiftLeft(int32_t numDigits);

    /**

     * Directly removes digits from the end of the BCD list.

     * Updates the scale and precision.

     *

     * CAUTION: it is the caller's responsibility to call {@link #compact} after this method.

     */

    void shiftRight(int32_t numDigits);

    /**

     * Directly removes digits from the front of the BCD list.

     * Updates precision.

     *

     * CAUTION: it is the caller's responsibility to call {@link #compact} after this method.

     */

    void popFromLeft(int32_t numDigits);

    /**

     * Sets the internal representation to zero. Clears any values stored in scale, precision,

     * hasDouble, origDouble, origDelta, exponent, and BCD data.

     */

    void setBcdToZero();

    /**

     * Sets the internal BCD state to represent the value in the given int. The int is guaranteed to

     * be either positive. The internal state is guaranteed to be empty when this method is called.

     *

     * @param n The value to consume.

     */

    void readIntToBcd(int32_t n);

    /**

     * Sets the internal BCD state to represent the value in the given long. The long is guaranteed to

     * be either positive. The internal state is guaranteed to be empty when this method is called.

     *

     * @param n The value to consume.

     */

    void readLongToBcd(int64_t n);

    void readDecNumberToBcd(const DecNum& dn);

    void readDoubleConversionToBcd(const char* buffer, int32_t length, int32_t point);

    void copyFieldsFrom(const DecimalQuantity& other);

    void copyBcdFrom(const DecimalQuantity &other);

    void moveBcdFrom(DecimalQuantity& src);

    /**

     * Removes trailing zeros from the BCD (adjusting the scale as required) and then computes the

     * precision. The precision is the number of digits in the number up through the greatest nonzero

     * digit.

     *

     * <p>This method must always be called when bcd changes in order for assumptions to be correct in

     * methods like {@link #fractionCount()}.

     */

    void compact();

    void _setToInt(int32_t n);

    void _setToLong(int64_t n);

    void _setToDoubleFast(double n);

    void _setToDecNum(const DecNum& dn, UErrorCode& status);

    static int32_t getVisibleFractionCount(UnicodeString value);

    void convertToAccurateDouble();

    /** Ensure that a byte array of at least 40 digits is allocated. */

    void ensureCapacity();

    void ensureCapacity(int32_t capacity);

    /** Switches the internal storage mechanism between the 64-bit long and the byte array. */

    void switchStorage();

};

} // namespace number::impl

U_NAMESPACE_END

#endif //__NUMBER_DECIMALQUANTITY_H__

#endif /* #if !UCONFIG_NO_FORMATTING */