// © 2020 and later: Unicode, Inc. and others.

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

#include "unicode/utypes.h"

#if !UCONFIG_NO_FORMATTING

#include <cmath>

#include "cmemory.h"

#include "number_decimalquantity.h"

#include "number_roundingutils.h"

#include "putilimp.h"

#include "uarrsort.h"

#include "uassert.h"

#include "unicode/fmtable.h"

#include "unicode/localpointer.h"

#include "unicode/measunit.h"

#include "unicode/measure.h"

#include "units_complexconverter.h"

#include "units_converter.h"

U_NAMESPACE_BEGIN

namespace units {

ComplexUnitsConverter::ComplexUnitsConverter(const MeasureUnitImpl &targetUnit,

                                             const ConversionRates &ratesInfo, UErrorCode &status)

    : units_(targetUnit.extractIndividualUnitsWithIndices(status)) {

    if (U_FAILURE(status)) {

        return;

    }

    U_ASSERT(units_.length() != 0);

    // Just borrowing a pointer to the instance

    MeasureUnitImpl *biggestUnit = &units_[0]->unitImpl;

    for (int32_t i = 1; i < units_.length(); i++) {

        if (UnitsConverter::compareTwoUnits(units_[i]->unitImpl, *biggestUnit, ratesInfo, status) > 0 &&

            U_SUCCESS(status)) {

            biggestUnit = &units_[i]->unitImpl;

        }

        if (U_FAILURE(status)) {

            return;

        }

    }

    this->init(*biggestUnit, ratesInfo, status);

}

ComplexUnitsConverter::ComplexUnitsConverter(StringPiece inputUnitIdentifier,

                                             StringPiece outputUnitsIdentifier, UErrorCode &status) {

    if (U_FAILURE(status)) {

        return;

    }

    MeasureUnitImpl inputUnit = MeasureUnitImpl::forIdentifier(inputUnitIdentifier, status);

    MeasureUnitImpl outputUnits = MeasureUnitImpl::forIdentifier(outputUnitsIdentifier, status);

    this->units_ = outputUnits.extractIndividualUnitsWithIndices(status);

    U_ASSERT(units_.length() != 0);

    this->init(inputUnit, ConversionRates(status), status);

}

ComplexUnitsConverter::ComplexUnitsConverter(const MeasureUnitImpl &inputUnit,

                                             const MeasureUnitImpl &outputUnits,

                                             const ConversionRates &ratesInfo, UErrorCode &status)

    : units_(outputUnits.extractIndividualUnitsWithIndices(status)) {

    if (U_FAILURE(status)) {

        return;

    }

    U_ASSERT(units_.length() != 0);

    this->init(inputUnit, ratesInfo, status);

}

void ComplexUnitsConverter::init(const MeasureUnitImpl &inputUnit,

                                 const ConversionRates &ratesInfo,

                                 UErrorCode &status) {

    // Sorts units in descending order. Therefore, we return -1 if

    // the left is bigger than right and so on.

    auto descendingCompareUnits = [](const void *context, const void *left, const void *right) {

        UErrorCode status = U_ZERO_ERROR;

        const auto *leftPointer = static_cast<const MeasureUnitImplWithIndex *const *>(left);

        const auto *rightPointer = static_cast<const MeasureUnitImplWithIndex *const *>(right);

        // Multiply by -1 to sort in descending order

        return (-1) * UnitsConverter::compareTwoUnits((**leftPointer).unitImpl,                       //

                                                      (**rightPointer).unitImpl,                      //

                                                      *static_cast<const ConversionRates *>(context), //

                                                      status);

    };

    uprv_sortArray(units_.getAlias(),                                                                  //

                   units_.length(),                                                                    //

                   sizeof units_[0], /* NOTE: we have already asserted that the units_ is not empty.*/ //

                   descendingCompareUnits,                                                             //

                   &ratesInfo,                                                                         //

                   false,                                                                              //

                   &status                                                                             //

    );

    // In case the `outputUnits` are `UMEASURE_UNIT_MIXED` such as `foot+inch`. In this case we need more

    // converters to convert from the `inputUnit` to the first unit in the `outputUnits`. Then, a

    // converter from the first unit in the `outputUnits` to the second unit and so on.

    //      For Example:

    //          - inputUnit is `meter`

    //          - outputUnits is `foot+inch`

    //              - Therefore, we need to have two converters:

    //                      1. a converter from `meter` to `foot`

    //                      2. a converter from `foot` to `inch`

    //          - Therefore, if the input is `2 meter`:

    //              1. convert `meter` to `foot` --> 2 meter to 6.56168 feet

    //              2. convert the residual of 6.56168 feet (0.56168) to inches, which will be (6.74016

    //              inches)

    //              3. then, the final result will be (6 feet and 6.74016 inches)

    for (int i = 0, n = units_.length(); i < n; i++) {

        if (i == 0) { // first element

            unitsConverters_.emplaceBackAndCheckErrorCode(status, inputUnit, units_[i]->unitImpl,

                                                          ratesInfo, status);

        } else {

            unitsConverters_.emplaceBackAndCheckErrorCode(status, units_[i - 1]->unitImpl,

                                                          units_[i]->unitImpl, ratesInfo, status);

        }

        if (U_FAILURE(status)) {

            return;

        }

    }

}

UBool ComplexUnitsConverter::greaterThanOrEqual(double quantity, double limit) const {

    U_ASSERT(unitsConverters_.length() > 0);

    // First converter converts to the biggest quantity.

    double newQuantity = unitsConverters_[0]->convert(quantity);

    return newQuantity >= limit;

}

MaybeStackVector<Measure> ComplexUnitsConverter::convert(double quantity,

                                                         icu::number::impl::RoundingImpl *rounder,

                                                         UErrorCode &status) const {

    // TODO: return an error for "foot-and-foot"?

    MaybeStackVector<Measure> result;

    int sign = 1;

    if (quantity < 0) {

        quantity *= -1;

        sign = -1;

    }

    // For N converters:

    // - the first converter converts from the input unit to the largest unit,

    // - the following N-2 converters convert to bigger units for which we want integers,

    // - the Nth converter (index N-1) converts to the smallest unit, for which

    //   we keep a double.

    MaybeStackArray<int64_t, 5> intValues(unitsConverters_.length() - 1, status);

    if (U_FAILURE(status)) {

        return result;

    }

    uprv_memset(intValues.getAlias(), 0, (unitsConverters_.length() - 1) * sizeof(int64_t));

    for (int i = 0, n = unitsConverters_.length(); i < n; ++i) {

        quantity = (*unitsConverters_[i]).convert(quantity);

        if (i < n - 1) {

            // If quantity is at the limits of double's precision from an

            // integer value, we take that integer value.

            int64_t flooredQuantity = floor(quantity * (1 + DBL_EPSILON));

            if (uprv_isNaN(quantity)) {

                // With clang on Linux: floor does not support NaN, resulting in

                // a giant negative number. For now, we produce "0 feet, NaN

                // inches". TODO(icu-units#131): revisit desired output.

                flooredQuantity = 0;

            }

            intValues[i] = flooredQuantity;

            // Keep the residual of the quantity.

            //   For example: `3.6 feet`, keep only `0.6 feet`

            double remainder = quantity - flooredQuantity;

            if (remainder < 0) {

                // Because we nudged flooredQuantity up by eps, remainder may be

                // negative: we must treat such a remainder as zero.

                quantity = 0;

            } else {

                quantity = remainder;

            }

        }   

    }

    applyRounder(intValues, quantity, rounder, status);

    // Initialize empty result. We use a MaybeStackArray directly so we can

    // assign pointers - for this privilege we have to take care of cleanup.

    MaybeStackArray<Measure *, 4> tmpResult(unitsConverters_.length(), status);

    if (U_FAILURE(status)) {

        return result;

    }

    // Package values into temporary Measure instances in tmpResult:

    for (int i = 0, n = unitsConverters_.length(); i < n; ++i) {

        if (i < n - 1) {

            Formattable formattableQuantity(intValues[i] * sign);

            // Measure takes ownership of the MeasureUnit*

            MeasureUnit *type = new MeasureUnit(units_[i]->unitImpl.copy(status).build(status));

            tmpResult[units_[i]->index] = new Measure(formattableQuantity, type, status);

        } else { // LAST ELEMENT

            Formattable formattableQuantity(quantity * sign);

            // Measure takes ownership of the MeasureUnit*

            MeasureUnit *type = new MeasureUnit(units_[i]->unitImpl.copy(status).build(status));

            tmpResult[units_[i]->index] = new Measure(formattableQuantity, type, status);

        }

    }

    // Transfer values into result and return:

    for(int32_t i = 0, n = unitsConverters_.length(); i < n; ++i) {

        U_ASSERT(tmpResult[i] != nullptr);

        result.emplaceBackAndCheckErrorCode(status, *tmpResult[i]);

        delete tmpResult[i];

    }

    return result;

}

void ComplexUnitsConverter::applyRounder(MaybeStackArray<int64_t, 5> &intValues, double &quantity,

                                         icu::number::impl::RoundingImpl *rounder,

                                         UErrorCode &status) const {

    if (rounder == nullptr) {

        // Nothing to do for the quantity.

        return;

    }

    number::impl::DecimalQuantity decimalQuantity;

    decimalQuantity.setToDouble(quantity);

    rounder->apply(decimalQuantity, status);

    if (U_FAILURE(status)) {

        return;

    }

    quantity = decimalQuantity.toDouble();

    int32_t lastIndex = unitsConverters_.length() - 1;

    if (lastIndex == 0) {

        // Only one element, no need to bubble up the carry

        return;

    }

    // Check if there's a carry, and bubble it back up the resulting intValues.

    int64_t carry = floor(unitsConverters_[lastIndex]->convertInverse(quantity) * (1 + DBL_EPSILON));

    if (carry <= 0) {

        return;

    }

    quantity -= unitsConverters_[lastIndex]->convert(carry);

    intValues[lastIndex - 1] += carry;

    // We don't use the first converter: that one is for the input unit

    for (int32_t j = lastIndex - 1; j > 0; j--) {

        carry = floor(unitsConverters_[j]->convertInverse(intValues[j]) * (1 + DBL_EPSILON));

        if (carry <= 0) {

            return;

        }

        intValues[j] -= round(unitsConverters_[j]->convert(carry));

        intValues[j - 1] += carry;

    }

}

} // namespace units

U_NAMESPACE_END

#endif /* #if !UCONFIG_NO_FORMATTING */