// © 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

#ifndef __UNITS_ROUTER_H__

#define __UNITS_ROUTER_H__

#include <limits>

#include "cmemory.h"

#include "measunit_impl.h"

#include "unicode/measunit.h"

#include "unicode/stringpiece.h"

#include "unicode/uobject.h"

#include "units_complexconverter.h"

#include "units_data.h"

U_NAMESPACE_BEGIN

// Forward declarations

class Measure;

namespace number {

class Precision;

}

namespace units {

struct RouteResult : UMemory {

    // A list of measures: a single measure for single units, multiple measures

    // for mixed units.

    //

    // TODO(icu-units/icu#21): figure out the right mixed unit API.

    MaybeStackVector<Measure> measures;

    // The output unit for this RouteResult. This may be a MIXED unit - for

    // example: "yard-and-foot-and-inch", for which `measures` will have three

    // elements.

    MeasureUnitImpl outputUnit;

    RouteResult(MaybeStackVector<Measure> measures, MeasureUnitImpl outputUnit)

        : measures(std::move(measures)), outputUnit(std::move(outputUnit)) {}

};

/**

 * Contains the complex unit converter and the limit which representing the smallest value that the

 * converter should accept. For example, if the converter is converting to `foot+inch` and the limit

 * equals 3.0, thus means the converter should not convert to a value less than `3.0 feet`.

 *

 * NOTE:

 *    if the limit doest not has a value `i.e. (std::numeric_limits<double>::lowest())`, this mean there

 *    is no limit for the converter.

 */

struct ConverterPreference : UMemory {

    ComplexUnitsConverter converter;

    double limit;

    UnicodeString precision;

    // The output unit for this ConverterPreference. This may be a MIXED unit -

    // for example: "yard-and-foot-and-inch".

    MeasureUnitImpl targetUnit;

    // In case there is no limit, the limit will be -inf.

    ConverterPreference(const MeasureUnitImpl &source, const MeasureUnitImpl &complexTarget,

                        UnicodeString precision, const ConversionRates &ratesInfo, UErrorCode &status)

        : ConverterPreference(source, complexTarget, std::numeric_limits<double>::lowest(), precision,

                              ratesInfo, status) {}

    ConverterPreference(const MeasureUnitImpl &source, const MeasureUnitImpl &complexTarget,

                        double limit, UnicodeString precision, const ConversionRates &ratesInfo,

                        UErrorCode &status)

        : converter(source, complexTarget, ratesInfo, status), limit(limit),

          precision(std::move(precision)), targetUnit(complexTarget.copy(status)) {}

};

} // namespace units

// Export explicit template instantiations of MaybeStackArray, MemoryPool and

// MaybeStackVector. This is required when building DLLs for Windows. (See

// datefmt.h, collationiterator.h, erarules.h and others for similar examples.)

//

// Note: These need to be outside of the units namespace, or Clang will generate

// a compile error.

#if U_PF_WINDOWS <= U_PLATFORM && U_PLATFORM <= U_PF_CYGWIN

template class U_I18N_API MaybeStackArray<units::ConverterPreference*, 8>;

template class U_I18N_API MemoryPool<units::ConverterPreference, 8>;

template class U_I18N_API MaybeStackVector<units::ConverterPreference, 8>;

#endif

namespace units {

/**

 * `UnitsRouter` responsible for converting from a single unit (such as `meter` or `meter-per-second`) to

 * one of the complex units based on the limits.

 * For example:

 *    if the input is `meter` and the output as following

 *    {`foot+inch`, limit: 3.0}

 *    {`inch`     , limit: no value (-inf)}

 *    Thus means if the input in `meter` is greater than or equal to `3.0 feet`, the output will be in

 *    `foot+inch`, otherwise, the output will be in `inch`.

 *

 * NOTE:

 *    the output units and the their limits MUST BE in order, for example, if the output units, from the

 *    previous example, are the following:

 *        {`inch`     , limit: no value (-inf)}

 *        {`foot+inch`, limit: 3.0}

 *     IN THIS CASE THE OUTPUT WILL BE ALWAYS IN `inch`.

 *

 * NOTE:

 *    the output units  and their limits will be extracted from the units preferences database by knowing

 *    the following:

 *        - input unit

 *        - locale

 *        - usage

 *

 * DESIGN:

 *    `UnitRouter` uses internally `ComplexUnitConverter` in order to convert the input units to the

 *    desired complex units and to check the limit too.

 */

class U_I18N_API UnitsRouter {

  public:

    UnitsRouter(StringPiece inputUnitIdentifier, StringPiece locale, StringPiece usage,

                UErrorCode &status);

    UnitsRouter(const MeasureUnit &inputUnit, StringPiece locale, StringPiece usage, UErrorCode &status);

    /**

     * Performs locale and usage sensitive unit conversion.

     * @param quantity The quantity to convert, expressed in terms of inputUnit.

     * @param rounder If not null, this RoundingImpl will be used to do rounding

     *     on the converted value. If the rounder lacks an fPrecision, the

     *     rounder will be modified to use the preferred precision for the usage

     *     and locale preference, alternatively with the default precision.

     * @param status Receives status.

     */

    RouteResult route(double quantity, icu::number::impl::RoundingImpl *rounder, UErrorCode &status) const;

    /**

     * Returns the list of possible output units, i.e. the full set of

     * preferences, for the localized, usage-specific unit preferences.

     *

     * The returned pointer should be valid for the lifetime of the

     * UnitsRouter instance.

     */

    const MaybeStackVector<MeasureUnit> *getOutputUnits() const;

  private:

    // List of possible output units. TODO: converterPreferences_ now also has

    // this data available. Maybe drop outputUnits_ and have getOutputUnits

    // construct a the list from data in converterPreferences_ instead?

    MaybeStackVector<MeasureUnit> outputUnits_;

    MaybeStackVector<ConverterPreference> converterPreferences_;

    static number::Precision parseSkeletonToPrecision(icu::UnicodeString precisionSkeleton,

                                                      UErrorCode &status);

    void init(const MeasureUnit &inputUnit, StringPiece locale, StringPiece usage, UErrorCode &status);

};

} // namespace units

U_NAMESPACE_END

#endif //__UNITS_ROUTER_H__

#endif /* #if !UCONFIG_NO_FORMATTING */