// © 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 "cstring.h"

#include "number_decimalquantity.h"

#include "resource.h"

#include "uassert.h"

#include "unicode/unistr.h"

#include "unicode/ures.h"

#include "units_data.h"

#include "uresimp.h"

#include "util.h"

#include <utility>

U_NAMESPACE_BEGIN

namespace units {

namespace {

using icu::number::impl::DecimalQuantity;

void trimSpaces(CharString& factor, UErrorCode& status){

   CharString trimmed;

   for (int i = 0 ; i < factor.length(); i++) {

       if (factor[i] == ' ') continue;

       trimmed.append(factor[i], status);

   }

   factor = std::move(trimmed);

}

/**

 * A ResourceSink that collects conversion rate information.

 *

 * This class is for use by ures_getAllItemsWithFallback.

 */

class ConversionRateDataSink : public ResourceSink {

  public:

    /**

     * Constructor.

     * @param out The vector to which ConversionRateInfo instances are to be

     * added. This vector must outlive the use of the ResourceSink.

     */

    explicit ConversionRateDataSink(MaybeStackVector<ConversionRateInfo> *out) : outVector(out) {}

    /**

     * Method for use by `ures_getAllItemsWithFallback`. Adds the unit

     * conversion rates that are found in `value` to the output vector.

     *

     * @param source This string must be "convertUnits": the resource that this

     * class supports reading.

     * @param value The "convertUnits" resource, containing unit conversion rate

     * information.

     * @param noFallback Ignored.

     * @param status The standard ICU error code output parameter.

     */

    void put(const char *source, ResourceValue &value, UBool /*noFallback*/, UErrorCode &status) {

        if (U_FAILURE(status)) { return; }

        if (uprv_strcmp(source, "convertUnits") != 0) {

            // This is very strict, however it is the cheapest way to be sure

            // that with `value`, we're looking at the convertUnits table.

            status = U_ILLEGAL_ARGUMENT_ERROR;

            return;

        }

        ResourceTable conversionRateTable = value.getTable(status);

        const char *srcUnit;

        // We're reusing `value`, which seems to be a common pattern:

        for (int32_t unit = 0; conversionRateTable.getKeyAndValue(unit, srcUnit, value); unit++) {

            ResourceTable unitTable = value.getTable(status);

            const char *key;

            UnicodeString baseUnit = ICU_Utility::makeBogusString();

            UnicodeString factor = ICU_Utility::makeBogusString();

            UnicodeString offset = ICU_Utility::makeBogusString();

            for (int32_t i = 0; unitTable.getKeyAndValue(i, key, value); i++) {

                if (uprv_strcmp(key, "target") == 0) {

                    baseUnit = value.getUnicodeString(status);

                } else if (uprv_strcmp(key, "factor") == 0) {

                    factor = value.getUnicodeString(status);

                } else if (uprv_strcmp(key, "offset") == 0) {

                    offset = value.getUnicodeString(status);

                }

            }

            if (U_FAILURE(status)) { return; }

            if (baseUnit.isBogus() || factor.isBogus()) {

                // We could not find a usable conversion rate: bad resource.

                status = U_MISSING_RESOURCE_ERROR;

                return;

            }

            // We don't have this ConversionRateInfo yet: add it.

            ConversionRateInfo *cr = outVector->emplaceBack();

            if (!cr) {

                status = U_MEMORY_ALLOCATION_ERROR;

                return;

            } else {

                cr->sourceUnit.append(srcUnit, status);

                cr->baseUnit.appendInvariantChars(baseUnit, status);

                cr->factor.appendInvariantChars(factor, status);

                trimSpaces(cr->factor, status);

                if (!offset.isBogus()) cr->offset.appendInvariantChars(offset, status);

            }

        }

        return;

    }

  private:

    MaybeStackVector<ConversionRateInfo> *outVector;

};

bool operator<(const UnitPreferenceMetadata &a, const UnitPreferenceMetadata &b) {

    return a.compareTo(b) < 0;

}

/**

 * A ResourceSink that collects unit preferences information.

 *

 * This class is for use by ures_getAllItemsWithFallback.

 */

class UnitPreferencesSink : public ResourceSink {

  public:

    /**

     * Constructor.

     * @param outPrefs The vector to which UnitPreference instances are to be

     * added. This vector must outlive the use of the ResourceSink.

     * @param outMetadata  The vector to which UnitPreferenceMetadata instances

     * are to be added. This vector must outlive the use of the ResourceSink.

     */

    explicit UnitPreferencesSink(MaybeStackVector<UnitPreference> *outPrefs,

                                 MaybeStackVector<UnitPreferenceMetadata> *outMetadata)

        : preferences(outPrefs), metadata(outMetadata) {}

    /**

     * Method for use by `ures_getAllItemsWithFallback`. Adds the unit

     * preferences info that are found in `value` to the output vector.

     *

     * @param source This string must be "unitPreferenceData": the resource that

     * this class supports reading.

     * @param value The "unitPreferenceData" resource, containing unit

     * preferences data.

     * @param noFallback Ignored.

     * @param status The standard ICU error code output parameter. Note: if an

     * error is returned, outPrefs and outMetadata may be inconsistent.

     */

    void put(const char *key, ResourceValue &value, UBool /*noFallback*/, UErrorCode &status) {

        if (U_FAILURE(status)) { return; }

        if (uprv_strcmp(key, "unitPreferenceData") != 0) {

            // This is very strict, however it is the cheapest way to be sure

            // that with `value`, we're looking at the convertUnits table.

            status = U_ILLEGAL_ARGUMENT_ERROR;

            return;

        }

        // The unitPreferenceData structure (see data/misc/units.txt) contains a

        // hierarchy of category/usage/region, within which are a set of

        // preferences. Hence three for-loops and another loop for the

        // preferences themselves:

        ResourceTable unitPreferenceDataTable = value.getTable(status);

        const char *category;

        for (int32_t i = 0; unitPreferenceDataTable.getKeyAndValue(i, category, value); i++) {

            ResourceTable categoryTable = value.getTable(status);

            const char *usage;

            for (int32_t j = 0; categoryTable.getKeyAndValue(j, usage, value); j++) {

                ResourceTable regionTable = value.getTable(status);

                const char *region;

                for (int32_t k = 0; regionTable.getKeyAndValue(k, region, value); k++) {

                    // `value` now contains the set of preferences for

                    // category/usage/region.

                    ResourceArray unitPrefs = value.getArray(status);

                    if (U_FAILURE(status)) { return; }

                    int32_t prefLen = unitPrefs.getSize();

                    // Update metadata for this set of preferences.

                    UnitPreferenceMetadata *meta = metadata->emplaceBack(

                        category, usage, region, preferences->length(), prefLen, status);

                    if (!meta) {

                        status = U_MEMORY_ALLOCATION_ERROR;

                        return;

                    }

                    if (U_FAILURE(status)) { return; }

                    if (metadata->length() > 1) {

                        // Verify that unit preferences are sorted and

                        // without duplicates.

                        if (!(*(*metadata)[metadata->length() - 2] <

                              *(*metadata)[metadata->length() - 1])) {

                            status = U_INVALID_FORMAT_ERROR;

                            return;

                        }

                    }

                    // Collect the individual preferences.

                    for (int32_t i = 0; unitPrefs.getValue(i, value); i++) {

                        UnitPreference *up = preferences->emplaceBack();

                        if (!up) {

                            status = U_MEMORY_ALLOCATION_ERROR;

                            return;

                        }

                        ResourceTable unitPref = value.getTable(status);

                        if (U_FAILURE(status)) { return; }

                        for (int32_t i = 0; unitPref.getKeyAndValue(i, key, value); ++i) {

                            if (uprv_strcmp(key, "unit") == 0) {

                                int32_t length;

                                const UChar *u = value.getString(length, status);

                                up->unit.appendInvariantChars(u, length, status);

                            } else if (uprv_strcmp(key, "geq") == 0) {

                                int32_t length;

                                const UChar *g = value.getString(length, status);

                                CharString geq;

                                geq.appendInvariantChars(g, length, status);

                                DecimalQuantity dq;

                                dq.setToDecNumber(geq.data(), status);

                                up->geq = dq.toDouble();

                            } else if (uprv_strcmp(key, "skeleton") == 0) {

                                up->skeleton = value.getUnicodeString(status);

                            }

                        }

                    }

                }

            }

        }

    }

  private:

    MaybeStackVector<UnitPreference> *preferences;

    MaybeStackVector<UnitPreferenceMetadata> *metadata;

};

int32_t binarySearch(const MaybeStackVector<UnitPreferenceMetadata> *metadata,

                     const UnitPreferenceMetadata &desired, bool *foundCategory, bool *foundUsage,

                     bool *foundRegion, UErrorCode &status) {

    if (U_FAILURE(status)) { return -1; }

    int32_t start = 0;

    int32_t end = metadata->length();

    *foundCategory = false;

    *foundUsage = false;

    *foundRegion = false;

    while (start < end) {

        int32_t mid = (start + end) / 2;

        int32_t cmp = (*metadata)[mid]->compareTo(desired, foundCategory, foundUsage, foundRegion);

        if (cmp < 0) {

            start = mid + 1;

        } else if (cmp > 0) {

            end = mid;

        } else {

            return mid;

        }

    }

    return -1;

}

/**

 * Finds the UnitPreferenceMetadata instance that matches the given category,

 * usage and region: if missing, region falls back to "001", and usage

 * repeatedly drops tailing components, eventually trying "default"

 * ("land-agriculture-grain" -> "land-agriculture" -> "land" -> "default").

 *

 * @param metadata The full list of UnitPreferenceMetadata instances.

 * @param category The category to search for. See getUnitCategory().

 * @param usage The usage for which formatting preferences is needed. If the

 * given usage is not known, automatic fallback occurs, see function description

 * above.

 * @param region The region for which preferences are needed. If there are no

 * region-specific preferences, this function automatically falls back to the

 * "001" region (global).

 * @param status The standard ICU error code output parameter.

 *   * If an invalid category is given, status will be U_ILLEGAL_ARGUMENT_ERROR.

 *   * If fallback to "default" or "001" didn't resolve, status will be

 *     U_MISSING_RESOURCE.

 * @return The index into the metadata vector which represents the appropriate

 * preferences. If appropriate preferences are not found, -1 is returned.

 */

int32_t getPreferenceMetadataIndex(const MaybeStackVector<UnitPreferenceMetadata> *metadata,

                                   StringPiece category, StringPiece usage, StringPiece region,

                                   UErrorCode &status) {

    if (U_FAILURE(status)) { return -1; }

    bool foundCategory, foundUsage, foundRegion;

    UnitPreferenceMetadata desired(category, usage, region, -1, -1, status);

    int32_t idx = binarySearch(metadata, desired, &foundCategory, &foundUsage, &foundRegion, status);

    if (U_FAILURE(status)) { return -1; }

    if (idx >= 0) { return idx; }

    if (!foundCategory) {

        // TODO: failures can happen if units::getUnitCategory returns a category

        // that does not appear in unitPreferenceData. Do we want a unit test that

        // checks unitPreferenceData has full coverage of categories? Or just trust

        // CLDR?

        status = U_ILLEGAL_ARGUMENT_ERROR;

        return -1;

    }

    U_ASSERT(foundCategory);

    while (!foundUsage) {

        int32_t lastDashIdx = desired.usage.lastIndexOf('-');

        if (lastDashIdx > 0) {

            desired.usage.truncate(lastDashIdx);

        } else if (uprv_strcmp(desired.usage.data(), "default") != 0) {

            desired.usage.truncate(0).append("default", status);

        } else {

            // "default" is not supposed to be missing for any valid category.

            status = U_MISSING_RESOURCE_ERROR;

            return -1;

        }

        idx = binarySearch(metadata, desired, &foundCategory, &foundUsage, &foundRegion, status);

        if (U_FAILURE(status)) { return -1; }

    }

    U_ASSERT(foundCategory);

    U_ASSERT(foundUsage);

    if (!foundRegion) {

        if (uprv_strcmp(desired.region.data(), "001") != 0) {

            desired.region.truncate(0).append("001", status);

            idx = binarySearch(metadata, desired, &foundCategory, &foundUsage, &foundRegion, status);

        }

        if (!foundRegion) {

            // "001" is not supposed to be missing for any valid usage.

            status = U_MISSING_RESOURCE_ERROR;

            return -1;

        }

    }

    U_ASSERT(foundCategory);

    U_ASSERT(foundUsage);

    U_ASSERT(foundRegion);

    U_ASSERT(idx >= 0);

    return idx;

}

} // namespace

UnitPreferenceMetadata::UnitPreferenceMetadata(StringPiece category, StringPiece usage,

                                               StringPiece region, int32_t prefsOffset,

                                               int32_t prefsCount, UErrorCode &status) {

    this->category.append(category, status);

    this->usage.append(usage, status);

    this->region.append(region, status);

    this->prefsOffset = prefsOffset;

    this->prefsCount = prefsCount;

}

int32_t UnitPreferenceMetadata::compareTo(const UnitPreferenceMetadata &other) const {

    int32_t cmp = uprv_strcmp(category.data(), other.category.data());

    if (cmp == 0) {

        cmp = uprv_strcmp(usage.data(), other.usage.data());

    }

    if (cmp == 0) {

        cmp = uprv_strcmp(region.data(), other.region.data());

    }

    return cmp;

}

int32_t UnitPreferenceMetadata::compareTo(const UnitPreferenceMetadata &other, bool *foundCategory,

                                          bool *foundUsage, bool *foundRegion) const {

    int32_t cmp = uprv_strcmp(category.data(), other.category.data());

    if (cmp == 0) {

        *foundCategory = true;

        cmp = uprv_strcmp(usage.data(), other.usage.data());

    }

    if (cmp == 0) {

        *foundUsage = true;

        cmp = uprv_strcmp(region.data(), other.region.data());

    }

    if (cmp == 0) {

        *foundRegion = true;

    }

    return cmp;

}

// TODO: this may be unnecessary. Fold into ConversionRates class? Or move to anonymous namespace?

void U_I18N_API getAllConversionRates(MaybeStackVector<ConversionRateInfo> &result, UErrorCode &status) {

    LocalUResourceBundlePointer unitsBundle(ures_openDirect(NULL, "units", &status));

    ConversionRateDataSink sink(&result);

    ures_getAllItemsWithFallback(unitsBundle.getAlias(), "convertUnits", sink, status);

}

const ConversionRateInfo *ConversionRates::extractConversionInfo(StringPiece source,

                                                                 UErrorCode &status) const {

    for (size_t i = 0, n = conversionInfo_.length(); i < n; ++i) {

        if (conversionInfo_[i]->sourceUnit.toStringPiece() == source) return conversionInfo_[i];

    }

    status = U_INTERNAL_PROGRAM_ERROR;

    return nullptr;

}

U_I18N_API UnitPreferences::UnitPreferences(UErrorCode &status) {

    LocalUResourceBundlePointer unitsBundle(ures_openDirect(NULL, "units", &status));

    UnitPreferencesSink sink(&unitPrefs_, &metadata_);

    ures_getAllItemsWithFallback(unitsBundle.getAlias(), "unitPreferenceData", sink, status);

}

// TODO: make outPreferences const?

//

// TODO: consider replacing `UnitPreference **&outPreferences` with slice class

// of some kind.

void U_I18N_API UnitPreferences::getPreferencesFor(StringPiece category, StringPiece usage,

                                                   StringPiece region,

                                                   const UnitPreference *const *&outPreferences,

                                                   int32_t &preferenceCount, UErrorCode &status) const {

    int32_t idx = getPreferenceMetadataIndex(&metadata_, category, usage, region, status);

    if (U_FAILURE(status)) {

        outPreferences = nullptr;

        preferenceCount = 0;

        return;

    }

    U_ASSERT(idx >= 0); // Failures should have been taken care of by `status`.

    const UnitPreferenceMetadata *m = metadata_[idx];

    outPreferences = unitPrefs_.getAlias() + m->prefsOffset;

    preferenceCount = m->prefsCount;

}

} // namespace units

U_NAMESPACE_END

#endif /* #if !UCONFIG_NO_FORMATTING */