/*
 * Copyright (c) 2021-2026, Tim Flynn <trflynn89@ladybird.org>
 *
 * SPDX-License-Identifier: BSD-2-Clause
 */

#include <AK/Array.h>
#include <AK/CharacterTypes.h>
#include <AK/Find.h>
#include <AK/HashMap.h>
#include <AK/NonnullOwnPtr.h>
#include <AK/Traits.h>
#include <LibUnicode/CharacterTypes.h>
#include <LibUnicode/ICU.h>

#include <unicode/uchar.h>
#include <unicode/uniset.h>
#include <unicode/uscript.h>
#include <unicode/uset.h>

namespace Unicode {

template<typename PropertyType>
struct PropertyName {
    Optional<StringView> long_name;
    Optional<StringView> short_name;
    Optional<StringView> additional_name;
};

// From uchar.h:
// Unicode allows for additional names, beyond the long and short name, which would be indicated by U_LONG_PROPERTY_NAME + i
static constexpr auto ADDITIONAL_NAME = static_cast<UPropertyNameChoice>(U_LONG_PROPERTY_NAME + 1);

}

template<typename PropertyType>
struct AK::Traits<Unicode::PropertyName<PropertyType>> {
    static constexpr bool equals(Unicode::PropertyName<PropertyType> const& candidate, StringView property)
    {
        return property == candidate.long_name || property == candidate.short_name || property == candidate.additional_name;
    }
};

namespace Unicode {

static constexpr GeneralCategory GENERAL_CATEGORY_CASED_LETTER = U_CHAR_CATEGORY_COUNT + 1;
static constexpr GeneralCategory GENERAL_CATEGORY_LETTER = U_CHAR_CATEGORY_COUNT + 2;
static constexpr GeneralCategory GENERAL_CATEGORY_MARK = U_CHAR_CATEGORY_COUNT + 3;
static constexpr GeneralCategory GENERAL_CATEGORY_NUMBER = U_CHAR_CATEGORY_COUNT + 4;
static constexpr GeneralCategory GENERAL_CATEGORY_PUNCTUATION = U_CHAR_CATEGORY_COUNT + 5;
static constexpr GeneralCategory GENERAL_CATEGORY_SYMBOL = U_CHAR_CATEGORY_COUNT + 6;
static constexpr GeneralCategory GENERAL_CATEGORY_SEPARATOR = U_CHAR_CATEGORY_COUNT + 7;
static constexpr GeneralCategory GENERAL_CATEGORY_OTHER = U_CHAR_CATEGORY_COUNT + 8;
static constexpr GeneralCategory GENERAL_CATEGORY_LIMIT = U_CHAR_CATEGORY_COUNT + 9;

static HashMap<GeneralCategory, NonnullOwnPtr<icu::UnicodeSet>> s_category_sets_with_case_closure;
static HashMap<Property, NonnullOwnPtr<icu::UnicodeSet>> s_property_sets_with_case_closure;

Optional<GeneralCategory> general_category_from_string(StringView general_category)
{
    static auto general_category_names = []() {
        Array<PropertyName<GeneralCategory>, GENERAL_CATEGORY_LIMIT.value()> names;

        auto set_names = [&](auto property, auto index, auto general_category) {
            if (char const* name = u_getPropertyValueName(property, general_category, U_LONG_PROPERTY_NAME))
                names[index.value()].long_name = StringView { name, strlen(name) };
            if (char const* name = u_getPropertyValueName(property, general_category, U_SHORT_PROPERTY_NAME))
                names[index.value()].short_name = StringView { name, strlen(name) };
            if (char const* name = u_getPropertyValueName(property, general_category, ADDITIONAL_NAME))
                names[index.value()].additional_name = StringView { name, strlen(name) };
        };

        for (GeneralCategory general_category = 0; general_category < U_CHAR_CATEGORY_COUNT; ++general_category)
            set_names(UCHAR_GENERAL_CATEGORY, general_category, static_cast<UCharCategory>(general_category.value()));

        set_names(UCHAR_GENERAL_CATEGORY_MASK, GENERAL_CATEGORY_CASED_LETTER, U_GC_LC_MASK);
        set_names(UCHAR_GENERAL_CATEGORY_MASK, GENERAL_CATEGORY_LETTER, U_GC_L_MASK);
        set_names(UCHAR_GENERAL_CATEGORY_MASK, GENERAL_CATEGORY_MARK, U_GC_M_MASK);
        set_names(UCHAR_GENERAL_CATEGORY_MASK, GENERAL_CATEGORY_NUMBER, U_GC_N_MASK);
        set_names(UCHAR_GENERAL_CATEGORY_MASK, GENERAL_CATEGORY_PUNCTUATION, U_GC_P_MASK);
        set_names(UCHAR_GENERAL_CATEGORY_MASK, GENERAL_CATEGORY_SYMBOL, U_GC_S_MASK);
        set_names(UCHAR_GENERAL_CATEGORY_MASK, GENERAL_CATEGORY_SEPARATOR, U_GC_Z_MASK);
        set_names(UCHAR_GENERAL_CATEGORY_MASK, GENERAL_CATEGORY_OTHER, U_GC_C_MASK);

        return names;
    }();

    if (auto index = find_index(general_category_names.begin(), general_category_names.end(), general_category); index != general_category_names.size())
        return static_cast<GeneralCategory>(index);
    return {};
}

static uint32_t get_icu_mask(GeneralCategory general_category)
{
    if (general_category == GENERAL_CATEGORY_CASED_LETTER)
        return U_GC_LC_MASK;
    if (general_category == GENERAL_CATEGORY_LETTER)
        return U_GC_L_MASK;
    if (general_category == GENERAL_CATEGORY_MARK)
        return U_GC_M_MASK;
    if (general_category == GENERAL_CATEGORY_NUMBER)
        return U_GC_N_MASK;
    if (general_category == GENERAL_CATEGORY_PUNCTUATION)
        return U_GC_P_MASK;
    if (general_category == GENERAL_CATEGORY_SYMBOL)
        return U_GC_S_MASK;
    if (general_category == GENERAL_CATEGORY_SEPARATOR)
        return U_GC_Z_MASK;
    if (general_category == GENERAL_CATEGORY_OTHER)
        return U_GC_C_MASK;

    return U_MASK(static_cast<UCharCategory>(general_category.value()));
}

bool code_point_has_general_category(u32 code_point, GeneralCategory general_category, CaseSensitivity case_sensitivity)
{
    auto icu_code_point = static_cast<UChar32>(code_point);
    auto category_mask = get_icu_mask(general_category);

    if ((U_GET_GC_MASK(icu_code_point) & category_mask) != 0)
        return true;

    if (case_sensitivity == CaseSensitivity::CaseSensitive)
        return false;

    auto& set = s_category_sets_with_case_closure.ensure(general_category, [&] {
        UErrorCode status = U_ZERO_ERROR;
        auto new_set = make<icu::UnicodeSet>();
        new_set->applyIntPropertyValue(UCHAR_GENERAL_CATEGORY_MASK, static_cast<int32_t>(category_mask), status);
        new_set->closeOver(USET_CASE_INSENSITIVE);
        new_set->freeze();
        return new_set;
    });

    return set->contains(icu_code_point);
}

bool code_point_is_printable(u32 code_point)
{
    return static_cast<bool>(u_isprint(static_cast<UChar32>(code_point)));
}

bool code_point_has_control_general_category(u32 code_point)
{
    return code_point_has_general_category(code_point, U_CONTROL_CHAR);
}

bool code_point_has_letter_general_category(u32 code_point)
{
    return code_point_has_general_category(code_point, GENERAL_CATEGORY_LETTER);
}

bool code_point_has_mark_general_category(u32 code_point)
{
    return code_point_has_general_category(code_point, GENERAL_CATEGORY_MARK);
}

bool code_point_has_number_general_category(u32 code_point)
{
    return code_point_has_general_category(code_point, GENERAL_CATEGORY_NUMBER);
}

bool code_point_has_punctuation_general_category(u32 code_point)
{
    return code_point_has_general_category(code_point, GENERAL_CATEGORY_PUNCTUATION);
}

bool code_point_has_separator_general_category(u32 code_point)
{
    return code_point_has_general_category(code_point, GENERAL_CATEGORY_SEPARATOR);
}

bool code_point_has_space_separator_general_category(u32 code_point)
{
    return code_point_has_general_category(code_point, U_SPACE_SEPARATOR);
}

bool code_point_has_symbol_general_category(u32 code_point)
{
    return code_point_has_general_category(code_point, GENERAL_CATEGORY_SYMBOL);
}

static constexpr Property PROPERTY_ANY = UCHAR_BINARY_LIMIT + 1;
static constexpr Property PROPERTY_ASCII = UCHAR_BINARY_LIMIT + 2;
static constexpr Property PROPERTY_ASSIGNED = UCHAR_BINARY_LIMIT + 3;
static constexpr Property PROPERTY_LIMIT = UCHAR_BINARY_LIMIT + 4;

Optional<Property> property_from_string(StringView property)
{
    static auto property_names = []() {
        Array<PropertyName<Property>, PROPERTY_LIMIT.value()> names;

        for (Property property = 0; property < UCHAR_BINARY_LIMIT; ++property) {
            auto icu_property = static_cast<UProperty>(property.value());

            if (char const* name = u_getPropertyName(icu_property, U_LONG_PROPERTY_NAME))
                names[property.value()].long_name = StringView { name, strlen(name) };
            if (char const* name = u_getPropertyName(icu_property, U_SHORT_PROPERTY_NAME))
                names[property.value()].short_name = StringView { name, strlen(name) };
            if (char const* name = u_getPropertyName(icu_property, ADDITIONAL_NAME))
                names[property.value()].additional_name = StringView { name, strlen(name) };
        }

        names[PROPERTY_ANY.value()] = { "Any"sv, {}, {} };
        names[PROPERTY_ASCII.value()] = { "ASCII"sv, {}, {} };
        names[PROPERTY_ASSIGNED.value()] = { "Assigned"sv, {}, {} };

        return names;
    }();

    if (auto index = find_index(property_names.begin(), property_names.end(), property); index != property_names.size())
        return static_cast<Property>(index);
    return {};
}

bool code_point_has_property(u32 code_point, Property property, CaseSensitivity case_sensitivity)
{
    auto icu_code_point = static_cast<UChar32>(code_point);

    if (property == PROPERTY_ANY)
        return is_unicode(code_point);
    if (property == PROPERTY_ASCII)
        return is_ascii(code_point);
    if (property == PROPERTY_ASSIGNED)
        return u_isdefined(icu_code_point) != 0;

    auto icu_property = static_cast<UProperty>(property.value());
    if (u_hasBinaryProperty(icu_code_point, icu_property))
        return true;

    if (case_sensitivity == CaseSensitivity::CaseSensitive)
        return false;

    auto& set = s_property_sets_with_case_closure.ensure(property, [&] {
        UErrorCode status = U_ZERO_ERROR;
        auto new_set = make<icu::UnicodeSet>();
        new_set->applyIntPropertyValue(icu_property, 1, status);
        new_set->closeOver(USET_CASE_INSENSITIVE);
        new_set->freeze();
        return new_set;
    });

    return set->contains(icu_code_point);
}

bool code_point_has_emoji_property(u32 code_point)
{
    return code_point_has_property(code_point, UCHAR_EMOJI);
}

bool code_point_has_emoji_modifier_base_property(u32 code_point)
{
    return code_point_has_property(code_point, UCHAR_EMOJI_MODIFIER_BASE);
}

bool code_point_has_emoji_presentation_property(u32 code_point)
{
    return code_point_has_property(code_point, UCHAR_EMOJI_PRESENTATION);
}

bool code_point_has_identifier_start_property(u32 code_point)
{
    return u_isIDStart(static_cast<UChar32>(code_point));
}

bool code_point_has_identifier_continue_property(u32 code_point)
{
    return u_isIDPart(static_cast<UChar32>(code_point));
}

bool code_point_has_regional_indicator_property(u32 code_point)
{
    return code_point_has_property(code_point, UCHAR_REGIONAL_INDICATOR);
}

bool code_point_has_variation_selector_property(u32 code_point)
{
    return code_point_has_property(code_point, UCHAR_VARIATION_SELECTOR);
}

bool code_point_has_white_space_property(u32 code_point)
{
    return code_point_has_property(code_point, UCHAR_WHITE_SPACE);
}

// https://tc39.es/ecma262/#table-binary-unicode-properties
bool is_ecma262_property(Property property)
{
    if (property == PROPERTY_ANY || property == PROPERTY_ASCII || property == PROPERTY_ASSIGNED)
        return true;

    switch (property.value()) {
    case UCHAR_ASCII_HEX_DIGIT:
    case UCHAR_ALPHABETIC:
    case UCHAR_BIDI_CONTROL:
    case UCHAR_BIDI_MIRRORED:
    case UCHAR_CASE_IGNORABLE:
    case UCHAR_CASED:
    case UCHAR_CHANGES_WHEN_CASEFOLDED:
    case UCHAR_CHANGES_WHEN_CASEMAPPED:
    case UCHAR_CHANGES_WHEN_LOWERCASED:
    case UCHAR_CHANGES_WHEN_NFKC_CASEFOLDED:
    case UCHAR_CHANGES_WHEN_TITLECASED:
    case UCHAR_CHANGES_WHEN_UPPERCASED:
    case UCHAR_DASH:
    case UCHAR_DEFAULT_IGNORABLE_CODE_POINT:
    case UCHAR_DEPRECATED:
    case UCHAR_DIACRITIC:
    case UCHAR_EMOJI:
    case UCHAR_EMOJI_COMPONENT:
    case UCHAR_EMOJI_MODIFIER:
    case UCHAR_EMOJI_MODIFIER_BASE:
    case UCHAR_EMOJI_PRESENTATION:
    case UCHAR_EXTENDED_PICTOGRAPHIC:
    case UCHAR_EXTENDER:
    case UCHAR_GRAPHEME_BASE:
    case UCHAR_GRAPHEME_EXTEND:
    case UCHAR_HEX_DIGIT:
    case UCHAR_IDS_BINARY_OPERATOR:
    case UCHAR_IDS_TRINARY_OPERATOR:
    case UCHAR_ID_CONTINUE:
    case UCHAR_ID_START:
    case UCHAR_IDEOGRAPHIC:
    case UCHAR_JOIN_CONTROL:
    case UCHAR_LOGICAL_ORDER_EXCEPTION:
    case UCHAR_LOWERCASE:
    case UCHAR_MATH:
    case UCHAR_NONCHARACTER_CODE_POINT:
    case UCHAR_PATTERN_SYNTAX:
    case UCHAR_PATTERN_WHITE_SPACE:
    case UCHAR_QUOTATION_MARK:
    case UCHAR_RADICAL:
    case UCHAR_REGIONAL_INDICATOR:
    case UCHAR_S_TERM:
    case UCHAR_SOFT_DOTTED:
    case UCHAR_TERMINAL_PUNCTUATION:
    case UCHAR_UNIFIED_IDEOGRAPH:
    case UCHAR_UPPERCASE:
    case UCHAR_VARIATION_SELECTOR:
    case UCHAR_WHITE_SPACE:
    case UCHAR_XID_CONTINUE:
    case UCHAR_XID_START:
        return true;
    default:
        return false;
    }
}

// https://tc39.es/ecma262/#table-binary-unicode-properties-of-strings
bool is_ecma262_string_property(Property property)
{
    switch (property.value()) {
    case UCHAR_BASIC_EMOJI:
    case UCHAR_EMOJI_KEYCAP_SEQUENCE:
    case UCHAR_RGI_EMOJI:
    case UCHAR_RGI_EMOJI_FLAG_SEQUENCE:
    case UCHAR_RGI_EMOJI_TAG_SEQUENCE:
    case UCHAR_RGI_EMOJI_MODIFIER_SEQUENCE:
    case UCHAR_RGI_EMOJI_ZWJ_SEQUENCE:
        return true;
    default:
        return false;
    }
}

Vector<String> get_property_strings(Property property)
{
    Vector<String> result;

    if (!is_ecma262_string_property(property))
        return result;

    UErrorCode status = U_ZERO_ERROR;
    auto const* icu_set = u_getBinaryPropertySet(static_cast<UProperty>(property.value()), &status);
    if (!icu_success(status) || !icu_set)
        return result;

    auto const* unicode_set = icu::UnicodeSet::fromUSet(icu_set);
    if (!unicode_set)
        return result;

    auto range_count = unicode_set->getRangeCount();
    for (int32_t i = 0; i < range_count; ++i) {
        auto start = unicode_set->getRangeStart(i);
        auto end = unicode_set->getRangeEnd(i);

        for (auto code_point = start; code_point <= end; ++code_point) {
            result.append(String::from_code_point(code_point));
        }
    }

    for (auto const& str : unicode_set->strings()) {
        result.append(icu_string_to_string(str));
    }

    return result;
}

Optional<Script> script_from_string(StringView script)
{
    static auto script_names = []() {
        Array<PropertyName<Script>, static_cast<size_t>(USCRIPT_CODE_LIMIT)> names;

        for (Script script = 0; script < USCRIPT_CODE_LIMIT; ++script) {
            auto icu_script = static_cast<UScriptCode>(script.value());

            if (char const* name = uscript_getName(icu_script))
                names[script.value()].long_name = StringView { name, strlen(name) };
            if (char const* name = uscript_getShortName(icu_script))
                names[script.value()].short_name = StringView { name, strlen(name) };
            if (char const* name = u_getPropertyValueName(UCHAR_SCRIPT, icu_script, ADDITIONAL_NAME))
                names[script.value()].additional_name = StringView { name, strlen(name) };
        }

        return names;
    }();

    if (auto index = find_index(script_names.begin(), script_names.end(), script); index != script_names.size())
        return static_cast<Script>(index);
    return {};
}

bool code_point_has_script(u32 code_point, Script script)
{
    UErrorCode status = U_ZERO_ERROR;

    auto icu_code_point = static_cast<UChar32>(code_point);
    auto icu_script = static_cast<UScriptCode>(script.value());

    if (auto result = uscript_getScript(icu_code_point, &status); icu_success(status))
        return result == icu_script;
    return false;
}

bool code_point_has_script_extension(u32 code_point, Script script)
{
    auto icu_code_point = static_cast<UChar32>(code_point);
    auto icu_script = static_cast<UScriptCode>(script.value());

    return static_cast<bool>(uscript_hasScript(icu_code_point, icu_script));
}

static constexpr BidiClass char_direction_to_bidi_class(UCharDirection direction)
{
    switch (direction) {
    case U_ARABIC_NUMBER:
        return BidiClass::ArabicNumber;
    case U_BLOCK_SEPARATOR:
        return BidiClass::BlockSeparator;
    case U_BOUNDARY_NEUTRAL:
        return BidiClass::BoundaryNeutral;
    case U_COMMON_NUMBER_SEPARATOR:
        return BidiClass::CommonNumberSeparator;
    case U_DIR_NON_SPACING_MARK:
        return BidiClass::DirNonSpacingMark;
    case U_EUROPEAN_NUMBER:
        return BidiClass::EuropeanNumber;
    case U_EUROPEAN_NUMBER_SEPARATOR:
        return BidiClass::EuropeanNumberSeparator;
    case U_EUROPEAN_NUMBER_TERMINATOR:
        return BidiClass::EuropeanNumberTerminator;
    case U_FIRST_STRONG_ISOLATE:
        return BidiClass::FirstStrongIsolate;
    case U_LEFT_TO_RIGHT:
        return BidiClass::LeftToRight;
    case U_LEFT_TO_RIGHT_EMBEDDING:
        return BidiClass::LeftToRightEmbedding;
    case U_LEFT_TO_RIGHT_ISOLATE:
        return BidiClass::LeftToRightIsolate;
    case U_LEFT_TO_RIGHT_OVERRIDE:
        return BidiClass::LeftToRightOverride;
    case U_OTHER_NEUTRAL:
        return BidiClass::OtherNeutral;
    case U_POP_DIRECTIONAL_FORMAT:
        return BidiClass::PopDirectionalFormat;
    case U_POP_DIRECTIONAL_ISOLATE:
        return BidiClass::PopDirectionalIsolate;
    case U_RIGHT_TO_LEFT:
        return BidiClass::RightToLeft;
    case U_RIGHT_TO_LEFT_ARABIC:
        return BidiClass::RightToLeftArabic;
    case U_RIGHT_TO_LEFT_EMBEDDING:
        return BidiClass::RightToLeftEmbedding;
    case U_RIGHT_TO_LEFT_ISOLATE:
        return BidiClass::RightToLeftIsolate;
    case U_RIGHT_TO_LEFT_OVERRIDE:
        return BidiClass::RightToLeftOverride;
    case U_SEGMENT_SEPARATOR:
        return BidiClass::SegmentSeparator;
    case U_WHITE_SPACE_NEUTRAL:
        return BidiClass::WhiteSpaceNeutral;
    case U_CHAR_DIRECTION_COUNT:
        break;
    }
    VERIFY_NOT_REACHED();
}

BidiClass bidirectional_class(u32 code_point)
{
    auto icu_code_point = static_cast<UChar32>(code_point);

    auto direction = u_charDirection(icu_code_point);
    return char_direction_to_bidi_class(direction);
}

LineBreakClass line_break_class(u32 code_point)
{
    auto icu_code_point = static_cast<UChar32>(code_point);
    auto icu_line_break = static_cast<ULineBreak>(u_getIntPropertyValue(icu_code_point, UCHAR_LINE_BREAK));

    switch (icu_line_break) {
    case U_LB_ALPHABETIC:
    case U_LB_HEBREW_LETTER:
        return LineBreakClass::Alphabetic;
    case U_LB_NUMERIC:
        return LineBreakClass::Numeric;
    case U_LB_IDEOGRAPHIC:
    case U_LB_H2:
    case U_LB_H3:
        return LineBreakClass::Ideographic;
    case U_LB_AMBIGUOUS:
        return LineBreakClass::Ambiguous;
    case U_LB_COMPLEX_CONTEXT:
        return LineBreakClass::ComplexContext;
    case U_LB_COMBINING_MARK:
        return LineBreakClass::CombiningMark;
    default:
        return LineBreakClass::Other;
    }
}

// 22.2.2.7.3 Canonicalize ( rer, ch ), https://tc39.es/ecma262/#sec-runtime-semantics-canonicalize-ch
u32 canonicalize(u32 code_point, bool unicode_mode)
{
    // 1. If HasEitherUnicodeFlag(rer) is true and rer.[[IgnoreCase]] is true, then
    //    a. If the file CaseFolding.txt of the Unicode Character Database provides a simple or common case folding mapping for ch, return the result of applying that mapping to ch.
    //    b. Return ch.
    if (unicode_mode)
        return u_foldCase(static_cast<UChar32>(code_point), U_FOLD_CASE_DEFAULT);

    // 2. If rer.[[IgnoreCase]] is false, return ch.
    // NOTE: This is handled by the caller.

    // 3. Assert: ch is a UTF-16 code unit.
    // 4. Let cp be the code point whose numeric value is the numeric value of ch.
    // NOTE: We already have a code point.

    // 5. Let u be toUppercase(« cp »), according to the Unicode Default Case Conversion algorithm.
    // 6. Let uStr be CodePointsToString(u).

    // OPTIMIZATION: For ASCII characters, toUppercase is just to_ascii_uppercase.
    //               Conditions in 7 & 9 are trivially satisfied (ASCII always maps to a single code point, and the result stays in the same range).
    if (code_point < 128)
        return to_ascii_uppercase(code_point);

    auto code_point_string = String::from_code_point(code_point);
    auto uppercased = code_point_string.to_uppercase();
    if (uppercased.is_error())
        return code_point;

    auto code_points = uppercased.value().code_points();

    // 7. If the length of uStr ≠ 1, return ch.
    if (code_points.length() != 1)
        return code_point;

    // 8. Let cu be uStr's single code unit element.
    auto it = code_points.begin();
    auto uppercased_code_point = *it;

    // 9. If the numeric value of ch ≥ 128 and the numeric value of cu < 128, return ch.
    if (code_point >= 128 && uppercased_code_point < 128)
        return code_point;

    // 10. Return cu.
    return uppercased_code_point;
}

Vector<CodePointRange> expand_range_case_insensitive(u32 from, u32 to)
{
    icu::UnicodeSet set(static_cast<UChar32>(from), static_cast<UChar32>(to));
    set.closeOver(USET_CASE_INSENSITIVE);

    Vector<CodePointRange> result;
    auto range_count = set.getRangeCount();
    result.ensure_capacity(range_count);

    for (int32_t i = 0; i < range_count; ++i)
        result.unchecked_append({ static_cast<u32>(set.getRangeStart(i)), static_cast<u32>(set.getRangeEnd(i)) });

    return result;
}

void for_each_case_folded_code_point(u32 code_point, Function<IterationDecision(u32)> callback)
{
    u32 canonical = canonicalize(code_point, true);

    icu::UnicodeSet closure(static_cast<UChar32>(canonical), static_cast<UChar32>(canonical));
    closure.closeOver(USET_CASE_INSENSITIVE);

    auto range_count = closure.getRangeCount();
    for (int32_t i = 0; i < range_count; ++i) {
        auto start = closure.getRangeStart(i);
        auto end = closure.getRangeEnd(i);
        for (auto cp = start; cp <= end; ++cp) {
            if (callback(static_cast<u32>(cp)) == IterationDecision::Break)
                return;
        }
    }
}

bool code_point_matches_range_ignoring_case(u32 code_point, u32 from, u32 to, bool unicode_mode)
{
    if (code_point >= from && code_point <= to)
        return true;

    icu::UnicodeSet candidates(static_cast<UChar32>(code_point), static_cast<UChar32>(code_point));
    candidates.closeOver(USET_CASE_INSENSITIVE);
    candidates.retain(static_cast<UChar32>(from), static_cast<UChar32>(to));

    if (candidates.isEmpty())
        return false;

    auto canonical_ch = canonicalize(code_point, unicode_mode);
    auto range_count = candidates.getRangeCount();
    for (auto i = 0; i < range_count; ++i) {
        auto start = candidates.getRangeStart(i);
        auto end = candidates.getRangeEnd(i);

        for (auto candidate_cp = start; candidate_cp <= end; ++candidate_cp) {
            if (canonicalize(candidate_cp, unicode_mode) == canonical_ch)
                return true;
        }
    }

    return false;
}

}

enum class ResolvedPropertyKind : u8 {
    Script,
    ScriptExtension,
    GeneralCategory,
    BinaryProperty,
};

static constexpr StringView string_view_from_ffi(unsigned char const* string, size_t length)
{
    VERIFY(string);
    return { reinterpret_cast<char const*>(string), length };
}

static constexpr Optional<StringView> optional_string_view_from_ffi(unsigned char const* string, size_t length)
{
    if (string)
        return string_view_from_ffi(string, length);
    return {};
}

static bool has_property(u32 code_point, StringView name, Optional<StringView> value)
{
    if (value.has_value()) {
        if (name.is_one_of("sc"sv, "Script"sv, "scx"sv, "Script_Extensions"sv)) {
            if (auto script = Unicode::script_from_string(*value); script.has_value()) {
                if (name.is_one_of("sc"sv, "Script"sv))
                    return Unicode::code_point_has_script(code_point, *script);
                return Unicode::code_point_has_script_extension(code_point, *script);
            }
        } else if (name.is_one_of("gc"sv, "General_Category"sv)) {
            if (auto category = Unicode::general_category_from_string(*value); category.has_value())
                return Unicode::code_point_has_general_category(code_point, *category);
        }

        return false;
    }

    if (auto property = Unicode::property_from_string(name); property.has_value())
        return Unicode::code_point_has_property(code_point, *property);

    if (auto category = Unicode::general_category_from_string(name); category.has_value())
        return Unicode::code_point_has_general_category(code_point, *category);

    if (auto script = Unicode::script_from_string(name); script.has_value())
        return Unicode::code_point_has_script(code_point, *script);

    return false;
}

static bool resolve_property(StringView name, Optional<StringView> value, unsigned char* out_kind, u32* out_id)
{
    if (value.has_value()) {
        if (name.is_one_of("sc"sv, "Script"sv, "scx"sv, "Script_Extensions"sv)) {
            if (auto script = Unicode::script_from_string(*value); script.has_value()) {
                *out_kind = to_underlying(name.is_one_of("scx"sv, "Script_Extensions"sv)
                        ? ResolvedPropertyKind::ScriptExtension
                        : ResolvedPropertyKind::Script);
                *out_id = script->value();
                return true;
            }
        } else if (name.is_one_of("gc"sv, "General_Category"sv)) {
            if (auto category = Unicode::general_category_from_string(*value); category.has_value()) {
                *out_kind = to_underlying(ResolvedPropertyKind::GeneralCategory);
                *out_id = category->value();
                return true;
            }
        }

        return false;
    }

    if (auto property = Unicode::property_from_string(name); property.has_value()) {
        *out_kind = to_underlying(ResolvedPropertyKind::BinaryProperty);
        *out_id = property->value();
        return true;
    }

    if (auto category = Unicode::general_category_from_string(name); category.has_value()) {
        *out_kind = to_underlying(ResolvedPropertyKind::GeneralCategory);
        *out_id = category->value();
        return true;
    }

    if (auto script = Unicode::script_from_string(name); script.has_value()) {
        *out_kind = to_underlying(ResolvedPropertyKind::Script);
        *out_id = script->value();
        return true;
    }

    return false;
}

extern "C" {

bool unicode_property_matches(u32, unsigned char const*, size_t, unsigned char const*, size_t);
bool unicode_property_matches_case_insensitive(u32, unsigned char const*, size_t, unsigned char const*, size_t);
bool unicode_property_all_case_equivalents_match(u32, unsigned char const*, size_t, unsigned char const*, size_t);

bool unicode_resolve_property(unsigned char const*, size_t, unsigned char const*, size_t, unsigned char*, u32*);
bool unicode_resolved_property_matches(u32, unsigned char, u32);

bool unicode_code_point_has_space_separator_general_category(u32);

bool unicode_code_point_has_identifier_start_property(u32);
bool unicode_code_point_has_identifier_continue_property(u32);

bool unicode_is_string_property(unsigned char const*, size_t);
bool unicode_is_valid_ecma262_property(unsigned char const*, size_t, unsigned char const*, size_t);
u32 unicode_get_string_property_data(unsigned char const*, size_t, u32*, u32);

u32 unicode_simple_case_fold(u32, bool);

bool unicode_code_point_matches_range_ignoring_case(u32, u32, u32, bool);
u32 unicode_get_case_closure(u32, u32*, u32);
}

extern "C" bool unicode_property_matches(
    u32 code_point,
    unsigned char const* name_ptr, size_t name_len,
    unsigned char const* value_ptr, size_t value_len)
{
    auto name = string_view_from_ffi(name_ptr, name_len);
    auto value = optional_string_view_from_ffi(value_ptr, value_len);

    return has_property(code_point, name, value);
}

extern "C" bool unicode_property_matches_case_insensitive(
    u32 code_point,
    unsigned char const* name_ptr, size_t name_len,
    unsigned char const* value_ptr, size_t value_len)
{
    auto name = string_view_from_ffi(name_ptr, name_len);
    auto value = optional_string_view_from_ffi(value_ptr, value_len);
    bool found = false;

    Unicode::for_each_case_folded_code_point(code_point, [&](u32 cp) {
        if (has_property(cp, name, value)) {
            found = true;
            return IterationDecision::Break;
        }
        return IterationDecision::Continue;
    });

    return found;
}

extern "C" bool unicode_property_all_case_equivalents_match(
    u32 code_point,
    unsigned char const* name_ptr, size_t name_len,
    unsigned char const* value_ptr, size_t value_len)
{
    auto name = string_view_from_ffi(name_ptr, name_len);
    auto value = optional_string_view_from_ffi(value_ptr, value_len);
    bool all_match = true;

    Unicode::for_each_case_folded_code_point(code_point, [&](u32 cp) {
        if (!has_property(cp, name, value)) {
            all_match = false;
            return IterationDecision::Break;
        }
        return IterationDecision::Continue;
    });

    return all_match;
}

extern "C" bool unicode_resolve_property(
    unsigned char const* name_ptr, size_t name_len,
    unsigned char const* value_ptr, size_t value_len,
    unsigned char* out_kind, u32* out_id)
{
    auto name = string_view_from_ffi(name_ptr, name_len);
    auto value = optional_string_view_from_ffi(value_ptr, value_len);

    return resolve_property(name, value, out_kind, out_id);
}

extern "C" bool unicode_resolved_property_matches(u32 code_point, unsigned char kind, u32 id)
{
    switch (static_cast<ResolvedPropertyKind>(kind)) {
    case ResolvedPropertyKind::Script:
        return Unicode::code_point_has_script(code_point, Unicode::Script { id });
    case ResolvedPropertyKind::ScriptExtension:
        return Unicode::code_point_has_script_extension(code_point, Unicode::Script { id });
    case ResolvedPropertyKind::GeneralCategory:
        return Unicode::code_point_has_general_category(code_point, Unicode::GeneralCategory { id });
    case ResolvedPropertyKind::BinaryProperty:
        return Unicode::code_point_has_property(code_point, Unicode::Property { id });
    }
    VERIFY_NOT_REACHED();
}

extern "C" bool unicode_code_point_has_space_separator_general_category(u32 code_point)
{
    return Unicode::code_point_has_space_separator_general_category(code_point);
}

extern "C" bool unicode_code_point_has_identifier_start_property(u32 code_point)
{
    return Unicode::code_point_has_identifier_start_property(code_point);
}

extern "C" bool unicode_code_point_has_identifier_continue_property(u32 code_point)
{
    return Unicode::code_point_has_identifier_continue_property(code_point);
}

extern "C" bool unicode_is_string_property(unsigned char const* name_ptr, size_t name_len)
{
    auto name = string_view_from_ffi(name_ptr, name_len);

    if (auto property = Unicode::property_from_string(name); property.has_value())
        return Unicode::is_ecma262_string_property(*property);

    return false;
}

extern "C" bool unicode_is_valid_ecma262_property(
    unsigned char const* name_ptr, size_t name_len,
    unsigned char const* value_ptr, size_t value_len)
{
    auto name = string_view_from_ffi(name_ptr, name_len);
    auto value = optional_string_view_from_ffi(value_ptr, value_len);

    if (value.has_value()) {
        if (name.is_one_of("sc"sv, "Script"sv, "scx"sv, "Script_Extensions"sv))
            return Unicode::script_from_string(*value).has_value();
        if (name.is_one_of("gc"sv, "General_Category"sv))
            return Unicode::general_category_from_string(*value).has_value();
        return false;
    }

    if (auto property = Unicode::property_from_string(name); property.has_value())
        return Unicode::is_ecma262_property(*property) || Unicode::is_ecma262_string_property(*property);

    return Unicode::general_category_from_string(name).has_value();
}

extern "C" u32 unicode_get_string_property_data(
    unsigned char const* name_ptr, size_t name_len,
    u32* out, u32 capacity)
{
    auto name = string_view_from_ffi(name_ptr, name_len);
    auto property = Unicode::property_from_string(name);
    if (!property.has_value() || !Unicode::is_ecma262_string_property(*property))
        return 0;

    auto strings = Unicode::get_property_strings(*property);

    Vector<Vector<u32>> multi_code_point_strings;
    for (auto const& string : strings) {
        Vector<u32> code_points;
        for (auto code_point : string.code_points())
            code_points.append(code_point);
        if (code_points.size() > 1)
            multi_code_point_strings.append(move(code_points));
    }

    u32 total_size = 1;
    for (auto const& code_points : multi_code_point_strings)
        total_size += 1 + static_cast<u32>(code_points.size());

    if (!out || capacity < total_size)
        return total_size;

    u32 offset = 0;
    out[offset++] = static_cast<u32>(multi_code_point_strings.size());

    for (auto const& code_points : multi_code_point_strings) {
        out[offset++] = static_cast<u32>(code_points.size());

        for (auto code_point : code_points)
            out[offset++] = code_point;
    }

    return total_size;
}

extern "C" u32 unicode_simple_case_fold(u32 code_point, bool unicode_mode)
{
    return Unicode::canonicalize(code_point, unicode_mode);
}

extern "C" bool unicode_code_point_matches_range_ignoring_case(u32 code_point, u32 from, u32 to, bool unicode_mode)
{
    return Unicode::code_point_matches_range_ignoring_case(code_point, from, to, unicode_mode);
}

extern "C" u32 unicode_get_case_closure(
    u32 code_point,
    u32* out_buffer,
    u32 buffer_capacity)
{
    u32 count = 0;

    Unicode::for_each_case_folded_code_point(code_point, [&](u32 cp) {
        if (count < buffer_capacity) {
            out_buffer[count++] = cp;
            return IterationDecision::Continue;
        }
        return IterationDecision::Break;
    });

    return count;
}