// © 2018 and later: Unicode, Inc. and others.

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

#include "unicode/utypes.h"

#if !UCONFIG_NO_FORMATTING

// Allow implicit conversion from char16_t* to UnicodeString for this file:

// Helpful in toString methods and elsewhere.

#define UNISTR_FROM_STRING_EXPLICIT

#include "numparse_types.h"

#include "string_segment.h"

#include "putilimp.h"

#include "unicode/utf16.h"

#include "unicode/uniset.h"

U_NAMESPACE_BEGIN

StringSegment::StringSegment(const UnicodeString& str, bool ignoreCase)

        : fStr(str), fStart(0), fEnd(str.length()),

          fFoldCase(ignoreCase) {}

int32_t StringSegment::getOffset() const {

    return fStart;

}

void StringSegment::setOffset(int32_t start) {

    fStart = start;

}

void StringSegment::adjustOffset(int32_t delta) {

    fStart += delta;

}

void StringSegment::adjustOffsetByCodePoint() {

    fStart += U16_LENGTH(getCodePoint());

}

void StringSegment::setLength(int32_t length) {

    fEnd = fStart + length;

}

void StringSegment::resetLength() {

    fEnd = fStr.length();

}

int32_t StringSegment::length() const {

    return fEnd - fStart;

}

char16_t StringSegment::charAt(int32_t index) const {

    return fStr.charAt(index + fStart);

}

UChar32 StringSegment::codePointAt(int32_t index) const {

    return fStr.char32At(index + fStart);

}

UnicodeString StringSegment::toUnicodeString() const {

    return UnicodeString(fStr.getBuffer() + fStart, fEnd - fStart);

}

const UnicodeString StringSegment::toTempUnicodeString() const {

    // Use the readonly-aliasing constructor for efficiency.

    return UnicodeString(FALSE, fStr.getBuffer() + fStart, fEnd - fStart);

}

UChar32 StringSegment::getCodePoint() const {

    char16_t lead = fStr.charAt(fStart);

    if (U16_IS_LEAD(lead) && fStart + 1 < fEnd) {

        return fStr.char32At(fStart);

    } else if (U16_IS_SURROGATE(lead)) {

        return -1;

    } else {

        return lead;

    }

}

bool StringSegment::startsWith(UChar32 otherCp) const {

    return codePointsEqual(getCodePoint(), otherCp, fFoldCase);

}

bool StringSegment::startsWith(const UnicodeSet& uniset) const {

    // TODO: Move UnicodeSet case-folding logic here.

    // TODO: Handle string matches here instead of separately.

    UChar32 cp = getCodePoint();

    if (cp == -1) {

        return false;

    }

    return uniset.contains(cp);

}

bool StringSegment::startsWith(const UnicodeString& other) const {

    if (other.isBogus() || other.length() == 0 || length() == 0) {

        return false;

    }

    int cp1 = getCodePoint();

    int cp2 = other.char32At(0);

    return codePointsEqual(cp1, cp2, fFoldCase);

}

int32_t StringSegment::getCommonPrefixLength(const UnicodeString& other) {

    return getPrefixLengthInternal(other, fFoldCase);

}

int32_t StringSegment::getCaseSensitivePrefixLength(const UnicodeString& other) {

    return getPrefixLengthInternal(other, false);

}

int32_t StringSegment::getPrefixLengthInternal(const UnicodeString& other, bool foldCase) {

    U_ASSERT(other.length() > 0);

    int32_t offset = 0;

    for (; offset < uprv_min(length(), other.length());) {

        // TODO: case-fold code points, not chars

        char16_t c1 = charAt(offset);

        char16_t c2 = other.charAt(offset);

        if (!codePointsEqual(c1, c2, foldCase)) {

            break;

        }

        offset++;

    }

    return offset;

}

bool StringSegment::codePointsEqual(UChar32 cp1, UChar32 cp2, bool foldCase) {

    if (cp1 == cp2) {

        return true;

    }

    if (!foldCase) {

        return false;

    }

    cp1 = u_foldCase(cp1, TRUE);

    cp2 = u_foldCase(cp2, TRUE);

    return cp1 == cp2;

}

bool StringSegment::operator==(const UnicodeString& other) const {

    return toTempUnicodeString() == other;

}

U_NAMESPACE_END

#endif /* #if !UCONFIG_NO_FORMATTING */