/*
 * Copyright (C) 2008, 2014 Apple Inc. All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1.  Redistributions of source code must retain the above copyright
 *     notice, this list of conditions and the following disclaimer.
 * 2.  Redistributions in binary form must reproduce the above copyright
 *     notice, this list of conditions and the following disclaimer in the
 *     documentation and/or other materials provided with the distribution.
 * 3.  Neither the name of Apple Inc. ("Apple") nor the names of
 *     its contributors may be used to endorse or promote products derived
 *     from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY APPLE AND ITS CONTRIBUTORS "AS IS" AND ANY
 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED. IN NO EVENT SHALL APPLE OR ITS CONTRIBUTORS BE LIABLE FOR ANY
 * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

#include "config.h"
#include <wtf/unicode/Collator.h>

// FIXME: Merge this with CollatorDefault.cpp into a single Collator.cpp source file.

#if !UCONFIG_NO_COLLATION

#include <mutex>
#include <unicode/ucol.h>
#include <wtf/NeverDestroyed.h>
#include <wtf/StringExtras.h>
#include <wtf/text/StringView.h>

#if OS(DARWIN) && USE(CF)
#include <CoreFoundation/CoreFoundation.h>
#include <wtf/RetainPtr.h>
#endif

namespace WTF {

static UCollator* cachedCollator;
static char* cachedCollatorLocale;
static bool cachedCollatorShouldSortLowercaseFirst;

static std::mutex& cachedCollatorMutex()
{
    static std::once_flag onceFlag;

    static LazyNeverDestroyed<std::mutex> mutex;
    std::call_once(onceFlag, []{
        mutex.construct();
    });

    return mutex;
}

#if !(OS(DARWIN) && USE(CF))

static inline const char* resolveDefaultLocale(const char* locale)
{
    return locale;
}

#else

static inline char* copyShortASCIIString(CFStringRef string)
{
    // OK to have a fixed size buffer and to only handle ASCII since we only use this for locale names.
    char buffer[256];
    if (!string || !CFStringGetCString(string, buffer, sizeof(buffer), kCFStringEncodingASCII))
        return strdup("");
    return strdup(buffer);
}

static char* copyDefaultLocale()
{
#if !PLATFORM(IOS)
    return copyShortASCIIString(static_cast<CFStringRef>(CFLocaleGetValue(adoptCF(CFLocaleCopyCurrent()).get(), kCFLocaleCollatorIdentifier)));
#else
    // FIXME: Documentation claims the code above would work on iOS 4.0 and later. After test that works, we should remove this and use that instead.
    return copyShortASCIIString(adoptCF(static_cast<CFStringRef>(CFPreferencesCopyValue(CFSTR("AppleCollationOrder"), kCFPreferencesAnyApplication, kCFPreferencesCurrentUser, kCFPreferencesAnyHost))).get());
#endif
}

static inline const char* resolveDefaultLocale(const char* locale)
{
    if (locale)
        return locale;
    // Since iOS and OS X don't set UNIX locale to match the user's selected locale, the ICU default locale is not the right one.
    // So, instead of passing null to ICU, we pass the name of the user's selected locale.
    static char* defaultLocale;
    static std::once_flag initializeDefaultLocaleOnce;
    std::call_once(initializeDefaultLocaleOnce, []{
        defaultLocale = copyDefaultLocale();
    });
    return defaultLocale;
}

#endif

static inline bool localesMatch(const char* a, const char* b)
{
    // Two null locales are equal, other locales are compared with strcmp.
    return a == b || (a && b && !strcmp(a, b));
}

Collator::Collator(const char* locale, bool shouldSortLowercaseFirst)
{
    UErrorCode status = U_ZERO_ERROR;

    {
        std::lock_guard<std::mutex> lock(cachedCollatorMutex());
        if (cachedCollator && localesMatch(cachedCollatorLocale, locale) && cachedCollatorShouldSortLowercaseFirst == shouldSortLowercaseFirst) {
            m_collator = cachedCollator;
            m_locale = cachedCollatorLocale;
            m_shouldSortLowercaseFirst = shouldSortLowercaseFirst;
            cachedCollator = nullptr;
            cachedCollatorLocale = nullptr;
            return;
        }
    }

    m_collator = ucol_open(resolveDefaultLocale(locale), &status);
    if (U_FAILURE(status)) {
        status = U_ZERO_ERROR;
        m_collator = ucol_open("", &status); // Fall back to Unicode Collation Algorithm.
    }
    ASSERT(U_SUCCESS(status));

    ucol_setAttribute(m_collator, UCOL_CASE_FIRST, shouldSortLowercaseFirst ? UCOL_LOWER_FIRST : UCOL_UPPER_FIRST, &status);
    ASSERT(U_SUCCESS(status));

    ucol_setAttribute(m_collator, UCOL_NORMALIZATION_MODE, UCOL_ON, &status);
    ASSERT(U_SUCCESS(status));

    m_locale = locale ? strdup(locale) : nullptr;
    m_shouldSortLowercaseFirst = shouldSortLowercaseFirst;
}

Collator::~Collator()
{
    {
        std::lock_guard<std::mutex> lock(cachedCollatorMutex());
        if (cachedCollator)
            ucol_close(cachedCollator);
        cachedCollator = m_collator;
        cachedCollatorLocale = m_locale;
        cachedCollatorShouldSortLowercaseFirst = m_shouldSortLowercaseFirst;
        m_collator = nullptr;
        m_locale = nullptr;
    }

    free(m_locale);
}

static int32_t getIndexLatin1(UCharIterator* iterator, UCharIteratorOrigin origin)
{
    switch (origin) {
    case UITER_START:
        return iterator->start;
    case UITER_CURRENT:
        return iterator->index;
    case UITER_LIMIT:
        return iterator->limit;
    case UITER_ZERO:
        return 0;
    case UITER_LENGTH:
        return iterator->length;
    }
    ASSERT_NOT_REACHED();
    return U_SENTINEL;
}

static int32_t moveLatin1(UCharIterator* iterator, int32_t delta, UCharIteratorOrigin origin)
{
    return iterator->index = getIndexLatin1(iterator, origin) + delta;
}

static UBool hasNextLatin1(UCharIterator* iterator)
{
    return iterator->index < iterator->limit;
}

static UBool hasPreviousLatin1(UCharIterator* iterator)
{
    return iterator->index > iterator->start;
}

static UChar32 currentLatin1(UCharIterator* iterator)
{
    ASSERT(iterator->index >= iterator->start);
    if (iterator->index >= iterator->limit)
        return U_SENTINEL;
    return static_cast<const LChar*>(iterator->context)[iterator->index];
}

static UChar32 nextLatin1(UCharIterator* iterator)
{
    ASSERT(iterator->index >= iterator->start);
    if (iterator->index >= iterator->limit)
        return U_SENTINEL;
    return static_cast<const LChar*>(iterator->context)[iterator->index++];
}

static UChar32 previousLatin1(UCharIterator* iterator)
{
    if (iterator->index <= iterator->start)
        return U_SENTINEL;
    return static_cast<const LChar*>(iterator->context)[--iterator->index];
}

static uint32_t getStateLatin1(const UCharIterator* iterator)
{
    return iterator->index;
}

static void setStateLatin1(UCharIterator* iterator, uint32_t state, UErrorCode*)
{
    iterator->index = state;
}

static UCharIterator createLatin1Iterator(const LChar* characters, int length)
{
    UCharIterator iterator;
    iterator.context = characters;
    iterator.length = length;
    iterator.start = 0;
    iterator.index = 0;
    iterator.limit = length;
    iterator.reservedField = 0;
    iterator.getIndex = getIndexLatin1;
    iterator.move = moveLatin1;
    iterator.hasNext = hasNextLatin1;
    iterator.hasPrevious = hasPreviousLatin1;
    iterator.current = currentLatin1;
    iterator.next = nextLatin1;
    iterator.previous = previousLatin1;
    iterator.reservedFn = nullptr;
    iterator.getState = getStateLatin1;
    iterator.setState = setStateLatin1;
    return iterator;
}

static UCharIterator createIterator(StringView string)
{
    if (string.is8Bit())
        return createLatin1Iterator(string.characters8(), string.length());
    UCharIterator iterator;
    uiter_setString(&iterator, string.characters16(), string.length());
    return iterator;
}

int Collator::collate(StringView a, StringView b) const
{
    UCharIterator iteratorA = createIterator(a);
    UCharIterator iteratorB = createIterator(b);
    UErrorCode status = U_ZERO_ERROR;
    int result = ucol_strcollIter(m_collator, &iteratorA, &iteratorB, &status);
    ASSERT(U_SUCCESS(status));
    return result;
}

static UCharIterator createIteratorUTF8(const char* string)
{
    UCharIterator iterator;
    uiter_setUTF8(&iterator, string, strlen(string));
    return iterator;
}

int Collator::collateUTF8(const char* a, const char* b) const
{
    UCharIterator iteratorA = createIteratorUTF8(a);
    UCharIterator iteratorB = createIteratorUTF8(b);
    UErrorCode status = U_ZERO_ERROR;
    int result = ucol_strcollIter(m_collator, &iteratorA, &iteratorB, &status);
    ASSERT(U_SUCCESS(status));
    return result;
}

} // namespace WTF

#endif