// This file is part of AsmJit project <https://asmjit.com>
//
// See asmjit.h or LICENSE.md for license and copyright information
// SPDX-License-Identifier: Zlib

#include "../core/api-build_p.h"
#include "../core/string.h"
#include "../core/support.h"

ASMJIT_BEGIN_NAMESPACE

// String - Globals
// ================

static const char String_baseN[] = "0123456789ABCDEF";

constexpr size_t kMinAllocSize = 128;
constexpr size_t kMaxAllocSize = SIZE_MAX - Globals::kGrowThreshold;

// Based on ZoneVector_growCapacity().
//
// NOTE: The sizes here include null terminators - that way we can have aligned allocations that are power of 2s
// initially.
static ASMJIT_FORCE_INLINE size_t String_growCapacity(size_t byteSize, size_t minimumByteSize) noexcept {
  static constexpr size_t kGrowThreshold = Globals::kGrowThreshold;

  ASMJIT_ASSERT(minimumByteSize < kMaxAllocSize);

  // This is more than exponential growth at the beginning.
  if (byteSize < kMinAllocSize) {
    byteSize = kMinAllocSize;
  }
  else if (byteSize < 512) {
    byteSize = 512;
  }

  if (byteSize < minimumByteSize) {
    // Exponential growth before we reach `kGrowThreshold`.
    byteSize = Support::alignUpPowerOf2(minimumByteSize);

    // Bail to `minimumByteSize` in case of overflow - most likely whatever that is happening afterwards would just fail.
    if (byteSize < minimumByteSize) {
      return minimumByteSize;
    }

    // Pretty much chunked growth advancing by `kGrowThreshold` after we exceed it.
    if (byteSize > kGrowThreshold) {
      // Align to kGrowThreshold.
      size_t remainder = minimumByteSize % kGrowThreshold;

      byteSize = minimumByteSize + remainder;

      // Bail to `minimumByteSize` in case of overflow.
      if (byteSize < minimumByteSize)
        return minimumByteSize;
    }
  }

  return Support::min<size_t>(byteSize, kMaxAllocSize);
}

// String - Clear & Reset
// ======================

Error String::reset() noexcept {
  if (_type == kTypeLarge)
    ::free(_large.data);

  _resetInternal();
  return kErrorOk;
}

Error String::clear() noexcept {
  if (isLargeOrExternal()) {
    _large.size = 0;
    _large.data[0] = '\0';
  }
  else {
    _raw.uptr[0] = 0;
  }

  return kErrorOk;
}

// String - Prepare
// ================

char* String::prepare(ModifyOp op, size_t size) noexcept {
  char* curData;
  size_t curSize;
  size_t curCapacity;

  if (isLargeOrExternal()) {
    curData = _large.data;
    curSize = _large.size;
    curCapacity = _large.capacity;
  }
  else {
    curData = _small.data;
    curSize = _small.type;
    curCapacity = kSSOCapacity;
  }

  if (op == ModifyOp::kAssign) {
    if (size > curCapacity) {
      // Prevent arithmetic overflow.
      if (ASMJIT_UNLIKELY(size >= kMaxAllocSize))
        return nullptr;

      size_t newCapacity = Support::alignUp<size_t>(size + 1, kMinAllocSize);
      char* newData = static_cast<char*>(::malloc(newCapacity));

      if (ASMJIT_UNLIKELY(!newData))
        return nullptr;

      if (_type == kTypeLarge)
        ::free(curData);

      _large.type = kTypeLarge;
      _large.size = size;
      _large.capacity = newCapacity - 1;
      _large.data = newData;

      newData[size] = '\0';
      return newData;
    }
    else {
      _setSize(size);
      curData[size] = '\0';
      return curData;
    }
  }
  else {
    // Prevent arithmetic overflow.
    if (ASMJIT_UNLIKELY(size >= kMaxAllocSize - curSize - 1))
      return nullptr;

    size_t newSize = size + curSize;
    size_t newSizePlusOne = newSize + 1;

    if (newSize > curCapacity) {
      size_t newCapacityPlusOne = String_growCapacity(size + 1u, newSizePlusOne);
      ASMJIT_ASSERT(newCapacityPlusOne >= newSizePlusOne);

      if (ASMJIT_UNLIKELY(newCapacityPlusOne < newSizePlusOne))
        return nullptr;

      char* newData = static_cast<char*>(::malloc(newCapacityPlusOne));
      if (ASMJIT_UNLIKELY(!newData))
        return nullptr;

      memcpy(newData, curData, curSize);

      if (_type == kTypeLarge)
        ::free(curData);

      _large.type = kTypeLarge;
      _large.size = newSize;
      _large.capacity = newCapacityPlusOne - 1;
      _large.data = newData;

      newData[newSize] = '\0';
      return newData + curSize;
    }
    else {
      _setSize(newSize);
      curData[newSize] = '\0';
      return curData + curSize;
    }
  }
}

// String - Assign
// ===============

Error String::assign(const char* data, size_t size) noexcept {
  char* dst = nullptr;

  // Null terminated string without `size` specified.
  if (size == SIZE_MAX)
    size = data ? strlen(data) : size_t(0);

  if (isLargeOrExternal()) {
    if (size <= _large.capacity) {
      dst = _large.data;
      _large.size = size;
    }
    else {
      size_t capacityPlusOne = Support::alignUp(size + 1, 32);
      if (ASMJIT_UNLIKELY(capacityPlusOne < size))
        return DebugUtils::errored(kErrorOutOfMemory);

      dst = static_cast<char*>(::malloc(capacityPlusOne));
      if (ASMJIT_UNLIKELY(!dst))
        return DebugUtils::errored(kErrorOutOfMemory);

      if (_type == kTypeLarge)
        ::free(_large.data);

      _large.type = kTypeLarge;
      _large.data = dst;
      _large.size = size;
      _large.capacity = capacityPlusOne - 1;
    }
  }
  else {
    if (size <= kSSOCapacity) {
      ASMJIT_ASSERT(size < 0xFFu);

      dst = _small.data;
      _small.type = uint8_t(size);
    }
    else {
      dst = static_cast<char*>(::malloc(size + 1));
      if (ASMJIT_UNLIKELY(!dst))
        return DebugUtils::errored(kErrorOutOfMemory);

      _large.type = kTypeLarge;
      _large.data = dst;
      _large.size = size;
      _large.capacity = size;
    }
  }

  // Optionally copy data from `data` and null-terminate.
  if (data && size) {
    // NOTE: It's better to use `memmove()`. If, for any reason, somebody uses
    // this function to substring the same string it would work as expected.
    ::memmove(dst, data, size);
  }

  dst[size] = '\0';
  return kErrorOk;
}

// String - Operations
// ===================

Error String::_opString(ModifyOp op, const char* str, size_t size) noexcept {
  if (size == SIZE_MAX)
    size = str ? strlen(str) : size_t(0);

  if (!size)
    return kErrorOk;

  char* p = prepare(op, size);
  if (!p)
    return DebugUtils::errored(kErrorOutOfMemory);

  memcpy(p, str, size);
  return kErrorOk;
}

Error String::_opChar(ModifyOp op, char c) noexcept {
  char* p = prepare(op, 1);
  if (!p)
    return DebugUtils::errored(kErrorOutOfMemory);

  *p = c;
  return kErrorOk;
}

Error String::_opChars(ModifyOp op, char c, size_t n) noexcept {
  if (!n)
    return kErrorOk;

  char* p = prepare(op, n);
  if (!p)
    return DebugUtils::errored(kErrorOutOfMemory);

  memset(p, c, n);
  return kErrorOk;
}

Error String::padEnd(size_t n, char c) noexcept {
  size_t size = this->size();
  return n > size ? appendChars(c, n - size) : kErrorOk;
}

Error String::_opNumber(ModifyOp op, uint64_t i, uint32_t base, size_t width, StringFormatFlags flags) noexcept {
  if (base == 0)
    base = 10;

  char buf[128];
  char* p = buf + ASMJIT_ARRAY_SIZE(buf);

  uint64_t orig = i;
  char sign = '\0';

  // Format Sign
  // -----------

  if (Support::test(flags, StringFormatFlags::kSigned) && int64_t(i) < 0) {
    i = uint64_t(-int64_t(i));
    sign = '-';
  }
  else if (Support::test(flags, StringFormatFlags::kShowSign)) {
    sign = '+';
  }
  else if (Support::test(flags, StringFormatFlags::kShowSpace)) {
    sign = ' ';
  }

  // Format Number
  // -------------

  switch (base) {
    case 2:
    case 8:
    case 16: {
      uint32_t shift = Support::ctz(base);
      uint32_t mask = base - 1;

      do {
        uint64_t d = i >> shift;
        size_t r = size_t(i & mask);

        *--p = String_baseN[r];
        i = d;
      } while (i);

      break;
    }

    case 10: {
      do {
        uint64_t d = i / 10;
        uint64_t r = i % 10;

        *--p = char(uint32_t('0') + uint32_t(r));
        i = d;
      } while (i);

      break;
    }

    default:
      return DebugUtils::errored(kErrorInvalidArgument);
  }

  size_t numberSize = (size_t)(buf + ASMJIT_ARRAY_SIZE(buf) - p);

  // Alternate Form
  // --------------

  if (Support::test(flags, StringFormatFlags::kAlternate)) {
    if (base == 8) {
      if (orig != 0)
        *--p = '0';
    }
    if (base == 16) {
      *--p = 'x';
      *--p = '0';
    }
  }

  // String Width
  // ------------

  if (sign != 0)
    *--p = sign;

  if (width > 256)
    width = 256;

  if (width <= numberSize)
    width = 0;
  else
    width -= numberSize;

  // Finalize
  // --------

  size_t prefixSize = (size_t)(buf + ASMJIT_ARRAY_SIZE(buf) - p) - numberSize;
  char* data = prepare(op, prefixSize + width + numberSize);

  if (!data)
    return DebugUtils::errored(kErrorOutOfMemory);

  memcpy(data, p, prefixSize);
  data += prefixSize;

  memset(data, '0', width);
  data += width;

  memcpy(data, p + prefixSize, numberSize);
  return kErrorOk;
}

Error String::_opHex(ModifyOp op, const void* data, size_t size, char separator) noexcept {
  char* dst;
  const uint8_t* src = static_cast<const uint8_t*>(data);

  if (!size)
    return kErrorOk;

  if (separator) {
    if (ASMJIT_UNLIKELY(size >= SIZE_MAX / 3))
      return DebugUtils::errored(kErrorOutOfMemory);

    dst = prepare(op, size * 3 - 1);
    if (ASMJIT_UNLIKELY(!dst))
      return DebugUtils::errored(kErrorOutOfMemory);

    size_t i = 0;
    for (;;) {
      dst[0] = String_baseN[(src[0] >> 4) & 0xF];
      dst[1] = String_baseN[(src[0]     ) & 0xF];
      if (++i == size)
        break;
      // This makes sure that the separator is only put between two hexadecimal bytes.
      dst[2] = separator;
      dst += 3;
      src++;
    }
  }
  else {
    if (ASMJIT_UNLIKELY(size >= SIZE_MAX / 2))
      return DebugUtils::errored(kErrorOutOfMemory);

    dst = prepare(op, size * 2);
    if (ASMJIT_UNLIKELY(!dst))
      return DebugUtils::errored(kErrorOutOfMemory);

    for (size_t i = 0; i < size; i++, dst += 2, src++) {
      dst[0] = String_baseN[(src[0] >> 4) & 0xF];
      dst[1] = String_baseN[(src[0]     ) & 0xF];
    }
  }

  return kErrorOk;
}

Error String::_opFormat(ModifyOp op, const char* fmt, ...) noexcept {
  Error err;
  va_list ap;

  va_start(ap, fmt);
  err = _opVFormat(op, fmt, ap);
  va_end(ap);

  return err;
}

Error String::_opVFormat(ModifyOp op, const char* fmt, va_list ap) noexcept {
  size_t startAt = (op == ModifyOp::kAssign) ? size_t(0) : size();
  size_t remainingCapacity = capacity() - startAt;

  char buf[1024];
  int fmtResult;
  size_t outputSize;

  va_list apCopy;
  va_copy(apCopy, ap);

  if (remainingCapacity >= 128) {
    fmtResult = vsnprintf(data() + startAt, remainingCapacity, fmt, ap);
    outputSize = size_t(fmtResult);

    if (ASMJIT_LIKELY(outputSize <= remainingCapacity)) {
      _setSize(startAt + outputSize);
      return kErrorOk;
    }
  }
  else {
    fmtResult = vsnprintf(buf, ASMJIT_ARRAY_SIZE(buf), fmt, ap);
    outputSize = size_t(fmtResult);

    if (ASMJIT_LIKELY(outputSize < ASMJIT_ARRAY_SIZE(buf)))
      return _opString(op, buf, outputSize);
  }

  if (ASMJIT_UNLIKELY(fmtResult < 0))
    return DebugUtils::errored(kErrorInvalidState);

  char* p = prepare(op, outputSize);
  if (ASMJIT_UNLIKELY(!p))
    return DebugUtils::errored(kErrorOutOfMemory);

  fmtResult = vsnprintf(p, outputSize + 1, fmt, apCopy);
  ASMJIT_ASSERT(size_t(fmtResult) == outputSize);

  return kErrorOk;
}

Error String::truncate(size_t newSize) noexcept {
  if (isLargeOrExternal()) {
    if (newSize < _large.size) {
      _large.data[newSize] = '\0';
      _large.size = newSize;
    }
  }
  else {
    if (newSize < _type) {
      _small.data[newSize] = '\0';
      _small.type = uint8_t(newSize);
    }
  }

  return kErrorOk;
}

bool String::equals(const char* other, size_t size) const noexcept {
  const char* aData = data();
  const char* bData = other;

  size_t aSize = this->size();
  size_t bSize = size;

  if (bSize == SIZE_MAX) {
    size_t i;
    for (i = 0; i < aSize; i++)
      if (aData[i] != bData[i] || bData[i] == 0)
        return false;
    return bData[i] == 0;
  }
  else {
    if (aSize != bSize)
      return false;
    return ::memcmp(aData, bData, aSize) == 0;
  }
}

// String - Tests
// ==============

#if defined(ASMJIT_TEST)
static void test_string_grow() noexcept {
  String s;
  size_t c = s.capacity();

  INFO("Testing string grow strategy (SSO capacity: %zu)", c);
  for (size_t i = 0; i < 1000000; i++) {
    s.append('x');
    if (s.capacity() != c) {
      c = s.capacity();
      INFO("  String reallocated to new capacity: %zu", c);
    }
  }

  // We don't expect a 1 million character string to occupy 4MiB, for example. So verify that!
  EXPECT_LT(c, size_t(4 * 1024 * 1024));
}

UNIT(core_string) {
  String s;

  INFO("Testing string functionality");

  EXPECT_FALSE(s.isLargeOrExternal());
  EXPECT_FALSE(s.isExternal());

  EXPECT_EQ(s.assign('a'), kErrorOk);
  EXPECT_EQ(s.size(), 1u);
  EXPECT_EQ(s.capacity(), String::kSSOCapacity);
  EXPECT_EQ(s.data()[0], 'a');
  EXPECT_EQ(s.data()[1], '\0');
  EXPECT_TRUE(s.equals("a"));
  EXPECT_TRUE(s.equals("a", 1));

  EXPECT_EQ(s.assignChars('b', 4), kErrorOk);
  EXPECT_EQ(s.size(), 4u);
  EXPECT_EQ(s.capacity(), String::kSSOCapacity);
  EXPECT_EQ(s.data()[0], 'b');
  EXPECT_EQ(s.data()[1], 'b');
  EXPECT_EQ(s.data()[2], 'b');
  EXPECT_EQ(s.data()[3], 'b');
  EXPECT_EQ(s.data()[4], '\0');
  EXPECT_TRUE(s.equals("bbbb"));
  EXPECT_TRUE(s.equals("bbbb", 4));

  EXPECT_EQ(s.assign("abc"), kErrorOk);
  EXPECT_EQ(s.size(), 3u);
  EXPECT_EQ(s.capacity(), String::kSSOCapacity);
  EXPECT_EQ(s.data()[0], 'a');
  EXPECT_EQ(s.data()[1], 'b');
  EXPECT_EQ(s.data()[2], 'c');
  EXPECT_EQ(s.data()[3], '\0');
  EXPECT_TRUE(s.equals("abc"));
  EXPECT_TRUE(s.equals("abc", 3));

  const char* large = "Large string that will not fit into SSO buffer";
  EXPECT_EQ(s.assign(large), kErrorOk);
  EXPECT_TRUE(s.isLargeOrExternal());
  EXPECT_EQ(s.size(), strlen(large));
  EXPECT_GT(s.capacity(), String::kSSOCapacity);
  EXPECT_TRUE(s.equals(large));
  EXPECT_TRUE(s.equals(large, strlen(large)));

  const char* additional = " (additional content)";
  EXPECT_TRUE(s.isLargeOrExternal());
  EXPECT_EQ(s.append(additional), kErrorOk);
  EXPECT_EQ(s.size(), strlen(large) + strlen(additional));

  EXPECT_EQ(s.clear(), kErrorOk);
  EXPECT_EQ(s.size(), 0u);
  EXPECT_TRUE(s.empty());
  EXPECT_EQ(s.data()[0], '\0');
  EXPECT_TRUE(s.isLargeOrExternal()); // Clear should never release the memory.

  EXPECT_EQ(s.appendUInt(1234), kErrorOk);
  EXPECT_TRUE(s.equals("1234"));

  EXPECT_EQ(s.assignUInt(0xFFFF, 16, 0, StringFormatFlags::kAlternate), kErrorOk);
  EXPECT_TRUE(s.equals("0xFFFF"));

  StringTmp<64> sTmp;
  EXPECT_TRUE(sTmp.isLargeOrExternal());
  EXPECT_TRUE(sTmp.isExternal());
  EXPECT_EQ(sTmp.appendChars(' ', 1000), kErrorOk);
  EXPECT_FALSE(sTmp.isExternal());

  test_string_grow();
}
#endif

ASMJIT_END_NAMESPACE
