// Copyright (c) Microsoft Corporation. All rights reserved.
// SPDX-License-Identifier: MIT

#include "azure/core/internal/strings.hpp"

#include <algorithm>

namespace {
// The locale invariant case table is generated with the following program
// followed by clang-format.
#if 0
// generate with
// cl /EHsc /W4 /WX .\casetable.cpp && .\casetable.exe
#include <iterator>
#include <numeric>
#include <stdio.h>

const int *PrintUpToLine(const int *first, const int *const last) {
    if (first != last) {
        printf("0x%02X,", *first);
        for (ptrdiff_t idx = 1; ++first != last && idx < 8; ++idx) {
            printf(" 0x%02X,", *first);
        }

        puts("");
    }

    return first;
}

int main() {
    using namespace std;
    int characters[256];
    iota(begin(characters), end(characters), 0);
    for (ptrdiff_t idx = 'a'; idx <= 'z'; ++idx) {
        characters[idx] = idx - ('a' - 'A');
    }

    const int *first = begin(characters);
    const auto last = first + size(characters);
    printf("{");
    while (first != last) {
        first = PrintUpToLine(first, last);
    }
    printf("};");
}

#endif

const unsigned char LocaleInvariantLowercaseTable[256] = {
    0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08, 0x09, 0x0A, 0x0B, 0x0C, 0x0D, 0x0E, 0x0F,
    0x10, 0x11, 0x12, 0x13, 0x14, 0x15, 0x16, 0x17, 0x18, 0x19, 0x1A, 0x1B, 0x1C, 0x1D, 0x1E, 0x1F,
    0x20, 0x21, 0x22, 0x23, 0x24, 0x25, 0x26, 0x27, 0x28, 0x29, 0x2A, 0x2B, 0x2C, 0x2D, 0x2E, 0x2F,
    0x30, 0x31, 0x32, 0x33, 0x34, 0x35, 0x36, 0x37, 0x38, 0x39, 0x3A, 0x3B, 0x3C, 0x3D, 0x3E, 0x3F,
    0x40, 0x61, 0x62, 0x63, 0x64, 0x65, 0x66, 0x67, 0x68, 0x69, 0x6A, 0x6B, 0x6C, 0x6D, 0x6E, 0x6F,
    0x70, 0x71, 0x72, 0x73, 0x74, 0x75, 0x76, 0x77, 0x78, 0x79, 0x7A, 0x5B, 0x5C, 0x5D, 0x5E, 0x5F,
    0x60, 0x61, 0x62, 0x63, 0x64, 0x65, 0x66, 0x67, 0x68, 0x69, 0x6A, 0x6B, 0x6C, 0x6D, 0x6E, 0x6F,
    0x70, 0x71, 0x72, 0x73, 0x74, 0x75, 0x76, 0x77, 0x78, 0x79, 0x7A, 0x7B, 0x7C, 0x7D, 0x7E, 0x7F,
    0x80, 0x81, 0x82, 0x83, 0x84, 0x85, 0x86, 0x87, 0x88, 0x89, 0x8A, 0x8B, 0x8C, 0x8D, 0x8E, 0x8F,
    0x90, 0x91, 0x92, 0x93, 0x94, 0x95, 0x96, 0x97, 0x98, 0x99, 0x9A, 0x9B, 0x9C, 0x9D, 0x9E, 0x9F,
    0xA0, 0xA1, 0xA2, 0xA3, 0xA4, 0xA5, 0xA6, 0xA7, 0xA8, 0xA9, 0xAA, 0xAB, 0xAC, 0xAD, 0xAE, 0xAF,
    0xB0, 0xB1, 0xB2, 0xB3, 0xB4, 0xB5, 0xB6, 0xB7, 0xB8, 0xB9, 0xBA, 0xBB, 0xBC, 0xBD, 0xBE, 0xBF,
    0xC0, 0xC1, 0xC2, 0xC3, 0xC4, 0xC5, 0xC6, 0xC7, 0xC8, 0xC9, 0xCA, 0xCB, 0xCC, 0xCD, 0xCE, 0xCF,
    0xD0, 0xD1, 0xD2, 0xD3, 0xD4, 0xD5, 0xD6, 0xD7, 0xD8, 0xD9, 0xDA, 0xDB, 0xDC, 0xDD, 0xDE, 0xDF,
    0xE0, 0xE1, 0xE2, 0xE3, 0xE4, 0xE5, 0xE6, 0xE7, 0xE8, 0xE9, 0xEA, 0xEB, 0xEC, 0xED, 0xEE, 0xEF,
    0xF0, 0xF1, 0xF2, 0xF3, 0xF4, 0xF5, 0xF6, 0xF7, 0xF8, 0xF9, 0xFA, 0xFB, 0xFC, 0xFD, 0xFE, 0xFF,
};
} // unnamed namespace

namespace Azure { namespace Core { namespace _internal {

  unsigned char StringExtensions::ToLower(const unsigned char symbol) noexcept
  {
    return LocaleInvariantLowercaseTable[symbol];
  }

  std::string const StringExtensions::ToLower(const std::string& src) noexcept
  {
    auto result = std::string(src);
    for (auto i = result.begin(); i < result.end(); i++)
    {
      *i = ToLower(static_cast<unsigned char>(*i));
    }
    return result;
  }

  bool StringExtensions::LocaleInvariantCaseInsensitiveEqual(
      const std::string& lhs,
      const std::string& rhs) noexcept
  {
    return std::equal(
        lhs.begin(),
        lhs.end(),
        rhs.begin(),
        rhs.end(),
        [](const char left, const char right) noexcept {
          return LocaleInvariantLowercaseTable[static_cast<unsigned char>(left)]
              == LocaleInvariantLowercaseTable[static_cast<unsigned char>(right)];
        });
  }

}}} // namespace Azure::Core::_internal
