//
// Copyright 2015 The ANGLE Project Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
//
// string_utils:
//   String helper functions.
//

#include "string_utils.h"

#include <algorithm>
#include <stdlib.h>
#include <string.h>
#include <fstream>
#include <sstream>

#include "common/platform.h"

namespace angle
{

const char kWhitespaceASCII[] = " \f\n\r\t\v";

std::vector<std::string> SplitString(const std::string &input,
                                     const std::string &delimiters,
                                     WhitespaceHandling whitespace,
                                     SplitResult resultType)
{
    std::vector<std::string> result;
    if (input.empty())
    {
        return result;
    }

    std::string::size_type start = 0;
    while (start != std::string::npos)
    {
        auto end = input.find_first_of(delimiters, start);

        std::string piece;
        if (end == std::string::npos)
        {
            piece = input.substr(start);
            start = std::string::npos;
        }
        else
        {
            piece = input.substr(start, end - start);
            start = end + 1;
        }

        if (whitespace == TRIM_WHITESPACE)
        {
            piece = TrimString(piece, kWhitespaceASCII);
        }

        if (resultType == SPLIT_WANT_ALL || !piece.empty())
        {
            result.push_back(piece);
        }
    }

    return result;
}

void SplitStringAlongWhitespace(const std::string &input,
                                std::vector<std::string> *tokensOut)
{

    std::istringstream stream(input);
    std::string line;

    while (std::getline(stream, line))
    {
        size_t prev = 0, pos;
        while ((pos = line.find_first_of(kWhitespaceASCII, prev)) != std::string::npos)
        {
            if (pos > prev)
                tokensOut->push_back(line.substr(prev, pos - prev));
            prev = pos + 1;
        }
        if (prev < line.length())
            tokensOut->push_back(line.substr(prev, std::string::npos));
    }
}

std::string TrimString(const std::string &input, const std::string &trimChars)
{
    auto begin = input.find_first_not_of(trimChars);
    if (begin == std::string::npos)
    {
        return "";
    }

    std::string::size_type end = input.find_last_not_of(trimChars);
    if (end == std::string::npos)
    {
        return input.substr(begin);
    }

    return input.substr(begin, end - begin + 1);
}

bool HexStringToUInt(const std::string &input, unsigned int *uintOut)
{
    unsigned int offset = 0;

    if (input.size() >= 2 && input[0] == '0' && input[1] == 'x')
    {
        offset = 2u;
    }

    // Simple validity check
    if (input.find_first_not_of("0123456789ABCDEFabcdef", offset) != std::string::npos)
    {
        return false;
    }

    std::stringstream inStream(input);
    inStream >> std::hex >> *uintOut;
    return !inStream.fail();
}

bool ReadFileToString(const std::string &path, std::string *stringOut)
{
    std::ifstream inFile(path.c_str());
    if (inFile.fail())
    {
        return false;
    }

    inFile.seekg(0, std::ios::end);
    stringOut->reserve(static_cast<std::string::size_type>(inFile.tellg()));
    inFile.seekg(0, std::ios::beg);

    stringOut->assign(std::istreambuf_iterator<char>(inFile), std::istreambuf_iterator<char>());
    return !inFile.fail();
}

Optional<std::vector<wchar_t>> WidenString(size_t length, const char *cString)
{
    std::vector<wchar_t> wcstring(length + 1);
#if !defined(ANGLE_PLATFORM_WINDOWS)
    size_t written = mbstowcs(wcstring.data(), cString, length + 1);
    if (written == 0)
    {
        return Optional<std::vector<wchar_t>>::Invalid();
    }
#else
    size_t convertedChars = 0;
    errno_t err = mbstowcs_s(&convertedChars, wcstring.data(), length + 1, cString, _TRUNCATE);
    if (err != 0)
    {
        return Optional<std::vector<wchar_t>>::Invalid();
    }
#endif
    return Optional<std::vector<wchar_t>>(wcstring);
}

bool BeginsWith(const std::string &str, const char *prefix)
{
    return strncmp(str.c_str(), prefix, strlen(prefix)) == 0;
}

bool BeginsWith(const char *str, const char *prefix)
{
    return strncmp(str, prefix, strlen(prefix)) == 0;
}

bool EndsWith(const std::string &str, const char *suffix)
{
    const auto len = strlen(suffix);
    if (len > str.size())
        return false;

    const char *end = str.c_str() + str.size() - len;

    return memcmp(end, suffix, len) == 0;
}

void ToLower(std::string *str)
{
    for (auto &ch : *str)
    {
        ch = static_cast<char>(::tolower(ch));
    }
}

}  // namespace angle
