#include "JsonUtil.h"

#include <charconv>

std::string jsonEscape(const std::string& value)
{
    std::string out;
    out.reserve(value.size());
    for (char ch : value)
    {
        switch (ch)
        {
        case '\\': out += "\\\\"; break;
        case '"': out += "\\\""; break;
        case '\n': out += "\\n"; break;
        case '\r': out += "\\r"; break;
        case '\t': out += "\\t"; break;
        default: out += ch; break;
        }
    }
    return out;
}

std::optional<float> findJsonFloat(const std::string& body, const std::string& key)
{
    const std::string quotedKey = "\"" + key + "\"";
    size_t pos = body.find(quotedKey);
    if (pos == std::string::npos)
        return std::nullopt;

    pos = body.find(':', pos + quotedKey.size());
    if (pos == std::string::npos)
        return std::nullopt;
    ++pos;

    while (pos < body.size() && (body[pos] == ' ' || body[pos] == '\t' || body[pos] == '\r' || body[pos] == '\n'))
        ++pos;

    size_t end = pos;
    while (end < body.size() && (body[end] == '-' || body[end] == '+' || body[end] == '.' || (body[end] >= '0' && body[end] <= '9') || body[end] == 'e' || body[end] == 'E'))
        ++end;

    float value = 0.0f;
    const auto result = std::from_chars(body.data() + pos, body.data() + end, value);
    if (result.ec != std::errc())
        return std::nullopt;
    return value;
}