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#include "ge0/parser.hpp"
#include "ge0/url_generator.hpp"
#include "coding/url.hpp"
#include "geometry/mercator.hpp"
#include "base/assert.hpp"
#include "base/math.hpp"
#include "base/string_utils.hpp"
#include <algorithm>
#include <sstream>
using namespace std;
namespace ge0
{
Ge0Parser::Ge0Parser()
{
for (size_t i = 0; i < 256; ++i)
m_base64ReverseCharTable[i] = 255;
for (uint8_t i = 0; i < 64; ++i)
{
char c = Base64Char(i);
m_base64ReverseCharTable[static_cast<uint8_t>(c)] = i;
}
}
bool Ge0Parser::Parse(string const & url, Result & result)
{
// Original URL format:
//
// +------------------ 1 byte: zoom level
// |+-------+--------- 9 bytes: lat,lon
// || | +--+---- Variable number of bytes: point name
// || | | |
// ge0://ZCoordba64/Name
// Alternative format (differs only in the prefix):
// http://ge0.me/ZCoordba64/Name
for (string const & prefix : {"ge0://", "http://ge0.me/", "https://ge0.me/"})
{
if (strings::StartsWith(url, prefix))
return ParseAfterPrefix(url, prefix.size(), result);
}
return false;
}
bool Ge0Parser::ParseAfterPrefix(string const & url, size_t from, Result & result)
{
size_t const kEncodedZoomAndCoordinatesLength = 10;
if (url.size() < from + kEncodedZoomAndCoordinatesLength)
return false;
size_t const kMaxNameLength = 256;
size_t const posZoom = from;
size_t const posLatLon = posZoom + 1;
size_t const posName = from + kEncodedZoomAndCoordinatesLength + 1;
size_t const lengthLatLon = posName - posLatLon - 1;
uint8_t const zoomI = DecodeBase64Char(url[posZoom]);
if (zoomI >= 64)
return false;
result.m_zoomLevel = DecodeZoom(zoomI);
if (!DecodeLatLon(url.substr(posLatLon, lengthLatLon), result.m_lat, result.m_lon))
return false;
ASSERT(mercator::ValidLat(result.m_lat), (result.m_lat));
ASSERT(mercator::ValidLon(result.m_lon), (result.m_lon));
if (url.size() >= posName)
{
CHECK_GREATER(posName, 0, ());
if (url[posName - 1] != '/')
return false;
result.m_name = DecodeName(url.substr(posName, min(url.size() - posName, kMaxNameLength)));
}
return true;
}
uint8_t Ge0Parser::DecodeBase64Char(char const c)
{
return m_base64ReverseCharTable[static_cast<uint8_t>(c)];
}
double Ge0Parser::DecodeZoom(uint8_t const zoomByte)
{
// Coding zoom - int newZoom = ((oldZoom - 4) * 4)
return static_cast<double>(zoomByte) / 4 + 4;
}
bool Ge0Parser::DecodeLatLon(string const & s, double & lat, double & lon)
{
int latInt = 0;
int lonInt = 0;
if (!DecodeLatLonToInt(s, latInt, lonInt))
return false;
lat = DecodeLatFromInt(latInt, (1 << kMaxCoordBits) - 1);
lon = DecodeLonFromInt(lonInt, (1 << kMaxCoordBits) - 1);
return true;
}
bool Ge0Parser::DecodeLatLonToInt(string const & s, int & lat, int & lon)
{
int shift = kMaxCoordBits - 3;
for (size_t i = 0; i < s.size(); ++i, shift -= 3)
{
uint8_t const a = DecodeBase64Char(s[i]);
if (a >= 64)
return false;
int const lat1 = (((a >> 5) & 1) << 2 | ((a >> 3) & 1) << 1 | ((a >> 1) & 1));
int const lon1 = (((a >> 4) & 1) << 2 | ((a >> 2) & 1) << 1 | (a & 1));
lat |= lat1 << shift;
lon |= lon1 << shift;
}
double const middleOfSquare = 1 << (3 * (kMaxPointBytes - s.size()) - 1);
lat += middleOfSquare;
lon += middleOfSquare;
return true;
}
double Ge0Parser::DecodeLatFromInt(int const lat, int const maxValue)
{
return static_cast<double>(lat) / maxValue * 180 - 90;
}
double Ge0Parser::DecodeLonFromInt(int const lon, int const maxValue)
{
return static_cast<double>(lon) / (maxValue + 1.0) * 360.0 - 180;
}
string Ge0Parser::DecodeName(string name)
{
ValidateName(name);
name = url::UrlDecode(name);
SpacesToUnderscore(name);
return name;
}
void Ge0Parser::SpacesToUnderscore(string & name)
{
for (size_t i = 0; i < name.size(); ++i)
{
if (name[i] == ' ')
name[i] = '_';
else if (name[i] == '_')
name[i] = ' ';
}
}
void Ge0Parser::ValidateName(string & name)
{
if (name.empty())
return;
for (size_t i = 0; i + 2 < name.size(); ++i)
{
if (name[i] == '%' && (!IsHexChar(name[i + 1]) || !IsHexChar(name[i + 2])))
{
name.resize(i);
return;
}
}
if (name[name.size() - 1] == '%')
name.resize(name.size() - 1);
else if (name.size() > 1 && name[name.size() - 2] == '%')
name.resize(name.size() - 2);
}
bool Ge0Parser::IsHexChar(char const a)
{
return ((a >= '0' && a <= '9') || (a >= 'A' && a <= 'F') || (a >= 'a' && a <= 'f'));
}
string DebugPrint(Ge0Parser::Result const & r)
{
ostringstream oss;
oss << "ParseResult [";
oss << "zoom=" << r.m_zoomLevel << ", ";
oss << "lat=" << r.m_lat << ", ";
oss << "lon=" << r.m_lon << ", ";
oss << "name=" << r.m_name << "]";
return oss.str();
}
} // namespace ge0
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