/*
 *  Copyright (C) 2005-2018 Team Kodi
 *  This file is part of Kodi - https://kodi.tv
 *
 *  SPDX-License-Identifier: GPL-2.0-or-later
 *  See LICENSES/README.md for more information.
 */

#include "HttpHeader.h"
#include "utils/StringUtils.h"

// header white space characters according to RFC 2616
const char* const CHttpHeader::m_whitespaceChars = " \t";


CHttpHeader::CHttpHeader()
{
  m_headerdone = false;
}

CHttpHeader::~CHttpHeader() = default;

void CHttpHeader::Parse(const std::string& strData)
{
  size_t pos = 0;
  const size_t len = strData.length();
  const char* const strDataC = strData.c_str();

  // According to RFC 2616 any header line can have continuation on next line, if next line is started from whitespace char
  // This code at first checks for whitespace char at the begging of the line, and if found, then current line is appended to m_lastHeaderLine
  // If current line is NOT started from whitespace char, then previously stored (and completed) m_lastHeaderLine is parsed and current line is assigned to m_lastHeaderLine (to be parsed later)
  while (pos < len)
  {
    size_t lineEnd = strData.find('\x0a', pos); // use '\x0a' instead of '\n' to be platform independent

    if (lineEnd == std::string::npos)
      return; // error: expected only complete lines

    const size_t nextLine = lineEnd + 1;
    if (lineEnd > pos && strDataC[lineEnd - 1] == '\x0d') // use '\x0d' instead of '\r' to be platform independent
      lineEnd--;

    if (m_headerdone)
      Clear(); // clear previous header and process new one

    if (strDataC[pos] == ' ' || strDataC[pos] == '\t') // same chars as in CHttpHeader::m_whitespaceChars
    { // line is started from whitespace char: this is continuation of previous line
      pos = strData.find_first_not_of(m_whitespaceChars, pos);

      m_lastHeaderLine.push_back(' '); // replace all whitespace chars at start of the line with single space
      m_lastHeaderLine.append(strData, pos, lineEnd - pos); // append current line
    }
    else
    { // this line is NOT continuation, this line is new header line
      if (!m_lastHeaderLine.empty())
        ParseLine(m_lastHeaderLine); // process previously stored completed line (if any)

      m_lastHeaderLine.assign(strData, pos, lineEnd - pos); // store current line to (possibly) complete later. Will be parsed on next turns.

      if (pos == lineEnd)
        m_headerdone = true; // current line is bare "\r\n" (or "\n"), means end of header; no need to process current m_lastHeaderLine
    }

    pos = nextLine; // go to next line (if any)
  }
}

bool CHttpHeader::ParseLine(const std::string& headerLine)
{
  const size_t valueStart = headerLine.find(':');

  if (valueStart != std::string::npos)
  {
    std::string strParam(headerLine, 0, valueStart);
    std::string strValue(headerLine, valueStart + 1);

    StringUtils::Trim(strParam, m_whitespaceChars);
    StringUtils::ToLower(strParam);

    StringUtils::Trim(strValue, m_whitespaceChars);

    if (!strParam.empty() && !strValue.empty())
      m_params.push_back(HeaderParams::value_type(strParam, strValue));
    else
      return false;
  }
  else if (m_protoLine.empty())
    m_protoLine = headerLine;

  return true;
}

void CHttpHeader::AddParam(const std::string& param, const std::string& value, const bool overwrite /*= false*/)
{
  std::string paramLower(param);
  StringUtils::ToLower(paramLower);
  StringUtils::Trim(paramLower, m_whitespaceChars);
  if (paramLower.empty())
    return;

  if (overwrite)
  { // delete ALL parameters with the same name
    // note: 'GetValue' always returns last added parameter,
    //       so you probably don't need to overwrite
    for (size_t i = 0; i < m_params.size();)
    {
      if (m_params[i].first == paramLower)
        m_params.erase(m_params.begin() + i);
      else
        ++i;
    }
  }

  std::string valueTrim(value);
  StringUtils::Trim(valueTrim, m_whitespaceChars);
  if (valueTrim.empty())
    return;

  m_params.push_back(HeaderParams::value_type(paramLower, valueTrim));
}

std::string CHttpHeader::GetValue(const std::string& strParam) const
{
  std::string paramLower(strParam);
  StringUtils::ToLower(paramLower);

  return GetValueRaw(paramLower);
}

std::string CHttpHeader::GetValueRaw(const std::string& strParam) const
{
  // look in reverse to find last parameter (probably most important)
  for (HeaderParams::const_reverse_iterator iter = m_params.rbegin(); iter != m_params.rend(); ++iter)
  {
    if (iter->first == strParam)
      return iter->second;
  }

  return "";
}

std::vector<std::string> CHttpHeader::GetValues(std::string strParam) const
{
  StringUtils::ToLower(strParam);
  std::vector<std::string> values;

  for (HeaderParams::const_iterator iter = m_params.begin(); iter != m_params.end(); ++iter)
  {
    if (iter->first == strParam)
      values.push_back(iter->second);
  }

  return values;
}

std::string CHttpHeader::GetHeader(void) const
{
  if (m_protoLine.empty() && m_params.empty())
    return "";

  std::string strHeader(m_protoLine + "\r\n");

  for (HeaderParams::const_iterator iter = m_params.begin(); iter != m_params.end(); ++iter)
    strHeader += ((*iter).first + ": " + (*iter).second + "\r\n");

  strHeader += "\r\n";
  return strHeader;
}

std::string CHttpHeader::GetMimeType(void) const
{
  std::string strValue(GetValueRaw("content-type"));

  std::string mimeType(strValue, 0, strValue.find(';'));
  StringUtils::TrimRight(mimeType, m_whitespaceChars);

  return mimeType;
}

std::string CHttpHeader::GetCharset(void) const
{
  std::string strValue(GetValueRaw("content-type"));
  if (strValue.empty())
    return strValue;

  StringUtils::ToUpper(strValue);
  const size_t len = strValue.length();

  // extract charset value from 'contenttype/contentsubtype;pram1=param1Val ; charset=XXXX\t;param2=param2Val'
  // most common form: 'text/html; charset=XXXX'
  // charset value can be in double quotes: 'text/xml; charset="XXX XX"'

  size_t pos = strValue.find(';');
  while (pos < len)
  {
    // move to the next non-whitespace character
    pos = strValue.find_first_not_of(m_whitespaceChars, pos + 1);

    if (pos != std::string::npos)
    {
      if (strValue.compare(pos, 8, "CHARSET=", 8) == 0)
      {
        pos += 8; // move position to char after 'CHARSET='
        size_t len = strValue.find(';', pos);
        if (len != std::string::npos)
          len -= pos;
        std::string charset(strValue, pos, len);  // intentionally ignoring possible ';' inside quoted string
                                                  // as we don't support any charset with ';' in name
        StringUtils::Trim(charset, m_whitespaceChars);
        if (!charset.empty())
        {
          if (charset[0] != '"')
            return charset;
          else
          { // charset contains quoted string (allowed according to RFC 2616)
            StringUtils::Replace(charset, "\\", ""); // unescape chars, ignoring possible '\"' and '\\'
            const size_t closingQ = charset.find('"', 1);
            if (closingQ == std::string::npos)
              return ""; // no closing quote

            return charset.substr(1, closingQ - 1);
          }
        }
      }
      pos = strValue.find(';', pos); // find next parameter
    }
  }

  return ""; // no charset is detected
}

void CHttpHeader::Clear()
{
  m_params.clear();
  m_protoLine.clear();
  m_headerdone = false;
  m_lastHeaderLine.clear();
}
