/*
 * Copyright 2013-2016 Emmanuel Engelhart <kelson@kiwix.org>
 * Copyright 2016 Matthieu Gautier <mgautier@kymeria.fr>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU  General Public License as published by
 * the Free Software Foundation; either version 3 of the License, or
 * any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
 * MA 02110-1301, USA.
 */

#include "tools.h"


#include <zlib.h>
#include <string.h>
#include <stdexcept>
#include <iostream>
#include <fstream>
#include <sstream>
#include <vector>
#include <cerrno>
#include <sys/stat.h>
#include <magic.h>

#ifdef _WIN32
#define SEPARATOR "\\"
#else
#define SEPARATOR "/"
#endif


/* Init file extensions hash */
static std::map<std::string, std::string> _create_extMimeTypes(){
  std::map<std::string, std::string> extMimeTypes;
  extMimeTypes["HTML"] = "text/html";
  extMimeTypes["html"] = "text/html";
  extMimeTypes["HTM"] = "text/html";
  extMimeTypes["htm"] = "text/html";
  extMimeTypes["PNG"] = "image/png";
  extMimeTypes["png"] = "image/png";
  extMimeTypes["TIFF"] = "image/tiff";
  extMimeTypes["tiff"] = "image/tiff";
  extMimeTypes["TIF"] = "image/tiff";
  extMimeTypes["tif"] = "image/tiff";
  extMimeTypes["JPEG"] = "image/jpeg";
  extMimeTypes["jpeg"] = "image/jpeg";
  extMimeTypes["JPG"] = "image/jpeg";
  extMimeTypes["jpg"] = "image/jpeg";
  extMimeTypes["GIF"] = "image/gif";
  extMimeTypes["gif"] = "image/gif";
  extMimeTypes["SVG"] = "image/svg+xml";
  extMimeTypes["svg"] = "image/svg+xml";
  extMimeTypes["TXT"] = "text/plain";
  extMimeTypes["txt"] = "text/plain";
  extMimeTypes["XML"] = "text/xml";
  extMimeTypes["xml"] = "text/xml";
  extMimeTypes["EPUB"] = "application/epub+zip";
  extMimeTypes["epub"] = "application/epub+zip";
  extMimeTypes["PDF"] = "application/pdf";
  extMimeTypes["pdf"] = "application/pdf";
  extMimeTypes["OGG"] = "application/ogg";
  extMimeTypes["ogg"] = "application/ogg";
  extMimeTypes["JS"] = "application/javascript";
  extMimeTypes["js"] = "application/javascript";
  extMimeTypes["JSON"] = "application/json";
  extMimeTypes["json"] = "application/json";
  extMimeTypes["CSS"] = "text/css";
  extMimeTypes["css"] = "text/css";
  extMimeTypes["otf"] = "application/vnd.ms-opentype";
  extMimeTypes["OTF"] = "application/vnd.ms-opentype";
  extMimeTypes["eot"] = "application/vnd.ms-fontobject";
  extMimeTypes["EOT"] = "application/vnd.ms-fontobject";
  extMimeTypes["ttf"] = "application/font-ttf";
  extMimeTypes["TTF"] = "application/font-ttf";
  extMimeTypes["woff"] = "application/font-woff";
  extMimeTypes["WOFF"] = "application/font-woff";
  extMimeTypes["vtt"] = "text/vtt";
  extMimeTypes["VTT"] = "text/vtt";
  
  return extMimeTypes;
}

static std::map<std::string, std::string> extMimeTypes = _create_extMimeTypes();

static std::map<std::string, std::string> fileMimeTypes;


extern std::string directoryPath;
extern bool inflateHtmlFlag;
extern bool uniqueNamespace;
extern magic_t magic;

/* Decompress an STL string using zlib and return the original data. */
inline std::string inflateString(const std::string& str) {
  z_stream zs; // z_stream is zlib's control structure
  memset(&zs, 0, sizeof(zs));

  if (inflateInit(&zs) != Z_OK)
    throw(std::runtime_error("inflateInit failed while decompressing."));

  zs.next_in = (Bytef*)str.data();
  zs.avail_in = str.size();

  int ret;
  char outbuffer[32768];
  std::string outstring;

  // get the decompressed bytes blockwise using repeated calls to inflate
  do {
    zs.next_out = reinterpret_cast<Bytef*>(outbuffer);
    zs.avail_out = sizeof(outbuffer);

    ret = inflate(&zs, 0);

    if (outstring.size() < zs.total_out) {
      outstring.append(outbuffer,
		       zs.total_out - outstring.size());
    }

  } while (ret == Z_OK);

  inflateEnd(&zs);

  if (ret != Z_STREAM_END) { // an error occurred that was not EOF
    std::ostringstream oss;
    oss << "Exception during zlib decompression: (" << ret << ") "
	<< zs.msg;
    throw(std::runtime_error(oss.str()));
  }

  return outstring;
}

inline bool seemsToBeHtml(const std::string &path) {
  if (path.find_last_of(".") != std::string::npos) {
    std::string mimeType = path.substr(path.find_last_of(".")+1);
    if (extMimeTypes.find(mimeType) != extMimeTypes.end()) {
      return "text/html" == extMimeTypes[mimeType];
    }
  }

  return false;
}

std::string getFileContent(const std::string &path) {
  std::ifstream in(path.c_str(), ::std::ios::binary);
  if (in) {
    std::string contents;
    in.seekg(0, std::ios::end);
    contents.resize(in.tellg());
    in.seekg(0, std::ios::beg);
    in.read(&contents[0], contents.size());
    in.close();

    /* Inflate if necessary */
    if (inflateHtmlFlag && seemsToBeHtml(path)) {
      try {
	contents = inflateString(contents);
      } catch(...) {
	std::cerr << "Can not initialize inflate stream for: " << path << std::endl;
      }
    }
    return(contents);
 }
  std::cerr << "zimwriterfs: unable to open file at path: " << path << std::endl;
  throw(errno);
}

unsigned int getFileSize(const std::string &path) {
  struct stat filestatus;
  stat(path.c_str(), &filestatus);
  return filestatus.st_size;
}    

bool fileExists(const std::string &path) {
  bool flag = false;
  std::fstream fin;
  fin.open(path.c_str(), std::ios::in);
  if (fin.is_open()) {
    flag = true;
  }
  fin.close();
  return flag;
}

/* base64 */
static const std::string base64_chars = 
             "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
             "abcdefghijklmnopqrstuvwxyz"
  "0123456789+/";

std::string base64_encode(unsigned char const* bytes_to_encode, unsigned int in_len) {
  std::string ret;
  int i = 0;
  int j = 0;
  unsigned char char_array_3[3];
  unsigned char char_array_4[4];

  while (in_len--) {
    char_array_3[i++] = *(bytes_to_encode++);
    if (i == 3) {
      char_array_4[0] = (char_array_3[0] & 0xfc) >> 2;
      char_array_4[1] = ((char_array_3[0] & 0x03) << 4) + ((char_array_3[1] & 0xf0) >> 4);
      char_array_4[2] = ((char_array_3[1] & 0x0f) << 2) + ((char_array_3[2] & 0xc0) >> 6);
      char_array_4[3] = char_array_3[2] & 0x3f;

      for(i = 0; (i <4) ; i++)
        ret += base64_chars[char_array_4[i]];
      i = 0;
    }
  }

  if (i)
    {
      for(j = i; j < 3; j++)
	char_array_3[j] = '\0';

      char_array_4[0] = (char_array_3[0] & 0xfc) >> 2;
      char_array_4[1] = ((char_array_3[0] & 0x03) << 4) + ((char_array_3[1] & 0xf0) >> 4);
      char_array_4[2] = ((char_array_3[1] & 0x0f) << 2) + ((char_array_3[2] & 0xc0) >> 6);
      char_array_4[3] = char_array_3[2] & 0x3f;

      for (j = 0; (j < i + 1); j++)
	ret += base64_chars[char_array_4[j]];

      while((i++ < 3))
	ret += '=';

    }

  return ret;

}

std::string decodeUrl(const std::string &encodedUrl) {
  std::string decodedUrl = encodedUrl;
  std::string::size_type pos = 0;
  char ch;

  while ((pos = decodedUrl.find('%', pos)) != std::string::npos &&
	 pos + 2 < decodedUrl.length()) {
    sscanf(decodedUrl.substr(pos + 1, 2).c_str(), "%x", (unsigned int*)&ch);
    decodedUrl.replace(pos, 3, 1, ch);
    ++pos;
  }

  return decodedUrl;
}

std::string removeLastPathElement(const std::string& path, const bool removePreSeparator, const bool removePostSeparator) {
  std::string newPath = path;
  size_t offset = newPath.find_last_of(SEPARATOR);
 
  if (removePreSeparator && offset == newPath.length()-1) {
    newPath = newPath.substr(0, offset);
    offset = newPath.find_last_of(SEPARATOR);
  }
  newPath = removePostSeparator ? newPath.substr(0, offset) : newPath.substr(0, offset+1);

  return newPath;
}

/* Split string in a token array */
std::vector<std::string> split(const std::string & str,
                                      const std::string & delims=" *-")
{
  std::string::size_type lastPos = str.find_first_not_of(delims, 0);
  std::string::size_type pos = str.find_first_of(delims, lastPos);
  std::vector<std::string> tokens;

  while (std::string::npos != pos || std::string::npos != lastPos)
    {
      tokens.push_back(str.substr(lastPos, pos - lastPos));
      lastPos = str.find_first_not_of(delims, pos);
      pos     = str.find_first_of(delims, lastPos);
    }

  return tokens;
}

std::vector<std::string> split(const char* lhs, const char* rhs){
  const std::string m1 (lhs), m2 (rhs);
  return split(m1, m2);
}

std::vector<std::string> split(const char* lhs, const std::string& rhs){
  return split(lhs, rhs.c_str());
}

std::vector<std::string> split(const std::string& lhs, const char* rhs){
  return split(lhs.c_str(), rhs);
}

/* Warning: the relative path must be with slashes */
std::string computeAbsolutePath(const std::string& path, const std::string& relativePath) {

  /* Add a trailing / to the path if necessary */
  std::string absolutePath = path[path.length()-1] == '/' ? path : removeLastPathElement(path, false, false);

  /* Go through relative path */
  std::vector<std::string> relativePathElements;
  std::stringstream relativePathStream(relativePath);
  std::string relativePathItem;
  while (std::getline(relativePathStream, relativePathItem, '/')) {
    if (relativePathItem == "..") {
      absolutePath = removeLastPathElement(absolutePath, true, false); 
    } else if (!relativePathItem.empty() && relativePathItem != ".") {
      absolutePath += relativePathItem;
      absolutePath += "/";
    }
  }
  
  /* Remove wront trailing / */
  return absolutePath.substr(0, absolutePath.length()-1);
}

/* Warning: the relative path must be with slashes */
std::string computeRelativePath(const std::string path, const std::string absolutePath) {
  std::vector<std::string> pathParts = split(path, "/");
  std::vector<std::string> absolutePathParts = split(absolutePath, "/");

  unsigned int commonCount = 0;
  while (commonCount < pathParts.size() && 
	 commonCount < absolutePathParts.size() && 
	 pathParts[commonCount] == absolutePathParts[commonCount]) {
    if (!pathParts[commonCount].empty()) {
      commonCount++;
    }
  }
    
  std::string relativePath;
  for (unsigned int i = commonCount ; i < pathParts.size()-1 ; i++) {
    relativePath += "../";
  }

  for (unsigned int i = commonCount ; i < absolutePathParts.size() ; i++) {
    relativePath += absolutePathParts[i];
    relativePath += i + 1 < absolutePathParts.size() ? "/" : "";
  }

  return relativePath;
}



static bool isLocalUrl(const std::string url) {
  if (url.find(":") != std::string::npos) {
    return (!(
	      url.find("://") != std::string::npos ||
	      url.find("//") == 0 ||
	      url.find("tel:") == 0 ||
	      url.find("geo:") == 0
	      ));
  }
  return true;
}

std::string extractRedirectUrlFromHtml(const GumboVector* head_children) {
  std::string url;
  
  for (int i = 0; i < head_children->length; ++i) {
    GumboNode* child = (GumboNode*)(head_children->data[i]);
    if (child->type == GUMBO_NODE_ELEMENT &&
	child->v.element.tag == GUMBO_TAG_META) {
      GumboAttribute* attribute;
      if (attribute = gumbo_get_attribute(&child->v.element.attributes, "http-equiv")) {
	if (!strcmp(attribute->value, "refresh")) {
	  if (attribute = gumbo_get_attribute(&child->v.element.attributes, "content")) {
	    std::string targetUrl = attribute->value;
	    std::size_t found = targetUrl.find("URL=") != std::string::npos ? targetUrl.find("URL=") : targetUrl.find("url=");
	    if (found!=std::string::npos) {
	      url = targetUrl.substr(found+4);
	    } else {
	      throw std::string("Unable to find the redirect/refresh target url from the HTML DOM");
	    }
	  }
	}
      }
    }
  }
  
  return url;
}

void getLinks(GumboNode* node, std::map<std::string, bool> &links) {
  if (node->type != GUMBO_NODE_ELEMENT) {
    return;
  }

  GumboAttribute* attribute = NULL;
  attribute = gumbo_get_attribute(&node->v.element.attributes, "href");
  if (attribute == NULL) {
    attribute = gumbo_get_attribute(&node->v.element.attributes, "src");
  }

  if (attribute != NULL && isLocalUrl(attribute->value)) {
    links[attribute->value] = true;
  }

  GumboVector* children = &node->v.element.children;
  for (int i = 0; i < children->length; ++i) {
    getLinks(static_cast<GumboNode*>(children->data[i]), links);
  }
}

void replaceStringInPlaceOnce(std::string& subject,
                              const std::string& search,
                              const std::string& replace) {
  size_t pos = 0;
  while ((pos = subject.find(search, pos)) != std::string::npos) {
    subject.replace(pos, search.length(), replace);
    pos += replace.length();
    return; /* Do it once */
  }
}

void replaceStringInPlace(std::string& subject,
                          const std::string& search,
                          const std::string& replace) {
  size_t pos = 0;
  while ((pos = subject.find(search, pos)) != std::string::npos) {
    subject.replace(pos, search.length(), replace);
    pos += replace.length();
  }

  return;
}

void stripTitleInvalidChars(std::string & str) {

  /* Remove unicode orientation invisible characters */
  replaceStringInPlace(str, "\u202A", "");
  replaceStringInPlace(str, "\u202C", "");
}

std::string getMimeTypeForFile(const std::string& filename) {
  std::string mimeType;

  /* Try to get the mimeType from the file extension */
  if (filename.find_last_of(".") != std::string::npos) {
    mimeType = filename.substr(filename.find_last_of(".")+1);
    if (extMimeTypes.find(mimeType) != extMimeTypes.end()) {
      return extMimeTypes[mimeType];
    }
  }

  /* Try to get the mimeType from the cache */
  if (fileMimeTypes.find(filename) != fileMimeTypes.end()) {
    return fileMimeTypes[filename];
  }

  /* Try to get the mimeType with libmagic */
  try {
    std::string path = directoryPath + "/" + filename;
    mimeType = std::string(magic_file(magic, path.c_str()));
    if (mimeType.find(";") != std::string::npos) {
      mimeType = mimeType.substr(0, mimeType.find(";"));
    }
    fileMimeTypes[filename] = mimeType;
    return mimeType;
  } catch (...) {
    return "";
  }
}

std::string getNamespaceForMimeType(const std::string& mimeType) {
  if (uniqueNamespace || mimeType.find("text") == 0 || mimeType.empty()) {
    if (uniqueNamespace || mimeType.find("text/html") == 0 || mimeType.empty()) {
      return "A";
    } else {
      return "-";
    }
  } else {
    if (mimeType == "application/font-ttf" || 
	mimeType == "application/font-woff" ||
	mimeType == "application/vnd.ms-opentype" ||
	mimeType == "application/vnd.ms-fontobject" ||
	mimeType == "application/javascript" ||
	mimeType == "application/json"
	) {
      return "-";
    } else {
      return "I";
    }
  }
}

inline std::string removeLocalTagAndParameters(const std::string &url) {
  std::string retVal = url;
  std::size_t found;

  /* Remove URL arguments */
  found = retVal.find("?");
  if (found != std::string::npos) {
    retVal = retVal.substr(0, found);
  }

  /* Remove local tag */
  found = retVal.find("#");
  if (found != std::string::npos) {
    retVal = retVal.substr(0, found);
  }

  return retVal;
}

std::string computeNewUrl(const std::string &aid, const std::string &url) {
  std::string filename = computeAbsolutePath(aid, url);
  std::string targetMimeType = getMimeTypeForFile(removeLocalTagAndParameters(decodeUrl(filename)));
  std::string originMimeType = getMimeTypeForFile(aid);
  std::string newUrl = "/" + getNamespaceForMimeType(targetMimeType) + "/" + filename;
  std::string baseUrl = "/" + getNamespaceForMimeType(originMimeType) + "/" + aid;
  return computeRelativePath(baseUrl, newUrl);
}