//: C26:CGImap.h
// From Thinking in C++, 2nd Edition
// Available at http://www.BruceEckel.com
// (c) Bruce Eckel 1999
// Copyright notice in Copyright.txt
// Tools for extracting and decoding data from 
// from CGI GETs and POSTs.
#include <string>
#include <vector>
#include <iostream>
using namespace std;

class CGIpair : public pair<string, string> {
public:
  CGIpair() {}
  CGIpair(string name, string value) {
    first = decodeURLString(name);
    second = decodeURLString(value);
  }
  // Automatic type conversion for boolean test:
  operator bool() const {
    return (first.length() != 0);
  } 
private:  
  static string decodeURLString(string URLstr) {
    const int len = URLstr.length();
    string result;
    for(int i = 0; i < len; i++) {
      if(URLstr[i] == '+')
        result += ' ';
      else if(URLstr[i] == '%') {
        result +=
          translateHex(URLstr[i + 1]) * 16 +
          translateHex(URLstr[i + 2]);
        i += 2; // Move past hex code
      } else // An ordinary character
        result += URLstr[i];
    }
    return result;
  }
  // Translate a single hex character; used by
  // decodeURLString():
  static char translateHex(char hex) {
    if(hex >= 'A')
      return (hex & 0xdf) - 'A' + 10;
    else
      return hex - '0';
  }
};

// Parses any CGI query and turns it into an
// STL vector of CGIpair which has an associative
// lookup operator[] like a map. A vector is used
// instead of a map because it keeps the original
// ordering of the fields in the Web page form.
class CGImap : public vector<CGIpair> {
  string gq;
  int index;
  // Prevent assignment and copy-construction:
  void operator=(CGImap&);
  CGImap(CGImap&);
public:
  CGImap(string query): index(0), gq(query){
    CGIpair p;
    while((p = nextPair()) != 0)
      push_back(p); 
  }
  // Look something up, as if it were a map:
  string operator[](const string& key) {
    iterator i = begin();
    while(i != end()) {
      if((*i).first == key)
        return (*i).second;
      i++;
    }
    return string(); // Empty string == not found
  }
  void dump(ostream& o, string nl = "<br>") {
    for(iterator i = begin(); i != end(); i++) {
      o << (*i).first << " = "
        << (*i).second << nl;
    }
  }
private:
  // Produces name-value pairs from the query 
  // string. Returns an empty Pair when there's 
  // no more query string left:
  CGIpair nextPair() {
    if(gq.length() == 0)
      return CGIpair(); // Error, return empty
    if(gq.find('=') == -1)
      return CGIpair(); // Error, return empty
    string name = gq.substr(0, gq.find('='));
    gq = gq.substr(gq.find('=') + 1);
    string value = gq.substr(0, gq.find('&'));
    gq = gq.substr(gq.find('&') + 1);
    return CGIpair(name, value);
  }
};

// Helper class for getting POST data:
class Post : public string {
public: 
  Post() {
    // For a CGI "POST," the server puts the
    // length of the content string in the 
    // environment variable CONTENT_LENGTH:
    char* clen = getenv("CONTENT_LENGTH");
    if(clen == 0) {
      cout << "Zero CONTENT_LENGTH, Make sure "
        "this is a POST and not a GET" << endl;
      return;
    }
    int len = atoi(clen);
    char* s = new char[len];
    cin.read(s, len); // Get the data
    append(s, len); // Add it to this string
    delete []s;
  }
}; ///:~