/**
 * \file environment.C
 * This file is part of LyX, the document processor.
 * Licence details can be found in the file COPYING.
 *
 * \author Angus Leeming
 * \author João Luis M. Assirati
 * \author Lars Gullik Bjønnes
 *
 * Full author contact details are available in file CREDITS.
 */

#include <config.h>

#include "support/environment.h"
#include "support/os.h"

#include <boost/tokenizer.hpp>

#include <cstdlib>
#include <map>
#include <sstream>

using std::string;
using std::vector;


namespace lyx {
namespace support {

string const getEnv(string const & envname)
{
	// f.ex. what about error checking?
	char const * const ch = getenv(envname.c_str());
	string const envstr = !ch ? "" : ch;
	return envstr;
}


vector<string> const getEnvPath(string const & name)
{
	typedef boost::char_separator<char> Separator;
	typedef boost::tokenizer<Separator> Tokenizer;

	string const env_var = getEnv(name);
	Separator const separator(string(1, os::path_separator()).c_str());
	Tokenizer const tokens(env_var, separator);
	Tokenizer::const_iterator it = tokens.begin();
	Tokenizer::const_iterator const end = tokens.end();

	std::vector<string> vars;
	for (; it != end; ++it)
		vars.push_back(os::internal_path(*it));

	return vars;
}


bool setEnv(string const & name, string const & value)
{
	// CHECK Look at and fix this.
	// f.ex. what about error checking?

#if defined (HAVE_SETENV)
	int const retval = ::setenv(name.c_str(), value.c_str(), true);

#elif defined (HAVE_PUTENV)
	static std::map<string, char *> varmap;

	string envstr = name + '=' + value;
	char * newptr = new char[envstr.size() + 1];
	envstr.copy(newptr, envstr.length());
	newptr[envstr.length()] = '\0';
	int const retval = ::putenv(newptr);

	char * oldptr = varmap[name];
	if (oldptr)
		delete oldptr;
	varmap[name] = newptr;

#else
#error No environment-setting function has been defined.
#endif
	return retval == 0;
}


void setEnvPath(string const & name, vector<string> const & env)
{
	char const separator(os::path_separator());
	std::ostringstream ss;
	vector<string>::const_iterator const begin = env.begin();
	vector<string>::const_iterator const end = env.end();
	vector<string>::const_iterator it = begin;
	for (; it != end; ++it) {
		if (it != begin)
			ss << separator;
#if defined(__CYGWIN__) || defined(__CYGWIN32__)
		// On cygwin, os::external_path returns either posix or
		// pseudo-win style paths, but here we always need posix style.
		// This fixes bug 2344.
		ss << os::internal_path(*it);
#else
		ss << os::external_path(*it);
#endif
	}
	setEnv(name, ss.str());
}


void prependEnvPath(string const & name, string const & prefix)
{
	vector<string> env_var = getEnvPath(name);

	typedef boost::char_separator<char> Separator;
	typedef boost::tokenizer<Separator> Tokenizer;

	Separator const separator(string(1, os::path_separator()).c_str());

	// Prepend each new element to the list, removing identical elements
	// that occur later in the list.
	Tokenizer const tokens(prefix, separator);
	vector<string> reversed_tokens(tokens.begin(), tokens.end());

	typedef vector<string>::const_reverse_iterator token_iterator;
	token_iterator it = reversed_tokens.rbegin();
	token_iterator const end = reversed_tokens.rend();
	for (; it != end; ++it) {
		vector<string>::iterator remove_it =
			std::remove(env_var.begin(), env_var.end(), *it);
		env_var.erase(remove_it, env_var.end());
		env_var.insert(env_var.begin(), *it);
	}

	setEnvPath(name, env_var);
}

} // namespace support
} // namespace lyx
