/*
Popup Plus plugin for Miranda IM

Copyright	© 2002 Luca Santarelli,
© 2004-2007 Victor Pavlychko
© 2010 MPK
© 2010 Merlin_de

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 2
of the License, or (at your option) 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., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
*/

#include "headers.h"

static inline bool myisspace(char ch)
{
	return (ch >= 0) && (ch <= 32);
}

int Formula::eval_neq(TCHAR *&s, Args *args, bool *vars) const
{
	int left = eval_sum(s, args, vars);
	while (*s)
	{
		if (myisspace(*s))
		{
			++s;
		}
		else
			if (*s == '<')
			{
				// this is needed due to side effects caused by min() macro...
				int tmp = eval_sum(++s, args, vars);
				left = min(left, tmp);
			}
			else
				if (*s == '>')
				{
					// this is needed due to side effects caused by max() macro...
					int tmp = eval_sum(++s, args, vars);
					left = max(left, tmp);
				}
				else
				{
					break;
				}
	}
	return left;
}

int Formula::eval_sum(TCHAR *&s, Args *args, bool *vars) const
{
	int left = eval_mul(s, args, vars);
	while (*s)
	{
		if (myisspace(*s))
		{
			++s;
		}
		else
			if (*s == '+')
			{
				left += eval_mul(++s, args, vars);
			}
			else
				if (*s == '-')
				{
					left -= eval_mul(++s, args, vars);
				}
				else
				{
					break;
				}
	}
	return left;
}

int Formula::eval_mul(TCHAR *&s, Args *args, bool *vars) const
{
	int left = eval_atom(s, args, vars);
	while (*s)
	{
		if (myisspace(*s))
		{
			++s;
		}
		else
			if (*s == '*')
			{
				left *= eval_atom(++s, args, vars);
			}
			else
				if (*s == '/')
				{
					if (int right = eval_atom(++s, args, vars))
						left /= right;
				}
				else
					if (*s == '%')
					{
						if (int right = eval_atom(++s, args, vars))
							left %= right;
					}
					else
					{
						break;
					}
	}
	return left;
}

int Formula::eval_atom(TCHAR *&s, Args *args, bool *vars) const
{
	while (*s)
	{
		if (myisspace(*s))
		{
			++s;
		}
		else
			if (*s == '(')
			{
				int res = eval_neq(++s, args, vars);
				if (*s == ')')
					++s;
				return res;
			}
			else
				if ((*s == '+') || (*s == '-'))
				{
					int sign = 1;
					if (*s == '-')
						sign = -1;
					return sign * eval_neq(++s, args, vars);
				}
				else
					if (*s == '!')
					{
						return !eval_neq(++s, args, vars);
					}
					else
						if ((*s >= '0') && (*s <= '9'))
						{
							int res = 0;
							while ((*s >= '0') && (*s <= '9'))
								res = res * 10 + *s++ - '0';
							return res;
						}
						else
						{
							if (!args)
								return 0;
							char buf[1024];
							char *bufptr = buf;
							while (((*s >= '0') && (*s <= '9')) || ((*s >= 'a') && (*s <= 'z')) || ((*s >= 'A') && (*s <= 'A')) || (*s == '_') || (*s == '.'))
								*bufptr++ = *s++;
							*bufptr = 0;
							int res = args->get(buf);
							if (vars) *vars = true;
							return res;
						}
	}
	return 0;
}

int Formula::eval(Args *args, bool *vars) const
{
	if (vars) *vars = false;
	TCHAR *s = m_str;
	int res = eval_neq(s, args, vars);
	return res;
}