/* Emacs style mode select   -*- C++ -*- 
 *-----------------------------------------------------------------------------
 *
 *
 *  PrBoom a Doom port merged with LxDoom and LSDLDoom
 *  based on BOOM, a modified and improved DOOM engine
 *  Copyright (C) 1999 by
 *  id Software, Chi Hoang, Lee Killough, Jim Flynn, Rand Phares, Ty Halderman
 *  Copyright (C) 1999-2000 by
 *  Jess Haas, Nicolas Kalkhof, Colin Phipps, Florian Schulze
 *  
 *  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.
 *
 * DESCRIPTION:
 *
 * Parsing.
 *
 * Takes lines of code, or groups of lines and runs them.
 * The main core of FraggleScript
 *
 * By Simon Howard, added to PrBoom by Florian Schulze
 *
 *-----------------------------------------------------------------------------
 */

#include <stdio.h>
#include <stdarg.h>
#include "c_io.h"
#include "doomtype.h"
#include "s_sound.h"
#include "w_wad.h"
#include "z_zone.h"

#include "t_parse.h"
#include "t_prepro.h"
#include "t_spec.h"
#include "t_oper.h"
#include "t_vari.h"
#include "t_func.h"

void parse_script();
void parse_data(char *data, char *end);
svalue_t evaluate_expression(int start, int stop);

mobj_t *trigger_obj;            // object which triggered script

char *tokens[T_MAXTOKENS];
tokentype_t tokentype[T_MAXTOKENS];
int num_tokens = 0;
int script_debug = false;

script_t *current_script;       // the current script
svalue_t nullvar = { svt_int,  {0} };      // null var for empty return
int killscript;         // when set to true, stop the script quickly
section_t *prev_section;       // the section from the previous statement

/************ Divide into tokens **************/

char *linestart;        // start of line
char *rover;            // current point reached in script

        // inline for speed
#define isnum(c) ( ((c)>='0' && (c)<='9') || (c)=='.' )
        // isop: is an 'operator' character, eg '=', '%'
#define isop(c)   !( ( (c)<='Z' && (c)>='A') || ( (c)<='z' && (c)>='a') || \
                     ( (c)<='9' && (c)>='0') || ( (c)=='_') )

        // for simplicity:
#define tt (tokentype[num_tokens-1])
#define tok (tokens[num_tokens-1])

section_t *current_section; // the section (if any) found in parsing the line
int bracetype;              // bracket_open or bracket_close
static void add_char(char c);

// next_token: end this token, go onto the next

static void next_token()
{
  if(tok[0] || tt==string)
    {
      num_tokens++;
      tokens[num_tokens-1] = tokens[num_tokens-2]
	+ strlen(tokens[num_tokens-2]) + 1;
      tok[0] = 0;
    }
  
  // get to the next token, ignoring spaces, newlines,
  // useless chars, comments etc
  
  while(1)
    {
      // empty whitespace
      if(*rover && (*rover==' ' || *rover<32))
	{
	  while((*rover==' ' || *rover<32) && *rover) rover++;
	}
      // end-of-script?
      if(!*rover)
	{
	  if(tokens[0][0])
	    {
	      C_Printf("%s %i %i\n", tokens[0],
		       rover-current_script->data, current_script->len);
	      // line contains text, but no semicolon: an error
	      script_error("missing ';'\n");
	    }
	  // empty line, end of command-list
	  return;
	}
      // 11/8 comments moved to new preprocessor
      
      break;  // otherwise
    }

  if(num_tokens>1 && *rover == '(' && tokentype[num_tokens-2] == name)
    tokentype[num_tokens-2] = function;
  
  if(*rover == '{' || *rover == '}')
    {
      if(*rover == '{')
	{
	  bracetype = bracket_open;
	  current_section = find_section_start(rover);
	}
      else            // closing brace
	{
	  bracetype = bracket_close;
	  current_section = find_section_end(rover);
	}
      if(!current_section)
	{
	  script_error("section not found!\n");
	  return;
	}
    }
  else if(*rover == ':')  // label
    {
      // ignore the label : reset
      num_tokens = 1;
      tokens[0][0] = 0; tt = name;
      rover++;        // ignore
    }
  else if(*rover == '\"')
    {
      tt = string;
      if(tokentype[num_tokens-2] == string)
	num_tokens--;   // join strings
      rover++;
    }
  else
    {
      tt = isop(*rover) ? operator :
	isnum(*rover) ? number : name;
    }
}

// return an escape sequence (prefixed by a '\')
// do not use all C escape sequences

static char escape_sequence(char c)
{
  if(c == 'n') return '\n';
  if(c == '\\') return '\\';
  if(c == '"') return '"';
  if(c == '?') return '?';
  if(c == 'a') return '\a';         // alert beep
  if(c == 't') return '\t';         //tab
  if(c == 'z') return *FC_TRANS;    // translucent toggle
  
  // font colours
  if(c >= '0' && c <= '9') return 128 + (c-'0');
  
  return c;
}

// add_char: add one character to the current token

static void add_char(char c)
{
  char *out = tok + strlen(tok);
  
  *out++ = c;
  *out = 0;
}

// get_tokens.
// Take a string, break it into tokens.

// individual tokens are stored inside the tokens[] array
// tokentype is also used to hold the type for each token:

//   name: a piece of text which starts with an alphabet letter.
//         probably a variable name. Some are converted into
//         function types later on in find_brackets
//   number: a number. like '12' or '1337'
//   operator: an operator such as '&&' or '+'. All FraggleScript
//             operators are either one character, or two character
//             (if 2 character, 2 of the same char or ending in '=')
//   string: a text string that was enclosed in quote "" marks in
//           the original text
//   unset: shouldn't ever end up being set really.
//   function: a function name (found in second stage parsing)

void get_tokens(char *s)
{
  rover = s;
  num_tokens = 1;
  tokens[0][0] = 0; tt = name;
  
  current_section = NULL;   // default to no section found
  
  next_token();
  linestart = rover;      // save the start
  
  if(*rover)
    while(1)
      {
	if(killscript) return;
	if(current_section)
	  {
	    // a { or } section brace has been found
	    break;        // stop parsing now
	  }
	else if(tt != string)
	  {
	    if(*rover == ';') break;     // check for end of command ';'
	  }
	
	switch(tt)
	  {
	  case unset:
	  case string:
	    while(*rover != '\"')     // dedicated loop for speed
	      {
		if(*rover == '\\')       // escape sequences
		  {
		    rover++;
		    add_char(escape_sequence(*rover));
		  }
		else
		  add_char(*rover);
		rover++;
	      }
	    rover++;
	    next_token();       // end of this token
	    continue;
	    
	  case operator:
	    // all 2-character operators either end in '=' or
	    // are 2 of the same character
	    // do not allow 2-characters for brackets '(' ')'
	    // which are still being considered as operators
	    
	    // operators are only 2-char max, do not need
	    // a seperate loop
	    
	    if((*tok && *rover != '=' && *rover!=*tok) ||
	       *tok == '(' || *tok == ')')
	      {
		// end of operator
		next_token();
		continue;
	      }
	    add_char(*rover);
	    break;
	    
	  case number:

	    // add while number chars are read

	    while(isnum(*rover))       // dedicated loop
	      add_char(*rover++);
	    next_token();
	    continue;
	    
	  case name:

	    // add the chars

	    while(!isop(*rover))        // dedicated loop
	      add_char(*rover++);
	    next_token();
	    continue;

	  default:
      break;
	  }
	rover++;
      }
  
  // check for empty last token

  if(!tok[0])
    {
      num_tokens = num_tokens - 1;
    }
  
  rover++;
}


void print_tokens()	// DEBUG
{
  int i;
  for(i=0; i<num_tokens; i++)
    {
      C_Printf("\n'%s' \t\t --", tokens[i]);
      switch(tokentype[i])
	{
	case string: C_Printf("string");        break;
	case operator: C_Printf("operator");    break;
	case name: C_Printf("name");            break;
	case number: C_Printf("number");        break;
	case unset : C_Printf("duh");           break;
	case function: C_Printf("function name"); break;
	}
    }
  C_Printf("\n");
  if(current_section)
    C_Printf("current section: offset %i\n",
	     (int)(current_section->start-current_script->data) );
}


// run_script
//
// the function called by t_script.c

void run_script(script_t *script)
{
  // set current script
  current_script = script;
  
  // start at the beginning of the script
  rover = current_script->data;
  
  parse_script(); // run it
}

void continue_script(script_t *script, char *continue_point)
{
  current_script = script;
  
  // continue from place specified
  rover = continue_point;
  
  parse_script(); // run 
}

void parse_script()
{
  // check for valid rover
  if(rover < current_script->data || 
     rover > current_script->data+current_script->len)
    {
      script_error("parse_script: trying to continue from point"
		   "outside script!\n");
      return;
    }
  
  trigger_obj = current_script->trigger;  // set trigger
  
  parse_data(current_script->data,
	     current_script->data+current_script->len);
  
  // dont clear global vars!
  if(current_script->scriptnum != -1)
    clear_variables(current_script);        // free variables
}

void parse_data(char *data, char *end)
{
  char *token_alloc;      // allocated memory for tokens
  
  killscript = false;     // dont kill the script straight away
  
  // allocate space for the tokens
  token_alloc = Z_Malloc(current_script->len + T_MAXTOKENS, PU_STATIC, 0);
  
  prev_section = NULL;  // clear it
  
  while(*rover)   // go through the script executing each statement
    {
      // past end of script?
      if(rover > end)
	break;
      
      // reset the tokens before getting the next line
      tokens[0] = token_alloc;
      
      prev_section = current_section; // store from prev. statement
      
      // get the line and tokens
      get_tokens(rover);
      
      if(killscript) break;
      
      if(!num_tokens)
	{
	  if(current_section)       // no tokens but a brace
	    {
	      // possible } at end of loop:
	      // refer to spec.c
	      spec_brace();
	    }
	  
	  continue;  // continue to next statement
	}
      
      if(script_debug) print_tokens();   // debug
      run_statement();         // run the statement
    }
  Z_Free(token_alloc);
}

void run_statement()
{
  // decide what to do with it
  
  // NB this stuff is a bit hardcoded:
  //    it could be nicer really but i'm
  //    aiming for speed
  
  // if() and while() will be mistaken for functions
  // during token processing
  if(tokentype[0] == function)
    {
      if(!strcmp(tokens[0], "if"))
	{
	  spec_if();
	  return;
	}
      else if(!strcmp(tokens[0], "while"))
	{
	  spec_while();
	  return;
	}
      else if(!strcmp(tokens[0], "for"))
	{
	  spec_for();
	  return;
	}
    }
  else if(tokentype[0] == name)
    {
      // NB: goto is a function so is not here

      // if a variable declaration, return now
      if(spec_variable()) return;
    }

  // just a plain expression
  evaluate_expression(0, num_tokens-1);
}

/***************** Evaluating Expressions ************************/

        // find a token, ignoring things in brackets        
int find_operator(int start, int stop, char *value)
{
  int i;
  int bracketlevel = 0;
  
  for(i=start; i<=stop; i++)
    {
      // only interested in operators
      if(tokentype[i] != operator) continue;
      
      // use bracketlevel to check the number of brackets
      // which we are inside
      bracketlevel += tokens[i][0]=='(' ? 1 :
	tokens[i][0]==')' ? -1 : 0;
      
      // only check when we are not in brackets
      if(!bracketlevel && !strcmp(value, tokens[i]))
	return i;
    }
  
  return -1;
}

        // go through tokens the same as find_operator, but backwards
int find_operator_backwards(int start, int stop, char *value)
{
  int i;
  int bracketlevel = 0;
  
  for(i=stop; i>=start; i--)      // check backwards
    {
      // operators only

      if(tokentype[i] != operator) continue;
      
      // use bracketlevel to check the number of brackets
      // which we are inside
      
      bracketlevel += tokens[i][0]=='(' ? -1 :
	tokens[i][0]==')' ? 1 : 0;
      
      // only check when we are not in brackets
      // if we find what we want, return it

      if(!bracketlevel && !strcmp(value, tokens[i]))
	return i;
    }
  
  return -1;
}

// simple_evaluate is used once evalute_expression gets to the level
// where it is evaluating just one token

// converts number tokens into svalue_ts and returns
// the same with string tokens
// name tokens are considered to be variables and
// attempts are made to find the value of that variable
// command tokens are executed (does not return a svalue_t)

extern svalue_t nullvar;

static svalue_t simple_evaluate(int n)
{
  svalue_t returnvar;
  svariable_t *var;
  
  switch(tokentype[n])
    {
    case string:
      returnvar.type = svt_string;
      returnvar.value.s = tokens[n];
      return returnvar;

    case number:
      if(strchr(tokens[n], '.'))
	{
	  returnvar.type = svt_fixed;
	  returnvar.value.f = (int)(atof(tokens[n]) * FRACUNIT);
	}
      else
	{
	  returnvar.type = svt_int;
	  returnvar.value.i = atoi(tokens[n]);
	}
      return returnvar;

    case name:
      var = find_variable(tokens[n]);
      if(!var)
	{
	  script_error("unknown variable '%s'\n", tokens[n]);
	  return nullvar;
	}
      else
	return getvariablevalue(var);

    default: return nullvar;
    }
}

// pointless_brackets checks to see if there are brackets surrounding
// an expression. eg. "(2+4)" is the same as just "2+4"
//
// because of the recursive nature of evaluate_expression, this function is
// neccesary as evaluating expressions such as "2*(2+4)" will inevitably
// lead to evaluating "(2+4)"

static void pointless_brackets(int *start, int *stop)
{
  int bracket_level, i;
  
  // check that the start and end are brackets
  
  while(tokens[*start][0] == '(' && tokens[*stop][0] == ')')
    {
      
      bracket_level = 0;
      
      // confirm there are pointless brackets..
      // if they are, bracket_level will only get to 0
      // at the last token
      // check up to <*stop rather than <=*stop to ignore
      // the last token
      
      for(i = *start; i<*stop; i++)
	{
	  if(tokentype[i] != operator) continue; // ops only
	  bracket_level += (tokens[i][0] == '(');
	  bracket_level -= (tokens[i][0] == ')');
	  if(bracket_level == 0) return; // stop if braces stop before end
	}
      
      // move both brackets in
      
      *start = *start + 1;
      *stop = *stop - 1;
    }
}

// evaluate_expresion is the basic function used to evaluate
// a FraggleScript expression.
// start and stop denote the tokens which are to be evaluated.
//
// works by recursion: it finds operators in the expression
// (checking for each in turn), then splits the expression into
// 2 parts, left and right of the operator found.
// The handler function for that particular operator is then
// called, which in turn calls evaluate_expression again to
// evaluate each side. When it reaches the level of being asked
// to evaluate just 1 token, it calls simple_evaluate

svalue_t evaluate_expression(int start, int stop)
{
  int i, n;
  
  if(killscript) return nullvar;  // killing the script
  
  // possible pointless brackets
  if(tokentype[start] == operator && tokentype[stop] == operator)
    pointless_brackets(&start, &stop);
  
  if(start == stop)       // only 1 thing to evaluate
    {
      return simple_evaluate(start);
    }
  
  // go through each operator in order of precedence
  
  for(i=0; i<num_operators; i++)
    {
      // check backwards for the token. it has to be
      // done backwards for left-to-right reading: eg so
      // 5-3-2 is (5-3)-2 not 5-(3-2)

      if( -1 != (n = (operators[i].direction==forward ?
		find_operator_backwards : find_operator)
		 (start, stop, operators[i].string)) )
	{
	  // C_Printf("operator %s, %i-%i-%i\n", operators[count].string, start, n, stop);

	  // call the operator function and evaluate this chunk of tokens

	  return operators[i].handler(start, n, stop);
	}
    }
  
  if(tokentype[start] == function)
    return evaluate_function(start, stop);
  
  // error ?
  {        
    char tempstr[128]="";
    
    for(i=start; i<=stop; i++)
      sprintf(tempstr,"%s %s", tempstr, tokens[i]);
    script_error("couldnt evaluate expression: %s\n",tempstr);
    return nullvar;
  }
  
}

void script_error(char *s, ...)
{
  va_list args;
  char tempstr[128];
  
  va_start(args, s);
  
  if(killscript) return;  //already killing script
  
  if(current_script->scriptnum == -1)
    C_Printf("global");
  else
    C_Printf("%i", current_script->scriptnum);
  
  // find the line number
  
  if(rover >= current_script->data &&
     rover <= current_script->data+current_script->len)
    {
      int linenum = 1;
      char *temp;
      for(temp = current_script->data; temp<linestart; temp++)
	if(*temp == '\n') linenum++;    // count EOLs
      C_Printf(", %i", linenum);
    }
  
  // print the error
  vsprintf(tempstr, s, args);
  C_Printf(": %s", tempstr);
  
  // make a noise
  S_StartSound(NULL, sfx_pldeth);
  
  killscript = true;
}

//
// sf: string value of an svalue_t
//

char *stringvalue(svalue_t v)
{
  static char buffer[128];
  
  switch(v.type)
    {
      case svt_string:
	return v.value.s;

      case svt_mobj:
	return "map object";

      case svt_fixed:
	{
	  double val = ((float)v.value.f) / FRACUNIT;
	  sprintf(buffer, "%g", val);
	  return buffer;
	}
      
      case svt_int:
      default:
	sprintf(buffer, "%i", v.value.i);
	return buffer;	
    }
}