/************************************
 * C02 Statement Compiling Routines *
 ************************************/

#include <stdio.h>
#include <stdlib.h>
#include <ctype.h>
#include <string.h>
#include <errno.h>

#include "common.h"
#include "asm.h"
#include "parse.h"
#include "label.h"
#include "vars.h"
#include "cond.h"
#include "expr.h"
#include "stmnt.h"

/* Begin Program Block */
void bgnblk(char blkchr) {
  DEBUG("Beginning program block\n", 0)
  if (blkchr) {
    expect(blkchr);
    inblck = TRUE;
  }
  else
    inblck = look('{');
  DEBUG("Set INBLCK to %d\n", inblck)
  setblk(inblck);
}

/* End Program Block                        *
 * Args: blkflg: End of Multiline Block     */
void endblk(int blkflg) {
  int lbtype;
  DEBUG("Ending program block with flag %d\n", blkflg)
  expect('}'); //Block End Character
  DEBUG("Found inblck set to %d\n", inblck)
  if (inblck != blkflg) ERROR("Encountered '}' without matching '{'\n", 0, EXIT_FAILURE)
  lbtype = poplbl();
  if (lbtype == LTDO) pdowhl(); //Parse While at End of Do Loop
}

/* Parse Shortcut If */
void prssif(char trmntr) {
  newlbl(cndlbl);         //Create Label for "if FALSE" expression
  prscnd(')', FALSE);     //Parse Condition
  expect('?');          
  prsxpr(':');            //Parse "if TRUE" expression
  newlbl(tmplbl);         //Create End of Expression Label
  asmlin("JMP", tmplbl);  //Jump over "if FALSE" expression
  setlbl(cndlbl);         //Emit "if FALSE" label
  prsxpr(trmntr);         //Parse "if FALSE" expression
  setlbl(tmplbl);         //Emit End of Expression Label
}

/* Process Array Index */
void prcidx(int idxtyp, char *name, char *index)
{
    if (strlen(index)) { 
      if (idxtyp == LITERAL) {
        strcat(name, "+");
        strcat(name, index);
      }
      else {
        asmlin("LDX", index);
        strcat(name,",X");
      }
    }
}

/* Process Assignment */
void prcasn(char trmntr) {
  expect('=');
  if (look('(')) prssif(trmntr); //Parse Shortcut If 
  else           prsxpr(trmntr); //Parse Expression
  DEBUG("Processing X assignment variable '%s'\n", xsnvar)
  if (xsnvar[0]) {
    if (strlen(xsnidx)) { //Process X variable Index
      asmlin("PHA", "");  //Save Accumulator
      asmlin("TXA", "");  //Transfer Return Value to Accumulator
	  prcidx(xsnivt, xsnvar, xsnidx); //Process Index
	  asmlin("STA", xsnvar); //Store Return Value
      asmlin("PLA", ""); //Restore Accumulator
    }
	else asmlin("STX", xsnvar); //Store Return Value
    xsnvar[0] = 0;
  }
  DEBUG("Processing Y assignment variable '%s'\n", ysnvar)
  if (ysnvar[0]) {
    if (strlen(ysnidx)) prcidx(ysnivt, ysnvar, ysnidx); //Process Index
    asmlin("STY", ysnvar); //Store Return Value
    ysnvar[0] = 0;
  }
  DEBUG("Checking if '%s' is a register\n", asnvar)
  if      (strcmp(asnvar, "X")==0) asmlin("TAX", "");
  else if (strcmp(asnvar, "Y")==0) asmlin("TAY", "");
  else if (strcmp(asnvar, "A")==0) return;
  DEBUG("Processing assignment variable '%s'\n", asnvar)
  if (strlen(asnidx)) prcidx(asnivt, asnvar, asnidx); //Process Index 
  asmlin("STA", asnvar); //Store Return Value
}

/* Parse and Return Array Index and Type */
int getidx(char* idx) {
    prsidx(TRUE);  //Parse Array Index
    if (valtyp == LITERAL) strncpy(idx, word, VARLEN);
	else strncpy(idx, value, VARLEN);
    DEBUG("Parsed index %s\n", idx)
    return valtyp;
}

/* Process Assignment Variable(s) */
void prcvar(char trmntr) {
  chksym(TRUE, word);
  strcpy(asnvar, word);  //save variable to assign to
  if (valtyp == VARIABLE && match('.')) prsmbr(asnvar);
  asntyp = valtyp; //Set Assigned Varable Type
  DEBUG("Set STA variable to %s\n", asnvar)
  if (asntyp == VARIABLE && look(';')) {
    asmlin("STA", asnvar);
    return;
  }
  if (asntyp == ARRAY) asnivt = getidx(asnidx); //Get Array Index and Type
  else asnidx[0] = 0;
  DEBUG("Set STA index to '%s'", asnidx) DETAIL(" and type to %d\n", asnivt)
  if (ispopr()) {
    if (prspst(trmntr, asnvar, asnidx)) expctd("post operator");
	return;
  }
  if (look(',')) {     
    if (asntyp == REGISTER) ERROR("Register %s not allowed in plural assignment\n", asnvar, EXIT_FAILURE)
    prsvar(FALSE); //get variable name
    strcpy(ysnvar, word);
    DEBUG("Set STY variable to %s\n", ysnvar)
    if (valtyp == ARRAY) ysnivt = getidx(ysnidx); //Get Array Index and Type
    else ysnidx[0] = 0;
    DEBUG("Set STY index to '%s'", ysnidx) DETAIL(" and type to %d\n", ysnivt)
    if (look(',')) {
      prsvar(FALSE); //get variable name
      strcpy(xsnvar, word);
      DEBUG("Set STX variable to %s\n", xsnvar)
      //if (valtyp == ARRAY) ERROR("Array element not allowed in third assignment\n", 0, EXIT_FAILURE) 
      if (valtyp == ARRAY) xsnivt = getidx(xsnidx); //Get Array Index and Type
      else xsnidx[0] = 0;
    }
  }
  prcasn(trmntr);
}

/* Parse 'asm' String Parameter */
void pasmst(char trmntr) {
  skpspc(); //Skip Spaces
  if (!match('"')) expctd("string");
  getstr();
  skpspc();
  expect(trmntr);
}

/* Parse and Compile 'asm' statement */
void pasm(void) {
  char opcode[LINELEN];
  expect('(');
  pasmst(',');    
  if (strlen(word)) setlbl(word);
  pasmst(',');
  strcpy(opcode, word);
  pasmst(')');
  expect(';');
  asmlin(opcode, word);
}

/* Parse and Compile an Assignment */
void prsasn(char trmntr) {
  getwrd();               //Get Variable to be Assigned
  prcvar(trmntr);
}

/* parse and compile 'break'/'continue' statement */
void pbrcnt(int lbflag) 
{
  DEBUG("Parsing BREAK/CONTINUE statement\n", 0)
  if (lstlbl(lbflag) < 0) ERROR("Break/continue statement outside of loop\n", 0, EXIT_FAILURE)
  DEBUG("Found Label '%s'\n", tmplbl)
  asmlin("JMP", tmplbl);
  expect(';'); 
}

/* parse and compile 'do' statement */
void pdo(void) {
  DEBUG("Parsing DO statement '%c'\n", nxtchr)
  newlbl(endlbl);         //Create End Label
  pshlbl(LTDWHL, endlbl); //and Push onto Stack
  reqlbl(loplbl);         //Get or Create/Set Loop Label
  pshlbl(LTDO, loplbl);   //Push onto Stack
  bgnblk(FALSE);          //Check For and Begin Block
}

/* parse and compile 'while' after 'do' statement */
void pdowhl(void) {
  DEBUG("Parsing WHILE after DO '%c'\n", nxtchr)
  getwrd();               //Check for While
  if (!wordis("WHILE")) expctd("while statement");
  expect('(');
  strcpy(cndlbl, loplbl); //Set Conditional Label to Loop Label
  prscnd(')', TRUE);      //Parse Conditional Expession
  poplbl();               //Pop While Conditional Label
  setlbl(endlbl);         //and Set Label to Emit on Next Line
  expect(';');            //Check for End of Statement
}


/* parse and compile for statement */
void pfor(void) {
  DEBUG("Parsing FOR statement '%c'\n", nxtchr);
  expect('(');
  prsasn(';');            //Process Initial Assignment     
  newlbl(forlbl);         //Create For Loop Conditional Label
  setlbl(forlbl);         //and Set to Emit on Next Line
  newlbl(endlbl);         //Create End Label
  pshlbl(LTEND, endlbl);  //and Push onto Stack
  newlbl(loplbl);         //Create Loop Label
  pshlbl(LTLOOP, loplbl); //and Push onto Stack
  newlbl(cndlbl);         //Create Conditional Label
  prscnd(';', TRUE);      //Parse Conditional Expession
  asmlin("JMP", endlbl);  //Jump over Increment
  setlbl(loplbl);         //Set to Emit on Next Line
  prsasn(')');            //Parse Increment Assignment
  asmlin("JMP", forlbl);  //Jump to Conditional
  setlbl(cndlbl);         //Emit Label at Start of Loop  
  bgnblk(FALSE);          //Check For and Begin Block
}

/* parse and compile if statement */
void pif(void) {
  DEBUG("Parsing IF statement\n", 0)
  expect('(');
  newlbl(cndlbl);      //Create New Label
  pshlbl(LTIF,cndlbl); //Push Onto Stack
  prscnd(')', FALSE);  //Parse Conditional Expession
  bgnblk(FALSE);       //Check For and Begin Block
}

/* parse and compile else statement */
void pelse(void) {
  DEBUG("Parsing ELSE statement\n", 0)
  strcpy(lbltmp, lblasm);   //Save Line Label
  lblasm[0] = 0;            //and Clear It
  if (toplbl(skplbl) != LTELSE) { //Get Chained ELSE Label or
    newlbl(skplbl);               //Create Skip Label
    pshlbl(LTELSE, skplbl);       //Push Onto Stack
  }
  asmlin("JMP", skplbl);    //Emit Jump over Block Code
  strcpy(lblasm, lbltmp);   //Restore Line Label
  bgnblk(FALSE);            //Check For and Begin Block
}

/* parse and compile if statement */
void pgoto(void) {
  DEBUG("Parsing GOTO statement\n", 0)
  getwrd();
  expect(';');  
  asmlin("JMP", word);
}

/* parse and compile inline statement */
void pinlne(void) {
  DEBUG("Parsing INLINE statement\n", 0)
  do { 
    DEBUG("Parsing inline parameter\n", 0)
    if (look('&')) {
      reqvar(FALSE); //Get Variable Name
      strcpy(word, "<");
      strcat(word, value);
      strcat(word, ", >");
      strcat(word, value);
      asmlin(BYTEOP, word);
    }
    else if (look('"')) {
      value[0] = 0;
      while (!match('"')) {
        CCMNT(nxtchr);
        sprintf(word, "$%hhX,", getnxt());
        strcat(value, word);
      }
      strcat(value,"0");
      CCMNT(nxtchr);
      skpchr(); //Skip Terminating Quote
      asmlin(BYTEOP, value);
    }
    else {
      prslit(0xFF);  //Parse Literal
      sprintf(word, "$%hhX", litval); //not needed?
      asmlin(BYTEOP, value);
    }
  } while (look(','));
  expect(';');
}

/* parse and compile pop statement */
void ppop(void) {
  DEBUG("Parsing POP statement\n", 0)
  do {  
    if (look('*')) term[0]=0; 
    else {
      reqvar(TRUE);
      strcpy(term, value);
      chkidx();
    } 
    asmlin("PLA", "");     //Pop Value off Stack
    if (term[0]) asmlin("STA", term);
  } while (look(','));
  expect(';');  
}

/* parse and compile push statement */
void ppush(void) {
  DEBUG("Parsing PUSH statement\n", 0)
  do { 
    if (!chkadr(1)) {
      prsxpr(0);        //Parse Expression
      asmlin("PHA",""); //Push Result on Stack
    }
  } while (look(','));
  expect(';');
}

/* parse and compile return statement */
void pretrn(void) {
  DEBUG("Parsing RETURN statement\n", 0)
  if (!look(';')) prsxpr(';');
  asmlin("RTS", "");
  lsrtrn = TRUE;  //Set RETURN flag
}

/* parse and compile select statement */
void pslct(void) {
  DEBUG("Parsing SELECT statement\n", 0)
  expect('(');
  prsxpr(')');            //Parse Expression
  newlbl(endlbl);         //Create New Label
  pshlbl(LTSLCT,endlbl);  //Push Onto Stack
  bgnblk('{');            //Require Beginning of Block
  fcase = TRUE;
  strcpy(xstmnt, "CASE"); //Require Next Statement to be CASE
}

/* process end of case block */
void ecase(void) {
  DEBUG("Processing end of CASE block\n", 0)
  if (poplbl(cndlbl) != LTCASE) ERROR("%s not at end of CASE block\n", word, EXIT_FAILURE)
  if (toplbl(endlbl) != LTSLCT) ERROR("Illegal nesting in SELECT statement\n", 0, EXIT_FAILURE)  
  asmlin("JMP", endlbl);  //Emit jump over default case
  setlbl(cndlbl);  //Set entry point label to emit
}

/* parse and compile select statement */
void pcase(void) {
  if (!fcase) ecase();     //Process end of case block
  skplbl[0] = 0;           //Clear Skip Label
  newlbl(cndlbl);          //Create Conditional Label
  pshlbl(LTCASE, cndlbl);  //and Push onto Stack
  while(TRUE) {
    prstrm();              //Parse CASE argument
    if (!fcase || valtyp != LITERAL || litval) 
      asmlin("CMP", term); //Emit Comparison
    if (look(',')) {
      chklbl(skplbl);      //Emit skip to beginning of CASE block
      asmlin("BEQ", skplbl);
      fcase = 0;
	  continue;            //Parse next argument
    }
    bgnblk(':');           //Emit branch to end of CASE block
    asmlin("BNE", cndlbl); 
    break;
  }
  if (skplbl[0]) setlbl(skplbl); //Set CASE block label if defined
  fcase = FALSE;
}

/* parse and compile default statement */
void pdflt(void) {
  expect(':');
  ecase(); //Process end of case block
}

/* parse and compile while statement */
void pwhile(void) {
  DEBUG("Parsing WHILE statement '%c'\n", nxtchr)
  expect('(');
  newlbl(endlbl);          //Create End Label
  pshlbl(LTEND, endlbl);   //and Push onto Stack
  reqlbl(loplbl);          //Get or Create/Set Loop Label
  pshlbl(LTLOOP, loplbl);  //Push onto Stack
  if (!look(')')) {  
    newlbl(cndlbl);          //Create Conditional Skip Label
    prscnd(')', TRUE);       //Parse Conditional Expession
    asmlin("JMP", endlbl);   //Emit Jump to End of Loop
    setlbl(cndlbl);          //and Set Label to Emit on Next Line
  }
  bgnblk(FALSE);           //Check For and Begin Block
}

/* generate unimplemented statement error */
void punimp(void) {
  ERROR("Unimplemented statement '%s' encountered\n", word, EXIT_FAILURE) 
}

/* Parse Function Call as Statement */
void prsfns(void) {
  strcpy(term, word);  //Copy Function Name
  prsfnc(';');            //Parse Function Call
  return;
}

/* parse and compile identifier (variable or function call) */
void prssym(void) {
  DEBUG("Parsing Identifier %s\n", word)
  valtyp = gettyp();
  if (valtyp == FUNCTION) prsfns();  //Parse Statement Function Call
  else prcvar(';'); //Parse Assignment
}

/* parse and compile program statement */
void pstmnt(void) {
  DEBUG("Parsing statement '%s'\n", word)
  if (wordis("DO")) {
    pdo();
    return;
  }
  if (wordis("ELSE")) {
    pelse();
    return;
  }
  if (wordis("FOR")) {
    pfor();
    return;  
  }
  if (wordis("IF")) {
    pif();
    return;
  }
  if (wordis("SWITCH")) {
    ERROR("SWITCH not implemented. Use SELECT.\n", word, EXIT_FAILURE)  
  }
  if (wordis("SELECT")) {
    pslct();
    return;
  }
  if (wordis("CASE")) {
    pcase();
    return;  
  }
  if (wordis("DEFAULT")) {
    pdflt();
    return;  
  }
  if (wordis("WHILE")) {
    pwhile();
    return;  
  }
  if(match(':')) {
    prslbl();  //Parse Label
    return;
  }
  if (wordis("ASM")) pasm();
  else if (wordis("BREAK")) 
    pbrcnt(LFEND);
  else if (wordis("CONTINUE"))
    pbrcnt(LFBGN);
  else if (wordis("GOTO"))
    pgoto();
  else if (wordis("INLINE"))
    pinlne();
  else if (wordis("POP"))
    ppop();
  else if (wordis("PUSH"))
    ppush();
  else if (wordis("RETURN"))
    pretrn();
  else
    prssym();
  if (lblcnt && !inblck) {
    DEBUG("Ending implied block\n", 0)
    if (poplbl() == LTDO)
      pdowhl(); //Parse While at End of Do Loop
  }
}