#ifndef _BASIC_H_
#define _BASIC_H_

#define BASIC_MAX_LINES         1000
#define BASIC_MAX_LINE_LENGTH   256

#define BASIC_OPTP_ADD    1     /* Add */
#define BASIC_OPTP_SUB    2     /* Subtract */
#define BASIC_OPTP_MUL    3     /* Multiply */
#define BASIC_OPTP_DIV    4     /* Divide */
#define BASIC_OPTP_MOD    5     /* Modulus */
#define BASIC_OPTP_EQL    6     /* Equality test */
#define BASIC_OPTP_ASN    7     /* Assignment */
#define BASIC_OPTP_STOR   8     /* Store line for later */

#define BASIC_LVAL_EXPR     0   
#define BASIC_LVAL_VAR      1
#define BASIC_LVAL_CONST    2
#define BASIC_RVAL_EXPR     3
#define BASIC_RVAL_VAR      4
#define BASIC_RVAL_CONST    5
#define BASIC_RVAL_PTR      6   /* Only used internally */

#define BASIC_PARSE_FOUND_LVAL          1
#define BASIC_PARSE_FOUND_RVAL          2
#define BASIC_PARSE_FIRSTTOKEN          4

#define BASIC_ERR_SYNTAX_MULTIPLE_LVALUES 1
#define BASIC_ERR_SYNTAX_TOKEN_LENGTH 2
#define BASIC_ERR_SYNTAX_GENERAL 3
#define BASIC_ERR_SYNTAX_MULTIPLE_RVALUES 4
#define BASIC_ERR_INVALID_ARGUMENTS 5
#define BASIC_ERR_INTERNAL_NULLPOINTER 6
#define BASIC_ERR_INTERNAL_MEMORY 7
#define BASIC_ERR_INTERNAL_UNDEFINED_BEHAVIOR 8
#define BASIC_ERR_INTERNAL_UNIMPLEMENTED 9
#define BASIC_ERR_MATH_DBZ 10

#define BASIC_TOKENIZER_TOKENS "+-/%*="
#define BASIC_TOKENIZER_MAX_LENGTH 512
#define BASIC_VARNAME_MAX_LENGTH 16

struct basic_line {
  int lineno;
  char content[BASIC_MAX_LINE_LENGTH];
  struct basic_line *nextline;
};
typedef struct basic_line basic_line;

struct basic_program {
  char name[128];
  basic_line *first;
};
typedef struct basic_program basic_program;

union basic_value {
  char c;
  int i;
  unsigned int uint;
  /* we don't handle floats yet. need to implement Fcomp, fpushf, fpushd.
   * float f;
   */
  char *str;
  void *ptr;
};
typedef union basic_value basic_value;

struct basic_expr {
  char type;
  char lval_type;
  char rval_type;
  char pad;
  basic_value lval;
  basic_value rval;
};
typedef struct basic_expr basic_expr;

#define BASIC_VARFLAG_INIT 1
#define BASIC_VARFLAG_TINT 2
#define BASIC_VARFLAG_TSTR 4

struct basic_variable {
  char *name;
  char flags;
  basic_value value;
};
typedef struct basic_variable basic_variable;

#define BASIC_CONST_TRUE 1
#define BASIC_CONST_FALSE 0

extern int basic_errno;

void basic_repl(basic_program *program);
basic_expr *basic_parse_expr(char *);

#endif /* _BASIC_H_ */