%{
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

extern int yylineno;
void yyerror(const char *s);
int yylex();

extern FILE *yyin;
%}

%union {
    int num;
    char *str;
}

%token <num> NUMBER
%token <str> IDENTIFIER
%token IF ELSE WHILE RETURN PRINT
%token AND OR NOT GE LE EQ NE

%nonassoc '>' '<' GE LE EQ NE
%left OR
%left AND
%left '=' '+' '-'
%left '*' '/' '%'
%right NOT UMINUS

%%

program:
    | program statement
    ;

statement:
    expr ';' semicolons
    | IF '(' expr ')' statement ELSE statement
    | IF '(' expr ')' statement
    | WHILE '(' expr ')' statement
    | RETURN expr ';' semicolons
    | PRINT expr ';' semicolons
    | '{' program '}'
    ;

semicolons:
    /* empty */
    | semicolons ';'
    ;

expr:
    NUMBER
    | IDENTIFIER
    | IDENTIFIER '=' expr
    | expr '+' expr
    | expr '-' expr
    | expr '*' expr
    | expr '/' expr
    | expr '%' expr
    | expr AND expr
    | expr OR expr
    | NOT expr
    | '-' expr %prec UMINUS
    | '+' expr
    | expr '>' expr
    | expr '<' expr
    | expr GE expr
    | expr LE expr
    | expr EQ expr
    | expr NE expr
    | '(' expr ')'
    ;

%%

void yyerror(const char *s) {
    fprintf(stderr, "Error at line %d: %s\n", yylineno, s);
    exit(1);
}

int main(int argc, char *argv[]) {
    if (argc < 2) {
        fprintf(stderr, "Usage: %s <input_file>\n", argv[0]);
        return 1;
    }

    FILE *input = fopen(argv[1], "r");
    if (!input) {
        perror("Error opening file");
        return 1;
    }

    yyin = input;
    yyparse();
    fclose(input);
    
    printf("Parsing completed successfully!\n");
    return 0;
}