#ifndef LEX_H
#define LEX_H

#include "error_buffer.h"

#define LEX_DEBUG

enum token_type {
    TOK_EOF,
    TOK_ERROR,

    TOK_NUMBER,
    TOK_PLUS,
    TOK_MINUS,
    TOK_MULTIPLY,
    TOK_DIVIDE,
    TOK_POWER,

    TOK_VARIABLE,
    TOK_FUNCTION,
    
    TOK_LEFT_PAREN,
    TOK_RIGHT_PAREN,
    TOK_COMMA
};

struct token {
    enum token_type type;
    union token_val {
        double num;
        size_t fn_idx;
    } val;
};

struct lexer {
    const char *start;
    const char *prev_p;
    const char *p;
    struct token tok;
    struct error_buffer eb;
    const char *variable_name;
};

void lex_init(struct lexer *lex, const char *str, const char *variable_name);

void lex_next(struct lexer *lex);
struct token *lex_token(struct lexer *lex);

void lex_print_position(const struct lexer *lex, struct error_buffer *eb);

enum error_code lex_get_error(const struct lexer *lex);
const char *lex_get_error_text(const struct lexer *lex);

const char *lex_token_str(enum token_type token);

#ifdef LEX_DEBUG
void lex_debug_print_token(const struct token *tok);
#endif /* LEX_DEBUG */

#endif /* LEX_H */