#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_X,
    TOK_FUNCTION,
    TOK_LEFT_PAREN,
    TOK_RIGHT_PAREN
};

enum math_fn {
    FN_ABS,
    FN_EXP,
    FN_LN,
    FN_LOG,
    FN_SIN,
    FN_COS,
    FN_TAN,
    FN_ASIN,
    FN_ACOS,
    FN_ATAN,
    FN_SINH,
    FN_COSH,
    FN_TANH
};

struct token {
    enum token_type type;
    union token_val {
        double num;
        enum math_fn fn;
    } val;
};

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

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

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);

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

#endif /* LEX_H */