#ifndef LEXER_UTILS_H
#define LEXER_UTILS_H

#include <stddef.h>
#include <sys/types.h>

struct lexer_context
{
    char *end_previous_token;
    ssize_t remaining_chars;

    struct token *previous_token;
    struct token *current_token;
};

/* @brief: frees all fields of ctx and sets ctx to NULL.
 */
void destroy_lexer_context(struct lexer_context **ctx);

enum lexing_mode
{
    LEXER_NORMAL,
    LEXER_QUOTE,
    LEXER_DOUBLE_QUOTE
};

enum token_type
{
    // Special characters
    TOKEN_NULL = 0,
    TOKEN_EOF,
    TOKEN_WORD,
    TOKEN_NEWLINE,

    // WARNING: quote and double quote should never be used inside a token.
    TOKEN_QUOTE,
    TOKEN_DOUBLE_QUOTE,

    TOKEN_GRAVE,
    TOKEN_SEMICOLON,
    TOKEN_COMMENT,
    TOKEN_PIPE,
    TOKEN_AMPERSAND,
    TOKEN_BACKSLASH,
    TOKEN_DOLLAR,
    TOKEN_LEFT_PAREN,
    TOKEN_RIGHT_PAREN,
    TOKEN_LEFT_BRACKET,
    TOKEN_RIGHT_BRACKET,
    TOKEN_LESS,
    TOKEN_GREATER,
    TOKEN_STAR,

    // Keywords
    TOKEN_IF,
    TOKEN_THEN,
    TOKEN_ELSE,
    TOKEN_FI,
    TOKEN_ELIF
};

struct token
{
    enum token_type type;
    char *data;
};

/*
 * @brief: return a newly allocated token, with the corresponding type.
 *         The data contains [size] char, starting from [begin].
 *
 * @return: NULL on error, a token otherwise.
 */
struct token *new_token(char *begin, ssize_t size);

/* @brief: frees the token given in argument
 */
void free_token(struct token **tok);

/*
 * @brief: checks if the stream used for the last token creation is empty.
 *         If it is, it calls stream_read() from IO_backend,
 *         and sets [remaining_chars].
 *         If not, it starts from the end of the last token.
 *         Also trims left blanks before returning.
 *
 * @return: char* stream from which we tokenise.
 */
void stream_init(struct lexer_context *ctx);

/*
 * @brief: drops the current stream and asks IOB for a new one
 */
void get_next_stream(struct lexer_context *ctx);

#endif /* LEXER_UTILS_H */