#ifndef BDL_LEXER_H
#define BDL_LEXER_H

#include "string_view.h"

typedef enum TokenType {
    TOKEN_UNKNOWN = 0,

    // Parentheses.
    TOKEN_LPAREN,
    TOKEN_RPAREN,
    TOKEN_LSQUARE,
    TOKEN_RSQUARE,
    TOKEN_LCURLY,
    TOKEN_RCURLY,

    // Primitive types.
    TOKEN_NUMBER,
    TOKEN_SYMBOL,
    TOKEN_STRING,
    TOKEN_NIL,
    TOKEN_TRUE,
    TOKEN_FALSE,

    // Keywords.
    TOKEN_LAMBDA,
    TOKEN_IF,
    TOKEN_DEF,
    TOKEN_SET,
    TOKEN_FUN,
    TOKEN_STRUCT,

    // Arithmetic ops.
    TOKEN_ADD,
    TOKEN_SUB,
    TOKEN_MUL,
    TOKEN_DIV,
    TOKEN_MOD,

    // Boolean operations.
    TOKEN_NOT,
    TOKEN_AND,
    TOKEN_OR,
    TOKEN_EQ,
    TOKEN_LT,
    TOKEN_GT,
    TOKEN_LE,
    TOKEN_GE,

    // Special operators.
    TOKEN_COLON,
    TOKEN_DOT,
    TOKEN_AT,

    // End of file.
    TOKEN_EOF,
} TokenType;

typedef struct Token {
    TokenType type;
    StringView value;
    size_t line;
    size_t col;
} Token;

typedef struct Scanner {
    StringView current;
    size_t line_number;
    size_t col_number;
    size_t offset;
} Scanner;

// Print a token to standard output for debugging purposes.
void print_token(Token tok);

// Same functionality as with StringView, but keeping track of line and column
// numbers.
char scan_next(Scanner *scanner);
char scan_peek(const Scanner *scanner);

// Check if the current scanner still have characters left.
bool scan_has_next(const Scanner *scanner);

// Advance the scanner until we ran out of whitespace.
void skip_whitespace(Scanner *scanner);

// Check if a given character is a delimiter.
bool is_delimiter(char c);

// Extract the token type from the current string.
TokenType find_token_type(const StringView value);

// Generate a list of tokens from the given string.
Token * tokenize(const StringView *sv);

// Display tokens from token list.
void print_tokens(Token *tokens);

#endif // BDL_LEXER_H