#include "tokenizer.h"

static bool streq(const char* a, const char* b) {
	while (*a != 0 && *b != 0) {
		if (*a != *b) return false;
		a++; b++;
	}
	return *a == *b;
}

static const char* ptr;
static t_tokentype current_token = TOKEN_ERROR;
static char identifier[255];
static int value;
static int line = 0;
static int row = 0;
static int current_tokenline = 0;
static int current_tokenrow = 0;

struct t_token_op {
	char* str;
	t_tokentype tokentype;
};

t_token_op tkn_tokens[] = {
	{ "let", TOKEN_LET },
	{ "if", TOKEN_IF },
	{ "then", TOKEN_THEN },
	{ "else", TOKEN_ELSE },
	{ "end", TOKEN_END },
	{ "for", TOKEN_FOR },
	{ "to", TOKEN_TO },
	{ "break", TOKEN_BREAK },
	{ "continue", TOKEN_CONTINUE },
	{ "goto", TOKEN_GOTO },
	{ "gosub", TOKEN_GOSUB },
	{ "return", TOKEN_RETURN },
	{ "rem", TOKEN_REM },
	{ "quit", TOKEN_QUIT },
	{ "and", TOKEN_AND },
	{ "or", TOKEN_OR },
	{ "not", TOKEN_NOT },
	{ "mod", TOKEN_MOD },
	{ "dim", TOKEN_DIM },
	{ "inc", TOKEN_INC },
	{ "dec", TOKEN_DEC },
	{ "strleft", TOKEN_STRLEFT },
	{ "strlen", TOKEN_STRLEN },
	{ "debug", TOKEN_DEBUG },
	{ "chr", TOKEN_CHR },
	{ "str", TOKEN_STR },
	{ "setsprite", TOKEN_SETSPRITE },
	{ "putsprite", TOKEN_PUTSPRITE },
	{ "locate", TOKEN_LOCATE },
	{ "print", TOKEN_PRINT },
	{ "putchar", TOKEN_PUTCHAR },
	{ "setchar", TOKEN_SETCHAR },
	{ "keypressed", TOKEN_KEYPRESSED },
	{ "anykey", TOKEN_ANYKEY },
	{ "updatescr", TOKEN_UPDATESCR },
	{ "color", TOKEN_COLOR },
	{ "border", TOKEN_BORDER },
};

#define CCHR *ptr
#define NEXT if(*ptr==10){line++;row=0;}else{row++;};ptr++

static void tkn_do_next() {
	identifier[0] = 0;
	value = 0;
	char* id = identifier;
	// Ignore whitespace
	while (CCHR != 0 && CCHR != 10 && CCHR <= 32) { NEXT; }
	// If zero, we are at the end of the file
	current_tokenline = line; current_tokenrow = row;
	if (CCHR == 0) { current_token = TOKEN_ENDFILE; return; }
	// if 13, we are at the end of the line
	if (CCHR == 10) { NEXT; current_token = TOKEN_ENDLINE; return; }
	// if 34, grab the string
	if (CCHR == 34) {
		NEXT;
		while (CCHR != 0 && CCHR != 34) { *id = CCHR; id++; NEXT; }
		if (CCHR == 0) { current_token = TOKEN_ERROR; return; }
		*id = 0; NEXT;
		current_token = TOKEN_STRING; return;
	}
	// If digit, grab the number
	if (CCHR >= 48 && CCHR <= 57) {
		do { value = value * 10 + (CCHR - 48); NEXT; } while (CCHR >= 48 && CCHR <= 57);
		current_token = TOKEN_NUMBER; return;
	}
	// if letter, grab the identifier
	if ((CCHR >= 65 && CCHR <= 90) || (CCHR >= 97 && CCHR <= 122)) {
		do { *id = CCHR; id++; NEXT; } while ((CCHR >= 48 && CCHR <= 57) || (CCHR >= 65 && CCHR <= 90) || (CCHR >= 97 && CCHR <= 122) || CCHR == 95);
		*id = 0;
		int i = 0; while (identifier[i] != 0) { if (identifier[i] < 95) { identifier[i] |= 32; };  i++; } // to lowecase
		// if it ends with ':', it's a label
		if (CCHR == ':') { NEXT;  current_token = TOKEN_LABEL; return; }
		// If it matches a keyword, it's a keyword
		for (auto token : tkn_tokens) {
			if (streq(token.str, identifier)) {
				current_token = token.tokentype;
				if (current_token == TOKEN_REM) { while (CCHR != 0 && CCHR != 13) { NEXT; } }
				return;
			}
		}
		// else, it's an identifier
		current_token = TOKEN_IDENTIFIER; return;
	}
	// Check if it's any of the operators
	if (CCHR == '+') { NEXT; current_token = TOKEN_PLUS; return; }
	if (CCHR == '-') { NEXT; current_token = TOKEN_MINUS; return; }
	if (CCHR == '*') { NEXT; current_token = TOKEN_ASTERISC; return; }
	if (CCHR == '/') { NEXT; current_token = TOKEN_SLASH; return; }
	if (CCHR == '(') { NEXT; current_token = TOKEN_LPAR; return; }
	if (CCHR == ')') { NEXT; current_token = TOKEN_RPAR; return; }
	if (CCHR == ':') { NEXT; current_token = TOKEN_COLON; return; }
	if (CCHR == ',') { NEXT; current_token = TOKEN_COMMA; return; }
	if (CCHR == '<') { NEXT; if (CCHR == '=') { NEXT; current_token = TOKEN_LEQ; } else { current_token = TOKEN_LT; } return; }
	if (CCHR == '>') { NEXT; if (CCHR == '=') { NEXT; current_token = TOKEN_GEQ; } else { current_token = TOKEN_GT; } return; }
	if (CCHR == '=') { NEXT; current_token = TOKEN_EQ; return; }
	if (CCHR == '%') { NEXT; current_token = TOKEN_MOD; return; }
	if (CCHR == 39)  { NEXT; current_token = TOKEN_REM; while (CCHR != 0 && CCHR != 10) { NEXT; };  return; }

	// if no match, it's an error
	current_token = TOKEN_ERROR; return;
}

void tkn_init(const char* buffer) {
	ptr = buffer;
	current_token = TOKEN_ERROR;
	value = line = row = current_tokenline = current_tokenrow = 0;
	identifier[0] = 0;
}

void tkn_next() { do { tkn_do_next(); } while (current_token == TOKEN_REM || current_token == TOKEN_ENDLINE); }

t_tokentype tkn_get_token() { return current_token; }
char* tkn_get_string() { return identifier; }
int tkn_get_value() { return value; }
int tkn_get_line() { return current_tokenline; }
int tkn_get_row() { return current_tokenrow; }