#include "scan.h"

using namespace std;

vector<Token> scan(string s) {
	size_t pt = 0;
	int line = 1;
	vector<Token> tokens;
	auto skipSpace = [&]() {
		while (pt < s.size() && isspace(s[pt])) {
			if (s[pt] == '\n') {
				line++;
			}
			pt++;
		}
	};
	for (skipSpace(); pt < s.size(); skipSpace()) {
		TokenType type;
		string t;
		if (s[pt] == ',') {
			type = TokenType::COMMA, pt++;
		} else if (s[pt] == ';') {
			type = TokenType::SEMI, pt++;
		} else if (s[pt] == '{') {
			type = TokenType::LB, pt++;
		} else if (s[pt] == '}') {
			type = TokenType::RB, pt++;
		} else if (s[pt] == '(') {
			type = TokenType::LP, pt++;
		} else if (s[pt] == ')') {
			type = TokenType::RP, pt++;
		} else if (s[pt] == '<') {
			type = TokenType::LT, pt++;
		} else if (s[pt] == '>') {
			type = TokenType::RT, pt++;
		} else if (s[pt] == '=') {
			type = TokenType::ASSIGN, pt++;
		} else if (s[pt] == '.') {
			type = TokenType::DOT, pt++;
		} else if (s[pt] == ':') {
			if (pt + 1 < s.size() && s[pt + 1] == ':') {
				type = TokenType::SCOPE, pt += 2;
			} else {
				type = TokenType::COLON, pt++;
			}
		} else if (s[pt] == '-') {
			if (pt + 1 < s.size() && s[pt + 1] == '>') {
				type = TokenType::IMPLY, pt += 2;
			} else {
				printf("error on line %d", line), exit(1);
			}
		} else if (isalpha(s[pt]) || s[pt] == '_') {
			size_t r = pt + 1;
			while (r < s.size() && (isalpha(s[r]) || s[r] == '_' || isdigit(s[r]))) {
				r++;
			}
			t = s.substr(pt, r - pt);
			if (t == "struct") {
				type = TokenType::STRUCT, t.clear();
			} else if (t == "Fn") {
				type = TokenType::FN, t.clear();
			} else if (t == "return") {
				type = TokenType::RETURN, t.clear();
			} else if (t == "typeof") {
				type = TokenType::TYPEOF, t.clear();
			} else if (t == "public") {
				type = TokenType::PUBLIC, t.clear();
			} else {
				type = TokenType::ID;
			}
			pt = r;
		} else {
			printf("error on line %d", line), exit(1);
		}
		tokens.push_back({line, type, t});
	}
	return tokens;
}