package stanhebben.zenscript;

import java.io.IOException;
import java.io.Reader;
import java.io.StringReader;
import java.util.HashMap;
import stanhebben.zenscript.parser.CompiledDFA;
import stanhebben.zenscript.parser.NFA;
import stanhebben.zenscript.parser.Token;
import stanhebben.zenscript.parser.TokenStream;

/**
 * A tokener is capable of splitting a single file into tokens. It's intended
 * for use by LL(*) parsers.
 * 
 * @author Stan Hebben
 */
public class ZenTokener extends TokenStream {
	private static final HashMap<String, Integer> KEYWORDS;

	public static final int T_ID = 1;
	public static final int T_INTVALUE = 2;
	public static final int T_FLOATVALUE = 3;
	public static final int T_STRINGVALUE = 4;
	public static final int T_AOPEN = 5;
	public static final int T_ACLOSE = 6;
	public static final int T_SQBROPEN = 7;
	public static final int T_SQBRCLOSE = 8;
	public static final int T_DOT2 = 9;
	public static final int T_DOT = 10;
	public static final int T_COMMA = 11;
	public static final int T_PLUSASSIGN = 12;
	public static final int T_PLUS = 13;
	public static final int T_MINUSASSIGN = 14;
	public static final int T_MINUS = 15;
	public static final int T_MULASSIGN = 16;
	public static final int T_MUL = 17;
	public static final int T_DIVASSIGN = 18;
	public static final int T_DIV = 19;
	public static final int T_MODASSIGN = 20;
	public static final int T_MOD = 21;
	public static final int T_ORASSIGN = 22;
	public static final int T_OR = 23;
	public static final int T_OR2 = 40;
	public static final int T_ANDASSIGN = 24;
	public static final int T_AND2 = 41;
	public static final int T_AND = 25;
	public static final int T_XORASSIGN = 26;
	public static final int T_XOR = 27;
	public static final int T_QUEST = 28;
	public static final int T_COLON = 29;
	public static final int T_BROPEN = 30;
	public static final int T_BRCLOSE = 31;
	public static final int T_TILDEASSIGN = 45;
	public static final int T_TILDE = 32;
	public static final int T_SEMICOLON = 33;
	public static final int T_LTEQ = 34;
	public static final int T_LT = 35;
	public static final int T_GTEQ = 36;
	public static final int T_GT = 37;
	public static final int T_EQ = 38;
	public static final int T_ASSIGN = 39;
	public static final int T_NOTEQ = 42;
	public static final int T_NOT = 43;
	public static final int T_DOLLAR = 44;

	public static final int T_ANY = 99;
	public static final int T_BOOL = 100;
	public static final int T_BYTE = 101;
	public static final int T_SHORT = 102;
	public static final int T_INT = 103;
	public static final int T_LONG = 104;
	public static final int T_FLOAT = 105;
	public static final int T_DOUBLE = 106;
	public static final int T_STRING = 107;
	public static final int T_FUNCTION = 108;
	public static final int T_IN = 109;
	public static final int T_VOID = 110;

	public static final int T_AS = 120;
	public static final int T_VERSION = 121;
	public static final int T_IF = 122;
	public static final int T_ELSE = 123;
	public static final int T_FOR = 124;
	public static final int T_RETURN = 125;
	public static final int T_VAR = 126;
	public static final int T_VAL = 127;

	public static final int T_NULL = 140;
	public static final int T_TRUE = 141;
	public static final int T_FALSE = 142;

	public static final int T_IMPORT = 160;

	private static final String[] REGEXPS = {
			"#[^\n]*[\n\\e]",
			"//[^\n]*[\n\\e]",
			"/\\*[^\\*]*(\\*[^/]*)*\\*/",
			"[ \t\r\n]*",
			"[a-zA-Z_][a-zA-Z_0-9]*",
			"\\-?(0|[1-9][0-9]*)\\.[0-9]+([eE][\\+\\-]?[0-9]+)?",
			"\\-?(0|[1-9][0-9]*)",
			"\"([^\"\\\\]|\\\\([\'\"\\\\/bfnrt]|u[0-9a-fA-F]{4}))*\"",
			"\'([^\'\\\\]|\\\\([\'\"\\\\/bfnrt]|u[0-9a-fA-F]{4}))*\'",
			"\\{",
			"\\}",
			"\\[",
			"\\]",
			"\\.\\.",
			"\\.",
			",",
			"\\+=",
			"\\+",
			"\\-=",
			"\\-",
			"\\*=",
			"\\*",
			"/=",
			"/",
			"%=",
			"%",
			"\\|=",
			"\\|\\|",
			"\\|",
			"&=",
			"&&",
			"&",
			"\\^=",
			"\\^",
			"\\?",
			":",
			"\\(",
			"\\)",
			"~=",
			"~",
			";",
			"<=",
			"<",
			">=",
			">",
			"==",
			"=",
			"!=",
			"!",
			"$"
	};
	private static final int[] FINALS = {
			-1,
			-1,
			-1,
			-1,
			T_ID,
			T_FLOATVALUE,
			T_INTVALUE,
			T_STRINGVALUE,
			T_STRINGVALUE,
			T_AOPEN,
			T_ACLOSE,
			T_SQBROPEN,
			T_SQBRCLOSE,
			T_DOT2,
			T_DOT,
			T_COMMA,
			T_PLUSASSIGN,
			T_PLUS,
			T_MINUSASSIGN,
			T_MINUS,
			T_MULASSIGN,
			T_MUL,
			T_DIVASSIGN,
			T_DIV,
			T_MODASSIGN,
			T_MOD,
			T_ORASSIGN,
			T_OR2,
			T_OR,
			T_ANDASSIGN,
			T_AND2,
			T_AND,
			T_XORASSIGN,
			T_XOR,
			T_QUEST,
			T_COLON,
			T_BROPEN,
			T_BRCLOSE,
			T_TILDEASSIGN,
			T_TILDE,
			T_SEMICOLON,
			T_LTEQ,
			T_LT,
			T_GTEQ,
			T_GT,
			T_EQ,
			T_ASSIGN,
			T_NOTEQ,
			T_NOT,
			T_DOLLAR
	};
	private static final CompiledDFA DFA = new NFA(REGEXPS, FINALS).toDFA().optimize().compile();

	static {
		KEYWORDS = new HashMap<String, Integer>();
		KEYWORDS.put("any", T_ANY);
		KEYWORDS.put("bool", T_BOOL);
		KEYWORDS.put("byte", T_BYTE);
		KEYWORDS.put("short", T_SHORT);
		KEYWORDS.put("int", T_INT);
		KEYWORDS.put("long", T_LONG);
		KEYWORDS.put("float", T_FLOAT);
		KEYWORDS.put("double", T_DOUBLE);
		KEYWORDS.put("string", T_STRING);
		KEYWORDS.put("function", T_FUNCTION);
		KEYWORDS.put("in", T_IN);
		KEYWORDS.put("void", T_VOID);

		KEYWORDS.put("as", T_AS);
		KEYWORDS.put("version", T_VERSION);
		KEYWORDS.put("if", T_IF);
		KEYWORDS.put("else", T_ELSE);
		KEYWORDS.put("for", T_FOR);
		KEYWORDS.put("return", T_RETURN);
		KEYWORDS.put("var", T_VAR);
		KEYWORDS.put("val", T_VAL);

		KEYWORDS.put("null", T_NULL);
		KEYWORDS.put("true", T_TRUE);
		KEYWORDS.put("false", T_FALSE);

		KEYWORDS.put("import", T_IMPORT);
	}

	private final IZenCompileEnvironment environment;

	/**
	 * Constructs a tokener from the given reader.
	 * 
	 * @param contents file reader
	 * @param environment compile environment
	 * @throws IOException if the file could not be read properly
	 */
	public ZenTokener(Reader contents, IZenCompileEnvironment environment) throws IOException {
		super(contents, DFA);

		this.environment = environment;
	}

	/**
	 * Constructs a tokener from the given string.
	 * 
	 * @param contents content string
	 * @param environment compile environment
	 * @throws IOException shouldn't happen
	 */
	public ZenTokener(String contents, IZenCompileEnvironment environment) throws IOException {
		super(new StringReader(contents), DFA);

		this.environment = environment;
	}

	/**
	 * Retrieves the compile environment of this tokener.
	 * 
	 * @return compile environment
	 */
	public IZenCompileEnvironment getEnvironment() {
		return environment;
	}

	// ##################################
	// ### TokenStream implementation ###
	// ##################################

	@Override
	public Token process(Token token) {
		if (token.getType() == T_ID) {
			if (KEYWORDS.containsKey(token.getValue())) {
				return new Token(token.getValue(), KEYWORDS.get(token.getValue()), token.getPosition());
			}
		}
		return token;
	}
}