package pins25.phase;

import pins25.common.*;

import java.util.Objects;

/**
 * Sintaksni analizator.
 */
public class SynAn implements AutoCloseable {

    /**
     * Leksikalni analizator.
     */
    private final LexAn lexAn;

    /**
     * Ustvari nov sintaksni analizator.
     *
     * @param srcFileName Ime izvorne datoteke.
     */
    public SynAn(final String srcFileName) {
        this.lexAn = new LexAn(srcFileName);
    }

    @Override
    public void close() {
        lexAn.close();
    }

    /**
     * Prevzame leksikalni analizator od leksikalnega analizatorja in preveri, ali
     * je prave vrste.
     *
     * @param symbol Pričakovana vrsta leksikalnega simbola.
     * @return Prevzeti leksikalni simbol.
     */
    private Token check(Token.Symbol symbol) {
        final Token token = lexAn.takeToken();
        if (token.symbol() != symbol)
            throw new Report.Error(token, "Unexpected symbol '" + token.lexeme() + "', expected " + symbol.prettyPrint() + ".");
        return token;
    }

    /**
     * Opravi sintaksno analizo.
     */
    public void parse() {
        parseProgram();

        if (lexAn.peekToken().symbol() != Token.Symbol.EOF)
            Report.warning(lexAn.peekToken(),
                    "Unexpected text '" + lexAn.peekToken().lexeme() + "...' at the end of the program.");
    }

    private void parseProgram() {
        System.out.println("program -> definition restdefs");
        parseDefinition();
        parseRestDefinitions();
    }

    private void parseRestDefinitions() {
        if (lexAn.peekToken().symbol() != Token.Symbol.EOF) {
            System.out.println("restdefs -> definition restdefs");
            parseDefinition();
            parseRestDefinitions();
        } else {
            System.out.println("restdefs -> ε");
        }
    }

    private void parseDefinition() {
        Token token = lexAn.peekToken();
        switch (token.symbol()) {
            case FUN:
                System.out.println("definition -> FUN IDENTIFIER LPAREN parameters RPAREN funcassign");
                check(Token.Symbol.FUN);
                check(Token.Symbol.IDENTIFIER);
                check(Token.Symbol.LPAREN);
                parseParameters();
                check(Token.Symbol.RPAREN);
                parseFunctionAssignment();
                break;

            case VAR:
                System.out.println("definition -> VAR IDENTIFIER ASSIGN initializers");
                check(Token.Symbol.VAR);
                check(Token.Symbol.IDENTIFIER);
                check(Token.Symbol.ASSIGN);
                parseInitializers();
                break;

            default:
                throw new Report.Error(token, "Unexpected symbol '" + token.lexeme() + "', expected FUN or VAR.");
        }
    }

    private void parseFunctionAssignment() {
        Token token = lexAn.peekToken();
        if (token.symbol() == Token.Symbol.ASSIGN) {
            System.out.println("funcassign -> ASSIGN statements");
            check(Token.Symbol.ASSIGN);
            parseStatements();
        } else {
            System.out.println("funcassign -> ε");
        }
    }

    private void parseParameters() {
        Token token = lexAn.peekToken();
        if (token.symbol() == Token.Symbol.IDENTIFIER) {
            System.out.println("parameters -> IDENTIFIER restparams");
            check(Token.Symbol.IDENTIFIER);
            parseRestParameters();
        } else {
            System.out.println("parameters -> ε");
        }
    }

    private void parseRestParameters() {
        Token token = lexAn.peekToken();
        if (token.symbol() == Token.Symbol.COMMA) {
            System.out.println("restparams -> COMMA IDENTIFIER restparams");
            check(Token.Symbol.COMMA);
            check(Token.Symbol.IDENTIFIER);
            parseRestParameters();
        } else {
            System.out.println("restparams -> ε");
        }
    }

    private void parseStatements() {
        System.out.println("statements -> statement reststmts");
        parseStatement();
        parseRestStatements();
    }

    private void parseExpressionAssign() {
        if (lexAn.peekToken().symbol() == Token.Symbol.ASSIGN) {
            System.out.println("exprassign -> ASSIGN expression");
            check(Token.Symbol.ASSIGN);
            parseExpression();
        } else {
            System.out.println("exprassign -> ε");
        }
    }

    private void parseElseStatement() {
        if (lexAn.peekToken().symbol() == Token.Symbol.ELSE) {
            System.out.println("elsestmt -> ELSE statements");
            check(Token.Symbol.ELSE);
            parseStatements();
        } else {
            System.out.println("elsestmt -> ε");
        }
    }

    private void parseRestStatements() {
        if (lexAn.peekToken().symbol() == Token.Symbol.COMMA) {
            System.out.println("reststmts -> COMMA statement reststmts");
            check(Token.Symbol.COMMA);
            parseStatement();
            parseRestStatements();
        } else {
            System.out.println("reststmts -> ε");
        }
    }

    private void parseStatement() {
        Token token = lexAn.peekToken();
        switch (token.symbol()) {
            case IF:
                System.out.println("statement -> if expression then statements elsestmt end");
                check(Token.Symbol.IF);
                parseExpression();
                check(Token.Symbol.THEN);
                parseStatements();
                parseElseStatement();
                check(Token.Symbol.END);
                break;

            case WHILE:
                System.out.println("statement -> while expression do statements end");
                check(Token.Symbol.WHILE);
                parseExpression();
                check(Token.Symbol.DO);
                parseStatements();
                check(Token.Symbol.END);
                break;

            case LET:
                System.out.println("statement -> let definition reststmtdefs in statements end");
                check(Token.Symbol.LET);
                parseDefinition();
                parseRestStatementDefinitions();
                check(Token.Symbol.IN);
                parseStatements();
                check(Token.Symbol.END);
                break;

            default:
                System.out.println("statement -> expression exprassign");
                parseExpression();
                parseExpressionAssign();
        }
    }

    private void parseRestStatementDefinitions() {
        switch (lexAn.peekToken().symbol()) {
            case IN:
                System.out.println("reststmtdefs -> ε");
                break;

            case FUN:
            case VAR:
                System.out.println("reststmtdefs -> definition reststmtdefs");
                parseDefinition();
                parseRestStatementDefinitions();
                break;
        }
    }

    private void parseInitializers() {
        switch (lexAn.peekToken().symbol()) {
            case INTCONST:
            case CHARCONST:
            case STRINGCONST:
                System.out.println("initializers -> initializer restinits");
                parseInitializer();
                parseRestInitializers();
                break;

            default:
                System.out.println("initializers -> ε");
                break;
        }
    }

    private void parseInitializer() {
        Token token = lexAn.peekToken();
        switch (token.symbol()) {
            case INTCONST:
                System.out.println("initializer -> INTCONST intconstmult");
                check(Token.Symbol.INTCONST);
                parseIntegerConstantMultiplier();
                break;

            case CHARCONST:
                System.out.println("initializer -> CHARCONST");
                check(Token.Symbol.CHARCONST);
                break;

            case STRINGCONST:
                System.out.println("initializer -> STRINGCONST");
                check(Token.Symbol.STRINGCONST);
                break;

            default:
                throw new Report.Error(token, "Unexpected symbol '" + token.lexeme() + "', expected integer, character or string constant.");
        }
    }

    private void parseRestInitializers() {
        Token token = lexAn.peekToken();
        if (token.symbol() == Token.Symbol.COMMA) {
            System.out.println("restinits -> COMMA initializer restinits");
            check(Token.Symbol.COMMA);
            parseInitializer();
            parseRestInitializers();
        } else {
            System.out.println("restinits -> ε");
        }
    }

    private void parseIntegerConstantMultiplier() {
        Token token = lexAn.peekToken();
        if (token.symbol() == Token.Symbol.MUL) {
            System.out.println("intconstmult -> MUL const");
            check(Token.Symbol.MUL);
            parseConstant();
        } else {
            System.out.println("intconstmult -> ε");
        }
    }

    private void parseConstant() {
        Token token = lexAn.peekToken();
        switch (token.symbol()) {
            case INTCONST:
                System.out.println("const -> INTCONST");
                check(Token.Symbol.INTCONST);
                break;

            case CHARCONST:
                System.out.println("const -> CHARCONST");
                check(Token.Symbol.CHARCONST);
                break;

            case STRINGCONST:
                System.out.println("const -> STRINGCONST");
                check(Token.Symbol.STRINGCONST);
                break;

            default:
                throw new Report.Error(token, "Unexpected symbol '" + token.lexeme() + "', expected integer, character or string constant.");
        }
    }


    private void parseExpression() {
        System.out.println("expression -> conjexpr restdisj");
        parseConjunctionExpression();
        parseRestDisjunctions();
    }

    private void parseRestDisjunctions() {
        if (lexAn.peekToken().symbol() == Token.Symbol.OR) {
            System.out.println("restdisj -> OR conjexpr restdisj");
            check(Token.Symbol.OR);
            parseConjunctionExpression();
            parseRestDisjunctions();
        }
    }

    private void parseConjunctionExpression() {
        System.out.println("conjexpr -> cmpexpr restconj");
        parseComparisonExpression();
        parseRestConjunctionExpressions();
    }

    private void parseRestConjunctionExpressions() {
        if (lexAn.peekToken().symbol() == Token.Symbol.AND) {
            System.out.println("restconj -> AND cmpexpr restconj");
            check(Token.Symbol.AND);
            parseComparisonExpression();
            parseRestConjunctionExpressions();
        } else {
            System.out.println("restconj -> ε");
        }
    }

    private void parseComparisonExpression() {
        System.out.println("cmpexpr -> addexpr restcmp");
        parseAdditionExpression();
        parseRestComparisons();
    }

    private void parseRestComparisons() {
        Token token = lexAn.peekToken();
        switch (token.symbol()) {
            case EQU:
            case NEQ:
            case LTH:
            case GTH:
            case LEQ:
            case GEQ:
                System.out.printf("restcmp -> %s addexpr\n", token.symbol());
                check(token.symbol());
                parseAdditionExpression();
                break;

            default:
                System.out.println("restcmp -> ε");
                break;
        }
    }

    private void parseAdditionExpression() {
        System.out.println("addexpr -> multexpr restadd");
        parseMultiplicationExpression();
        parseRestAdditions();
    }

    private void parseRestAdditions() {
        Token token = lexAn.peekToken();
        switch (token.symbol()) {
            case ADD:
            case SUB:
                System.out.printf("restadd -> %s multexpr restadd\n", token.symbol());
                check(token.symbol());
                parseMultiplicationExpression();
                parseRestAdditions();
                break;

            default:
                System.out.println("restadd -> ε");
                break;
        }
    }

    private void parseMultiplicationExpression() {
        System.out.println("multexpr -> prefixexpr restmult");
        parsePrefixExpression();
        parseRestMultiplicationExpressions();
    }

    private void parseRestMultiplicationExpressions() {
        Token token = lexAn.peekToken();
        switch (token.symbol()) {
            case MUL:
            case DIV:
            case MOD:
                System.out.printf("restmult -> %s prefixexpr restmult\n", token.symbol());
                check(token.symbol());
                parsePrefixExpression();
                parseRestMultiplicationExpressions();
                break;

            default:
                System.out.println("restmult -> ε");
                break;
        }
    }

    private void parsePrefixExpression() {
        Token token = lexAn.peekToken();
        switch (token.symbol()) {
            case ADD:
            case SUB:
            case NOT:
            case PTR:
                System.out.printf("prefixexpr -> %s prefixexpr\n", token.symbol());
                check(token.symbol());
                parsePrefixExpression();
                break;

            default:
                System.out.println("prefixexpr -> postfixexpr");
                parsePostfixExpression();
                break;
        }
    }

    private void parsePostfixExpression() {
        System.out.println("postfixexpr -> primary postfixop");
        parsePrimary();
        parsePostfixOperator();
    }

    private void parsePostfixOperator() {
        if (lexAn.peekToken().symbol() == Token.Symbol.PTR) {
            System.out.println("postfixop -> PTR postfixop");
            check(Token.Symbol.PTR);
            parsePostfixOperator();
        } else {
            System.out.println("postfixop -> ε");
        }
    }

    private void parsePrimary() {
        Token token = lexAn.peekToken();
        switch (token.symbol()) {
            case IDENTIFIER:
                System.out.println("primary -> IDENTIFIER exprargs");
                check(Token.Symbol.IDENTIFIER);
                parseExpressionArguments();
                break;

            case LPAREN:
                System.out.println("primary -> LPAREN expression RPAREN");
                check(Token.Symbol.LPAREN);
                parseExpression();
                check(Token.Symbol.RPAREN);
                break;

            case INTCONST:
            case CHARCONST:
            case STRINGCONST:
                System.out.println("primary -> const");
                parseConstant();
                break;

            default:
                throw new Report.Error(token, "Unexpected symbol '" + token.lexeme() + "', expected identifier, constant or '('.");
        }
    }

    private void parseExpressionArguments() {
        if (lexAn.peekToken().symbol() == Token.Symbol.LPAREN) {
            System.out.println("exprargs -> LPAREN arguments RPAREN");
            check(Token.Symbol.LPAREN);
            parseArguments();
            check(Token.Symbol.RPAREN);
        } else {
            System.out.println("exprargs -> ε");
        }
    }

    private void parseArguments() {
        Token token = lexAn.peekToken();
        if (token.symbol() == Token.Symbol.RPAREN) {
            System.out.println("arguments -> ε");
        } else {
            System.out.println("arguments -> expression restargs");
            parseExpression();
            parseRestArguments();
        }
    }

    private void parseRestArguments() {
        if (lexAn.peekToken().symbol() == Token.Symbol.COMMA) {
            System.out.println("restargs -> COMMA restargs");
            check(Token.Symbol.COMMA);
            parseExpression();
            parseRestArguments();
        } else {
            System.out.println("restargs -> ε");
        }
    }


    // --- ZAGON ---

    /**
     * Zagon sintaksnega analizatorja kot samostojnega programa.
     *
     * @param cmdLineArgs Argumenti v ukazni vrstici.
     */
    public static void main(final String[] cmdLineArgs) {
        System.out.println("This is PINS'25 compiler (syntax analysis):");

        try {
            if (cmdLineArgs.length == 0)
                throw new Report.Error("No source file specified in the command line.");
            if (cmdLineArgs.length > 1)
                Report.warning("Unused arguments in the command line.");

            try (SynAn synAn = new SynAn(cmdLineArgs[0])) {
                synAn.parse();
            }

            // Upajmo, da kdaj pridemo to te tocke.
            // A zavedajmo se sledecega:
            // 1. Prevod je zaradi napak v programu lahko napacen :-o
            // 2. Izvorni program se zdalec ni tisto, kar je programer hotel, da bi bil ;-)
            Report.info("Done.");
        } catch (Report.Error error) {
            // Izpis opisa napake.
            System.err.println(error.getMessage());
            System.exit(1);
        }
    }

}