/*
 * provide names and student id numbers here
 */

package regex;

import dk.brics.automaton.RegExp;
import dk.brics.automaton.RunAutomaton;

public class RegexTest {

    private final RunAutomaton r;

    public RegexTest(String regex) {
        System.out.println("regular expression = " + regex);
        r = new RunAutomaton(new RegExp(regex).toAutomaton());
    }

    public long dfaMatch(String input, int index) {
        long start = System.nanoTime();
        int length = r.run(input, index);
        long end = System.nanoTime();

        if (length == -1) {
            System.out.println("No match found!");
        } else {
            String s = input.substring(index, index + length);
            System.out.println("Found: " + s);
        }

        return end - start;
    }

    void runTest(String input, int index) {
        System.out.println("input string = " + input);
        System.out.println("index = " + index);

        long dfaMatchTime = dfaMatch(input, index);
        System.out.println("dfaMatchTime " + dfaMatchTime);
    }

    private void check(String input, boolean expectOk) {
        boolean accepted = r.run(input);
        System.out.println("Testing input: " + input);
        if (expectOk && !accepted || !expectOk && accepted) {
            throw new RuntimeException("Unexpected result for " + input);
        }
    }

    void assertOk(String input) {
        check(input, true);
    }

    void assertFail(String input) {
        check(input, false);
    }

    static void checkId() {
        RegexTest reId = new RegexTest("[a-z][a-z0-9]*");
        reId.assertOk("id");
        reId.assertOk("d0d");
        reId.assertFail("Id");
        reId.assertFail("0");
        reId.assertFail("0d");
        reId.assertFail("aD");
        System.out.println();
    }

    static void checkNAT() {
        RegexTest reNAT = new RegexTest("[0]|[1-9][0-9]*");
        reNAT.assertOk("2");
        reNAT.assertOk("14451");
        reNAT.assertFail("Id");
        reNAT.assertFail("-145711");
        reNAT.assertFail("01");
        System.out.println();
    }

    static void checkFLOAT() {
        String UnsignedInt = "([0]|([1-9][0-9]*))";
        String SignedInt = "[\\+\\-]?" + UnsignedInt;
        String UnsignedReal = "(" + UnsignedInt + "\\." + "[0-9]+" + "([eE]" + SignedInt + ")?" + ")";

        UnsignedReal += "|(" + UnsignedInt + "[eE]" + SignedInt + ")";

        String Number = UnsignedInt + "|" + UnsignedReal;

        RegexTest reFLOAT = new RegexTest(Number);
        reFLOAT.assertOk("3.14e-7");
        reFLOAT.assertFail("3.14e-07");
        reFLOAT.assertOk("1");
        reFLOAT.assertOk("0.1");
        reFLOAT.assertOk("3e4");
        reFLOAT.assertFail("00");
        reFLOAT.assertFail("01s");
        reFLOAT.assertFail("Id");
        reFLOAT.assertFail("-145711");
        reFLOAT.assertFail("04.1");
        System.out.println();

    }

    static void checkString() {
        // String           ::= (UnescapedChar | "\" EscapedChar)*
        // UnescapedChar    ::= Char - ["] = "\"
        //                      (* All Unicode chars but quote and backslash *)
        // EscapedChar      ::= ["] | "\"
        RegexTest reString = new RegexTest("([^\\\"\\\\]|\\\\[\\\"\\\\])*");
        reString.assertOk("");
        reString.assertOk("abc");
        reString.assertOk("a\\\"b\\\"c");
        reString.assertOk("\\\"");
        reString.assertFail("a\"b\"c");
        reString.assertFail("\"");
        reString.assertFail("\\");
        reString.assertFail("\\x");
        reString.assertFail("\\\\\"");
        System.out.println();
    }

    public static void main(String[] args) {
        checkId();
        checkNAT();
        checkFLOAT();
        checkString();
        System.out.println("Passed.");
    }
}