package model.asn1;

import model.asn1.exceptions.ParseException;
import model.asn1.parsing.BytesReader;
import org.junit.jupiter.api.Test;

import static org.junit.jupiter.api.Assertions.*;

public class ASN1LengthTest {
    @Test
    void testConstructor() {
        assertEquals(0, new ASN1Length(0).getLength());
        assertEquals(1, new ASN1Length(1).getLength());
    }

    @Test
    void testParse() throws Exception { // TODO: Exception
        BytesReader reader = new BytesReader(new Byte[]{0x0});
        assertEquals(0, new ASN1Length(reader).getLength());
        assertEquals(1, reader.getIndex());

        reader = new BytesReader(new Byte[]{0x20});
        assertEquals(0x20, new ASN1Length(reader).getLength());
        assertEquals(1, reader.getIndex());

        reader = new BytesReader(new Byte[]{-127, 0x30});
        assertEquals(0x30, new ASN1Length(reader).getLength());
        assertEquals(2, reader.getIndex());

        reader = new BytesReader(new Byte[]{-126, -22, 0x60});
        assertEquals(60000, new ASN1Length(reader).getLength());
        assertEquals(3, reader.getIndex());

        reader = new BytesReader(new Byte[]{-127, 127});
        assertEquals(127, new ASN1Length(reader).getLength());
        assertEquals(2, reader.getIndex());

        reader = new BytesReader(new Byte[]{-124, 1, 1, 1, 1});
        assertEquals(16843009, new ASN1Length(reader).getLength());
        assertEquals(5, reader.getIndex());

        reader = new BytesReader(new Byte[]{-127, -97});
        assertEquals(159, new ASN1Length(reader).getLength());
        assertEquals(2, reader.getIndex());
    }

    @Test
    void testParseFail() throws ParseException {
        // First byte 0b10000000
        assertThrows(ParseException.class, () ->
                new ASN1Length(new BytesReader(new Byte[]{-128}))
        );

        // First byte 0b11111111
        assertThrows(ParseException.class, () ->
                new ASN1Length(new BytesReader(new Byte[]{-1}))
        );

        // Multibyte, requested 2 bytes but have none.
        assertThrows(ParseException.class, () ->
                new ASN1Length(new BytesReader(new Byte[]{-126}))
        );

        // Multibyte, requested 2 bytes but have one.
        assertThrows(ParseException.class, () ->
                new ASN1Length(new BytesReader(new Byte[]{-126, 0x1}))
        );

        // But this one should work (0b01111111)
        new ASN1Length(new BytesReader(new Byte[]{-127, 127}));

        // Multibyte, too long.
        assertThrows(ParseException.class, () ->
                new ASN1Length(new BytesReader(new Byte[]{-124, -1, -1, -1, -1}))
        );
        // But this one should work, except for it is too large
        new ASN1Length(new BytesReader(new Byte[]{-125, -1, -1, -1}));
    }

    @Test
    void testEncode() {
        // Short form
        assertArrayEquals(new Byte[]{0x0}, new ASN1Length(0).encodeDER());
        assertArrayEquals(new Byte[]{0x1}, new ASN1Length(1).encodeDER());
        assertArrayEquals(new Byte[]{127}, new ASN1Length(127).encodeDER());

        // Long form
        // 0b10000001, 0b10000000
        assertArrayEquals(new Byte[]{-127, -128}, new ASN1Length(128).encodeDER());
        // 0b10000010, 0b11111111, 0b11111111
        assertArrayEquals(new Byte[]{-126, -1, -1}, new ASN1Length(65535).encodeDER());
    }
}