using Unity.SharpZipLib.Checksum;
using NUnit.Framework;
using System;
using System.Diagnostics;
namespace Unity.SharpZipLib.Tests.Checksum
{
    [TestFixture]
    [Category("Checksum")]
    internal class ChecksumTests
    {
        private readonly
                // Represents ASCII string of "123456789"
                byte[] check = { 49, 50, 51, 52, 53, 54, 55, 56, 57 };
        // Represents string "123456789123456789123456789123456789"
        private readonly byte[] longCheck = {
            49, 50, 51, 52, 53, 54, 55, 56, 57,
            49, 50, 51, 52, 53, 54, 55, 56, 57,
            49, 50, 51, 52, 53, 54, 55, 56, 57,
            49, 50, 51, 52, 53, 54, 55, 56, 57
        };
        [Test]
        public void Adler_32()
        {
            var underTestAdler32 = new Adler32();
            Assert.AreEqual(0x00000001, underTestAdler32.Value);
            underTestAdler32.Update(check);
            Assert.AreEqual(0x091E01DE, underTestAdler32.Value);
            underTestAdler32.Reset();
            Assert.AreEqual(0x00000001, underTestAdler32.Value);
            exceptionTesting(underTestAdler32);
        }
        const long BufferSize = 256 * 1024 * 1024;
        [Test]
        public void Adler_32_Performance()
        {
            var rand = new Random(1);
            var buffer = new byte[BufferSize];
            rand.NextBytes(buffer);
            var adler = new Adler32();
            Assert.AreEqual(0x00000001, adler.Value);
            var sw = new Stopwatch();
            sw.Start();
            adler.Update(buffer);
            sw.Stop();
            Console.WriteLine($"Adler32 Hashing of 256 MiB: {sw.Elapsed.TotalSeconds:f4} second(s)");
            adler.Update(check);
            Assert.AreEqual(0xD4897DA3, adler.Value);
            exceptionTesting(adler);
        }
        [Test]
        public void CRC_32_BZip2()
        {
            var underTestBZip2Crc = new BZip2Crc();
            Assert.AreEqual(0x0, underTestBZip2Crc.Value);
            underTestBZip2Crc.Update(check);
            Assert.AreEqual(0xFC891918, underTestBZip2Crc.Value);
            underTestBZip2Crc.Reset();
            Assert.AreEqual(0x0, underTestBZip2Crc.Value);
            exceptionTesting(underTestBZip2Crc);
        }
        [Test]
        public void CRC_32_BZip2_Long()
        {
            var underTestCrc32 = new BZip2Crc();
            underTestCrc32.Update(longCheck);
            Assert.AreEqual(0xEE53D2B2, underTestCrc32.Value);
        }
        [Test]
        public void CRC_32_BZip2_Unaligned()
        {
            // Extract "456" and CRC
            var underTestCrc32 = new BZip2Crc();
            underTestCrc32.Update(new ArraySegment<byte>(check, 3, 3));
            Assert.AreEqual(0x001D0511, underTestCrc32.Value);
        }
        [Test]
        public void CRC_32_BZip2_Long_Unaligned()
        {
            // Extract "789123456789123456" and CRC
            var underTestCrc32 = new BZip2Crc();
            underTestCrc32.Update(new ArraySegment<byte>(longCheck, 15, 18));
            Assert.AreEqual(0x025846E0, underTestCrc32.Value);
        }
        [Test]
        public void CRC_32()
        {
            var underTestCrc32 = new Crc32();
            Assert.AreEqual(0x0, underTestCrc32.Value);
            underTestCrc32.Update(check);
            Assert.AreEqual(0xCBF43926, underTestCrc32.Value);
            underTestCrc32.Reset();
            Assert.AreEqual(0x0, underTestCrc32.Value);
            exceptionTesting(underTestCrc32);
        }
        [Test]
        public void CRC_32_Long()
        {
            var underTestCrc32 = new Crc32();
            underTestCrc32.Update(longCheck);
            Assert.AreEqual(0x3E29169C, underTestCrc32.Value);
        }
        [Test]
        public void CRC_32_Unaligned()
        {
            // Extract "456" and CRC
            var underTestCrc32 = new Crc32();
            underTestCrc32.Update(new ArraySegment<byte>(check, 3, 3));
            Assert.AreEqual(0xB1A8C371, underTestCrc32.Value);
        }
        [Test]
        public void CRC_32_Long_Unaligned()
        {
            // Extract "789123456789123456" and CRC
            var underTestCrc32 = new Crc32();
            underTestCrc32.Update(new ArraySegment<byte>(longCheck, 15, 18));
            Assert.AreEqual(0x31CA9A2E, underTestCrc32.Value);
        }
        private void exceptionTesting(IChecksum crcUnderTest)
        {
            bool exception = false;
            try
            {
                crcUnderTest.Update(null);
            }
            catch (ArgumentNullException)
            {
                exception = true;
            }
            Assert.IsTrue(exception, "Passing a null buffer should cause an ArgumentNullException");
            // reset exception
            exception = false;
            try
            {
                crcUnderTest.Update(new ArraySegment<byte>(null, 0, 0));
            }
            catch (ArgumentNullException)
            {
                exception = true;
            }
            Assert.IsTrue(exception, "Passing a null buffer should cause an ArgumentNullException");
            // reset exception
            exception = false;
            try
            {
                crcUnderTest.Update(new ArraySegment<byte>(check, -1, 9));
            }
            catch (ArgumentOutOfRangeException)
            {
                exception = true;
            }
            Assert.IsTrue(exception, "Passing a negative offset should cause an ArgumentOutOfRangeException");
            // reset exception
            exception = false;
            try
            {
                crcUnderTest.Update(new ArraySegment<byte>(check, 10, 0));
            }
            catch (ArgumentException)
            {
                exception = true;
            }
            Assert.IsTrue(exception, "Passing an offset greater than buffer.Length should cause an ArgumentException");
            // reset exception
            exception = false;
            try
            {
                crcUnderTest.Update(new ArraySegment<byte>(check, 0, -1));
            }
            catch (ArgumentOutOfRangeException)
            {
                exception = true;
            }
            Assert.IsTrue(exception, "Passing a negative count should cause an ArgumentOutOfRangeException");
            // reset exception
            exception = false;
            try
            {
                crcUnderTest.Update(new ArraySegment<byte>(check, 0, 10));
            }
            catch (ArgumentException)
            {
                exception = true;
            }
            Assert.IsTrue(exception, "Passing a count + offset greater than buffer.Length should cause an ArgumentException");
        }
    }
}