using Microsoft.VisualStudio.TestTools.UnitTesting;
using System;
using System.IO;
using System.Runtime.InteropServices;
using Quik.Stb;

namespace Quik.StbImage.Tests
{
    [TestClass]
    public class LoadImage
    {
        [TestMethod("Set Global Options")]
        public void SetGlobals()
        {
            Quik.Stb.StbImage.FlipVerticallyOnLoad = true;
            Quik.Stb.StbImage.UnpremultiplyOnLoad = true;
        }

        private StbiStreamWrapper PrepareImage(string path, out stbi_io_callbacks cb)
        {
            Stream? str = GetType().Assembly.GetManifestResourceStream(path);
            Assert.IsNotNull(str, $"Could not find test image resource {path}.");

            StbiStreamWrapper wrapper = new StbiStreamWrapper(str);
            wrapper.CreateCallbacks(out cb);
            return wrapper;
        }

        [TestMethod("Load a PNG")]
        public unsafe void LoadPng()
        {
            // TODO: Fill these up!
            const int TEST_CHANNELS = 0;
            const int TEST_WIDTH    = 0;
            const int TEST_HEIGHT   = 0;

            int x, y, numChannels;
            using StbiStreamWrapper str = PrepareImage("Quik.StbImage.Tests.res.test.png", out stbi_io_callbacks cb);
            byte *image = Stbi.load_from_callbacks(&cb, null, &x, &y, &numChannels, (int)StbiEnum.STBI_default);

            if (image == null)
            {
                IntPtr reasonPtr = (IntPtr)Stbi.failure_reason();
                string? reason = Marshal.PtrToStringUTF8((IntPtr)reasonPtr);
                Assert.Fail("Could not load image: {0}.", reason ?? "None specified. (stbi_failure_reason() is null)");
            }

            Assert.AreEqual(TEST_CHANNELS, numChannels, "Channel count does not match.");
            Assert.AreEqual(TEST_WIDTH, x, "Width does not match.");
            Assert.AreEqual(TEST_HEIGHT, y, "Height does not match.");

            Stbi.image_free(image);
        }
    }
}