// Copyright (c) .NET Foundation. All rights reserved.
// Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.

using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Reflection;
using System.Runtime.InteropServices;
using System.Text;
using Microsoft.AspNetCore.Blazor.Components;
using Microsoft.AspNetCore.Blazor.Razor;
using Microsoft.AspNetCore.Blazor.Rendering;
using Microsoft.AspNetCore.Blazor.RenderTree;
using Microsoft.AspNetCore.Blazor.Test.Helpers;
using Microsoft.AspNetCore.Razor.Language;
using Microsoft.CodeAnalysis;
using Microsoft.CodeAnalysis.CSharp;
using Xunit;
using Xunit.Sdk;

namespace Microsoft.AspNetCore.Blazor.Build.Test
{
    public class RazorIntegrationTestBase
    {
        internal const string ArbitraryWindowsPath = "x:\\dir\\subdir\\Test";
        internal const string ArbitraryMacLinuxPath = "/dir/subdir/Test";

        private RazorProjectEngine _projectEngine;

        public RazorIntegrationTestBase()
        {
            Configuration = BlazorExtensionInitializer.DefaultConfiguration;
            FileSystem = new VirtualRazorProjectFileSystem();
            WorkingDirectory = RuntimeInformation.IsOSPlatform(OSPlatform.Windows) ? ArbitraryWindowsPath : ArbitraryMacLinuxPath;

            DefaultBaseNamespace = "Test"; // Matches the default working directory
            DefaultFileName = "TestComponent.cshtml";
        }

        internal virtual RazorConfiguration Configuration { get; }

        internal virtual string DefaultBaseNamespace { get; }

        internal virtual string DefaultFileName { get; }
        
        internal virtual VirtualRazorProjectFileSystem FileSystem { get; }

        internal virtual RazorProjectEngine ProjectEngine
        {
            get
            {
                if (_projectEngine == null)
                {
                    _projectEngine = CreateProjectEngine();
                }

                return _projectEngine;
            }
        }

        internal virtual string WorkingDirectory { get; }

        internal RazorProjectEngine CreateProjectEngine()
        {
            return RazorProjectEngine.Create(Configuration, FileSystem, b =>
            {
                BlazorExtensionInitializer.Register(b);
            });
        }

        protected CompileToCSharpResult CompileToCSharp(string cshtmlContent)
        {
            return CompileToCSharp(WorkingDirectory, DefaultFileName, cshtmlContent);
        }

        protected CompileToCSharpResult CompileToCSharp(string cshtmlRelativePath, string cshtmlContent)
        {
            return CompileToCSharp(WorkingDirectory, cshtmlRelativePath, cshtmlContent);
        }

        protected CompileToCSharpResult CompileToCSharp(string cshtmlRootPath, string cshtmlRelativePath, string cshtmlContent)
        {
            // FilePaths in Razor are **always** are of the form '/a/b/c.cshtml'
            var filePath = cshtmlRelativePath.Replace('\\', '/');
            if (!filePath.StartsWith('/'))
            {
                filePath = '/' + filePath;
            }

            var projectItem = new VirtualProjectItem(
                cshtmlRootPath,
                filePath,
                Path.Combine(cshtmlRootPath, cshtmlRelativePath),
                cshtmlRelativePath,
                Encoding.UTF8.GetBytes(cshtmlContent));

            var codeDocument = ProjectEngine.Process(projectItem);
            return new CompileToCSharpResult
            {
                CodeDocument = codeDocument,
                Code = codeDocument.GetCSharpDocument().GeneratedCode,
                Diagnostics = codeDocument.GetCSharpDocument().Diagnostics,
            };
        }

        protected CompileToAssemblyResult CompileToAssembly(string cshtmlRelativePath, string cshtmlContent)
        {
            return CompileToAssembly(WorkingDirectory, cshtmlRelativePath, cshtmlContent);
        }

        protected CompileToAssemblyResult CompileToAssembly(string cshtmlRootDirectory, string cshtmlRelativePath, string cshtmlContent)
        {
            var cSharpResult = CompileToCSharp(cshtmlRootDirectory, cshtmlRelativePath, cshtmlContent);
            return CompileToAssembly(cSharpResult);
        }

        protected CompileToAssemblyResult CompileToAssembly(CompileToCSharpResult cSharpResult)
        {
            if (cSharpResult.Diagnostics.Any())
            {
                var diagnosticsLog = string.Join(Environment.NewLine, cSharpResult.Diagnostics.Select(d => d.ToString()).ToArray());
                throw new InvalidOperationException($"Aborting compilation to assembly because RazorCompiler returned nonempty diagnostics: {diagnosticsLog}");
            }

            var syntaxTrees = new[]
            {
                CSharpSyntaxTree.ParseText(cSharpResult.Code)
            };
            var referenceAssembliesContainingTypes = new[]
            {
                typeof(System.Runtime.AssemblyTargetedPatchBandAttribute), // System.Runtime
                typeof(BlazorComponent),
                typeof(RazorIntegrationTestBase), // Reference this assembly, so that we can refer to test component types
            };
            var references = referenceAssembliesContainingTypes
                .SelectMany(type => type.Assembly.GetReferencedAssemblies().Concat(new[] { type.Assembly.GetName() }))
                .Distinct()
                .Select(Assembly.Load)
                .Select(assembly => MetadataReference.CreateFromFile(assembly.Location))
                .ToList();
            var options = new CSharpCompilationOptions(OutputKind.DynamicallyLinkedLibrary);
            var assemblyName = "TestAssembly" + Guid.NewGuid().ToString("N");
            var compilation = CSharpCompilation.Create(assemblyName,
                syntaxTrees,
                references,
                options);

            using (var peStream = new MemoryStream())
            {
                compilation.Emit(peStream);

                var diagnostics = compilation
                    .GetDiagnostics()
                    .Where(d => d.Severity != DiagnosticSeverity.Hidden);
                return new CompileToAssemblyResult
                {
                    Diagnostics = diagnostics,
                    Assembly = diagnostics.Any() ? null : Assembly.Load(peStream.ToArray())
                };
            }
        }

        protected IComponent CompileToComponent(string cshtmlSource)
        {
            var assemblyResult = CompileToAssembly(WorkingDirectory, DefaultFileName, cshtmlSource);

            var componentFullTypeName = $"{DefaultBaseNamespace}.{Path.GetFileNameWithoutExtension(DefaultFileName)}";
            return CompileToComponent(assemblyResult, componentFullTypeName);
        }

        protected IComponent CompileToComponent(CompileToCSharpResult cSharpResult, string fullTypeName)
        {
            return CompileToComponent(CompileToAssembly(cSharpResult), fullTypeName);
        }

        protected IComponent CompileToComponent(CompileToAssemblyResult assemblyResult, string fullTypeName)
        {
            Assert.Empty(assemblyResult.Diagnostics);

            var componentType = assemblyResult.Assembly.GetType(fullTypeName);
            if (componentType == null)
            {
                throw new XunitException(
                    $"Failed to find component type '{fullTypeName}'. Found types:" + Environment.NewLine +
                    string.Join(Environment.NewLine, assemblyResult.Assembly.ExportedTypes.Select(t => t.FullName)));
            }

            return (IComponent)Activator.CreateInstance(componentType);
        }

        protected static string FullTypeName<T>() => typeof(T).FullName.Replace('+', '.');

        protected RenderTreeFrame[] GetRenderTree(IComponent component)
        {
            var renderer = new TestRenderer();
            renderer.AttachComponent(component);
            component.SetParameters(ParameterCollection.Empty);
            return renderer.LatestBatchReferenceFrames;
        }

        protected ArrayRange<RenderTreeFrame> GetFrames(RenderFragment fragment)
        {
            var builder = new RenderTreeBuilder(new TestRenderer());
            fragment(builder);
            return builder.GetFrames();
        }

        protected class CompileToCSharpResult
        {
            public RazorCodeDocument CodeDocument { get; set; }
            public string Code { get; set; }
            public IEnumerable<RazorDiagnostic> Diagnostics { get; set; }
        }

        protected class CompileToAssemblyResult
        {
            public Assembly Assembly { get; set; }
            public string VerboseLog { get; set; }
            public IEnumerable<Diagnostic> Diagnostics { get; set; }
        }

        private class TestRenderer : Renderer
        {
            public TestRenderer() : base(new TestServiceProvider())
            {
            }

            public RenderTreeFrame[] LatestBatchReferenceFrames { get; private set; }

            public void AttachComponent(IComponent component)
                => AssignComponentId(component);

            protected override void UpdateDisplay(RenderBatch renderBatch)
            {
                LatestBatchReferenceFrames = renderBatch.ReferenceFrames.ToArray();
            }
        }
    }
}