// 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.Linq;
using System.Text;
using Microsoft.AspNetCore.Razor.Language.Intermediate;

namespace Microsoft.AspNetCore.Razor.Language.CodeGeneration
{
    internal class DefaultDocumentWriter : DocumentWriter
    {
        private readonly CodeTarget _codeTarget;
        private readonly RazorCodeGenerationOptions _options;

        public DefaultDocumentWriter(CodeTarget codeTarget, RazorCodeGenerationOptions options)
        {
            _codeTarget = codeTarget;
            _options = options;
        }

        public override RazorCSharpDocument WriteDocument(RazorCodeDocument codeDocument, DocumentIntermediateNode documentNode)
        {
            if (codeDocument == null)
            {
                throw new ArgumentNullException(nameof(codeDocument));
            }

            if (documentNode == null)
            {
                throw new ArgumentNullException(nameof(documentNode));
            }

            var context = new DefaultCodeRenderingContext(
                new CodeWriter(),
                _codeTarget.CreateNodeWriter(),
                codeDocument,
                documentNode,
                _options);
            context.Visitor = new Visitor(_codeTarget, context);

            context.Visitor.VisitDocument(documentNode);

            var cSharp = context.CodeWriter.GenerateCode();
            return new DefaultRazorCSharpDocument(
                cSharp,
                _options,
                context.Diagnostics.ToArray(),
                context.LineMappings.ToArray());
        }

        private class Visitor : IntermediateNodeVisitor
        {
            private readonly DefaultCodeRenderingContext _context;
            private readonly CodeTarget _target;

            public Visitor(CodeTarget target, DefaultCodeRenderingContext context)
            {
                _target = target;
                _context = context;
            }

            private DefaultCodeRenderingContext Context => _context;

            public override void VisitDocument(DocumentIntermediateNode node)
            {
                if (!Context.Options.SuppressChecksum)
                {
                    // See http://msdn.microsoft.com/en-us/library/system.codedom.codechecksumpragma.checksumalgorithmid.aspx
                    const string Sha1AlgorithmId = "{ff1816ec-aa5e-4d10-87f7-6f4963833460}";

                    var sourceDocument = Context.SourceDocument;

                    var checksum = sourceDocument.GetChecksum();
                    var fileHashBuilder = new StringBuilder(checksum.Length * 2);
                    foreach (var value in checksum)
                    {
                        fileHashBuilder.Append(value.ToString("x2"));
                    }

                    var bytes = fileHashBuilder.ToString();

                    if (!string.IsNullOrEmpty(bytes))
                    {
                        Context.CodeWriter
                            .Write("#pragma checksum \"")
                            .Write(sourceDocument.FilePath)
                            .Write("\" \"")
                            .Write(Sha1AlgorithmId)
                            .Write("\" \"")
                            .Write(bytes)
                            .WriteLine("\"");
                    }
                }

                Context.CodeWriter
                    .WriteLine("// <auto-generated/>")
                    .WriteLine("#pragma warning disable 1591");

                VisitDefault(node);

                Context.CodeWriter.WriteLine("#pragma warning restore 1591");
            }

            public override void VisitUsingDirective(UsingDirectiveIntermediateNode node)
            {
                Context.NodeWriter.WriteUsingDirective(Context, node);
            }

            public override void VisitNamespaceDeclaration(NamespaceDeclarationIntermediateNode node)
            {
                using (Context.CodeWriter.BuildNamespace(node.Content))
                {
                    Context.CodeWriter.WriteLine("#line hidden");
                    VisitDefault(node);
                }
            }

            public override void VisitClassDeclaration(ClassDeclarationIntermediateNode node)
            {
                using (Context.CodeWriter.BuildClassDeclaration(node.Modifiers, node.Name, node.BaseType, node.Interfaces))
                {
                    VisitDefault(node);
                }
            }

            public override void VisitMethodDeclaration(MethodDeclarationIntermediateNode node)
            {
                Context.CodeWriter.WriteLine("#pragma warning disable 1998");

                for (var i = 0; i < node.Modifiers.Count; i++)
                {
                    Context.CodeWriter.Write(node.Modifiers[i]);
                    Context.CodeWriter.Write(" ");
                }

                Context.CodeWriter
                    .Write(node.ReturnType)
                    .Write(" ")
                    .Write(node.Name)
                    .WriteLine("()");

                using (Context.CodeWriter.BuildScope())
                {
                    VisitDefault(node);
                }

                Context.CodeWriter.WriteLine("#pragma warning restore 1998");
            }

            public override void VisitFieldDeclaration(FieldDeclarationIntermediateNode node)
            {
                Context.CodeWriter.WriteField(node.Modifiers, node.Type, node.Name);
            }

            public override void VisitPropertyDeclaration(PropertyDeclarationIntermediateNode node)
            {
                Context.CodeWriter.WriteAutoPropertyDeclaration(node.Modifiers, node.Type, node.Name);
            }

            public override void VisitExtension(ExtensionIntermediateNode node)
            {
                node.WriteNode(_target, Context);
            }

            public override void VisitCSharpExpression(CSharpExpressionIntermediateNode node)
            {
                Context.NodeWriter.WriteCSharpExpression(Context, node);
            }

            public override void VisitCSharpCode(CSharpCodeIntermediateNode node)
            {
                Context.NodeWriter.WriteCSharpCode(Context, node);
            }

            public override void VisitHtmlAttribute(HtmlAttributeIntermediateNode node)
            {
                Context.NodeWriter.WriteHtmlAttribute(Context, node);
            }

            public override void VisitHtmlAttributeValue(HtmlAttributeValueIntermediateNode node)
            {
                Context.NodeWriter.WriteHtmlAttributeValue(Context, node);
            }

            public override void VisitCSharpExpressionAttributeValue(CSharpExpressionAttributeValueIntermediateNode node)
            {
                Context.NodeWriter.WriteCSharpExpressionAttributeValue(Context, node);
            }

            public override void VisitCSharpCodeAttributeValue(CSharpCodeAttributeValueIntermediateNode node)
            {
                Context.NodeWriter.WriteCSharpCodeAttributeValue(Context, node);
            }

            public override void VisitHtml(HtmlContentIntermediateNode node)
            {
                Context.NodeWriter.WriteHtmlContent(Context, node);
            }

            public override void VisitTagHelper(TagHelperIntermediateNode node)
            {
                var tagHelperRenderingContext = new TagHelperRenderingContext();

                using (Context.Push(tagHelperRenderingContext))
                {
                    VisitDefault(node);
                }
            }

            public override void VisitDefault(IntermediateNode node)
            {
                Context.RenderChildren(node);
            }
        }
    }
}