// 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.Linq;
using Microsoft.AspNetCore.Razor;
using Microsoft.AspNetCore.Razor.Chunks.Generators;
using Microsoft.AspNetCore.Razor.Generator;
using Microsoft.AspNetCore.Razor.Parser;
using Microsoft.AspNetCore.Razor.Parser.Internal;
using Microsoft.AspNetCore.Razor.Parser.SyntaxTree;
using Microsoft.AspNetCore.Razor.Text;
using Xunit;

namespace Microsoft.AspNetCore.Mvc.Razor.Host.Test
{
    public class MvcRazorCodeParserTest
    {
        [Fact]
        public void Constructor_AddsModelKeyword()
        {
            var parser = new TestMvcCSharpRazorCodeParser();

            Assert.True(parser.HasDirective("model"));
        }

        [Fact]
        public void ParseModelKeyword_HandlesSingleInstance()
        {
            // Arrange + Act
            var document = "@model    Foo";
            var spans = ParseDocument(document);

            // Assert
            var factory = SpanFactory.CreateCsHtml();
            var expectedSpans = new Span[]
            {
                factory.EmptyHtml(),
                factory.CodeTransition(SyntaxConstants.TransitionString)
                    .Accepts(AcceptedCharacters.None),
                factory.MetaCode("model ")
                    .Accepts(AcceptedCharacters.None),
                factory.Code("   Foo")
                    .As(new ModelChunkGenerator("Foo"))
                    .Accepts(AcceptedCharacters.AnyExceptNewline),
                factory.EmptyHtml()
            };
            Assert.Equal(expectedSpans, spans.ToArray());
        }

        [Fact]
        public void ParseModelKeyword_HandlesNullableTypes()
        {
            // Arrange + Act
            var document = $"@model Foo?{Environment.NewLine}Bar";
            var spans = ParseDocument(document);

            // Assert
            var factory = SpanFactory.CreateCsHtml();
            var expectedSpans = new Span[]
            {
                factory.EmptyHtml(),
                factory.CodeTransition(SyntaxConstants.TransitionString)
                    .Accepts(AcceptedCharacters.None),
                factory.MetaCode("model ")
                    .Accepts(AcceptedCharacters.None),
                factory.Code("Foo?" + Environment.NewLine)
                    .As(new ModelChunkGenerator("Foo?"))
                    .Accepts(AcceptedCharacters.AnyExceptNewline),
                factory.Markup("Bar")
                    .With(new MarkupChunkGenerator())
            };
            Assert.Equal(expectedSpans, spans.ToArray());
        }

        [Fact]
        public void ParseModelKeyword_HandlesArrays()
        {
            // Arrange + Act
            var document = $"@model Foo[[]][]{Environment.NewLine}Bar";
            var spans = ParseDocument(document);

            // Assert
            var factory = SpanFactory.CreateCsHtml();
            var expectedSpans = new Span[]
            {
                factory.EmptyHtml(),
                factory.CodeTransition(SyntaxConstants.TransitionString)
                    .Accepts(AcceptedCharacters.None),
                factory.MetaCode("model ")
                    .Accepts(AcceptedCharacters.None),
                factory.Code("Foo[[]][]" + Environment.NewLine)
                    .As(new ModelChunkGenerator("Foo[[]][]"))
                    .Accepts(AcceptedCharacters.AnyExceptNewline),
                factory.Markup("Bar")
                    .With(new MarkupChunkGenerator())
            };
            Assert.Equal(expectedSpans, spans.ToArray());
        }

        [Fact]
        public void ParseModelKeyword_HandlesVSTemplateSyntax()
        {
            // Arrange + Act
            var document = "@model $rootnamespace$.MyModel";
            var spans = ParseDocument(document);

            // Assert
            var factory = SpanFactory.CreateCsHtml();
            var expectedSpans = new Span[]
            {
                factory.EmptyHtml(),
                factory.CodeTransition(SyntaxConstants.TransitionString)
                    .Accepts(AcceptedCharacters.None),
                factory.MetaCode("model ")
                    .Accepts(AcceptedCharacters.None),
                factory.Code("$rootnamespace$.MyModel")
                    .As(new ModelChunkGenerator("$rootnamespace$.MyModel"))
                    .Accepts(AcceptedCharacters.AnyExceptNewline),
                factory.EmptyHtml()
            };
            Assert.Equal(expectedSpans, spans.ToArray());
        }

        [Fact]
        public void ParseModelKeyword_ErrorOnMissingModelType()
        {
            // Arrange + Act
            List<RazorError> errors = new List<RazorError>();
            var document = "@model   ";
            var spans = ParseDocument(document, errors);

            // Assert
            var factory = SpanFactory.CreateCsHtml();
            var expectedSpans = new Span[]
            {
                factory.EmptyHtml(),
                factory.CodeTransition(SyntaxConstants.TransitionString)
                    .Accepts(AcceptedCharacters.None),
                factory.MetaCode("model ")
                    .Accepts(AcceptedCharacters.None),
                factory.Code("  ")
                    .As(new ModelChunkGenerator(string.Empty))
                    .Accepts(AcceptedCharacters.AnyExceptNewline),
                factory.EmptyHtml()
            };
            var expectedErrors = new[]
            {
                new RazorError("The 'model' keyword must be followed by a type name on the same line.", new SourceLocation(1, 0, 1), 5)
            };
            Assert.Equal(expectedSpans, spans.ToArray());
            Assert.Equal(expectedErrors, errors.ToArray());
        }

        [Fact]
        public void ParseModelKeyword_ErrorOnMultipleModelStatements()
        {
            // Arrange + Act
            List<RazorError> errors = new List<RazorError>();
            var document =
                "@model Foo" + Environment.NewLine
              + "@model Bar";
            var spans = ParseDocument(document, errors);

            // Assert
            var factory = SpanFactory.CreateCsHtml();
            var expectedSpans = new Span[]
            {
                factory.EmptyHtml(),
                factory.CodeTransition(SyntaxConstants.TransitionString)
                    .Accepts(AcceptedCharacters.None),
                factory.MetaCode("model ")
                    .Accepts(AcceptedCharacters.None),
                factory.Code("Foo" + Environment.NewLine)
                    .As(new ModelChunkGenerator("Foo"))
                    .Accepts(AcceptedCharacters.AnyExceptNewline),
                factory.EmptyHtml(),
                factory.CodeTransition(SyntaxConstants.TransitionString)
                    .Accepts(AcceptedCharacters.None),
                factory.MetaCode("model ")
                    .Accepts(AcceptedCharacters.None),
                factory.Code("Bar")
                    .As(new ModelChunkGenerator("Bar"))
                    .Accepts(AcceptedCharacters.AnyExceptNewline),
                factory.EmptyHtml()
            };

            var expectedErrors = new[]
            {
                new RazorError(
                    "Only one 'model' statement is allowed in a file.",
                    PlatformNormalizer.NormalizedSourceLocation(13, 1, 1),
                    5)
            };
            expectedSpans.Zip(spans, (exp, span) => new { expected = exp, span = span }).ToList().ForEach(i => Assert.Equal(i.expected, i.span));
            Assert.Equal(expectedSpans, spans.ToArray());
            Assert.Equal(expectedErrors, errors.ToArray());
        }

        [Fact]
        public void ParseModelKeyword_ErrorOnModelFollowedByInherits()
        {
            // Arrange + Act
            List<RazorError> errors = new List<RazorError>();
            var document =
                "@model Foo" + Environment.NewLine
              + "@inherits Bar";
            var spans = ParseDocument(document, errors);

            // Assert
            var factory = SpanFactory.CreateCsHtml();
            var expectedSpans = new Span[]
            {
                factory.EmptyHtml(),
                factory.CodeTransition(SyntaxConstants.TransitionString)
                    .Accepts(AcceptedCharacters.None),
                factory.MetaCode("model ")
                    .Accepts(AcceptedCharacters.None),
                factory.Code("Foo" + Environment.NewLine)
                    .As(new ModelChunkGenerator("Foo"))
                    .Accepts(AcceptedCharacters.AnyExceptNewline),
                factory.EmptyHtml(),
                factory.CodeTransition(SyntaxConstants.TransitionString)
                    .Accepts(AcceptedCharacters.None),
                factory.MetaCode("inherits ")
                    .Accepts(AcceptedCharacters.None),
                factory.Code("Bar")
                    .As(new SetBaseTypeChunkGenerator("Bar"))
                    .Accepts(AcceptedCharacters.AnyExceptNewline),
                factory.EmptyHtml()
            };

            var expectedErrors = new[]
            {
                new RazorError(
                    "The 'inherits' keyword is not allowed when a 'model' keyword is used.",
                    PlatformNormalizer.NormalizedSourceLocation(21, 1, 9),
                    length: 8)
            };
            expectedSpans.Zip(spans, (exp, span) => new { expected = exp, span = span }).ToList().ForEach(i => Assert.Equal(i.expected, i.span));
            Assert.Equal(expectedSpans, spans.ToArray());
            Assert.Equal(expectedErrors, errors.ToArray());
        }

        [Fact]
        public void ParseModelKeyword_ErrorOnInheritsFollowedByModel()
        {
            // Arrange + Act
            List<RazorError> errors = new List<RazorError>();
            var document =
                "@inherits Bar" + Environment.NewLine
              + "@model Foo";
            var spans = ParseDocument(document, errors);

            // Assert
            var factory = SpanFactory.CreateCsHtml();
            var expectedSpans = new Span[]
            {
                factory.EmptyHtml(),
                factory.CodeTransition(SyntaxConstants.TransitionString)
                    .Accepts(AcceptedCharacters.None),
                factory.MetaCode("inherits ")
                    .Accepts(AcceptedCharacters.None),
                factory.Code("Bar" + Environment.NewLine)
                    .As(new SetBaseTypeChunkGenerator("Bar"))
                    .Accepts(AcceptedCharacters.AnyExceptNewline),
                factory.EmptyHtml(),
                factory.CodeTransition(SyntaxConstants.TransitionString)
                    .Accepts(AcceptedCharacters.None),
                factory.MetaCode("model ")
                    .Accepts(AcceptedCharacters.None),
                factory.Code("Foo")
                    .As(new ModelChunkGenerator("Foo"))
                    .Accepts(AcceptedCharacters.AnyExceptNewline),
                factory.EmptyHtml()
            };

            var expectedErrors = new[]
            {
                new RazorError(
                    "The 'inherits' keyword is not allowed when a 'model' keyword is used.",
                    new SourceLocation(9, 0, 9),
                    length: 8)
            };
            expectedSpans.Zip(spans, (exp, span) => new { expected = exp, span = span }).ToList().ForEach(i => Assert.Equal(i.expected, i.span));
            Assert.Equal(expectedSpans, spans.ToArray());
            Assert.Equal(expectedErrors, errors.ToArray());
        }

        private static List<Span> ParseDocument(string documentContents, IList<RazorError> errors = null)
        {
            errors = errors ?? new List<RazorError>();
            var markupParser = new HtmlMarkupParser();
            var codeParser = new TestMvcCSharpRazorCodeParser();
            var context = new ParserContext(
                new SeekableTextReader(documentContents),
                codeParser,
                markupParser,
                markupParser,
                new ErrorSink());
            codeParser.Context = context;
            markupParser.Context = context;
            markupParser.ParseDocument();

            ParserResults results = context.CompleteParse();
            foreach (RazorError error in results.ParserErrors)
            {
                errors.Add(error);
            }
            return results.Document.Flatten().ToList();
        }

        private sealed class TestMvcCSharpRazorCodeParser : MvcRazorCodeParser
        {
            public bool HasDirective(string directive)
            {
                Action handler;
                return TryGetDirectiveHandler(directive, out handler);
            }
        }
    }
}