// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.

// Most of the code in this file comes from the default Roslyn Analyzer project template

using System.Globalization;
using System.Text;
using Microsoft.CodeAnalysis;
using Microsoft.CodeAnalysis.Diagnostics;

namespace TestHelper;

/// <summary>
/// Superclass of all Unit Tests for DiagnosticAnalyzers
/// </summary>
public abstract partial class DiagnosticVerifier
{
    #region To be implemented by Test classes
    /// <summary>
    /// Get the CSharp analyzer being tested - to be implemented in non-abstract class
    /// </summary>
    protected virtual DiagnosticAnalyzer GetCSharpDiagnosticAnalyzer()
    {
        return null;
    }

    /// <summary>
    /// Get the Visual Basic analyzer being tested (C#) - to be implemented in non-abstract class
    /// </summary>
    protected virtual DiagnosticAnalyzer GetBasicDiagnosticAnalyzer()
    {
        return null;
    }
    #endregion

    #region Verifier wrappers

    /// <summary>
    /// Called to test a C# DiagnosticAnalyzer when applied on the single inputted string as a source
    /// Note: input a DiagnosticResult for each Diagnostic expected
    /// </summary>
    /// <param name="source">A class in the form of a string to run the analyzer on</param>
    /// <param name="expected"> DiagnosticResults that should appear after the analyzer is run on the source</param>
    protected void VerifyCSharpDiagnostic(string source, params DiagnosticResult[] expected)
    {
        VerifyDiagnostics(new[] { source }, LanguageNames.CSharp, GetCSharpDiagnosticAnalyzer(), expected);
    }

    /// <summary>
    /// Called to test a VB DiagnosticAnalyzer when applied on the single inputted string as a source
    /// Note: input a DiagnosticResult for each Diagnostic expected
    /// </summary>
    /// <param name="source">A class in the form of a string to run the analyzer on</param>
    /// <param name="expected">DiagnosticResults that should appear after the analyzer is run on the source</param>
    protected void VerifyBasicDiagnostic(string source, params DiagnosticResult[] expected)
    {
        VerifyDiagnostics(new[] { source }, LanguageNames.VisualBasic, GetBasicDiagnosticAnalyzer(), expected);
    }

    /// <summary>
    /// Called to test a C# DiagnosticAnalyzer when applied on the inputted strings as a source
    /// Note: input a DiagnosticResult for each Diagnostic expected
    /// </summary>
    /// <param name="sources">An array of strings to create source documents from to run the analyzers on</param>
    /// <param name="expected">DiagnosticResults that should appear after the analyzer is run on the sources</param>
    protected void VerifyCSharpDiagnostic(string[] sources, params DiagnosticResult[] expected)
    {
        VerifyDiagnostics(sources, LanguageNames.CSharp, GetCSharpDiagnosticAnalyzer(), expected);
    }

    /// <summary>
    /// Called to test a VB DiagnosticAnalyzer when applied on the inputted strings as a source
    /// Note: input a DiagnosticResult for each Diagnostic expected
    /// </summary>
    /// <param name="sources">An array of strings to create source documents from to run the analyzers on</param>
    /// <param name="expected">DiagnosticResults that should appear after the analyzer is run on the sources</param>
    protected void VerifyBasicDiagnostic(string[] sources, params DiagnosticResult[] expected)
    {
        VerifyDiagnostics(sources, LanguageNames.VisualBasic, GetBasicDiagnosticAnalyzer(), expected);
    }

    /// <summary>
    /// General method that gets a collection of actual diagnostics found in the source after the analyzer is run,
    /// then verifies each of them.
    /// </summary>
    /// <param name="sources">An array of strings to create source documents from to run the analyzers on</param>
    /// <param name="language">The language of the classes represented by the source strings</param>
    /// <param name="analyzer">The analyzer to be run on the source code</param>
    /// <param name="expected">DiagnosticResults that should appear after the analyzer is run on the sources</param>
    private void VerifyDiagnostics(string[] sources, string language, DiagnosticAnalyzer analyzer, params DiagnosticResult[] expected)
    {
        var diagnostics = GetSortedDiagnostics(sources, language, analyzer);
        VerifyDiagnosticResults(diagnostics, analyzer, expected);
    }

    #endregion

    #region Actual comparisons and verifications
    /// <summary>
    /// Checks each of the actual Diagnostics found and compares them with the corresponding DiagnosticResult in the array of expected results.
    /// Diagnostics are considered equal only if the DiagnosticResultLocation, Id, Severity, and Message of the DiagnosticResult match the actual diagnostic.
    /// </summary>
    /// <param name="actualResults">The Diagnostics found by the compiler after running the analyzer on the source code</param>
    /// <param name="analyzer">The analyzer that was being run on the sources</param>
    /// <param name="expectedResults">Diagnostic Results that should have appeared in the code</param>
    private static void VerifyDiagnosticResults(IEnumerable<Diagnostic> actualResults, DiagnosticAnalyzer analyzer, params DiagnosticResult[] expectedResults)
    {
        int expectedCount = expectedResults.Length;
        int actualCount = actualResults.Count();

        if (expectedCount != actualCount)
        {
            string diagnosticsOutput = actualResults.Any() ? FormatDiagnostics(analyzer, actualResults.ToArray()) : "    NONE.";

            Assert.True(false,
                string.Format(CultureInfo.InvariantCulture, "Mismatch between number of diagnostics returned, expected \"{0}\" actual \"{1}\"\r\n\r\nDiagnostics:\r\n{2}\r\n", expectedCount, actualCount, diagnosticsOutput));
        }

        for (int i = 0; i < expectedResults.Length; i++)
        {
            var actual = actualResults.ElementAt(i);
            var expected = expectedResults[i];

            if (expected.Line == -1 && expected.Column == -1)
            {
                if (actual.Location != Location.None)
                {
                    Assert.True(false,
                        string.Format(CultureInfo.InvariantCulture, "Expected:\nA project diagnostic with No location\nActual:\n{0}",
                        FormatDiagnostics(analyzer, actual)));
                }
            }
            else
            {
                VerifyDiagnosticLocation(analyzer, actual, actual.Location, expected.Locations.First());
                var additionalLocations = actual.AdditionalLocations.ToArray();

                if (additionalLocations.Length != expected.Locations.Length - 1)
                {
                    Assert.True(false,
                        string.Format(
                            CultureInfo.InvariantCulture,
                            "Expected {0} additional locations but got {1} for Diagnostic:\r\n    {2}\r\n",
                            expected.Locations.Length - 1, additionalLocations.Length,
                            FormatDiagnostics(analyzer, actual)));
                }

                for (int j = 0; j < additionalLocations.Length; ++j)
                {
                    VerifyDiagnosticLocation(analyzer, actual, additionalLocations[j], expected.Locations[j + 1]);
                }
            }

            if (actual.Id != expected.Id)
            {
                Assert.True(false,
                    string.Format(
                        CultureInfo.InvariantCulture,
                        "Expected diagnostic id to be \"{0}\" was \"{1}\"\r\n\r\nDiagnostic:\r\n    {2}\r\n",
                        expected.Id, actual.Id, FormatDiagnostics(analyzer, actual)));
            }

            if (actual.Severity != expected.Severity)
            {
                Assert.True(false,
                    string.Format(
                        CultureInfo.InvariantCulture,
                        "Expected diagnostic severity to be \"{0}\" was \"{1}\"\r\n\r\nDiagnostic:\r\n    {2}\r\n",
                        expected.Severity, actual.Severity, FormatDiagnostics(analyzer, actual)));
            }

            if (actual.GetMessage(CultureInfo.InvariantCulture) != expected.Message)
            {
                Assert.True(false,
                    string.Format(
                        CultureInfo.InvariantCulture,
                        "Expected diagnostic message to be \"{0}\" was \"{1}\"\r\n\r\nDiagnostic:\r\n    {2}\r\n",
                        expected.Message, actual.GetMessage(CultureInfo.InvariantCulture), FormatDiagnostics(analyzer, actual)));
            }
        }
    }

    /// <summary>
    /// Helper method to VerifyDiagnosticResult that checks the location of a diagnostic and compares it with the location in the expected DiagnosticResult.
    /// </summary>
    /// <param name="analyzer">The analyzer that was being run on the sources</param>
    /// <param name="diagnostic">The diagnostic that was found in the code</param>
    /// <param name="actual">The Location of the Diagnostic found in the code</param>
    /// <param name="expected">The DiagnosticResultLocation that should have been found</param>
    private static void VerifyDiagnosticLocation(DiagnosticAnalyzer analyzer, Diagnostic diagnostic, Location actual, DiagnosticResultLocation expected)
    {
        var actualSpan = actual.GetLineSpan();

        Assert.True(actualSpan.Path == expected.Path || (actualSpan.Path != null && actualSpan.Path.Contains("Test0.") && expected.Path.Contains("Test.")),
            string.Format(
                CultureInfo.InvariantCulture,
                "Expected diagnostic to be in file \"{0}\" was actually in file \"{1}\"\r\n\r\nDiagnostic:\r\n    {2}\r\n",
                expected.Path, actualSpan.Path, FormatDiagnostics(analyzer, diagnostic)));

        var actualLinePosition = actualSpan.StartLinePosition;

        // Only check line position if there is an actual line in the real diagnostic
        if (actualLinePosition.Line > 0)
        {
            if (actualLinePosition.Line + 1 != expected.Line)
            {
                Assert.True(false,
                    string.Format(
                        CultureInfo.InvariantCulture,
                        "Expected diagnostic to be on line \"{0}\" was actually on line \"{1}\"\r\n\r\nDiagnostic:\r\n    {2}\r\n",
                        expected.Line, actualLinePosition.Line + 1, FormatDiagnostics(analyzer, diagnostic)));
            }
        }

        // Only check column position if there is an actual column position in the real diagnostic
        if (actualLinePosition.Character > 0)
        {
            if (actualLinePosition.Character + 1 != expected.Column)
            {
                Assert.True(false,
                    string.Format(
                        CultureInfo.InvariantCulture,
                        "Expected diagnostic to start at column \"{0}\" was actually at column \"{1}\"\r\n\r\nDiagnostic:\r\n    {2}\r\n",
                        expected.Column, actualLinePosition.Character + 1, FormatDiagnostics(analyzer, diagnostic)));
            }
        }
    }
    #endregion

    #region Formatting Diagnostics
    /// <summary>
    /// Helper method to format a Diagnostic into an easily readable string
    /// </summary>
    /// <param name="analyzer">The analyzer that this verifier tests</param>
    /// <param name="diagnostics">The Diagnostics to be formatted</param>
    /// <returns>The Diagnostics formatted as a string</returns>
    private static string FormatDiagnostics(DiagnosticAnalyzer analyzer, params Diagnostic[] diagnostics)
    {
        var builder = new StringBuilder();
        for (int i = 0; i < diagnostics.Length; ++i)
        {
            builder.AppendLine("// " + diagnostics[i].ToString());

            var analyzerType = analyzer.GetType();
            var rules = analyzer.SupportedDiagnostics;

            foreach (var rule in rules)
            {
                if (rule != null && rule.Id == diagnostics[i].Id)
                {
                    var location = diagnostics[i].Location;
                    if (location == Location.None)
                    {
                        builder.AppendFormat(CultureInfo.InvariantCulture, "GetGlobalResult({0}.{1})", analyzerType.Name, rule.Id);
                    }
                    else
                    {
                        Assert.True(location.IsInSource,
                            $"Test base does not currently handle diagnostics in metadata locations. Diagnostic in metadata: {diagnostics[i]}\r\n");

                        string resultMethodName = diagnostics[i].Location.SourceTree.FilePath.EndsWith(".cs", StringComparison.Ordinal) ? "GetCSharpResultAt" : "GetBasicResultAt";
                        var linePosition = diagnostics[i].Location.GetLineSpan().StartLinePosition;

                        builder.AppendFormat(
                            CultureInfo.InvariantCulture,
                            "{0}({1}, {2}, {3}.{4})",
                            resultMethodName,
                            linePosition.Line + 1,
                            linePosition.Character + 1,
                            analyzerType.Name,
                            rule.Id);
                    }

                    if (i != diagnostics.Length - 1)
                    {
                        builder.Append(',');
                    }

                    builder.AppendLine();
                    break;
                }
            }
        }
        return builder.ToString();
    }
    #endregion
}
