// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.
// See the LICENSE file in the project root for more information.

using System;
using System.Collections.Generic;
using System.Diagnostics.CodeAnalysis;
using System.Linq;
using Microsoft.CodeAnalysis;
using Microsoft.CodeAnalysis.CSharp.Syntax;
using Microsoft.CodeAnalysis.Shared.Extensions;
using Microsoft.CodeAnalysis.Text;
using Roslyn.Utilities;

namespace Microsoft.CodeAnalysis.CSharp.ExtractMethod;

internal static class Extensions
{
    public static StatementSyntax? GetStatementUnderContainer(this SyntaxNode node)
    {
        Contract.ThrowIfNull(node);

        for (var current = node; current is object; current = current.Parent)
        {
            if (current.Parent != null &&
                current.Parent.IsStatementContainerNode())
            {
                return current as StatementSyntax;
            }
        }

        return null;
    }

    public static StatementSyntax GetParentLabeledStatementIfPossible(this SyntaxNode node)
        => (StatementSyntax)((node.Parent is LabeledStatementSyntax) ? node.Parent : node);

    public static bool IsStatementContainerNode([NotNullWhen(returnValue: true)] this SyntaxNode? node)
        => node is BlockSyntax or SwitchSectionSyntax or GlobalStatementSyntax;

    public static BlockSyntax? GetBlockBody(this SyntaxNode? node)
    {
        switch (node)
        {
            case BaseMethodDeclarationSyntax m: return m.Body;
            case AccessorDeclarationSyntax a: return a.Body;
            case SimpleLambdaExpressionSyntax s: return s.Body as BlockSyntax;
            case ParenthesizedLambdaExpressionSyntax p: return p.Body as BlockSyntax;
            case AnonymousMethodExpressionSyntax a: return a.Block;
            default: return null;
        }
    }

    public static bool UnderValidContext(this SyntaxNode node)
    {
        Contract.ThrowIfNull(node);

        if (!node.GetAncestorsOrThis<SyntaxNode>().Any(predicate))
        {
            return false;
        }

        return true;

        bool predicate(SyntaxNode n)
        {
            if (n is BaseMethodDeclarationSyntax or
                AccessorDeclarationSyntax or
                BlockSyntax or
                GlobalStatementSyntax or
                CompilationUnitSyntax)
            {
                return true;
            }

            if (n is ConstructorInitializerSyntax constructorInitializer)
            {
                return constructorInitializer.ContainsInArgument(node.Span);
            }

            return false;
        }
    }

    public static bool ContainsInArgument(this ConstructorInitializerSyntax initializer, TextSpan textSpan)
    {
        if (initializer == null)
        {
            return false;
        }

        return initializer.ArgumentList.Arguments.Any(a => a.Span.Contains(textSpan));
    }

    public static bool ContainedInValidType(this SyntaxNode node)
    {
        Contract.ThrowIfNull(node);
        foreach (var ancestor in node.AncestorsAndSelf())
        {
            if (ancestor is TypeDeclarationSyntax)
            {
                return true;
            }

            if (ancestor is NamespaceDeclarationSyntax)
            {
                return false;
            }
        }

        return true;
    }

    public static bool PartOfConstantInitializerExpression(this SyntaxNode node)
    {
        return node.PartOfConstantInitializerExpression<FieldDeclarationSyntax>(n => n.Modifiers) ||
               node.PartOfConstantInitializerExpression<LocalDeclarationStatementSyntax>(n => n.Modifiers);
    }

    private static bool PartOfConstantInitializerExpression<T>(this SyntaxNode node, Func<T, SyntaxTokenList> modifiersGetter) where T : SyntaxNode
    {
        var decl = node.GetAncestor<T>();
        if (decl == null)
        {
            return false;
        }

        if (!modifiersGetter(decl).Any(SyntaxKind.ConstKeyword))
        {
            return false;
        }

        // we are under decl with const modifier, check we are part of initializer expression
        var equal = node.GetAncestor<EqualsValueClauseSyntax>();
        if (equal == null)
        {
            return false;
        }

        return equal.Value != null && equal.Value.Span.Contains(node.Span);
    }

    public static bool ContainArgumentlessThrowWithoutEnclosingCatch(this IEnumerable<SyntaxToken> tokens, TextSpan textSpan)
    {
        foreach (var token in tokens)
        {
            if (token.Kind() != SyntaxKind.ThrowKeyword)
            {
                continue;
            }

            if (token.Parent is not ThrowStatementSyntax throwStatement || throwStatement.Expression != null)
            {
                continue;
            }

            var catchClause = token.GetAncestor<CatchClauseSyntax>();
            if (catchClause == null || !textSpan.Contains(catchClause.Span))
            {
                return true;
            }
        }

        return false;
    }

    public static bool ContainPreprocessorCrossOver(this IEnumerable<SyntaxToken> tokens, TextSpan textSpan)
    {
        var activeRegions = 0;
        var activeIfs = 0;

        foreach (var trivia in tokens.GetAllTrivia())
        {
            if (!textSpan.Contains(trivia.Span))
            {
                continue;
            }

            switch (trivia.Kind())
            {
                case SyntaxKind.RegionDirectiveTrivia:
                    activeRegions++;
                    break;
                case SyntaxKind.EndRegionDirectiveTrivia:
                    if (activeRegions <= 0)
                    {
                        return true;
                    }

                    activeRegions--;
                    break;
                case SyntaxKind.IfDirectiveTrivia:
                    activeIfs++;
                    break;
                case SyntaxKind.EndIfDirectiveTrivia:
                    if (activeIfs <= 0)
                    {
                        return true;
                    }

                    activeIfs--;
                    break;
                case SyntaxKind.ElseDirectiveTrivia:
                case SyntaxKind.ElifDirectiveTrivia:
                    if (activeIfs <= 0)
                    {
                        return true;
                    }

                    break;
            }
        }

        return activeIfs != 0 || activeRegions != 0;
    }

    public static IEnumerable<SyntaxTrivia> GetAllTrivia(this IEnumerable<SyntaxToken> tokens)
    {
        foreach (var token in tokens)
        {
            foreach (var trivia in token.LeadingTrivia)
            {
                yield return trivia;
            }

            foreach (var trivia in token.TrailingTrivia)
            {
                yield return trivia;
            }
        }
    }

    public static bool HasSyntaxAnnotation(this HashSet<SyntaxAnnotation> set, SyntaxNode node)
        => set.Any(a => node.GetAnnotatedNodesAndTokens(a).Any());

    public static bool HasHybridTriviaBetween(this SyntaxToken token1, SyntaxToken token2)
    {
        if (token1.TrailingTrivia.Any(t => !t.IsElastic()))
        {
            return true;
        }

        if (token2.LeadingTrivia.Any(t => !t.IsElastic()))
        {
            return true;
        }

        return false;
    }

    public static bool IsArrayInitializer([NotNullWhen(returnValue: true)] this SyntaxNode? node)
        => node is InitializerExpressionSyntax && node.Parent is EqualsValueClauseSyntax;

    public static bool IsExpressionInCast([NotNullWhen(returnValue: true)] this SyntaxNode? node)
        => node is ExpressionSyntax && node.Parent is CastExpressionSyntax;

    public static bool IsObjectType(this ITypeSymbol? type)
        => type == null || type.SpecialType == SpecialType.System_Object;

    public static bool BetweenFieldAndNonFieldMember(this SyntaxToken token1, SyntaxToken token2)
    {
        if (token1.RawKind != (int)SyntaxKind.SemicolonToken || !(token1.Parent is FieldDeclarationSyntax))
        {
            return false;
        }

        var field = token2.GetAncestor<FieldDeclarationSyntax>();
        return field == null;
    }
}