// 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.Collections.Immutable;
using System.Linq;
using Microsoft.CodeAnalysis.FindSymbols;
using Microsoft.CodeAnalysis.LanguageService;
using Microsoft.CodeAnalysis.PooledObjects;
using Microsoft.CodeAnalysis.Shared.Utilities;
using Roslyn.Utilities;

namespace Microsoft.CodeAnalysis.Shared.Extensions;

internal static partial class IFindReferencesResultExtensions
{
    public static IEnumerable<Location> GetDefinitionLocationsToShow(
        this ISymbol definition)
    {
        return definition.IsKind(SymbolKind.Namespace)
            ? [definition.Locations.First()]
            : definition.Locations;
    }

    public static ImmutableArray<ReferencedSymbol> FilterToItemsToShow(
        this ImmutableArray<ReferencedSymbol> result, FindReferencesSearchOptions options)
    {
        return result.WhereAsArray(r => ShouldShow(r, options));
    }

    public static bool ShouldShow(
        this ReferencedSymbol referencedSymbol, FindReferencesSearchOptions options)
    {
        // If the reference has any locations then we will present it.
        if (referencedSymbol.Locations.Any())
        {
            return true;
        }

        return referencedSymbol.Definition.ShouldShowWithNoReferenceLocations(
            options, showMetadataSymbolsWithoutReferences: true);
    }

    public static bool ShouldShowWithNoReferenceLocations(
        this ISymbol definition, FindReferencesSearchOptions options, bool showMetadataSymbolsWithoutReferences)
    {
        if (options.DisplayAllDefinitions)
        {
            return true;
        }

        // If the definition is implicit and we have no references, then we don't want to
        // clutter the UI with it.
        if (definition.IsImplicitlyDeclared)
        {
            return false;
        }

        // If we're associating property references with an accessor, then we don't want to show
        // a property if it is has no references.  Similarly, if we're associated associating
        // everything with the property, then we don't want to include accessors if there are no
        // references to them.
        if (options.AssociatePropertyReferencesWithSpecificAccessor)
        {
            if (definition.Kind == SymbolKind.Property)
            {
                return false;
            }
        }
        else
        {
            if (definition.IsPropertyAccessor())
            {
                return false;
            }
        }

        // Otherwise we still show the item even if there are no references to it.
        // And it's at least a source definition.
        if (definition.Locations.Any(static loc => loc.IsInSource))
        {
            return true;
        }

        if (showMetadataSymbolsWithoutReferences &&
            definition.Locations.Any(static loc => loc.IsInMetadata))
        {
            return true;
        }

        return false;
    }

    public static ImmutableArray<ReferencedSymbol> FilterToAliasMatches(
        this ImmutableArray<ReferencedSymbol> result,
        IAliasSymbol? aliasSymbol)
    {
        if (aliasSymbol == null)
        {
            return result;
        }

        var q = from r in result
                let aliasLocations = r.Locations.WhereAsArray(loc => SymbolEquivalenceComparer.Instance.Equals(loc.Alias, aliasSymbol))
                where aliasLocations.Any()
                select new ReferencedSymbol(r.Definition, aliasLocations);

        return [.. q];
    }

    public static ImmutableArray<ReferencedSymbol> FilterNonMatchingMethodNames(
        this ImmutableArray<ReferencedSymbol> result,
        Solution solution,
        ISymbol symbol)
    {
        return symbol.IsOrdinaryMethod()
            ? FilterNonMatchingMethodNamesWorker(result, solution, symbol)
            : result;
    }

    private static ImmutableArray<ReferencedSymbol> FilterNonMatchingMethodNamesWorker(
        ImmutableArray<ReferencedSymbol> references,
        Solution solution,
        ISymbol symbol)
    {
        using var _ = ArrayBuilder<ReferencedSymbol>.GetInstance(out var result);
        foreach (var reference in references)
        {
            var isCaseSensitive = solution.Services.GetLanguageServices(reference.Definition.Language).GetRequiredService<ISyntaxFactsService>().IsCaseSensitive;
            var comparer = isCaseSensitive ? StringComparer.Ordinal : StringComparer.OrdinalIgnoreCase;
            if (reference.Definition.IsOrdinaryMethod() &&
                !comparer.Equals(reference.Definition.Name, symbol.Name))
            {
                continue;
            }

            result.Add(reference);
        }

        return result.ToImmutableAndClear();
    }
}