// ==========================================================================
//  Squidex Headless CMS
// ==========================================================================
//  Copyright (c) Squidex UG (haftungsbeschraenkt)
//  All rights reserved. Licensed under the MIT license.
// ==========================================================================

using Squidex.Domain.Apps.Core.Contents;
using Squidex.Domain.Apps.Core.Schemas;
using Squidex.Infrastructure;
using Squidex.Infrastructure.Json.Objects;

#pragma warning disable SA1313 // Parameter names should begin with lower-case letter

namespace Squidex.Domain.Apps.Core.ExtractReferenceIds
{
    internal static class ReferencesExtractor
    {
        public record struct Args(JsonValue Value, ISet<DomainId> Result, int Take, ResolvedComponents Components);

        public static void Extract(IField field, JsonValue value, HashSet<DomainId> result, int take, ResolvedComponents components)
        {
            var args = new Args(value, result, take, components);

            ExtractCore(field, args);
        }

        public static void Extract(IEnumerable<IField> schema, ContentData data, HashSet<DomainId> result, int take, ResolvedComponents components)
        {
            foreach (var field in schema)
            {
                Extract(field, data, result, take, components);
            }
        }

        public static void Extract(IField field, ContentData data, HashSet<DomainId> result, int take, ResolvedComponents components)
        {
            if (CanHaveReferences(field.RawProperties) && data.TryGetValue(field.Name, out var fieldData) && fieldData != null)
            {
                foreach (var (_, value) in fieldData)
                {
                    Extract(field, value, result, take, components);
                }
            }
        }

        private static void ExtractCore(IField field, Args args)
        {
            switch (field)
            {
                case IField<AssetsFieldProperties>:
                    AddIds(ref args);
                    break;
                case IField<ReferencesFieldProperties>:
                    AddIds(ref args);
                    break;
                case IField<ComponentFieldProperties>:
                    ExtractFromComponent(args.Value, args);
                    break;
                case IField<ComponentsFieldProperties>:
                    ExtractFromComponents(args);
                    break;
                case IArrayField arrayField:
                    ExtractFromArray(arrayField, args);
                    break;
            }
        }

        private static void ExtractFromArray(IArrayField field, Args args)
        {
            if (args.Value.Value is JsonArray a)
            {
                foreach (var value in a)
                {
                    ExtractFromItem(field, value, args);
                }
            }
        }

        private static void ExtractFromComponents(Args args)
        {
            if (args.Value.Value is JsonArray a)
            {
                foreach (var value in a)
                {
                    ExtractFromComponent(value, args);
                }
            }
        }

        private static void ExtractFromItem(IArrayField field, JsonValue value, Args args)
        {
            if (value.Value is JsonObject o)
            {
                foreach (var nestedField in field.Fields)
                {
                    if (CanHaveReferences(nestedField.RawProperties) && o.TryGetValue(nestedField.Name, out var nested))
                    {
                        ExtractCore(nestedField, args with { Value = nested });
                    }
                }
            }
        }

        private static void ExtractFromComponent(JsonValue value, Args args)
        {
            if (value.Value is JsonObject o)
            {
                if (o.TryGetValue(Component.Discriminator, out var found) && found.Value is string s)
                {
                    var id = DomainId.Create(s);

                    if (args.Components.TryGetValue(id, out var schema))
                    {
                        foreach (var componentField in schema.Fields)
                        {
                            if (CanHaveReferences(componentField.RawProperties) && o.TryGetValue(componentField.Name, out var nested))
                            {
                                ExtractCore(componentField, args with { Value = nested });
                            }
                        }
                    }
                }
            }
        }

        private static bool CanHaveReferences(FieldProperties properties)
        {
            return
                properties is ArrayFieldProperties ||
                properties is ReferencesFieldProperties ||
                properties is AssetsFieldProperties ||
                properties is ComponentFieldProperties ||
                properties is ComponentsFieldProperties;
        }

        private static void AddIds(ref Args args)
        {
            var added = 0;

            if (args.Value.Value is JsonArray a)
            {
                foreach (var id in a)
                {
                    if (id.Value is string s)
                    {
                        args.Result.Add(DomainId.Create(s));

                        added++;

                        if (added >= args.Take)
                        {
                            break;
                        }
                    }
                }
            }
        }
    }
}