using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace InABox.Core
{
    public interface IEntityFormUtils
    {
        public abstract bool CanEditForm(IDigitalFormInstance form, Entity entity);

        public abstract Entity NewEntity(DigitalForm form);

        public abstract void OnSave(IDigitalFormInstance form, Entity entity);
    }

    public abstract class EntityFormUtils<TForm, TEntity, TEntityLink> : IEntityFormUtils
        where TForm : EntityForm<TEntity, TEntityLink, TForm>
        where TEntity : Entity, new()
        where TEntityLink : EntityLink<TEntity>, new()
    {
        public abstract bool CanEditForm(TForm form, TEntity entity);
        public abstract TEntity NewEntity(DigitalForm form);
        public abstract void OnSave(TForm form, TEntity entity);

        void IEntityFormUtils.OnSave(IDigitalFormInstance form, Entity entity) => OnSave((TForm)form, (TEntity)entity);

        bool IEntityFormUtils.CanEditForm(IDigitalFormInstance form, Entity entity) => CanEditForm((form as TForm)!, (entity as TEntity)!);

        Entity IEntityFormUtils.NewEntity(DigitalForm form) => NewEntity(form);
    }

    public class DelegateEntityFormUtils<TForm, TEntity, TEntityLink> : EntityFormUtils<TForm, TEntity, TEntityLink>
        where TForm : EntityForm<TEntity, TEntityLink, TForm>
        where TEntity : Entity, new()
        where TEntityLink : EntityLink<TEntity>, new()
    {
        public delegate bool CanEditEvent(TForm form, TEntity entity);
        public delegate TEntity NewEntityEvent(DigitalForm form);
        public delegate void OnSaveEvent(TForm form, TEntity entity);

        public CanEditEvent OnCanEdit;
        public NewEntityEvent? OnNewEntity;
        public OnSaveEvent? SaveEvent;

        public DelegateEntityFormUtils(CanEditEvent canEditForm, NewEntityEvent? onNewEntity = null, OnSaveEvent? onSave = null)
        {
            OnCanEdit = canEditForm;
            OnNewEntity = onNewEntity;
            SaveEvent = onSave;
        }

        public override bool CanEditForm(TForm form, TEntity entity) => OnCanEdit(form, entity);

        public override TEntity NewEntity(DigitalForm form) => OnNewEntity?.Invoke(form) ?? new TEntity();

        public override void OnSave(TForm form, TEntity entity) => SaveEvent?.Invoke(form, entity);
        
    }

    public static class DFUtils
    {

        private static List<Type>? _fieldTypes;

        public static List<Type> GetFieldTypes(bool includeObsolete = false)
        {
            _fieldTypes ??= CoreUtils.Entities.Where(x => x.IsClass && !x.IsGenericType && x.HasInterface<IDFLayoutFormField>()).ToList();
            return includeObsolete ? _fieldTypes : _fieldTypes.Where(x => !x.HasInterface<IDFLayoutObsoleteField>()).ToList();
        }

        public static Type? GetFieldType(string typeName)
        {
            var type = GetFieldTypes(true).Where(x => x.FullName == typeName).FirstOrDefault();
            if(type != null) return type;

            if(Enum.TryParse(typeName, out DigitalFormVariableType variableType))
            {
                // For the old types
                switch (variableType)
                {
                    case DigitalFormVariableType.String:
                        return typeof(DFLayoutStringField);
                    case DigitalFormVariableType.Boolean:
                        return typeof(DFLayoutBooleanField);
                    case DigitalFormVariableType.Integer:
                        return typeof(DFLayoutIntegerField);
                    case DigitalFormVariableType.Double:
                        return typeof(DFLayoutDoubleField);
                    case DigitalFormVariableType.Date:
                        return typeof(DFLayoutDateField);
                    case DigitalFormVariableType.Time:
                        return typeof(DFLayoutTimeField);
                    case DigitalFormVariableType.Choice:
                        return typeof(DFLayoutOptionField);
                    case DigitalFormVariableType.Lookup:
                        return typeof(DFLayoutLookupField);
                    case DigitalFormVariableType.SignaturePad:
                        return typeof(DFLayoutSignaturePad);
                    case DigitalFormVariableType.EmbeddedImage:
                        return typeof(DFLayoutEmbeddedImage);
                    case DigitalFormVariableType.MultiImage:
                        return typeof(DFLayoutMultiImage);
                }
            }
            return null;
        }


        private static Dictionary<string, Tuple<Type, Type>>? _formInstanceTypes;
        private static Dictionary<string, Tuple<Type, Type>> FormInstanceTypes
        {
            get
            {
                _formInstanceTypes ??= CoreUtils.Entities.Where(x => x.HasInterface<IDigitalFormInstance>())
                    .Select(x =>
                    {
                        var inter = x.GetInterfaceDefinition(typeof(IDigitalFormInstance<>));
                        if (inter != null)
                        {
                            var link = inter.GenericTypeArguments[0];
                            var entityLinkDef = link.GetSuperclassDefinition(typeof(EntityLink<>));
                            if (entityLinkDef != null)
                            {
                                var entityType = entityLinkDef.GenericTypeArguments[0];
                                return new Tuple<string, Type, Type>(entityType.Name, x, entityType);
                            }
                        }
                        return null;
                    }).Where(x => x != null).ToDictionary(x => x!.Item1, x => new Tuple<Type, Type>(x!.Item2, x!.Item3));
                return _formInstanceTypes;
            }
        }

        public static IEnumerable<Type> GetFormInstanceTypes()
        {
            return FormInstanceTypes.Select(x => x.Value.Item1);
        }

        public static Type? GetFormInstanceType(string appliesTo)
        {
            if (FormInstanceTypes.TryGetValue(appliesTo, out var result))
            {
                return result.Item1;
            }
            return null;
        }
        
        private static Dictionary<Type, IEntityFormUtils> _formUtils = new Dictionary<Type, IEntityFormUtils>();

        public static void AddFormUtils<TForm, TEntity, TEntityLink>(
            DelegateEntityFormUtils<TForm, TEntity, TEntityLink>.CanEditEvent editFormFunc,
            DelegateEntityFormUtils<TForm, TEntity, TEntityLink>.NewEntityEvent? newEntityFunc = null,
            DelegateEntityFormUtils<TForm, TEntity, TEntityLink>.OnSaveEvent? beforeSaveFunc = null)
            where TForm : EntityForm<TEntity, TEntityLink, TForm>
            where TEntity : Entity, new()
            where TEntityLink : EntityLink<TEntity>, new()
        {
            _formUtils.Add(typeof(TForm), new DelegateEntityFormUtils<TForm, TEntity, TEntityLink>(editFormFunc, newEntityFunc, beforeSaveFunc));
        }
        
        public static void AddFormUtils<TForm, TEntity, TEntityLink>(EntityFormUtils<TForm, TEntity, TEntityLink> formUtils)
            where TForm : EntityForm<TEntity, TEntityLink, TForm>
            where TEntity : Entity, new()
            where TEntityLink : EntityLink<TEntity>, new()
        {
            _formUtils.Add(typeof(TForm), formUtils);
        }

        public static bool CanEditForm(Type TForm, IDigitalFormInstance Form, Entity Entity)
        {
            if(_formUtils.TryGetValue(TForm, out var utils))
            {
                return utils.CanEditForm(Form, Entity);
            }
            return false;
        }
        
        public static bool CanEditForm<TForm, TEntity, TEntityLink>(TForm Form, TEntity Entity)
            where TForm : EntityForm<TEntity, TEntityLink, TForm>
            where TEntity : Entity, new()
            where TEntityLink : EntityLink<TEntity>, new()
        {
            return CanEditForm(typeof(TForm), Form, Entity);
        }

        public static Entity NewEntity(Type TForm, Type TEntity, DigitalForm form)
        {
            if (_formUtils.TryGetValue(TForm, out var utils))
            {
                return utils.NewEntity(form);
            }
            return (Activator.CreateInstance(TEntity) as Entity)!;
        }

        public static TEntity NewEntity<TForm, TEntity, TEntityLink>(DigitalForm form)
            where TForm : EntityForm<TEntity, TEntityLink, TForm>
            where TEntity : Entity, new()
            where TEntityLink : EntityLink<TEntity>, new()
        {
            return (TEntity)NewEntity(typeof(TForm), typeof(TEntity), form);
        }

        public static void OnSave(Type TForm, IDigitalFormInstance form, Entity entity)
        {
            if (_formUtils.TryGetValue(TForm, out var utils))
            {
                utils.OnSave(form, entity);
            }
        }
        
        public static void OnSave<TForm, TEntity, TEntityLink>(TForm form, TEntity entity)
            where TForm : EntityForm<TEntity, TEntityLink, TForm>
            where TEntity : Entity, new()
            where TEntityLink : EntityLink<TEntity>, new()
        {
            OnSave(typeof(TForm), form, entity);
        }

        public static Type? FormEntityType(DigitalForm form)
        {
            return FormEntityType(form.AppliesTo);
        }
        public static Type? FormEntityType(string appliesTo)
        {
            return CoreUtils.Entities.FirstOrDefault(x => string.Equals(x.Name, appliesTo));
        }

        public static Type FormEntityLinkType(Type TForm)
        {
            var formInstanceType = TForm.GetInterfaceDefinition(typeof(IDigitalFormInstance<>))
                ?? throw new Exception("Form does not implement IDigitalFormInstance<>");
            return formInstanceType.GenericTypeArguments[0];
        }

        public static Type FormEntityType(Type TForm)
        {
            var linkType = FormEntityLinkType(TForm);
            var linkInterface = linkType.GetInterfaceDefinition(typeof(IEntityLink<>));
            return linkInterface!.GenericTypeArguments[0];
        }

        /*public static IEntityLink GetParentLink(IDigitalFormInstance formInstance)
        {

            var parentlink = CoreUtils.HasProperty(formInstance.GetType(), "Parent")
                ? CoreUtils.GetPropertyValue(formInstance, "Parent") as IEntityLink
                : null;
        }*/

        public static IColumns RequiredEntityColumns(Type TEntity, IEnumerable<DigitalFormVariable> variables)
        {
            var entityColumns = LookupFactory.RequiredColumns(TEntity);
            foreach(var variable in variables)
            {
                var property = variable.GetProperties().Property;
                if (!property.IsNullOrWhiteSpace())
                {
                    entityColumns.Add(property);
                }
            }
            return entityColumns;
        }
        public static Columns<TEntity> EntityColumns<TEntity>(IEnumerable<DigitalFormVariable> variables) =>
            (RequiredEntityColumns(typeof(TEntity), variables) as Columns<TEntity>)!;
    }
}