using System.Collections.Concurrent;
using System.Reflection;
using System.Text.RegularExpressions;
using InABox.Core;

namespace InABox.Database
{
    public static class UserTrackingCache
    {
        public static ConcurrentBag<UserTracking> Cache = new();
        public static DateTime Date = DateTime.MinValue;
    }

    // public interface ICacheStore<T>
    // {
    //     void LoadCache();
    //     T GetCacheItem();
    //     void UpdateCache();
    // }

    public class Store<T> : IStore, IStore<T> where T : Entity, new()
    {
        public bool IsSubStore { get; set; }

        public Guid UserGuid { get; set; }
        public string UserID { get; set; }

        public string Platform { get; set; }
        public string Version { get; set; }
        public IProvider Provider { get; set; }

        public virtual void Init()
        {
            
        }
        
        private Type GetTrackingType(Type type)
        {
            var attr = type.GetCustomAttribute<UserTrackingAttribute>();

            if (attr == null)
                return type;

            if (!attr.Enabled)
                return null;

            if (attr.Parent != null)
                return GetTrackingType(attr.Parent);

            return type;
        }

        private void UpdateUserTracking(UserTrackingAction action)
        {
            if (IsSubStore)
                return;

            if (!DbFactory.IsSupported<UserTracking>())
                return;

            if (string.IsNullOrWhiteSpace(UserID))
                return;

            var type = GetTrackingType(typeof(T));
            if (type == null)
                return;

            if (UserTrackingCache.Date != DateTime.Today)
            {
                var tdata = Provider.Query(
                    new Filter<UserTracking>(x => x.Date).IsEqualTo(DateTime.Today),
                    new Columns<UserTracking>().Default(ColumnType.IncludeForeignKeys)
                );
                UserTrackingCache.Cache = new ConcurrentBag<UserTracking>(tdata.Rows.Select(x => x.ToObject<UserTracking>()));
                UserTrackingCache.Date = DateTime.Today;
            }

            var tracking = UserTrackingCache.Cache.FirstOrDefault(x =>
                Equals(x.User.ID, UserGuid) && DateTime.Equals(x.Date, DateTime.Today) && string.Equals(x.Type, type.Name));
            if (tracking == null)
            {
                tracking = new UserTracking();
                tracking.Date = DateTime.Today;
                tracking.Type = type.Name;
                tracking.User.ID = UserGuid;
                UserTrackingCache.Cache.Add(tracking);
            }

            tracking.Increment(DateTime.Now, action);
            Provider.Save(tracking);
        }

        protected IStore FindSubStore(Type t)
        {
            var defType = typeof(Store<>).MakeGenericType(t);

            var subType = DbFactory.Stores.Where(myType => myType.IsSubclassOf(defType)).FirstOrDefault();

            var result = (IStore)Activator.CreateInstance(subType == null ? defType : subType);
            result.UserGuid = UserGuid;
            result.UserID = UserID;
            result.Platform = Platform;
            result.Version = Version;
            result.IsSubStore = true;
            result.Provider = Provider;
            return result;
        }

        protected IStore<TEntity> FindSubStore<TEntity>() where TEntity : Entity, new()
        {
            var defType = typeof(Store<>).MakeGenericType(typeof(TEntity));

            var subType = DbFactory.Stores.Where(myType => myType.IsSubclassOf(defType)).FirstOrDefault();

            var store = (Store<TEntity>)Activator.CreateInstance(subType == null ? defType : subType);
            store.UserGuid = UserGuid;
            store.UserID = UserID;
            store.Platform = Platform;
            store.Version = Version;
            store.IsSubStore = true;
            store.Provider = Provider;
            return store;
        }

        private Filter<T>? RunScript(ScriptType type, Filter<T>? filter)
        {
            var scriptname = type.ToString();
            var key = string.Format("{0} {1}", typeof(T).EntityName(), scriptname);

            if (DbFactory.LoadedScripts.ContainsKey(key))
            {
                var script = DbFactory.LoadedScripts[key];

                Logger.Send(LogType.Information, UserID, string.Format("{0}.{1} Executing..", typeof(T).EntityName(), scriptname));
                try
                {
                    script.SetValue("Store", this);
                    script.SetValue("Filter", filter);
                    var result = script.Execute();
                    Logger.Send(LogType.Information, UserID, string.Format("{0}.{1} returns {2}", typeof(T).EntityName(), scriptname, result));
                    return result ? script.GetValue("Filter") as Filter<T> : filter;
                }
                catch (Exception eExec)
                {
                    Logger.Send(LogType.Information, UserID,
                        string.Format("{0}.{1} Invoke Exception: {2}", typeof(T).EntityName(), scriptname, eExec.Message));
                }
            }

            return filter;
        }

        private IEnumerable<T> RunScript(ScriptType type, IEnumerable<T> entities)
        {
            var scriptname = type.ToString();
            var variable = typeof(T).EntityName().Split('.').Last() + "s";
            var key = string.Format("{0} {1}", typeof(T).EntityName(), scriptname);
            if (DbFactory.LoadedScripts.ContainsKey(key))
            {
                var script = DbFactory.LoadedScripts[key];
                script.SetValue("Store", this);
                script.SetValue(variable, entities);
                Logger.Send(LogType.Information, UserID, string.Format("{0}.{1} Executing..", typeof(T).EntityName(), scriptname));
                foreach (var entity in entities)
                    try
                    {
                        var result = script.Execute();
                        Logger.Send(LogType.Information, UserID,
                            string.Format("{0}.{1} returns {2}: {3}", typeof(T).EntityName(), scriptname, result, entity));
                        return result ? script.GetValue(variable) as IEnumerable<T> : entities;
                    }
                    catch (Exception eExec)
                    {
                        var stack = new List<string>();
                        var eStack = eExec;
                        while (eStack != null)
                        {
                            stack.Add(eStack.Message);
                            eStack = eStack.InnerException;
                        }

                        stack.Reverse();
                        var message = string.Join("\n", stack);
                        Logger.Send(LogType.Information, UserID,
                            string.Format("{0}.{1} Invoke Exception: {2}", typeof(T).EntityName(), scriptname, message));
                    }
            }

            return entities;
        }

        private CoreTable RunScript(ScriptType type, CoreTable table)
        {
            var scriptname = type.ToString();
            var variable = typeof(T).EntityName().Split('.').Last() + "s";
            var key = string.Format("{0} {1}", typeof(T).EntityName(), scriptname);

            if (DbFactory.LoadedScripts.ContainsKey(key))
            {
                var script = DbFactory.LoadedScripts[key];
                Logger.Send(LogType.Information, UserID, string.Format("{0}.{1} Executing..", typeof(T).EntityName(), scriptname));
                try
                {
                    script.SetValue("Store", this);
                    script.SetValue(variable, table);
                    var result = script.Execute();
                    Logger.Send(LogType.Information, UserID,
                        string.Format("{0}.{1} returns {2}: {3}", typeof(T).EntityName(), scriptname, result, table));
                    return result ? script.GetValue(variable) as CoreTable : table;
                }
                catch (Exception eExec)
                {
                    Logger.Send(LogType.Information, UserID,
                        string.Format("{0}.{1} Invoke Exception: {2}", typeof(T).EntityName(), scriptname, eExec.Message));
                }
            }

            return table;
        }

        //#region Session / Transaction Handling
        //void //OpenSession(String action, bool write)
        //{
        //    if (!IsSubStore)
        //        Provider.OpenSession<T>(action, write);
        //}
        //void //CloseSession(String action, bool write)
        //{
        //    if (!IsSubStore)
        //        Provider.CloseSession<T>(action, write);
        //}
        //#endregion

        #region List Functions

        private IEnumerable<object[]> DoList(Filter<T>? filter = null, Columns<T>? columns = null, SortOrder<T>? sort = null)
        {
            UpdateUserTracking(UserTrackingAction.Read);

            //last = DateTime.Now;
            //OpenSession("List", false);
            //LogStep("OpenSession");

            try
            {
                var flt = PrepareFilter(filter);

                flt = RunScript(ScriptType.BeforeQuery, flt);

                var result = Provider.List(flt, columns, sort);

                //LogStep("PopulateTable");
                AfterList(result);

                //CloseSession("List", false);
                //LogStep("CloseSession");

                return result;
            }
            catch (Exception e)
            {
                //CloseSession("List", false);
                throw new Exception(e.Message + "\n\n" + e.StackTrace + "\n");
            }
        }

        public IEnumerable<object[]> List(Filter<T>? filter = null, Columns<T>? columns = null, SortOrder<T>? sort = null)
        {
            return DoList(filter, columns, sort);
        }

        public IEnumerable<object[]> List(Filter<Entity>? filter = null, Columns<Entity>? columns = null, SortOrder<Entity>? sort = null)
        {
            return DoList((Filter<T>?)filter, (Columns<T>)columns, (SortOrder<T>)sort);
        }

        protected virtual void AfterList(IEnumerable<object[]> data)
        {
        }

        #endregion

        #region Query Functions

        protected virtual CoreTable OnQuery(Filter<T>? filter, Columns<T>? columns, SortOrder<T>? sort)
        {
            return Provider.Query(filter, columns, sort);
        }
        
        private CoreTable DoQuery(Filter<T>? filter = null, Columns<T>? columns = null, SortOrder<T>? sort = null)
        {
            UpdateUserTracking(UserTrackingAction.Read);

            //last = DateTime.Now;
            //OpenSession("Query", false);
            //LogStep("OpenSession");

            try
            {
                var flt = PrepareFilter(filter);

                flt = RunScript(ScriptType.BeforeQuery, flt);

                var result = OnQuery(filter, columns, sort);

                //LogStep("PopulateTable");
                AfterQuery(result);

                result = RunScript(ScriptType.AfterQuery, result);

                //CloseSession("Query", false);
                //LogStep("CloseSession");

                return result;
            }
            catch (Exception e)
            {
                //CloseSession("Query", false);
                throw new Exception(e.Message + "\n\n" + e.StackTrace + "\n");
            }
        }

        public CoreTable Query(Filter<T>? filter = null, Columns<T>? columns = null, SortOrder<T>? sort = null)
        {
            return DoQuery(filter, columns, sort);
        }

        public CoreTable Query(Filter<Entity>? filter = null, Columns<Entity>? columns = null, SortOrder<Entity>? sort = null)
        {
            return DoQuery((Filter<T>?)filter, (Columns<T>)columns, (SortOrder<T>)sort);
        }

        protected virtual void AfterQuery(CoreTable data)
        {
        }

        #endregion

        #region Load Functions

        protected virtual Filter<T>? PrepareFilter(Filter<T>? filter)
        {
            return filter;
        }

        private T[] DoLoad(Filter<T>? filter = null, SortOrder<T>? sort = null)
        {
            UpdateUserTracking(UserTrackingAction.Read);

            //OpenSession("Load", false);

            T[] results = null;

            try
            {
                var flt = PrepareFilter(filter);

                flt = RunScript(ScriptType.BeforeQuery, flt);

                results = Provider.Load(flt, sort);

                AfterLoad(results);

                //CloseSession("Load", false);

                results = RunScript(ScriptType.AfterLoad, results) as T[];

                return results;
            }
            catch (Exception e)
            {
                //CloseSession("Load", false);
                throw new Exception(e.Message + "\n\n" + e.StackTrace + "\n");
            }
        }

        public Entity[] Load(Filter<Entity>? filter = null, SortOrder<Entity>? sort = null)
        {
            return DoLoad((Filter<T>?)filter, sort != null ? (SortOrder<T>)sort : null);
        }

        public T[] Load(Filter<T>? filter = null, SortOrder<T>? sort = null)
        {
            return DoLoad(filter, sort);
        }

        protected virtual void AfterLoad(IEnumerable<T> items)
        {
            foreach (var item in items)
                item.SetObserving(true);
        }

        #endregion

        #region Saving Functions

        private static readonly Regex IsNumeric = new(@"^\d+$");

        private void CheckAutoIncrement(params T[] entities)
        {
            if (ProcessNumericAutoInc(entities))
                return;
            ProcessStringAutoIncrement(entities);
        }

        public static string AutoIncrementPrefix { get; set; }
        
        private bool ProcessStringAutoIncrement(params T[] entities)
        {
            if (!entities.Any())
                return false;

            var autoinc = entities.First() as IStringAutoIncrement<T>;
            if (autoinc != null)
            {
                var prop = CoreUtils.GetPropertyFromExpression<T, string>(autoinc.AutoIncrementField());
                var bRequired = false;
                foreach (var entity in entities)
                    bRequired = bRequired || string.IsNullOrWhiteSpace(prop.GetValue(entity) as string);
                if (bRequired)
                {
                    
                    var filter = new Filter<T>(prop.Name).IsGreaterThanOrEqualTo(String.Format("{0}0", AutoIncrementPrefix))
                        .And(prop.Name).IsLessThanOrEqualTo(String.Format("{0}9999999999", AutoIncrementPrefix));
                    
                    var filter2 = autoinc.AutoIncrementFilter();
                    if (filter2 != null)
                        filter = filter.And(filter2);

                    // if (!string.IsNullOrWhiteSpace(AutoIncrementPrefix))
                    // {
                    //     var prefixfilter = new Filter<T>(prop.Name).BeginsWith(AutoIncrementPrefix);
                    //     filter = filter == null ? prefixfilter : filter.And(prefixfilter);
                    // }

                    var newvalue = 0;
                    var row = Provider.Query(
                        filter,
                        new Columns<T>(new[] { prop.Name }),
                        new SortOrder<T>(prop.Name, SortDirection.Descending),
                        1
                    ).Rows.FirstOrDefault();
                    if (row != null)
                    {
                        var id = row.Get<string>(prop.Name);
                        if (!string.IsNullOrWhiteSpace(AutoIncrementPrefix))
                            id = id.Substring(AutoIncrementPrefix.Length);
                        id = new string(id.Where(c => char.IsDigit(c)).ToArray());
                        int.TryParse(id, out newvalue);
                    }
                    foreach (var entity in entities)
                        if (string.IsNullOrWhiteSpace(prop.GetValue(entity) as string))
                        {
                            newvalue++;
                            prop.SetValue(entity, AutoIncrementPrefix + string.Format(autoinc.AutoIncrementFormat(), newvalue));
                        }

                    return true;
                }
            }

            return false;
        }
        
        private bool ProcessNumericAutoInc(params T[] entities)
        {
            if (!entities.Any())
                return false;
            var autoinc = entities.First() as INumericAutoIncrement<T>;
            if (autoinc != null)
            {
                var prop = CoreUtils.GetPropertyFromExpression(autoinc.AutoIncrementField());
                
                var bRequired = false;
                foreach (var entity in entities)
                    bRequired = bRequired || prop.GetValue(entity).Equals(0);
                if (bRequired)
                {
                    
                    var row = Provider.Query(
                        autoinc.AutoIncrementFilter(), 
                        new Columns<T>(new[] { prop.Name }), 
                        new SortOrder<T>(prop.Name,SortDirection.Descending),
                        1
                    ).Rows.FirstOrDefault();
                    int newvalue = row != null ? row.Get<int>(prop.Name) : 0;

                    foreach (var entity in entities)
                    {
                        if (prop.GetValue(entity).Equals(0))
                        {
                            newvalue++;
                            prop.SetValue(entity, newvalue);
                        }
                    }
                    return true;
                }
            }

            return false;
        }

        protected virtual void BeforeSave(T entity)
        {
            // Process any AutoIncrement Fields before we apply the Unique Code test
            // Thus, if we have a unique autoincrement, it will be populated prior to validation
            CheckAutoIncrement(entity);

            // Check for (a) blank code fields and (b) duplicate codes
            // There may be more than one code on an entity (why would you do this?)
            // so it's a bit trickier that I would hope

            Filter<T> codes = null;
            var columns = new Columns<T>(x => x.ID);
            var props = CoreUtils.PropertyList(typeof(T), x => x.GetCustomAttributes<UniqueCodeEditor>().Any(), true);
            foreach (var key in props.Keys)
                if (entity.HasOriginalValue(key) || entity.ID == Guid.Empty)
                {
                    var code = CoreUtils.GetPropertyValue(entity, key) as string;
                    if (string.IsNullOrWhiteSpace(code))
                        throw new NullCodeException(typeof(T), key);

                    var expr = CoreUtils.GetPropertyExpression<T, object>(key); //CoreUtils.GetMemberExpression(typeof(T),key)
                    codes = codes == null ? new Filter<T>(expr).IsEqualTo(code) : codes.Or(expr).IsEqualTo(code);
                    columns.Add(key);
                }

            if (codes != null)
            {
                var filter = new Filter<T>(x => x.ID).IsNotEqualTo(entity.ID);
                filter = filter.And(codes);
                var others = Provider.Query(filter, columns);

                var duplicates = new Dictionary<string, object>();
                foreach (var row in others.Rows)
                foreach (var key in props.Keys)
                {
                    var eval = CoreUtils.GetPropertyValue(entity, key);
                    var cval = row.Get<string>(key);
                    if (Equals(eval, cval))
                        duplicates[key] = eval;
                }

                if (duplicates.Any())
                    throw new DuplicateCodeException(typeof(T), duplicates);
            }
        }

        protected virtual void AfterSave(T entity)
        {
        }

        protected virtual void OnSave(T entity, ref string auditnote)
        {
            CheckAutoIncrement(entity);
            Provider.Save(entity);
        }

        private void DoSave(T entity, string auditnote)
        {
            UpdateUserTracking(UserTrackingAction.Write);

            entity = RunScript(ScriptType.BeforeSave, new[] { entity }).First();

            //OpenSession("Save", true);

            //try
            //{

            var changes = entity.ChangedValues();

            //UpdateInternalLinks(entity);

            BeforeSave(entity);

            //OpenSession("Save", true);
            try
            {
                OnSave(entity, ref auditnote);
            }
            catch (Exception e)
            {
                //CloseSession("Save", true);
                throw e;
            }
            //CloseSession("Save", true);

            if (DbFactory.IsSupported<AuditTrail>())
            {
                var notes = new List<string>();
                if (!string.IsNullOrEmpty(auditnote))
                    notes.Add(auditnote);
                if (!string.IsNullOrEmpty(changes))
                    notes.Add(changes);
                if (notes.Any()) AuditTrail(entity, notes);
            }

            AfterSave(entity);

            //UpdateExternalLinks(entity, false);

            entity.CommitChanges();

            //CloseSession("Save", false);

            entity = RunScript(ScriptType.AfterSave, new[] { entity }).First();
            //}
            //catch (Exception e)
            //{
            //	//CloseSession("Save", false);
            //    throw new Exception(e.Message + "\n\n" + e.StackTrace + "\n");
            //}
        }

        protected void AuditTrail(IEnumerable<Entity> entities, IEnumerable<string> notes)
        {
            var updates = new List<AuditTrail>();
            foreach (var entity in entities)
            {
                var audit = new AuditTrail
                {
                    EntityID = entity.ID,
                    Timestamp = DateTime.Now,
                    User = UserID,
                    Note = string.Join(": ", notes)
                };
                updates.Add(audit);
            }

            Provider.Save(updates);
        }

        protected void AuditTrail(Entity entity, IEnumerable<string> notes)
        {
            AuditTrail(new[] { entity }, notes);
        }

        public void Save(T entity, string auditnote)
        {
            DoSave(entity, auditnote);
        }

        public void Save(Entity entity, string auditnote)
        {
            var ent = (T)entity;
            DoSave(ent, auditnote);
        }

        public void Save(IEnumerable<T> entities, string auditnote)
        {
            DoSave(entities, auditnote);
        }

        public void Save(IEnumerable<Entity> entities, string auditnote)
        {
            var updates = new List<T>();
            foreach (var entity in entities)
                updates.Add((T)entity);
            DoSave(updates, auditnote);
        }

        protected virtual void OnSave(IEnumerable<T> entities, ref string auditnote)
        {
            CheckAutoIncrement(entities.ToArray());
            Provider.Save(entities);
        }

        private void DoSave(IEnumerable<T> entities, string auditnote)
        {
            UpdateUserTracking(UserTrackingAction.Write);

            entities = RunScript(ScriptType.BeforeSave, entities.ToList());

            //OpenSession("Save", true);

            //try
            //{

            var changes = new Dictionary<T, string>();
            foreach (var entity in entities)
            {
                changes[entity] = entity.ChangedValues();
                //UpdateInternalLinks(entity);
                BeforeSave(entity);
            }

            try
            {
                //OpenSession("Save", true);
                OnSave(entities, ref auditnote);
                //CloseSession("Save", true);
            }
            catch (Exception e)
            {
                //CloseSession("Save", true);
                throw e;
            }

            if (DbFactory.IsSupported<AuditTrail>())
            {
                var audittrails = new List<AuditTrail>();
                foreach (var entity in entities)
                {
                    var notes = new List<string>();

                    if (!string.IsNullOrEmpty(auditnote))
                        notes.Add(auditnote);

                    if (changes.ContainsKey(entity) && !string.IsNullOrEmpty(changes[entity]))
                        notes.Add(changes[entity]);

                    if (notes.Any())
                    {
                        var audit = new AuditTrail
                        {
                            EntityID = entity.ID,
                            Timestamp = DateTime.Now,
                            User = UserID,
                            Note = string.Join(": ", notes)
                        };
                        audittrails.Add(audit);
                        //Provider.Save<AuditTrail>(audit);
                    }
                }

                if (audittrails.Any())
                    Provider.Save(audittrails);
            }

            foreach (var entity in entities)
            {
                AfterSave(entity);
                //UpdateExternalLinks(entity, false);
                entity.CommitChanges();
            }

            entities = RunScript(ScriptType.AfterSave, entities);

            //}
            //catch (Exception e)
            //{
            //    throw e;
            //}
        }

        #endregion

        #region Delete Functions

        protected virtual void BeforeDelete(T entity)
        {
        }

        protected virtual void OnDelete(T entity)
        {
            Provider.Delete(entity, UserID);
        }
        protected virtual void OnDelete(IEnumerable<T> entities)
        {
            Provider.Delete(entities, UserID);
        }

        private void DoDelete(T entity, string auditnote)
        {
            UpdateUserTracking(UserTrackingAction.Write);

            entity = RunScript(ScriptType.BeforeDelete, new[] { entity }).First();

            //OpenSession("Delete",false);
            try
            {
                BeforeDelete(entity);

                //OpenSession("Delete",true);
                try
                {
                    OnDelete(entity);
                }
                catch (Exception e)
                {
                    //CloseSession("Delete", true);
                    throw e;
                }
                //CloseSession("Delete",true);

                AfterDelete(entity);

                //UpdateExternalLinks(entity, true);

                //CloseSession("Delete", false);

                entity = RunScript(ScriptType.AfterDelete, new[] { entity }).First();
            }
            catch (Exception e)
            {
                //CloseSession("Delete", false);
                throw new Exception(e.Message + "\n\n" + e.StackTrace + "\n");
            }
        }

        private void DoDelete(IEnumerable<T> entities, string auditnote)
        {
            UpdateUserTracking(UserTrackingAction.Write);

            entities = RunScript(ScriptType.BeforeDelete, entities);

            //OpenSession("Delete", false);
            try
            {
                foreach (var entity in entities)
                    BeforeDelete(entity);

                //OpenSession("Delete", true);
                try
                {
                    OnDelete(entities);
                }
                catch (Exception e)
                {
                    ////CloseSession("Delete", true);
                    throw e;
                }

                ////CloseSession("Delete", true);

                foreach (var entity in entities) AfterDelete(entity);
                //UpdateExternalLinks(entity, true);
                ////CloseSession("Delete", false);

                entities = RunScript(ScriptType.AfterDelete, entities);
            }
            catch (Exception e)
            {
                ////CloseSession("Delete", false);
                throw new Exception(e.Message + "\n\n" + e.StackTrace + "\n");
            }
        }

        public void Delete(T entity, string auditnote)
        {
            DoDelete(entity, auditnote);
        }

        public void Delete(Entity entity, string auditnote)
        {
            DoDelete((T)entity, auditnote);
        }

        public void Delete(IEnumerable<T> entities, string auditnote)
        {
            DoDelete(entities, auditnote);
        }

        public void Delete(IEnumerable<Entity> entities, string auditnote)
        {
            var updates = new List<T>();
            foreach (var entity in entities)
                updates.Add((T)entity);
            DoDelete(updates, auditnote);
        }

        protected virtual void AfterDelete(T entity)
        {
        }

        #endregion

        #region BulkUpdate Functions

        public void BulkUpdate(IEnumerable<Entity> entities)
        {
            BulkUpdate((IEnumerable<T>)entities);
        }

        public virtual void BulkUpdate(IEnumerable<T> entities)
        {
            UpdateUserTracking(UserTrackingAction.Write);
            Provider.Save(entities);
        }

        #endregion
    }
}