/*
 
Copyright (c) 2017 Ahmed Kh. Zamil

Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all
copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
SOFTWARE.

*/

using Esiur.Data;
using Esiur.Core;
using Esiur.Proxy;
using Esiur.Resource.Template;
using Esiur.Security.Permissions;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using Esiur.Net.IIP;
using System.Text.RegularExpressions;
using Esiur.Misc;
using System.Collections.Concurrent;
using System.Collections;
using System.Data;

namespace Esiur.Resource;

// Centeral Resource Issuer
public static class Warehouse
{
    //static byte prefixCounter;

    //static AutoList<IStore, Instance> stores = new AutoList<IStore, Instance>(null);
    static ConcurrentDictionary<uint, WeakReference<IResource>> resources = new ConcurrentDictionary<uint, WeakReference<IResource>>();
    static ConcurrentDictionary<IStore, List<WeakReference<IResource>>> stores = new ConcurrentDictionary<IStore, List<WeakReference<IResource>>>();


    static uint resourceCounter = 0;

 
    static KeyList<TemplateType, KeyList<Guid, TypeTemplate>> templates
        = new KeyList<TemplateType, KeyList<Guid, TypeTemplate>>()
        {
            [TemplateType.Unspecified] = new KeyList<Guid, TypeTemplate>(),
            [TemplateType.Resource] = new KeyList<Guid, TypeTemplate>(),
            [TemplateType.Record] = new KeyList<Guid, TypeTemplate>(),
            [TemplateType.Wrapper] = new KeyList<Guid, TypeTemplate>(),
            [TemplateType.Enum] = new KeyList<Guid, TypeTemplate>(),
        };

    static bool warehouseIsOpen = false;

    public delegate void StoreEvent(IStore store);//, string name);
                                                  // public delegate void StoreDisconnectedEvent(IStore store);

    public static event StoreEvent StoreConnected;
    //public static event StoreEvent StoreOpen;
    public static event StoreEvent StoreDisconnected;

    public delegate AsyncReply<IStore> ProtocolInstance(string name, object properties);

    public static KeyList<string, ProtocolInstance> Protocols { get; } = GetSupportedProtocols();

    private static Regex urlRegex = new Regex(@"^(?:([\S]*)://([^/]*)/?)");

    //private static object resourcesLock = new object();

    static KeyList<string, ProtocolInstance> GetSupportedProtocols()
    {
        var rt = new KeyList<string, ProtocolInstance>();
        rt.Add("iip", async (name, attributes) => await Warehouse.New<DistributedConnection>(name, null, null, null, attributes));
        return rt;
    }

    /// <summary>
    /// Get a store by its name.
    /// </summary>
    /// <param name="name">Store instance name</param>
    /// <returns></returns>
    public static IStore GetStore(string name)
    {
        foreach (var s in stores)
            if (s.Key.Instance.Name == name)
                return s.Key;
        return null;
    }

    public static WeakReference<IResource>[] Resources => resources.Values.ToArray();

    /// <summary>
    /// Get a resource by instance Id.
    /// </summary>
    /// <param name="id">Instance Id</param>
    /// <returns></returns>
    public static AsyncReply<IResource> GetById(uint id)
    {
        if (resources.ContainsKey(id))
        {
            IResource r;
            if (resources[id].TryGetTarget(out r))
                return new AsyncReply<IResource>(r);
            else
                return new AsyncReply<IResource>(null);
        }
        else
            return new AsyncReply<IResource>(null);
    }

    static void LoadGenerated()
    {
        foreach (var assembly in AppDomain.CurrentDomain.GetAssemblies())
        {
            var generatedType = assembly.GetType("Esiur.Generated");
            if (generatedType != null)
            {
                var resourceTypes = (Type[])generatedType.GetProperty("Resources").GetValue(null);
                foreach (var t in resourceTypes)
                {
                    PutTemplate(new TypeTemplate(t));
                }

                var recordTypes = (Type[])generatedType.GetProperty("Records").GetValue(null);
                foreach (var t in recordTypes)
                {
                    PutTemplate(new TypeTemplate(t));
                }

                var enumsTypes = (Type[])generatedType.GetProperty("Enums").GetValue(null);
                foreach (var t in recordTypes)
                {
                    PutTemplate(new TypeTemplate(t));
                }
            }
        }
    }

    /// <summary>
    /// Open the warehouse.
    /// This function issues the initialize trigger to all stores and resources.
    /// </summary>
    /// <returns>True, if no problem occurred.</returns>
    public static async AsyncReply<bool> Open()
    {
        if (warehouseIsOpen)
            return false;

        // Load generated models
        LoadGenerated();


        warehouseIsOpen = true;

        var resSnap = resources.Select(x =>
        {
            IResource r;
            if (x.Value.TryGetTarget(out r))
                return r;
            else
                return null;
        }).Where(r => r != null).ToArray();

        foreach (var r in resSnap)
        {
            //IResource r;
            //if (rk.Value.TryGetTarget(out r))
            //{
            var rt = await r.Trigger(ResourceTrigger.Initialize);
            //if (!rt)
            //  return false;

            if (!rt)
            {
                Console.WriteLine($"Resource failed at Initialize {r.Instance.Name} [{r.Instance.Template.ClassName}]");
            }
            //}
        }

        foreach (var r in resSnap)
        {
            //IResource r;
            //if (rk.Value.TryGetTarget(out r))
            //{
            var rt = await r.Trigger(ResourceTrigger.SystemInitialized);
            if (!rt)
            {
                Console.WriteLine($"Resource failed at SystemInitialized {r.Instance.Name} [{r.Instance.Template.ClassName}]");
            }
            //return false;
            //}
        }


        return true;

        /*
        var bag = new AsyncBag<bool>();

        //foreach (var store in stores)
        //    bag.Add(store.Trigger(ResourceTrigger.Initialize));


        bag.Seal();

        var rt = new AsyncReply<bool>();
        bag.Then((x) =>
        {
            foreach (var b in x)
                if (!b)
                {
                    rt.Trigger(false);
                    return;
                }

            var rBag = new AsyncBag<bool>();
            foreach (var rk in resources)
            {
                IResource r;
                if (rk.Value.TryGetTarget(out r))
                    rBag.Add(r.Trigger(ResourceTrigger.Initialize));
            }

            rBag.Seal();

            rBag.Then(y =>
            {
                foreach (var b in y)
                    if (!b)
                    {
                        rt.Trigger(false);
                        return;
                    }

                rt.Trigger(true);
                warehouseIsOpen = true;
            });

        });


        return rt;
        */
    }

    /// <summary>
    /// Close the warehouse.
    /// This function issues terminate trigger to all resources and stores.
    /// </summary>
    /// <returns>True, if no problem occurred.</returns>
    public static AsyncReply<bool> Close()
    {

        var bag = new AsyncBag<bool>();

        foreach (var resource in resources.Values)
        {
            IResource r;
            if (resource.TryGetTarget(out r))
            {
                if (!(r is IStore))
                    bag.Add(r.Trigger(ResourceTrigger.Terminate));

            }
        }

        foreach (var store in stores)
            bag.Add(store.Key.Trigger(ResourceTrigger.Terminate));


        foreach (var resource in resources.Values)
        {
            IResource r;
            if (resource.TryGetTarget(out r))
            {
                if (!(r is IStore))
                    bag.Add(r.Trigger(ResourceTrigger.SystemTerminated));
            }
        }


        foreach (var store in stores)
            bag.Add(store.Key.Trigger(ResourceTrigger.SystemTerminated));

        bag.Seal();

        var rt = new AsyncReply<bool>();
        bag.Then((x) =>
        {
            foreach (var b in x)
                if (!b)
                {
                    rt.Trigger(false);
                    return;
                }

            rt.Trigger(true);
        });

        return rt;
    }


    /*
    private static IResource[] QureyIn(string[] path, int index, IEnumerable<IResource> resources)// AutoList<IResource, Instance> resources)
    {
        var rt = new List<IResource>();

        if (index == path.Length - 1)
        {
            if (path[index] == "")
                foreach (IResource child in resources)
                  rt.Add(child);
             else
                foreach (IResource child in resources)
                    if (child.Instance.Name == path[index])
                        rt.Add(child);
        }
        else
            foreach (IResource child in resources)
                if (child.Instance.Name == path[index])
                    rt.AddRange(QureyIn(path, index+1, child.Instance.Children<IResource>()));

        return rt.ToArray();
    }

    public static AsyncReply<IResource[]> Query(string path)
    {
        if (path == null || path == "")
        {
            var roots = stores.Where(s => s.Instance.Parents<IResource>().Count() == 0).ToArray();
            return new AsyncReply<IResource[]>(roots);
        }
        else
        {
            var rt = new AsyncReply<IResource[]>();
            Get(path).Then(x =>
            {
                var p = path.Split('/');

                if (x == null)
                {
                    rt.Trigger(QureyIn(p, 0, stores));
                }
                else
                {
                    var ar = QureyIn(p, 0, stores).Where(r => r != x).ToList();
                    ar.Insert(0, x);
                    rt.Trigger(ar.ToArray());
                }
            });

            return rt;

        }

    }
    */



    public static async AsyncReply<IResource[]> Query(string path)
    {
        var rt = new AsyncReply<IResource[]>();

        var p = path.Trim().Split('/');
        IResource resource;

        foreach (var store in stores.Keys)
            if (p[0] == store.Instance.Name)
            {

                if (p.Length == 1)
                    return new IResource[] { store };

                var res = await store.Get(String.Join("/", p.Skip(1).ToArray()));
                if (res != null)
                    return new IResource[] { res };


                resource = store;
                for (var i = 1; i < p.Length; i++)
                {
                    var children = await resource.Instance.Children<IResource>(p[i]);
                    if (children.Length > 0)
                    {
                        if (i == p.Length - 1)
                            return children;
                        else
                            resource = children[0];
                    }
                    else
                        break;
                }

                return null;
            }



        return null;
    }

    /// <summary>
    /// Get a resource by its path.
    /// Resource path is sperated by '/' character, e.g. "system/http".
    /// </summary>
    /// <param name="path"></param>
    /// <returns>Resource instance.</returns>
    public static async AsyncReply<T> Get<T>(string path, object attributes = null, IResource parent = null, IPermissionsManager manager = null)
        where T : IResource
    {
        //var rt = new AsyncReply<IResource>();

        // Should we create a new store ?

        if (urlRegex.IsMatch(path))
        {

            var url = urlRegex.Split(path);

            if (Protocols.ContainsKey(url[1]))
            {
                if (!warehouseIsOpen)
                    await Open();

                var handler = Protocols[url[1]];
                var store = await handler(url[2], attributes);

                try
                {
                    //await Put(store, url[2], null, parent, null, 0, manager, attributes);

                    if (url[3].Length > 0 && url[3] != "")
                        return (T)await store.Get(url[3]);
                    else
                        return (T)store;

                }
                catch (Exception ex)
                {
                    Warehouse.Remove(store);
                    throw ex;
                }

            }


            //    store.Get(url[3]).Then(r =>
            //        {
            //            rt.Trigger(r);
            //        }).Error(e =>
            //        {
            //            Warehouse.Remove(store);
            //            rt.TriggerError(e);
            //        });
            //    else
            //        rt.Trigger(store);

            //    store.Trigger(ResourceTrigger.Open).Then(x =>
            //    {

            //        warehouseIsOpen = true;
            //        await Put(store, url[2], null, parent, null, 0, manager, attributes);

            //        if (url[3].Length > 0 && url[3] != "")
            //            store.Get(url[3]).Then(r =>
            //            {
            //                rt.Trigger(r);
            //            }).Error(e =>
            //            {
            //                Warehouse.Remove(store);
            //                rt.TriggerError(e);
            //            });
            //        else
            //            rt.Trigger(store);
            //    }).Error(e =>
            //    {
            //        rt.TriggerError(e);
            //        //Warehouse.Remove(store);
            //    });

            //    return rt;
            //}
        }


        //await Query(path).Then(rs =>
        //{
        //    //                rt.TriggerError(new Exception());
        //    if (rs != null && rs.Length > 0)
        //        rt.Trigger(rs.First());
        //    else
        //        rt.Trigger(null);
        //});

        //return rt;

        var res = await Query(path);

        if (res.Length == 0)
            return default(T);
        else
            return (T)res.First();

    }


    //public static async AsyncReply<T> Push<T>(string path, T resource) where T : IResource
    //{
    //    await Put(path, resource);
    //    return resource;
    //}

    /// <summary>
    /// Put a resource in the warehouse.
    /// </summary>
    /// <param name="name">Resource name.</param>
    /// <param name="resource">Resource instance.</param>
    /// <param name="store">IStore that manages the resource. Can be null if the resource is a store.</param>
    /// <param name="parent">Parent resource. if not presented the store becomes the parent for the resource.</param>
    public static async AsyncReply<T> Put<T>(string name, T resource, IStore store = null, IResource parent = null, TypeTemplate customTemplate = null, ulong age = 0, IPermissionsManager manager = null, object attributes = null) where T : IResource
    {
        if (resource.Instance != null)
            throw new Exception("Resource has a store.");

        var path = name.TrimStart('/').Split('/');

        if (path.Length > 1)
        {
            if (parent != null)
                throw new Exception("Parent can't be set when using path in instance name");

            parent = await Warehouse.Get<IResource>(string.Join("/", path.Take(path.Length - 1)));

            if (parent == null)
                throw new Exception("Can't find parent");

            store = store ?? parent.Instance.Store;
        }

        var instanceName = path.Last();


        var resourceReference = new WeakReference<IResource>(resource);

        if (store == null)
        {
            // assign parent's store as a store
            if (parent != null)
            {
                // assign parent as a store
                if (parent is IStore)
                {
                    store = (IStore)parent;
                    List<WeakReference<IResource>> list;
                    if (stores.TryGetValue(store, out list))
                        lock (((ICollection)list).SyncRoot)
                            list.Add(resourceReference);
                    //stores[store].Add(resourceReference);
                }
                else
                {
                    store = parent.Instance.Store;

                    List<WeakReference<IResource>> list;
                    if (stores.TryGetValue(store, out list))
                        lock (((ICollection)list).SyncRoot)
                            list.Add(resourceReference);
                }
            }
            // assign self as a store (root store)
            else if (resource is IStore)
            {
                store = (IStore)resource;
            }
            else
                throw new Exception("Can't find a store for the resource.");
        }

        resource.Instance = new Instance(resourceCounter++, instanceName, resource, store, customTemplate, age);

        if (attributes != null)
            resource.Instance.SetAttributes(Map<string,object>.FromObject(attributes));

        if (manager != null)
            resource.Instance.Managers.Add(manager);

        if (store == parent)
            parent = null;




        try
        {
            if (resource is IStore)
                stores.TryAdd(resource as IStore, new List<WeakReference<IResource>>());


            if (!await store.Put(resource))
                throw new Exception("Store failed to put the resource");
            //return default(T);


            if (parent != null)
            {
                await parent.Instance.Store.AddChild(parent, resource);
                await store.AddParent(resource, parent);
            }

            var t = resource.GetType();
            Global.Counters["T-" + t.Namespace + "." + t.Name]++;


            resources.TryAdd(resource.Instance.Id, resourceReference);

            if (warehouseIsOpen)
            {
                await resource.Trigger(ResourceTrigger.Initialize);
                if (resource is IStore)
                    await resource.Trigger(ResourceTrigger.Open);
            }

            if (resource is IStore)
                StoreConnected?.Invoke(resource as IStore);
        }
        catch (Exception ex)
        {
            Warehouse.Remove(resource);
            throw ex;
        }

        return resource;

    }

    public static async AsyncReply<IResource> New(Type type, string name = null, IStore store = null, IResource parent = null, IPermissionsManager manager = null, object attributes = null, object properties = null)
    {

        type = ResourceProxy.GetProxy(type);


        /*
        if (arguments != null)
        {
            var constructors = type.GetConstructors(System.Reflection.BindingFlags.Public);

            foreach(var constructor in constructors)
            {
                var pi = constructor.GetParameters();
                if (pi.Length == constructor.le)
            }

            // cast arguments
            ParameterInfo[] pi = fi.GetParameters();

            object[] args = new object[pi.Length];

            for (var i = 0; i < pi.Length; i++)
            {
                if (pi[i].ParameterType == typeof(DistributedConnection))
                {
                    args[i] = this;
                }
                else if (namedArgs.ContainsKey(pi[i].Name))
                {
                    args[i] = DC.CastConvert(namedArgs[pi[i].Name], pi[i].ParameterType);
                }
            }

            constructors[0].
        }
        */
        var res = Activator.CreateInstance(type) as IResource;


        if (properties != null)
        {
            var ps = Map<string,object>.FromObject(properties);

            foreach (var p in ps)
            {

                var pi = type.GetProperty(p.Key, System.Reflection.BindingFlags.Public | System.Reflection.BindingFlags.Instance);
                if (pi != null)
                {
                    if (pi.CanWrite)
                    {
                        try
                        {
                            pi.SetValue(res, p.Value);
                        }
                        catch (Exception ex)
                        {
                            Global.Log(ex);
                        }
                    }
                }
                else
                {
                    var fi = type.GetField(p.Key, System.Reflection.BindingFlags.Public | System.Reflection.BindingFlags.Instance);
                    if (fi != null)
                    {
                        try
                        {
                            fi.SetValue(res, p.Value);
                        }
                        catch (Exception ex)
                        {
                            Global.Log(ex);
                        }
                    }
                }
            }
        }

        if (store != null || parent != null || res is IStore)
        {
            //if (!await Put(name, res, store, parent, null, 0, manager, attributes))
            //    return null;

            await Put(name, res, store, parent, null, 0, manager, attributes);
        }

        return res;

    }

    public static async AsyncReply<T> New<T>(string name, IStore store = null, IResource parent = null, IPermissionsManager manager = null, object attributes = null, object properties = null)
        where T : IResource
    {
        return (T)(await New(typeof(T), name, store, parent, manager, attributes, properties));
    }

    /// <summary>
    /// Put a resource template in the templates warehouse.
    /// </summary>
    /// <param name="template">Resource template.</param>
    public static void PutTemplate(TypeTemplate template)
    {
        templates[template.Type][template.ClassId] = template;
    }


    /// <summary>
    /// Get a template by type from the templates warehouse. If not in the warehouse, a new ResourceTemplate is created and added to the warehouse.
    /// </summary>
    /// <param name="type">.Net type.</param>
    /// <returns>Resource template.</returns>
    public static TypeTemplate GetTemplateByType(Type type)
    {

        TemplateType templateType = TemplateType.Unspecified;

        if (Codec.InheritsClass(type, typeof(DistributedResource)))
            templateType = TemplateType.Wrapper;
        if (Codec.ImplementsInterface(type, typeof(IResource)))
            templateType = TemplateType.Resource;
        else if (Codec.ImplementsInterface(type, typeof(IRecord)))
            templateType = TemplateType.Record;
        else if (type.IsEnum)
            templateType = TemplateType.Enum;
        else
            return null;

        var baseType = ResourceProxy.GetBaseType(type);

        if (baseType == typeof(IResource)
            || baseType == typeof(IRecord))
            return null;

        var template = templates[templateType].Values.FirstOrDefault(x => x.DefinedType == type);

        // loaded ?
        if (template == null)
        {
            template = new TypeTemplate(baseType, true);
            TypeTemplate.GetDependencies(template);
        }

        return template;
    }

    /// <summary>
    /// Get a template by class Id from the templates warehouse. If not in the warehouse, a new ResourceTemplate is created and added to the warehouse.
    /// </summary>
    /// <param name="classId">Class Id.</param>
    /// <returns>Resource template.</returns>
    public static TypeTemplate GetTemplateByClassId(Guid classId, TemplateType templateType = TemplateType.Unspecified)
    {
        if (templateType == TemplateType.Unspecified)
        {
            // look in resources
            var template = templates[TemplateType.Resource][classId];
            if (template != null)
                return template;

            // look in records
            template = templates[TemplateType.Record][classId];
            if (template != null)
                return template;

            // look in enums
            template = templates[TemplateType.Enum][classId];
            if (template != null)
                return template;


            // look in wrappers
            template = templates[TemplateType.Wrapper][classId];
            return template;
        }
        else
            return templates[templateType][classId];
    }

    /// <summary>
    /// Get a template by class name from the templates warehouse. If not in the warehouse, a new ResourceTemplate is created and added to the warehouse.
    /// </summary>
    /// <param name="className">Class name.</param>
    /// <returns>Resource template.</returns>
    public static TypeTemplate GetTemplateByClassName(string className, TemplateType templateType = TemplateType.Unspecified)
    {
        if (templateType == TemplateType.Unspecified)
        {
            // look in resources
            var template = templates[TemplateType.Resource].Values.FirstOrDefault(x => x.ClassName == className);
            if (template != null)
                return template;

            // look in records
            template = templates[TemplateType.Record].Values.FirstOrDefault(x => x.ClassName == className);
            if (template != null)
                return template;

            // look in wrappers
            template = templates[TemplateType.Wrapper].Values.FirstOrDefault(x => x.ClassName == className);
            return template;
        }
        else
        {
            return templates[templateType].Values.FirstOrDefault(x => x.ClassName == className);
        }
    }

    public static bool Remove(IResource resource)
    {

        if (resource.Instance == null)
            return false;

        //lock (resourcesLock)
        //{

        WeakReference<IResource> resourceReference;

        if (resources.ContainsKey(resource.Instance.Id))
            resources.TryRemove(resource.Instance.Id, out resourceReference);
        else
            return false;
        //}

        if (resource != resource.Instance.Store)
        {
            List<WeakReference<IResource>> list;
            if (stores.TryGetValue(resource.Instance.Store, out list))
            {

                lock (((ICollection)list).SyncRoot)
                    list.Remove(resourceReference);

                //list.TryTake(resourceReference);
            }//.Remove(resourceReference);
        }
        if (resource is IStore)
        {
            var store = resource as IStore;

            List<WeakReference<IResource>> toBeRemoved;// = stores[store];

            stores.TryRemove(store, out toBeRemoved);

            //lock (resourcesLock)
            //{
            //    // remove all objects associated with the store
            //    toBeRemoved = resources.Values.Where(x =>
            //   {
            //       IResource r;
            //       if (x.TryGetTarget(out r))
            //           return r.Instance.Store == resource;
            //       else
            //           return false;
            //   }).ToArray();
            //}


            foreach (var o in toBeRemoved)
            {
                IResource r;
                if (o.TryGetTarget(out r))
                    Remove(r);
            }

            StoreDisconnected?.Invoke(resource as IStore);
        }

        if (resource.Instance.Store != null)
            resource.Instance.Store.Remove(resource);

        resource.Destroy();

        return true;
    }
}
