using ICSharpCode.SharpZipLib.Zip;
using RageCoop.Core;
using RageCoop.Core.Scripting;
using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Reflection;

namespace RageCoop.Client.Scripting
{
    /// <summary>
    /// 
    /// </summary>
    public class ClientResource
    {
        /// <summary>
        /// Name of the resource
        /// </summary>
        public string Name { get; internal set; }
        /// <summary>
        /// A resource-specific folder that can be used to store your files.
        /// </summary>
        public string DataFolder { get; internal set; }
        /// <summary>
        /// Get all <see cref="ClientScript"/> instance in this resource.
        /// </summary>
        public List<ClientScript> Scripts { get; internal set; } = new List<ClientScript>();
        /// <summary>
        /// Get the <see cref="ResourceFile"/> where this script is loaded from.
        /// </summary>
        public Dictionary<string, ResourceFile> Files { get; internal set; } = new Dictionary<string, ResourceFile>();

        /// <summary>
        /// A <see cref="Core.Logger"/> instance that can be used to debug your resource.
        /// </summary>
        public Logger Logger { get; internal set; }
    }
    internal class Resources
    {
        public Resources()
        {
            BaseScriptType = "RageCoop.Client.Scripting.ClientScript";
            Logger = Main.Logger;
        }
        private void StartAll()
        {
            lock (LoadedResources)
            {
                foreach (var d in LoadedResources)
                {
                    foreach (var s in d.Scripts)
                    {
                        try
                        {
                            s.CurrentResource=d;
                            s.OnStart();
                        }
                        catch (Exception ex)
                        {
                            Logger.Error("Error occurred when starting script:"+s.GetType().FullName);
                            Logger?.Error(ex);
                        }
                    }
                }
            }
        }
        private void StopAll()
        {
            lock (LoadedResources)
            {
                foreach (var d in LoadedResources)
                {
                    foreach (var s in d.Scripts)
                    {
                        try
                        {
                            s.OnStop();
                        }
                        catch (Exception ex)
                        {
                            Logger.Error("Error occurred when stopping script:"+s.GetType().FullName);
                            Logger?.Error(ex);
                        }
                    }
                }
            }
        }
        public void Load(string path, string[] zips)
        {
            LoadedResources.Clear();
            foreach (var zip in zips)
            {
                var zipPath = Path.Combine(path, zip);
                Logger?.Info($"Loading resource: {Path.GetFileNameWithoutExtension(zip)}");
                LoadResource(new ZipFile(zipPath), Path.Combine(path, "data"));
            }
            StartAll();
        }
        public void Unload()
        {
            StopAll();
            if (LoadedResources.Count > 0)
            {
                API.QueueAction(() => Util.Reload());
            }
            LoadedResources.Clear();
        }
        private List<string> ToIgnore = new List<string>
        {
            "RageCoop.Client.dll",
            "RageCoop.Core.dll",
            "RageCoop.Server.dll",
            "ScriptHookVDotNet3.dll"
        };
        private List<ClientResource> LoadedResources = new List<ClientResource>();
        private string BaseScriptType;
        public Logger Logger { get; set; }

        private void LoadResource(ZipFile file, string dataFolderRoot)
        {
            List<Action> toLoad = new List<Action>(10);
            var r = new ClientResource()
            {
                Logger = Main.Logger,
                Scripts = new List<ClientScript>(),
                Name=Path.GetFileNameWithoutExtension(file.Name),
                DataFolder=Path.Combine(dataFolderRoot, Path.GetFileNameWithoutExtension(file.Name))
            };
            Directory.CreateDirectory(r.DataFolder);

            foreach (ZipEntry entry in file)
            {
                ResourceFile rFile;
                r.Files.Add(entry.Name, rFile=new ResourceFile()
                {
                    Name=entry.Name,
                    IsDirectory=entry.IsDirectory,
                });
                if (!entry.IsDirectory)
                {
                    rFile.GetStream=() => { return file.GetInputStream(entry); };
                    if (entry.Name.EndsWith(".dll") && !entry.Name.Contains("/"))
                    {
                        // Don't load API assembly
                        if (Path.GetFileName(entry.Name).CanBeIgnored()) { continue; }
                        var tmp = Path.GetTempFileName();
                        var f = File.OpenWrite(tmp);
                        rFile.GetStream().CopyTo(f);
                        f.Close();
                        if (!IsManagedAssembly(tmp))
                        {
                            continue;
                        }
                        var asm=Assembly.LoadFrom(tmp);
                        toLoad.Add(() => LoadScriptsFromAssembly(rFile,asm, entry.Name,r));
                    }
                }
            }
            foreach(var a in toLoad)
            {
                a();
            }
            LoadedResources.Add(r);
            file.Close();
        }
        private bool LoadScriptsFromAssembly(ResourceFile rfile, Assembly assembly, string filename, ClientResource toload)
        {
            int count = 0;

            try
            {
                // Find all script types in the assembly
                foreach (var type in assembly.GetTypes().Where(x => IsSubclassOf(x, BaseScriptType)))
                {
                    ConstructorInfo constructor = type.GetConstructor(System.Type.EmptyTypes);
                    if (constructor != null && constructor.IsPublic)
                    {
                        try
                        {
                            // Invoke script constructor
                            var script = constructor.Invoke(null) as ClientScript;
                            // script.CurrentResource = toload;
                            script.CurrentFile=rfile;
                            script.CurrentResource=toload;
                            toload.Scripts.Add(script);
                            count++;
                        }
                        catch (Exception ex)
                        {
                            Logger?.Error($"Error occurred when loading script: {type.FullName}.");
                            Logger?.Error(ex);
                        }
                    }
                    else
                    {
                        Logger?.Error($"Script {type.FullName} has an invalid contructor.");
                    }
                }
            }
            catch (ReflectionTypeLoadException ex)
            {
                Logger?.Error($"Failed to load assembly {rfile.Name}: ");
                Logger?.Error(ex);
                foreach (var e in ex.LoaderExceptions)
                {
                    Logger?.Error(e);
                }
                return false;
            }

            Logger?.Info($"Loaded {count} script(s) in {rfile.Name}");
            return count != 0;
        }
        private bool IsManagedAssembly(string filename)
        {
            try
            {
                using (Stream file = new FileStream(filename, FileMode.Open, FileAccess.Read))
                {
                    if (file.Length < 64)
                        return false;

                    using (BinaryReader bin = new BinaryReader(file))
                    {
                        // PE header starts at offset 0x3C (60). Its a 4 byte header.
                        file.Position = 0x3C;
                        uint offset = bin.ReadUInt32();
                        if (offset == 0)
                            offset = 0x80;

                        // Ensure there is at least enough room for the following structures:
                        //     24 byte PE Signature & Header
                        //     28 byte Standard Fields         (24 bytes for PE32+)
                        //     68 byte NT Fields               (88 bytes for PE32+)
                        // >= 128 byte Data Dictionary Table
                        if (offset > file.Length - 256)
                            return false;

                        // Check the PE signature. Should equal 'PE\0\0'.
                        file.Position = offset;
                        if (bin.ReadUInt32() != 0x00004550)
                            return false;

                        // Read PE magic number from Standard Fields to determine format.
                        file.Position += 20;
                        var peFormat = bin.ReadUInt16();
                        if (peFormat != 0x10b /* PE32 */ && peFormat != 0x20b /* PE32Plus */)
                            return false;

                        // Read the 15th Data Dictionary RVA field which contains the CLI header RVA.
                        // When this is non-zero then the file contains CLI data otherwise not.
                        file.Position = offset + (peFormat == 0x10b ? 232 : 248);
                        return bin.ReadUInt32() != 0;
                    }
                }
            }
            catch
            {
                // This is likely not a valid assembly if any IO exceptions occur during reading
                return false;
            }
        }
        private bool IsSubclassOf(Type type, string baseTypeName)
        {
            for (Type t = type.BaseType; t != null; t = t.BaseType)
                if (t.FullName == baseTypeName)
                    return true;
            return false;
        }
    }

}