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

namespace com.bbbirder.injection
{
    public static class FixHelper
    {
        public static HashSet<string> fixedAssemblies = new();
        /// <summary>
        /// Fix all injections in all assemblies in current domain
        /// </summary>
        public static void InstallAll()
        {
            var allAssemblies = AppDomain.CurrentDomain.GetAssemblies();
            foreach (var assembly in allAssemblies)
            {
                Install(assembly);
            }
            DebugHelper.Log($"fixed {allInjections.Length} injections successfully!");
        }

        /// <summary>
        /// Fix injections who are provided from the specific assembly
        /// </summary>
        /// <remarks>
        ///   <para>
        ///   Be aware that the injections may refer to another assembly
        ///   </para>
        /// </remarks>
        /// <param name="assembly"></param>
        public static void Install(Assembly assembly)
        {
            var assemblyName = assembly.GetName().Name;
            if (fixedAssemblies.Contains(assemblyName)) return;
            foreach (var injection in GetAllInjections(new[] { assembly }))
            {
                FixMethod(injection);
                DryInject(injection);
            }
            fixedAssemblies.Add(assemblyName);
        }

        /// <summary>
        /// check if the assembly of target type is injected
        /// </summary>
        /// <param name="type"></param>
        /// <returns></returns>
        public static bool IsInjected(Type type)
        {
            var mark = type.Assembly.GetType($"{Constants.INJECTED_MARK_NAMESPACE}.{Constants.INJECTED_MARK_NAME}");
            return mark != null;
        }

        public static MethodInfo GetOriginMethodFor(MethodInfo targetMethod)
        {
            var oriName = Constants.GetOriginMethodName(targetMethod.Name, targetMethod.GetSignature());
            return targetMethod.DeclaringType.GetMethod(oriName, bindingFlags);
        }

        public static void DryInject(InjectionInfo injection)
        {
            injection.onStartFix?.Invoke();
            var injectMethod = injection.DryInjectMethod;
            if (injectMethod == null) return;

            var targetType = injection.DryInjectAssmemble;
            var sfldName = injection.DryInjectMethodName;

            // set static field value
            FieldInfo sfld;
            sfld = targetType.GetField(sfldName, bindingFlags ^ BindingFlags.Instance);
            var @delegate = injectMethod.CreateDelegate(sfld.FieldType);
            var combined = Delegate.Combine(sfld.GetValue(null) as Delegate, @delegate);
            sfld.SetValue(null, combined);
        }

        public static void FixMethod(InjectionInfo injection)
        {
            injection.onStartFix?.Invoke();
            var targetMethod = injection.InjectedMethod;
            var fixingMethod = injection.FixingMethod;
            var fixingDelegate = injection.FixingDelegate;

            if ((targetMethod ?? fixingMethod ?? (object)fixingDelegate) == null)
            {
                return;
            }

            var targetType = targetMethod.DeclaringType;
            var methodName = targetMethod.Name;
            // set static field value
            FieldInfo sfld;


            try
            {
                var sfldName = Constants.GetInjectedFieldName(methodName, targetMethod.GetSignature());
                sfld = targetType.GetField(sfldName, bindingFlags ^ BindingFlags.Instance);
            }
            catch (Exception e)
            {
                var msg = $"error on set fixing field {methodName} on {targetType}\n{e.Message}\n{e.StackTrace}";
                DebugHelper.LogError(msg);
                throw;
            }

            try
            {
                if (sfld is null)
                {
                    throw new($"Unable to fix target method {methodName} in type {targetType}, this may caused by injection issues."
                    + " Try to inject manually in [Tools/bbbirder/Unity Injection] if you see this in Editor mode");
                }
                var @delegate = fixingDelegate ?? fixingMethod.CreateDelegate(sfld.FieldType);
                if (@delegate is null)
                {
                    throw new($"Unable to create delegate for replace method {fixingMethod}, whose target is {methodName}");
                }
                var combined = Delegate.Combine(sfld.GetValue(null) as Delegate, @delegate);
                sfld.SetValue(null, combined);
            }
            catch (Exception e)
            {
                var msg = $"error on create and set delegate for injection method {methodName}\n{e.Message}\n{e.StackTrace}";
                DebugHelper.LogError(msg);
                throw;
            }

            // set overwrite origin field
            var originName = Constants.GetOriginMethodName(methodName, targetMethod.GetSignature());
            var originMethod = targetType.GetMethod(originName, bindingFlags);
            try
            {
                var oriDelegate = originMethod.CreateDelegate(sfld.FieldType);
                if (oriDelegate is null)
                {
                    throw new($"create original delegate for {methodName} failed");
                }
                injection.OriginReceiver?.Invoke(oriDelegate);
            }
            catch (Exception e)
            {
                var msg = $"error on create and set delegate for original method {methodName}\n{e.Message}\n{e.StackTrace}";
                DebugHelper.LogError(msg);
                throw;
            }
        }


        /// <summary>
        /// Get all injections in current domain.
        /// </summary>
        /// <param name="assemblies">The assemblies to search in. All loaded assemblies if omitted</param>
        /// <returns></returns>
        public static InjectionInfo[] GetAllInjections(Assembly[] assemblies = null)
        {
            assemblies ??= AppDomain.CurrentDomain.GetAssemblies();
            var injections = assemblies
                // .Where(a=>a.MayContainsInjection()) 
                .SelectMany(a => Retriever.GetAllAttributes<InjectionAttribute>(a))
                .SelectMany(attr => attr.ProvideInjections())
                ;
            var injections2 = assemblies
                .SelectMany(a => Retriever.GetAllSubtypes<IInjection>(a))
                .Where(type => !type.IsInterface && !type.IsAbstract)
                .Select(type => System.Activator.CreateInstance(type) as IInjection)
                .SelectMany(ii => ii.ProvideInjections())
                ;
            return injections.Concat(injections2).ToArray();
        }

        public static string[] GetAllInjectionSources()
        {
            var attributeSources = Retriever.GetAllAttributes<InjectionAttribute>()
                .Select(attr => attr.targetInfo.Module.Assembly);
            var subtypeSources = Retriever.GetAllSubtypes<IInjection>()
                .Select(t => t.Assembly);
            return attributeSources.Concat(subtypeSources)
                .Distinct()
                .Select(ass => ass.GetAssemblyPath())
                .Distinct()
                .ToArray();
        }

        public static string GetAssemblyPath(this Assembly assembly)
        {
            if (assembly == null)
            {
                return null;
            }
            if (assembly.IsDynamic)
            {
                return null;
            }
            if (assembly.CodeBase == null)
            {
                return null;
            }
            string text = "file:///";
            string codeBase = assembly.CodeBase;
            if (codeBase.StartsWith(text, StringComparison.InvariantCultureIgnoreCase))
            {
                codeBase = codeBase.Substring(text.Length);
                codeBase = codeBase.Replace('\\', '/');
                if (File.Exists(codeBase))
                {
                    return codeBase;
                }
                if (!Path.IsPathRooted(codeBase))
                {
                    codeBase = (!File.Exists("/" + codeBase)) ? Path.GetFullPath(codeBase) : ("/" + codeBase);
                }
                if (File.Exists(codeBase))
                {
                    return codeBase;
                }
                try
                {
                    codeBase = assembly.Location;
                }
                catch
                {
                    return null;
                }
                if (File.Exists(codeBase))
                {
                    return codeBase;
                }
            }
            if (File.Exists(assembly.Location))
            {
                return assembly.Location;
            }
            return null;
        }

        public static string GetSignature(this MethodBase method)
        {
            var builder = new StringBuilder();
            builder.Append(method.Name);
            if (method.IsGenericMethod)
            {
                builder.Append('`');
                builder.Append(method.GetGenericArguments().Length);
            }
            builder.Append('(');

            var parameters = method.GetParameters();
            for (int i = 0; i < parameters.Length; i++)
            {
                var parameterDefinition = parameters[i];
                if (i > 0)
                {
                    builder.Append(",");
                }

                AppendTypeFullName(builder, parameterDefinition.ParameterType);
            }

            builder.Append(')');
            return builder.ToString();

            static void AppendTypeFullName(StringBuilder builder, Type type)
            {
                if (!string.IsNullOrEmpty(type.Namespace))
                {
                    builder.Append(type.Namespace);
                    builder.Append("::");
                }

                var stack = new Stack<Type>();
                var declaringType = type;
                while (null != declaringType)
                {
                    stack.Push(declaringType);
                    declaringType = declaringType.DeclaringType;
                }
                while (stack.TryPop(out var name)) AppendNestedType(builder, name);
            }
            static void AppendNestedType(StringBuilder builder, Type type)
            {
                builder.Append(type.Name);
                if (type.IsGenericType)
                {
                    builder.Append('<');
                    var args = type.GenericTypeArguments;
                    for (int i = 0; i < args.Length; i++)
                    {
                        if (i != 0)
                        {
                            builder.Append(',');
                        }
                        AppendTypeFullName(builder, args[i]);
                    }
                    builder.Append('>');
                }
            }
        }

        static InjectionInfo[] m_allInjections;
        public static InjectionInfo[] allInjections => m_allInjections ??= GetAllInjections();

        static BindingFlags bindingFlags = 0
            | BindingFlags.Static
            | BindingFlags.Instance
            | BindingFlags.Public
            | BindingFlags.NonPublic
            ;
    }
}